[1/4] Split up s390-linux-tdep.c into two files

Message ID 20171123153733.31261-2-prudo@linux.vnet.ibm.com
State New, archived
Headers

Commit Message

Philipp Rudo Nov. 23, 2017, 3:37 p.m. UTC
  Currently all target dependent code for s390 is in one file
(s390-linux-tdep.c).  This includes code general for the architecture as
well as code specific for uses in GNU/Linux (user space).  Up until now
this was ok as GNU/Linux was the only supported OS.  In preparation to
support the new Linux kernel 'OS' split up the existing s390 code into a
general s390-tdep and a GNU/Linux specific s390-linux-tdep.

gdb/ChangeLog:

	* s390-tdep.h: New file.
	* s390-tdep.c: New file.
	* s390-linux-nat.c (s390-tdep.h): new include.
	* Makefile.in (ALL_TARGET_OBS): Add s390-tdep.o.
	(HFILES_NO_SRCDIR): Add s390-tdep.h.
	(ALLDEPFILES): Add s390-tdep.c.
	* configure.tgt (s390*-*-linux*): Add s390-tdep.o.
	* s390-linux-tdep.h (HWCAP_S390_*, S390_*_REGNUM)
	(S390_IS_GREGSET_REGNUM, S390_IS_FPREGSET_REGNUM)
	(S390_IS_TDBREGSET_REGNUM, s390_sizeof_gregset)
	(s390x_sizeof_gregset, s390_sizeof_fpregset): Move to s390-tdep.h
	(s390_gregset, s390_fpregset, s390_vxrs_low_regset)
	(s390_vxrs_high_regset): Move declaratin to s390-tdep.h
	* s390-linux-tdep.c (s390-tdep.h): New include.
	(s390_gdbarch_init): Rename to...
	(s390_linux_gdbarch_init): ...this and adjust.
	(_initialize_s390_tdep): Rename to...
	(_initialize_s390_linux_tdep): ...this and adjust.
	(s390_abi_kind, s390_vector_abi_kind, gdbarch_tdep)
	(enum named opcodes, s390_prologue_data): Move to s390-tdep.h
	(s390_readinstruction, is_ri, is_ril, is_rr, is_rre, is_rs, is_rsy)
	(is_rx, is_rxy, s390_break_insn, s390_breakpoint)
	(s390_is_partial_instruction, s390_software_single_step)
	(is_non_branch_ril, s390_displaced_step_copy_insn)
	(s390_displaced_step_fixup, s390_displaced_step_hw_singlestep)
	(s390_addr, s390_store, s390_load, s390_check_for_saved)
	(s390_analyze_prologue, s390_skip_prologue)
	(s390_register_call_saved, s390_register_name)
	(s390_cannot_store_register, s390_write_pc, s390_dwarf_regmap)
	(s390_dwarf_reg_to_regnum, regnum_is_gpr_full, regnum_is_vxr_full)
	(s390_value_from_register, s390_pseudo_register_name)
	(s390_pseudo_register_type, s390_pseudo_register_read)
	(s390_pseudo_register_write, s390_pseudo_register_reggroup_p)
	(s390_ax_pseudo_register_collect)
	(s390_ax_pseudo_register_push_stack, s390_gen_return_address)
	(s390_gregmap, s390_fpregmap, s390_regmap_vxrs_low)
	(s390_regmap_vxrs_high, 390_gregset, s390_fpregset)
	(s390_vxrs_low_regset, s390_vxrs_high_regset)
	(s390_addr_bits_remove, s390_address_class_type_flags)
	(s390_address_class_type_flags_to_name)
	(s390_address_class_name_to_type_flags, s390_effective_inner_type)
	(s390_function_arg_float, s390_function_arg_vector)
	(is_power_of_two, s390_function_arg_integer, s390_arg_state)
	(s390_handle_arg, s390_push_dummy_call, s390_dummy_id)
	(s390_frame_align, s390_register_return_value, s390_return_value)
	(s390_stack_frame_destroyed_p, s390_unwind_pc, s390_unwind_sp)
	(s390_unwind_pseudo_register, s390_adjust_frame_regnum)
	(s390_dwarf2_prev_register)
	(s390_dwarf2_frame_init_reg): Move to s390-tdep.c
---
 gdb/Makefile.in       |    3 +
 gdb/configure.tgt     |    4 +-
 gdb/s390-linux-nat.c  |    1 +
 gdb/s390-linux-tdep.c | 2707 +------------------------------------------------
 gdb/s390-linux-tdep.h |  194 +---
 gdb/s390-tdep.c       | 2607 +++++++++++++++++++++++++++++++++++++++++++++++
 gdb/s390-tdep.h       |  386 +++++++
 7 files changed, 3023 insertions(+), 2879 deletions(-)
 create mode 100644 gdb/s390-tdep.c
 create mode 100644 gdb/s390-tdep.h
  

Comments

Philipp Rudo Nov. 24, 2017, 4:55 p.m. UTC | #1
Hi Uli,

thanks for the review.

I already feared you will find something. The short answer to most of your
comments is that the split isn't a 100% clean. The new s390-tdep isn't pure
architecture code but mixed with common Linux ELF abi code. If you wanted
it clean we had to split up s390-tdep even further. But I don't know is if
it is worth the work.

More details are below.


On Thu, 23 Nov 2017 21:26:03 +0100 (CET)
"Ulrich Weigand" <uweigand@de.ibm.com> wrote:

> Philipp Rudo wrote:
> 
> > Currently all target dependent code for s390 is in one file
> > (s390-linux-tdep.c).  This includes code general for the architecture as
> > well as code specific for uses in GNU/Linux (user space).  Up until now
> > this was ok as GNU/Linux was the only supported OS.  In preparation to
> > support the new Linux kernel 'OS' split up the existing s390 code into a
> > general s390-tdep and a GNU/Linux specific s390-linux-tdep.  
> 
> Thanks for working on this!
> 
> A couple of comments on the particular split:
> 
> 
> > -static void
> > -s390_write_pc (struct regcache *regcache, CORE_ADDR pc)
> > -{
> > -  struct gdbarch *gdbarch = regcache->arch ();
> > -  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
> > -
> > -  regcache_cooked_write_unsigned (regcache, tdep->pc_regnum, pc);
> > -
> > -  /* Set special SYSTEM_CALL register to 0 to prevent the kernel from
> > -     messing with the PC we just installed, if we happen to be within
> > -     an interrupted system call that the kernel wants to restart.
> > -
> > -     Note that after we return from the dummy call, the SYSTEM_CALL and
> > -     ORIG_R2 registers will be automatically restored, and the kernel
> > -     continues to restart the system call at this point.  */
> > -  if (register_size (gdbarch, S390_SYSTEM_CALL_REGNUM) > 0)
> > -    regcache_cooked_write_unsigned (regcache, S390_SYSTEM_CALL_REGNUM, 0);
> > -}  
> 
> This seems a typical Linux issue.  Other OSes won't have the ORIG_R2
> and SYSTEM_CALL registers and may not need this particular handling.

You are right for the kernel we will have to treat it different. I moved it
back to s390-linux-tdep.
 
> > -/* Maps for register sets.  */
> > -
> > -static const struct regcache_map_entry s390_gregmap[] =
> > -  {
> > -    { 1, S390_PSWM_REGNUM },
> > -    { 1, S390_PSWA_REGNUM },
> > -    { 16, S390_R0_REGNUM },
> > -    { 16, S390_A0_REGNUM },
> > -    { 1, S390_ORIG_R2_REGNUM },
> > -    { 0 }
> > -  };
> > -
> > -static const struct regcache_map_entry s390_fpregmap[] =
> > -  {
> > -    { 1, S390_FPC_REGNUM, 8 },
> > -    { 16, S390_F0_REGNUM, 8 },
> > -    { 0 }
> > -  };
> > -
> >  static const struct regcache_map_entry s390_regmap_upper[] =
> >    {
> >      { 16, S390_R0_UPPER_REGNUM, 4 },  
> 
> Not sure I understand your split here.  "ORIG_R2" is not a real register
> and only exists on Linux, so it shouldn't move to s390-tdep.c.  On the
> other hand, the split between upper halves and lower halves seems more
> generic and could happen elsewhere ...

This is a little more complicated.

For the upper/lower split you are right, it is architecture. However i see
it as legacy code and I don't plan to add any support for 31-bit systems on
64-bit machines. So i decided to leave the definition where it is used.

For orig_r2 you are right (again), it only exist in user space. However
(again) the kernel uses the same prstatus definitions like the user space,
including a field for orig_r2 (although it is not used). Thats why i moved it
to the common 'Linux ELF abi' s390-tdep.

 
> > +/* Set up GNU/Linux gdbarch.  Allocates struct gdbarch if needed.  */
> >  
> >  static struct gdbarch *
> > -s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
> > +s390_linux_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
> >  {  
> 
> This is wrong.  The way the split setup between generic part and Linux
> part is supposed to be working is this:
> 
> - The generic part (and only it) has a _initialize routine that calls
>    register_gdbarch_init (bfd_arch_s390, s390_gdbarch_init);
> 
> - In the s390_gdbarch_init routine, the generic setup is done, and at
>   the point where the platform-specific setup should begin, we call
>    gdbarch_init_osabi (info, gdbarch);
> 
> - The OS-specific part also has a _initialize routine, which calls
>   gdbarch_register_osabi (bfd_arch_s390, bfd_mach_s390_31, GDB_OSABI_LINUX,
>                           s390_linux_init_abi);
>   gdbarch_register_osabi (bfd_arch_s390, bfd_mach_s390_64, GDB_OSABI_LINUX,
>                           s390_linux_init_abi);
>   (may be the same or two different handlers for 31- vs 64-bit, whatever
>   is more practical)
> 
> - The common gdbarch_init_osabi detects which OS handler to use and calls it.
> 
> This method is same across all Linux (and really all) targets; there is
> no point for us to try to do it differently, that would just cause confusion.

I played around with osabi and never got it to work the way I wanted it to.
My problem was that ELF doesn't distinguish the kernel and user space. So the
default ELF sniffer always used the GDB_OSABI_LINUX and never gave my
GDB_OSABI_LINUX_KERNEL a chance. I cannot recall all details and will give it
a second chance. Please give me some time.

 
> > -      /* Optional GNU/Linux-specific "registers".  */
> > -      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.linux");
> > -      if (feature)
> > -	{
> > -	  tdesc_numbered_register (feature, tdesc_data,
> > -				   S390_ORIG_R2_REGNUM, "orig_r2");
> > -
> > -	  if (tdesc_numbered_register (feature, tdesc_data,
> > -				       S390_LAST_BREAK_REGNUM, "last_break"))
> > -	    have_linux_v1 = 1;
> > -
> > -	  if (tdesc_numbered_register (feature, tdesc_data,
> > -				       S390_SYSTEM_CALL_REGNUM, "system_call"))
> > -	    have_linux_v2 = 1;
> > -
> > -	  if (have_linux_v2 > have_linux_v1)
> > -	    valid_p = 0;
> > -	}  
> 
> The Linux specific feature should be handled here, the others in the 
> generic part.

My plan was to take care of this when we change to dynamically creating
the tdesc. Then we could number the registers directly when creating the tdesc
(at least I hope so). To be honest I haven't done it yet as with all those
have_* variables there are some nasty dependencies in the function...


> > -/* GNU/Linux-specific optional registers.  */
> > -#define S390_ORIG_R2_REGNUM 67
> > -#define S390_LAST_BREAK_REGNUM 68
> > -#define S390_SYSTEM_CALL_REGNUM 69  
> 
> Ideally, these should also remain here as Linux specific registers.
> This can be done e.g. like ppc-linux-tdep.h does it.

The ppc way is actually pretty nice. I will use it.

Thanks
Philipp
  
Philipp Rudo Nov. 28, 2017, 9:34 a.m. UTC | #2
Hi Uli,

On Fri, 24 Nov 2017 20:25:11 +0100 (CET)
"Ulrich Weigand" <uweigand@de.ibm.com> wrote:

> Hi Phillip,
> 
> > I already feared you will find something. The short answer to most of your
> > comments is that the split isn't a 100% clean. The new s390-tdep isn't pure
> > architecture code but mixed with common Linux ELF abi code. If you wanted
> > it clean we had to split up s390-tdep even further. But I don't know is if
> > it is worth the work.  
> 
> So in general, for all platforms where there is split between ARCH-tdep.c
> and ARCH-linux-tdep.c, the former contains code that is applicable to all
> targets on that architecture, while the latter contains code that is used
> only on Linux targets.  We should really do the same on s390.
> 
> Now, it is true that in many cases the split isn't 100% clean.  For example,
> on many platforms most OSes use mostly the same calling convention, but with
> maybe some minor changes.  Then, it makes sense to have to bulk of the
> calling convention stuff in ARCH-tdep.c, but have it check some ABI variant
> flag in tdep to modify its behavior.  So your moving all those parts to
> s390-tdep.c is perfectly fine with me.
> 
> However, s390-tdep.c should *not* contain anything that would *break*
> running GDB on some non-Linux OS (I'm e.g. thinking of BSD or OpenSolaris
> here, both of which were actually ported to s390 by some people).  That's
> why e.g. moving the orig_r2 stuff to s390-tdep.c is not a good idea.
> 
> Now, your use case is special.  We currently do not support recognizing
> the Linux kernel as a separate target, different from Linux user-space
> programs, on *any* architecture.  It is well possible that we'll have to
> add something here.  But that is not a s390-specific problem; we'll want
> to have that capability on *all* Linux architectures in the end.  So
> creating some non-standard s390-tdep.c / s390-linux-tdep.c split just
> for that reason isn't useful since it wouldn't help other platforms.
> 
> Whether the Linux kernel target should use (or not use) the ARCH-linux-tdep.c
> file is an interesting question, but it should be answered the same way on
> all architectures.

Yeah i know. I just hoped i could take the quick and dirty way out...

I think it is best when we defer the question whether the kernel target should
use s390-linux-tdep till after the split is final. Then we have a stable base
we can use.

Is there anything in s390-tdep.c left you think that should be moved?
Otherwise ...
 
> > > Not sure I understand your split here.  "ORIG_R2" is not a real register
> > > and only exists on Linux, so it shouldn't move to s390-tdep.c.  On the
> > > other hand, the split between upper halves and lower halves seems more
> > > generic and could happen elsewhere ...  
> > 
> > This is a little more complicated.
> > 
> > For the upper/lower split you are right, it is architecture. However i see
> > it as legacy code and I don't plan to add any support for 31-bit systems on
> > 64-bit machines. So i decided to leave the definition where it is used.
> > 
> > For orig_r2 you are right (again), it only exist in user space. However
> > (again) the kernel uses the same prstatus definitions like the user space,
> > including a field for orig_r2 (although it is not used). Thats why i moved it
> > to the common 'Linux ELF abi' s390-tdep.  
> 
> Thinking about this again, all the regsets should probably remain
> in s390-linux-tdep.c.  This stuff is usually different between OSes anyway.
> 
> For the kernel structure, you can provide your own regset that simply
> ignores the orig_r2 field in the structure.

... i'll move the regsets and s390_register_call_saved to s390-linux-tdep. The
way the latter currently is implemented doesn't support any other OS than Linux.

For the kernel target I would provide appropriate replacements.
 
> > > This method is same across all Linux (and really all) targets; there is
> > > no point for us to try to do it differently, that would just cause confusion.  
> > 
> > I played around with osabi and never got it to work the way I wanted it to.
> > My problem was that ELF doesn't distinguish the kernel and user space. So the
> > default ELF sniffer always used the GDB_OSABI_LINUX and never gave my
> > GDB_OSABI_LINUX_KERNEL a chance. I cannot recall all details and will give it
> > a second chance. Please give me some time.  
> 
> As said above, this is really a different problem.  The first issue is that
> on s390, we should use the same split between ARCH-tdep.c and ARCH-linux-tdep.c
> as everybody else, and that means using an OSABI sniffer.
> 
> The second issue is that we somehow need to distinguish between Linux kernel
> debugging and Linux user-space debugging.  I'm not sure what the best way to
> do this is; we could have a separate GDB_OSABI_LINUX_KERNEL as you mention
> and would then have to adapt the (common code) sniffer routines.
> 
> Or maybe both kernel and user space should use GDB_OSABI_LINUX and then
> the Linux ABI routine just handles them differently?  Hard to say for me
> at the moment (probably because I haven't seen the actual kernel code yet).

Totally fair. I played a little bit around with OSABI for s390 yesterday. In
principle i got it to work. However I had to refractor s390_gdbarch_init quite
a bit and introduced a bug somewhere. Let me have a closer look at it and come
back to you when I have a proper patch set.

My plan is to add the usage of OSABI on top of the split as is (with the small
changes described above). This makes it easier to find bugs i might introduce
which would otherwise be cloaked by the split. Any rejections?

For the kernel target I think it is best when we defer the discussion till we
have the s390 code work with OSABI. Then we have a way to test.

In principle i think that introducing a GDB_OSABI_LINUX_KERNEL and adept the
sniffer will be much cleaner. However the second way will be much easier to
implement.
 
> > > The Linux specific feature should be handled here, the others in the 
> > > generic part.  
> > 
> > My plan was to take care of this when we change to dynamically creating
> > the tdesc. Then we could number the registers directly when creating the tdesc
> > (at least I hope so). To be honest I haven't done it yet as with all those
> > have_* variables there are some nasty dependencies in the function...  
> 
> It shouldn't be really difficult to split those up.  Again, e.g. ppc does
> the same thing already today.  All the have_ flags can stay in the common
> tdep struct, which makes this easier.

My problem aren't the tdep->have_* fields but the corresponding variables
defined in s390_gdbarch_init. With them all there are dependencies all over the
function.

For the hack i did yesterday i looked at i386. Meaning i allocated the
gdbarch_tdep right at the beginning of the function and used its fields instead
of the variables. The way I see it ppc/rs6k works more the less the same.

Thanks
Philipp
  

Patch

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 0a1a769541..e6308e93fe 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -888,6 +888,7 @@  ALL_TARGET_OBS = \
 	rs6000-tdep.o \
 	rx-tdep.o \
 	s390-linux-tdep.o \
+	s390-tdep.o \
 	score-tdep.o \
 	sh-linux-tdep.o \
 	sh-nbsd-tdep.o \
@@ -1453,6 +1454,7 @@  HFILES_NO_SRCDIR = \
 	rs6000-aix-tdep.h \
 	rs6000-tdep.h \
 	s390-linux-tdep.h \
+	s390-tdep.h \
 	score-tdep.h \
 	selftest-arch.h \
 	sentinel-frame.h \
@@ -2664,6 +2666,7 @@  ALLDEPFILES = \
 	rx-tdep.c \
 	s390-linux-nat.c \
 	s390-linux-tdep.c \
+	s390-tdep.c \
 	score-tdep.c \
 	ser-go32.c \
 	ser-mingw.c \
diff --git a/gdb/configure.tgt b/gdb/configure.tgt
index 1fce0798e2..2c558f15a5 100644
--- a/gdb/configure.tgt
+++ b/gdb/configure.tgt
@@ -513,8 +513,8 @@  powerpc*-*-*)
 
 s390*-*-linux*)
 	# Target: S390 running Linux
-	gdb_target_obs="s390-linux-tdep.o solib-svr4.o linux-tdep.o \
-			linux-record.o"
+	gdb_target_obs="s390-tdep.o s390-linux-tdep.o solib-svr4.o \
+			linux-tdep.o linux-record.o"
 	build_gdbserver=yes
 	;;
 
diff --git a/gdb/s390-linux-nat.c b/gdb/s390-linux-nat.c
index 03b14a9ecc..decb68fcfb 100644
--- a/gdb/s390-linux-nat.c
+++ b/gdb/s390-linux-nat.c
@@ -30,6 +30,7 @@ 
 #include "nat/linux-ptrace.h"
 #include "gdbcmd.h"
 
+#include "s390-tdep.h"
 #include "s390-linux-tdep.h"
 #include "elf/common.h"
 
diff --git a/gdb/s390-linux-tdep.c b/gdb/s390-linux-tdep.c
index a0d4cdd740..9efc68554c 100644
--- a/gdb/s390-linux-tdep.c
+++ b/gdb/s390-linux-tdep.c
@@ -1,4 +1,4 @@ 
-/* Target-dependent code for GDB, the GNU debugger.
+/* Target-dependent code for GNU/Linux on s390.
 
    Copyright (C) 2001-2017 Free Software Foundation, Inc.
 
@@ -42,6 +42,7 @@ 
 #include "solib-svr4.h"
 #include "prologue-value.h"
 #include "linux-tdep.h"
+#include "s390-tdep.h"
 #include "s390-linux-tdep.h"
 #include "linux-record.h"
 #include "record-full.h"
@@ -80,98 +81,6 @@ 
 #define XML_SYSCALL_FILENAME_S390 "syscalls/s390-linux.xml"
 #define XML_SYSCALL_FILENAME_S390X "syscalls/s390x-linux.xml"
 
-/* Holds the current set of options to be passed to the disassembler.  */
-static char *s390_disassembler_options;
-
-enum s390_abi_kind
-{
-  ABI_LINUX_S390,
-  ABI_LINUX_ZSERIES
-};
-
-enum s390_vector_abi_kind
-{
-  S390_VECTOR_ABI_NONE,
-  S390_VECTOR_ABI_128
-};
-
-/* The tdep structure.  */
-
-struct gdbarch_tdep
-{
-  /* ABI version.  */
-  enum s390_abi_kind abi;
-
-  /* Vector ABI.  */
-  enum s390_vector_abi_kind vector_abi;
-
-  /* Pseudo register numbers.  */
-  int gpr_full_regnum;
-  int pc_regnum;
-  int cc_regnum;
-  int v0_full_regnum;
-
-  int have_linux_v1;
-  int have_linux_v2;
-  int have_tdb;
-  bool have_gs;
-};
-
-
-/* ABI call-saved register information.  */
-
-static int
-s390_register_call_saved (struct gdbarch *gdbarch, int regnum)
-{
-  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
-
-  switch (tdep->abi)
-    {
-    case ABI_LINUX_S390:
-      if ((regnum >= S390_R6_REGNUM && regnum <= S390_R15_REGNUM)
-	  || regnum == S390_F4_REGNUM || regnum == S390_F6_REGNUM
-	  || regnum == S390_A0_REGNUM)
-	return 1;
-
-      break;
-
-    case ABI_LINUX_ZSERIES:
-      if ((regnum >= S390_R6_REGNUM && regnum <= S390_R15_REGNUM)
-	  || (regnum >= S390_F8_REGNUM && regnum <= S390_F15_REGNUM)
-	  || (regnum >= S390_A0_REGNUM && regnum <= S390_A1_REGNUM))
-	return 1;
-
-      break;
-    }
-
-  return 0;
-}
-
-static int
-s390_cannot_store_register (struct gdbarch *gdbarch, int regnum)
-{
-  /* The last-break address is read-only.  */
-  return regnum == S390_LAST_BREAK_REGNUM;
-}
-
-static void
-s390_write_pc (struct regcache *regcache, CORE_ADDR pc)
-{
-  struct gdbarch *gdbarch = regcache->arch ();
-  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
-
-  regcache_cooked_write_unsigned (regcache, tdep->pc_regnum, pc);
-
-  /* Set special SYSTEM_CALL register to 0 to prevent the kernel from
-     messing with the PC we just installed, if we happen to be within
-     an interrupted system call that the kernel wants to restart.
-
-     Note that after we return from the dummy call, the SYSTEM_CALL and
-     ORIG_R2 registers will be automatically restored, and the kernel
-     continues to restart the system call at this point.  */
-  if (register_size (gdbarch, S390_SYSTEM_CALL_REGNUM) > 0)
-    regcache_cooked_write_unsigned (regcache, S390_SYSTEM_CALL_REGNUM, 0);
-}
 
 /* The "guess_tracepoint_registers" gdbarch method.  */
 
@@ -207,587 +116,6 @@  s390_guess_tracepoint_registers (struct gdbarch *gdbarch,
   regcache_raw_supply (regcache, S390_PSWM_REGNUM, reg);
 }
 
-
-/* DWARF Register Mapping.  */
-
-static const short s390_dwarf_regmap[] =
-{
-  /* 0-15: General Purpose Registers.  */
-  S390_R0_REGNUM, S390_R1_REGNUM, S390_R2_REGNUM, S390_R3_REGNUM,
-  S390_R4_REGNUM, S390_R5_REGNUM, S390_R6_REGNUM, S390_R7_REGNUM,
-  S390_R8_REGNUM, S390_R9_REGNUM, S390_R10_REGNUM, S390_R11_REGNUM,
-  S390_R12_REGNUM, S390_R13_REGNUM, S390_R14_REGNUM, S390_R15_REGNUM,
-
-  /* 16-31: Floating Point Registers / Vector Registers 0-15. */
-  S390_F0_REGNUM, S390_F2_REGNUM, S390_F4_REGNUM, S390_F6_REGNUM,
-  S390_F1_REGNUM, S390_F3_REGNUM, S390_F5_REGNUM, S390_F7_REGNUM,
-  S390_F8_REGNUM, S390_F10_REGNUM, S390_F12_REGNUM, S390_F14_REGNUM,
-  S390_F9_REGNUM, S390_F11_REGNUM, S390_F13_REGNUM, S390_F15_REGNUM,
-
-  /* 32-47: Control Registers (not mapped).  */
-  -1, -1, -1, -1, -1, -1, -1, -1,
-  -1, -1, -1, -1, -1, -1, -1, -1,
-
-  /* 48-63: Access Registers.  */
-  S390_A0_REGNUM, S390_A1_REGNUM, S390_A2_REGNUM, S390_A3_REGNUM,
-  S390_A4_REGNUM, S390_A5_REGNUM, S390_A6_REGNUM, S390_A7_REGNUM,
-  S390_A8_REGNUM, S390_A9_REGNUM, S390_A10_REGNUM, S390_A11_REGNUM,
-  S390_A12_REGNUM, S390_A13_REGNUM, S390_A14_REGNUM, S390_A15_REGNUM,
-
-  /* 64-65: Program Status Word.  */
-  S390_PSWM_REGNUM,
-  S390_PSWA_REGNUM,
-
-  /* 66-67: Reserved.  */
-  -1, -1,
-
-  /* 68-83: Vector Registers 16-31.  */
-  S390_V16_REGNUM, S390_V18_REGNUM, S390_V20_REGNUM, S390_V22_REGNUM,
-  S390_V17_REGNUM, S390_V19_REGNUM, S390_V21_REGNUM, S390_V23_REGNUM,
-  S390_V24_REGNUM, S390_V26_REGNUM, S390_V28_REGNUM, S390_V30_REGNUM,
-  S390_V25_REGNUM, S390_V27_REGNUM, S390_V29_REGNUM, S390_V31_REGNUM,
-
-  /* End of "official" DWARF registers.  The remainder of the map is
-     for GDB internal use only.  */
-
-  /* GPR Lower Half Access.  */
-  S390_R0_REGNUM, S390_R1_REGNUM, S390_R2_REGNUM, S390_R3_REGNUM,
-  S390_R4_REGNUM, S390_R5_REGNUM, S390_R6_REGNUM, S390_R7_REGNUM,
-  S390_R8_REGNUM, S390_R9_REGNUM, S390_R10_REGNUM, S390_R11_REGNUM,
-  S390_R12_REGNUM, S390_R13_REGNUM, S390_R14_REGNUM, S390_R15_REGNUM,
-};
-
-enum { s390_dwarf_reg_r0l = ARRAY_SIZE (s390_dwarf_regmap) - 16 };
-
-/* Convert DWARF register number REG to the appropriate register
-   number used by GDB.  */
-static int
-s390_dwarf_reg_to_regnum (struct gdbarch *gdbarch, int reg)
-{
-  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
-  int gdb_reg = -1;
-
-  /* In a 32-on-64 debug scenario, debug info refers to the full
-     64-bit GPRs.  Note that call frame information still refers to
-     the 32-bit lower halves, because s390_adjust_frame_regnum uses
-     special register numbers to access GPRs.  */
-  if (tdep->gpr_full_regnum != -1 && reg >= 0 && reg < 16)
-    return tdep->gpr_full_regnum + reg;
-
-  if (reg >= 0 && reg < ARRAY_SIZE (s390_dwarf_regmap))
-    gdb_reg = s390_dwarf_regmap[reg];
-
-  if (tdep->v0_full_regnum == -1)
-    {
-      if (gdb_reg >= S390_V16_REGNUM && gdb_reg <= S390_V31_REGNUM)
-	gdb_reg = -1;
-    }
-  else
-    {
-      if (gdb_reg >= S390_F0_REGNUM && gdb_reg <= S390_F15_REGNUM)
-	gdb_reg = gdb_reg - S390_F0_REGNUM + tdep->v0_full_regnum;
-    }
-
-  return gdb_reg;
-}
-
-/* Translate a .eh_frame register to DWARF register, or adjust a
-   .debug_frame register.  */
-static int
-s390_adjust_frame_regnum (struct gdbarch *gdbarch, int num, int eh_frame_p)
-{
-  /* See s390_dwarf_reg_to_regnum for comments.  */
-  return (num >= 0 && num < 16) ? num + s390_dwarf_reg_r0l : num;
-}
-
-
-/* Pseudo registers.  */
-
-static int
-regnum_is_gpr_full (struct gdbarch_tdep *tdep, int regnum)
-{
-  return (tdep->gpr_full_regnum != -1
-	  && regnum >= tdep->gpr_full_regnum
-	  && regnum <= tdep->gpr_full_regnum + 15);
-}
-
-/* Check whether REGNUM indicates a full vector register (v0-v15).
-   These pseudo-registers are composed of f0-f15 and v0l-v15l.  */
-
-static int
-regnum_is_vxr_full (struct gdbarch_tdep *tdep, int regnum)
-{
-  return (tdep->v0_full_regnum != -1
-	  && regnum >= tdep->v0_full_regnum
-	  && regnum <= tdep->v0_full_regnum + 15);
-}
-
-/* Return the name of register REGNO.  Return the empty string for
-   registers that shouldn't be visible.  */
-
-static const char *
-s390_register_name (struct gdbarch *gdbarch, int regnum)
-{
-  if (regnum >= S390_V0_LOWER_REGNUM
-      && regnum <= S390_V15_LOWER_REGNUM)
-    return "";
-  return tdesc_register_name (gdbarch, regnum);
-}
-
-static const char *
-s390_pseudo_register_name (struct gdbarch *gdbarch, int regnum)
-{
-  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
-
-  if (regnum == tdep->pc_regnum)
-    return "pc";
-
-  if (regnum == tdep->cc_regnum)
-    return "cc";
-
-  if (regnum_is_gpr_full (tdep, regnum))
-    {
-      static const char *full_name[] = {
-	"r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
-	"r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15"
-      };
-      return full_name[regnum - tdep->gpr_full_regnum];
-    }
-
-  if (regnum_is_vxr_full (tdep, regnum))
-    {
-      static const char *full_name[] = {
-	"v0", "v1", "v2", "v3", "v4", "v5", "v6", "v7",
-	"v8", "v9", "v10", "v11", "v12", "v13", "v14", "v15"
-      };
-      return full_name[regnum - tdep->v0_full_regnum];
-    }
-
-  internal_error (__FILE__, __LINE__, _("invalid regnum"));
-}
-
-static struct type *
-s390_pseudo_register_type (struct gdbarch *gdbarch, int regnum)
-{
-  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
-
-  if (regnum == tdep->pc_regnum)
-    return builtin_type (gdbarch)->builtin_func_ptr;
-
-  if (regnum == tdep->cc_regnum)
-    return builtin_type (gdbarch)->builtin_int;
-
-  if (regnum_is_gpr_full (tdep, regnum))
-    return builtin_type (gdbarch)->builtin_uint64;
-
-  if (regnum_is_vxr_full (tdep, regnum))
-    return tdesc_find_type (gdbarch, "vec128");
-
-  internal_error (__FILE__, __LINE__, _("invalid regnum"));
-}
-
-static enum register_status
-s390_pseudo_register_read (struct gdbarch *gdbarch, struct regcache *regcache,
-			   int regnum, gdb_byte *buf)
-{
-  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
-  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
-  int regsize = register_size (gdbarch, regnum);
-  ULONGEST val;
-
-  if (regnum == tdep->pc_regnum)
-    {
-      enum register_status status;
-
-      status = regcache_raw_read_unsigned (regcache, S390_PSWA_REGNUM, &val);
-      if (status == REG_VALID)
-	{
-	  if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)
-	    val &= 0x7fffffff;
-	  store_unsigned_integer (buf, regsize, byte_order, val);
-	}
-      return status;
-    }
-
-  if (regnum == tdep->cc_regnum)
-    {
-      enum register_status status;
-
-      status = regcache_raw_read_unsigned (regcache, S390_PSWM_REGNUM, &val);
-      if (status == REG_VALID)
-	{
-	  if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)
-	    val = (val >> 12) & 3;
-	  else
-	    val = (val >> 44) & 3;
-	  store_unsigned_integer (buf, regsize, byte_order, val);
-	}
-      return status;
-    }
-
-  if (regnum_is_gpr_full (tdep, regnum))
-    {
-      enum register_status status;
-      ULONGEST val_upper;
-
-      regnum -= tdep->gpr_full_regnum;
-
-      status = regcache_raw_read_unsigned (regcache, S390_R0_REGNUM + regnum, &val);
-      if (status == REG_VALID)
-	status = regcache_raw_read_unsigned (regcache, S390_R0_UPPER_REGNUM + regnum,
-					     &val_upper);
-      if (status == REG_VALID)
-	{
-	  val |= val_upper << 32;
-	  store_unsigned_integer (buf, regsize, byte_order, val);
-	}
-      return status;
-    }
-
-  if (regnum_is_vxr_full (tdep, regnum))
-    {
-      enum register_status status;
-
-      regnum -= tdep->v0_full_regnum;
-
-      status = regcache_raw_read (regcache, S390_F0_REGNUM + regnum, buf);
-      if (status == REG_VALID)
-	status = regcache_raw_read (regcache,
-				    S390_V0_LOWER_REGNUM + regnum, buf + 8);
-      return status;
-    }
-
-  internal_error (__FILE__, __LINE__, _("invalid regnum"));
-}
-
-static void
-s390_pseudo_register_write (struct gdbarch *gdbarch, struct regcache *regcache,
-			    int regnum, const gdb_byte *buf)
-{
-  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
-  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
-  int regsize = register_size (gdbarch, regnum);
-  ULONGEST val, psw;
-
-  if (regnum == tdep->pc_regnum)
-    {
-      val = extract_unsigned_integer (buf, regsize, byte_order);
-      if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)
-	{
-	  regcache_raw_read_unsigned (regcache, S390_PSWA_REGNUM, &psw);
-	  val = (psw & 0x80000000) | (val & 0x7fffffff);
-	}
-      regcache_raw_write_unsigned (regcache, S390_PSWA_REGNUM, val);
-      return;
-    }
-
-  if (regnum == tdep->cc_regnum)
-    {
-      val = extract_unsigned_integer (buf, regsize, byte_order);
-      regcache_raw_read_unsigned (regcache, S390_PSWM_REGNUM, &psw);
-      if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)
-	val = (psw & ~((ULONGEST)3 << 12)) | ((val & 3) << 12);
-      else
-	val = (psw & ~((ULONGEST)3 << 44)) | ((val & 3) << 44);
-      regcache_raw_write_unsigned (regcache, S390_PSWM_REGNUM, val);
-      return;
-    }
-
-  if (regnum_is_gpr_full (tdep, regnum))
-    {
-      regnum -= tdep->gpr_full_regnum;
-      val = extract_unsigned_integer (buf, regsize, byte_order);
-      regcache_raw_write_unsigned (regcache, S390_R0_REGNUM + regnum,
-				   val & 0xffffffff);
-      regcache_raw_write_unsigned (regcache, S390_R0_UPPER_REGNUM + regnum,
-				   val >> 32);
-      return;
-    }
-
-  if (regnum_is_vxr_full (tdep, regnum))
-    {
-      regnum -= tdep->v0_full_regnum;
-      regcache_raw_write (regcache, S390_F0_REGNUM + regnum, buf);
-      regcache_raw_write (regcache, S390_V0_LOWER_REGNUM + regnum, buf + 8);
-      return;
-    }
-
-  internal_error (__FILE__, __LINE__, _("invalid regnum"));
-}
-
-/* 'float' values are stored in the upper half of floating-point
-   registers, even though we are otherwise a big-endian platform.  The
-   same applies to a 'float' value within a vector.  */
-
-static struct value *
-s390_value_from_register (struct gdbarch *gdbarch, struct type *type,
-			  int regnum, struct frame_id frame_id)
-{
-  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
-  struct value *value = default_value_from_register (gdbarch, type,
-						     regnum, frame_id);
-  check_typedef (type);
-
-  if ((regnum >= S390_F0_REGNUM && regnum <= S390_F15_REGNUM
-       && TYPE_LENGTH (type) < 8)
-      || regnum_is_vxr_full (tdep, regnum)
-      || (regnum >= S390_V16_REGNUM && regnum <= S390_V31_REGNUM))
-    set_value_offset (value, 0);
-
-  return value;
-}
-
-/* Register groups.  */
-
-static int
-s390_pseudo_register_reggroup_p (struct gdbarch *gdbarch, int regnum,
-				 struct reggroup *group)
-{
-  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
-
-  /* We usually save/restore the whole PSW, which includes PC and CC.
-     However, some older gdbservers may not support saving/restoring
-     the whole PSW yet, and will return an XML register description
-     excluding those from the save/restore register groups.  In those
-     cases, we still need to explicitly save/restore PC and CC in order
-     to push or pop frames.  Since this doesn't hurt anything if we
-     already save/restore the whole PSW (it's just redundant), we add
-     PC and CC at this point unconditionally.  */
-  if (group == save_reggroup || group == restore_reggroup)
-    return regnum == tdep->pc_regnum || regnum == tdep->cc_regnum;
-
-  if (group == vector_reggroup)
-    return regnum_is_vxr_full (tdep, regnum);
-
-  if (group == general_reggroup && regnum_is_vxr_full (tdep, regnum))
-    return 0;
-
-  return default_register_reggroup_p (gdbarch, regnum, group);
-}
-
-/* The "ax_pseudo_register_collect" gdbarch method.  */
-
-static int
-s390_ax_pseudo_register_collect (struct gdbarch *gdbarch,
-				 struct agent_expr *ax, int regnum)
-{
-  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
-  if (regnum == tdep->pc_regnum)
-    {
-      ax_reg_mask (ax, S390_PSWA_REGNUM);
-    }
-  else if (regnum == tdep->cc_regnum)
-    {
-      ax_reg_mask (ax, S390_PSWM_REGNUM);
-    }
-  else if (regnum_is_gpr_full (tdep, regnum))
-    {
-      regnum -= tdep->gpr_full_regnum;
-      ax_reg_mask (ax, S390_R0_REGNUM + regnum);
-      ax_reg_mask (ax, S390_R0_UPPER_REGNUM + regnum);
-    }
-  else if (regnum_is_vxr_full (tdep, regnum))
-    {
-      regnum -= tdep->v0_full_regnum;
-      ax_reg_mask (ax, S390_F0_REGNUM + regnum);
-      ax_reg_mask (ax, S390_V0_LOWER_REGNUM + regnum);
-    }
-  else
-    {
-      internal_error (__FILE__, __LINE__, _("invalid regnum"));
-    }
-  return 0;
-}
-
-/* The "ax_pseudo_register_push_stack" gdbarch method.  */
-
-static int
-s390_ax_pseudo_register_push_stack (struct gdbarch *gdbarch,
-				    struct agent_expr *ax, int regnum)
-{
-  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
-  if (regnum == tdep->pc_regnum)
-    {
-      ax_reg (ax, S390_PSWA_REGNUM);
-      if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)
-	{
-	  ax_zero_ext (ax, 31);
-	}
-    }
-  else if (regnum == tdep->cc_regnum)
-    {
-      ax_reg (ax, S390_PSWM_REGNUM);
-      if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)
-	ax_const_l (ax, 12);
-      else
-	ax_const_l (ax, 44);
-      ax_simple (ax, aop_rsh_unsigned);
-      ax_zero_ext (ax, 2);
-    }
-  else if (regnum_is_gpr_full (tdep, regnum))
-    {
-      regnum -= tdep->gpr_full_regnum;
-      ax_reg (ax, S390_R0_REGNUM + regnum);
-      ax_reg (ax, S390_R0_UPPER_REGNUM + regnum);
-      ax_const_l (ax, 32);
-      ax_simple (ax, aop_lsh);
-      ax_simple (ax, aop_bit_or);
-    }
-  else if (regnum_is_vxr_full (tdep, regnum))
-    {
-      /* Too large to stuff on the stack.  */
-      return 1;
-    }
-  else
-    {
-      internal_error (__FILE__, __LINE__, _("invalid regnum"));
-    }
-  return 0;
-}
-
-/* The "gen_return_address" gdbarch method.  Since this is supposed to be
-   just a best-effort method, and we don't really have the means to run
-   the full unwinder here, just collect the link register.  */
-
-static void
-s390_gen_return_address (struct gdbarch *gdbarch,
-			 struct agent_expr *ax, struct axs_value *value,
-			 CORE_ADDR scope)
-{
-  value->type = register_type (gdbarch, S390_R14_REGNUM);
-  value->kind = axs_lvalue_register;
-  value->u.reg = S390_R14_REGNUM;
-}
-
-
-/* A helper for s390_software_single_step, decides if an instruction
-   is a partial-execution instruction that needs to be executed until
-   completion when in record mode.  If it is, returns 1 and writes
-   instruction length to a pointer.  */
-
-static int
-s390_is_partial_instruction (struct gdbarch *gdbarch, CORE_ADDR loc, int *len)
-{
-  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
-  uint16_t insn;
-
-  insn = read_memory_integer (loc, 2, byte_order);
-
-  switch (insn >> 8)
-    {
-    case 0xa8: /* MVCLE */
-      *len = 4;
-      return 1;
-
-    case 0xeb:
-      {
-        insn = read_memory_integer (loc + 4, 2, byte_order);
-        if ((insn & 0xff) == 0x8e)
-          {
-            /* MVCLU */
-            *len = 6;
-            return 1;
-          }
-      }
-      break;
-    }
-
-  switch (insn)
-    {
-    case 0xb255: /* MVST */
-    case 0xb263: /* CMPSC */
-    case 0xb2a5: /* TRE */
-    case 0xb2a6: /* CU21 */
-    case 0xb2a7: /* CU12 */
-    case 0xb9b0: /* CU14 */
-    case 0xb9b1: /* CU24 */
-    case 0xb9b2: /* CU41 */
-    case 0xb9b3: /* CU42 */
-    case 0xb92a: /* KMF */
-    case 0xb92b: /* KMO */
-    case 0xb92f: /* KMC */
-    case 0xb92d: /* KMCTR */
-    case 0xb92e: /* KM */
-    case 0xb93c: /* PPNO */
-    case 0xb990: /* TRTT */
-    case 0xb991: /* TRTO */
-    case 0xb992: /* TROT */
-    case 0xb993: /* TROO */
-      *len = 4;
-      return 1;
-    }
-
-  return 0;
-}
-
-/* Implement the "software_single_step" gdbarch method, needed to single step
-   through instructions like MVCLE in record mode, to make sure they are
-   executed to completion.  Without that, record will save the full length
-   of destination buffer on every iteration, even though the CPU will only
-   process about 4kiB of it each time, leading to O(n**2) memory and time
-   complexity.  */
-
-static std::vector<CORE_ADDR>
-s390_software_single_step (struct regcache *regcache)
-{
-  struct gdbarch *gdbarch = regcache->arch ();
-  CORE_ADDR loc = regcache_read_pc (regcache);
-  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
-  int len;
-  uint16_t insn;
-
-  /* Special handling only if recording.  */
-  if (!record_full_is_used ())
-    return {};
-
-  /* First, match a partial instruction.  */
-  if (!s390_is_partial_instruction (gdbarch, loc, &len))
-    return {};
-
-  loc += len;
-
-  /* Second, look for a branch back to it.  */
-  insn = read_memory_integer (loc, 2, byte_order);
-  if (insn != 0xa714) /* BRC with mask 1 */
-    return {};
-
-  insn = read_memory_integer (loc + 2, 2, byte_order);
-  if (insn != (uint16_t) -(len / 2))
-    return {};
-
-  loc += 4;
-
-  /* Found it, step past the whole thing.  */
-  return {loc};
-}
-
-static int
-s390_displaced_step_hw_singlestep (struct gdbarch *gdbarch,
-				   struct displaced_step_closure *closure)
-{
-  return 1;
-}
-
-
-/* Maps for register sets.  */
-
-static const struct regcache_map_entry s390_gregmap[] =
-  {
-    { 1, S390_PSWM_REGNUM },
-    { 1, S390_PSWA_REGNUM },
-    { 16, S390_R0_REGNUM },
-    { 16, S390_A0_REGNUM },
-    { 1, S390_ORIG_R2_REGNUM },
-    { 0 }
-  };
-
-static const struct regcache_map_entry s390_fpregmap[] =
-  {
-    { 1, S390_FPC_REGNUM, 8 },
-    { 16, S390_F0_REGNUM, 8 },
-    { 0 }
-  };
-
 static const struct regcache_map_entry s390_regmap_upper[] =
   {
     { 16, S390_R0_UPPER_REGNUM, 4 },
@@ -824,18 +152,6 @@  static const struct regcache_map_entry s390_regmap_tdb[] =
     { 0 }
   };
 
-static const struct regcache_map_entry s390_regmap_vxrs_low[] =
-  {
-    { 16, S390_V0_LOWER_REGNUM, 8 },
-    { 0 }
-  };
-
-static const struct regcache_map_entry s390_regmap_vxrs_high[] =
-  {
-    { 16, S390_V16_REGNUM, 16 },
-    { 0 }
-  };
-
 static const struct regcache_map_entry s390_regmap_gs[] =
   {
     { 1, REGCACHE_MAP_SKIP, 8 },
@@ -854,7 +170,6 @@  static const struct regcache_map_entry s390_regmap_gsbc[] =
     { 0 }
   };
 
-
 /* Supply the TDB regset.  Like regcache_supply_regset, but invalidate
    the TDB registers unless the TDB format field is valid.  */
 
@@ -871,18 +186,6 @@  s390_supply_tdb_regset (const struct regset *regset, struct regcache *regcache,
     regcache_supply_regset (regset, regcache, regnum, NULL, len);
 }
 
-const struct regset s390_gregset = {
-  s390_gregmap,
-  regcache_supply_regset,
-  regcache_collect_regset
-};
-
-const struct regset s390_fpregset = {
-  s390_fpregmap,
-  regcache_supply_regset,
-  regcache_collect_regset
-};
-
 static const struct regset s390_upper_regset = {
   s390_regmap_upper,
   regcache_supply_regset,
@@ -913,18 +216,6 @@  const struct regset s390_tdb_regset = {
   regcache_collect_regset
 };
 
-const struct regset s390_vxrs_low_regset = {
-  s390_regmap_vxrs_low,
-  regcache_supply_regset,
-  regcache_collect_regset
-};
-
-const struct regset s390_vxrs_high_regset = {
-  s390_regmap_vxrs_high,
-  regcache_supply_regset,
-  regcache_collect_regset
-};
-
 const struct regset s390_gs_regset = {
   s390_regmap_gs,
   regcache_supply_regset,
@@ -1049,1034 +340,6 @@  s390_core_read_description (struct gdbarch *gdbarch,
     }
 }
 
-
-/* Decoding S/390 instructions.  */
-
-/* Named opcode values for the S/390 instructions we recognize.  Some
-   instructions have their opcode split across two fields; those are the
-   op1_* and op2_* enums.  */
-enum
-  {
-    op1_lhi  = 0xa7,   op2_lhi  = 0x08,
-    op1_lghi = 0xa7,   op2_lghi = 0x09,
-    op1_lgfi = 0xc0,   op2_lgfi = 0x01,
-    op_lr    = 0x18,
-    op_lgr   = 0xb904,
-    op_l     = 0x58,
-    op1_ly   = 0xe3,   op2_ly   = 0x58,
-    op1_lg   = 0xe3,   op2_lg   = 0x04,
-    op_lm    = 0x98,
-    op1_lmy  = 0xeb,   op2_lmy  = 0x98,
-    op1_lmg  = 0xeb,   op2_lmg  = 0x04,
-    op_st    = 0x50,
-    op1_sty  = 0xe3,   op2_sty  = 0x50,
-    op1_stg  = 0xe3,   op2_stg  = 0x24,
-    op_std   = 0x60,
-    op_stm   = 0x90,
-    op1_stmy = 0xeb,   op2_stmy = 0x90,
-    op1_stmg = 0xeb,   op2_stmg = 0x24,
-    op1_aghi = 0xa7,   op2_aghi = 0x0b,
-    op1_ahi  = 0xa7,   op2_ahi  = 0x0a,
-    op1_agfi = 0xc2,   op2_agfi = 0x08,
-    op1_afi  = 0xc2,   op2_afi  = 0x09,
-    op1_algfi= 0xc2,   op2_algfi= 0x0a,
-    op1_alfi = 0xc2,   op2_alfi = 0x0b,
-    op_ar    = 0x1a,
-    op_agr   = 0xb908,
-    op_a     = 0x5a,
-    op1_ay   = 0xe3,   op2_ay   = 0x5a,
-    op1_ag   = 0xe3,   op2_ag   = 0x08,
-    op1_slgfi= 0xc2,   op2_slgfi= 0x04,
-    op1_slfi = 0xc2,   op2_slfi = 0x05,
-    op_sr    = 0x1b,
-    op_sgr   = 0xb909,
-    op_s     = 0x5b,
-    op1_sy   = 0xe3,   op2_sy   = 0x5b,
-    op1_sg   = 0xe3,   op2_sg   = 0x09,
-    op_nr    = 0x14,
-    op_ngr   = 0xb980,
-    op_la    = 0x41,
-    op1_lay  = 0xe3,   op2_lay  = 0x71,
-    op1_larl = 0xc0,   op2_larl = 0x00,
-    op_basr  = 0x0d,
-    op_bas   = 0x4d,
-    op_bcr   = 0x07,
-    op_bc    = 0x0d,
-    op_bctr  = 0x06,
-    op_bctgr = 0xb946,
-    op_bct   = 0x46,
-    op1_bctg = 0xe3,   op2_bctg = 0x46,
-    op_bxh   = 0x86,
-    op1_bxhg = 0xeb,   op2_bxhg = 0x44,
-    op_bxle  = 0x87,
-    op1_bxleg= 0xeb,   op2_bxleg= 0x45,
-    op1_bras = 0xa7,   op2_bras = 0x05,
-    op1_brasl= 0xc0,   op2_brasl= 0x05,
-    op1_brc  = 0xa7,   op2_brc  = 0x04,
-    op1_brcl = 0xc0,   op2_brcl = 0x04,
-    op1_brct = 0xa7,   op2_brct = 0x06,
-    op1_brctg= 0xa7,   op2_brctg= 0x07,
-    op_brxh  = 0x84,
-    op1_brxhg= 0xec,   op2_brxhg= 0x44,
-    op_brxle = 0x85,
-    op1_brxlg= 0xec,   op2_brxlg= 0x45,
-    op_svc   = 0x0a,
-  };
-
-
-/* Read a single instruction from address AT.  */
-
-#define S390_MAX_INSTR_SIZE 6
-static int
-s390_readinstruction (bfd_byte instr[], CORE_ADDR at)
-{
-  static int s390_instrlen[] = { 2, 4, 4, 6 };
-  int instrlen;
-
-  if (target_read_memory (at, &instr[0], 2))
-    return -1;
-  instrlen = s390_instrlen[instr[0] >> 6];
-  if (instrlen > 2)
-    {
-      if (target_read_memory (at + 2, &instr[2], instrlen - 2))
-	return -1;
-    }
-  return instrlen;
-}
-
-
-/* The functions below are for recognizing and decoding S/390
-   instructions of various formats.  Each of them checks whether INSN
-   is an instruction of the given format, with the specified opcodes.
-   If it is, it sets the remaining arguments to the values of the
-   instruction's fields, and returns a non-zero value; otherwise, it
-   returns zero.
-
-   These functions' arguments appear in the order they appear in the
-   instruction, not in the machine-language form.  So, opcodes always
-   come first, even though they're sometimes scattered around the
-   instructions.  And displacements appear before base and extension
-   registers, as they do in the assembly syntax, not at the end, as
-   they do in the machine language.  */
-static int
-is_ri (bfd_byte *insn, int op1, int op2, unsigned int *r1, int *i2)
-{
-  if (insn[0] == op1 && (insn[1] & 0xf) == op2)
-    {
-      *r1 = (insn[1] >> 4) & 0xf;
-      /* i2 is a 16-bit signed quantity.  */
-      *i2 = (((insn[2] << 8) | insn[3]) ^ 0x8000) - 0x8000;
-      return 1;
-    }
-  else
-    return 0;
-}
-
-
-static int
-is_ril (bfd_byte *insn, int op1, int op2,
-	unsigned int *r1, int *i2)
-{
-  if (insn[0] == op1 && (insn[1] & 0xf) == op2)
-    {
-      *r1 = (insn[1] >> 4) & 0xf;
-      /* i2 is a signed quantity.  If the host 'int' is 32 bits long,
-	 no sign extension is necessary, but we don't want to assume
-	 that.  */
-      *i2 = (((insn[2] << 24)
-	      | (insn[3] << 16)
-	      | (insn[4] << 8)
-	      | (insn[5])) ^ 0x80000000) - 0x80000000;
-      return 1;
-    }
-  else
-    return 0;
-}
-
-
-static int
-is_rr (bfd_byte *insn, int op, unsigned int *r1, unsigned int *r2)
-{
-  if (insn[0] == op)
-    {
-      *r1 = (insn[1] >> 4) & 0xf;
-      *r2 = insn[1] & 0xf;
-      return 1;
-    }
-  else
-    return 0;
-}
-
-
-static int
-is_rre (bfd_byte *insn, int op, unsigned int *r1, unsigned int *r2)
-{
-  if (((insn[0] << 8) | insn[1]) == op)
-    {
-      /* Yes, insn[3].  insn[2] is unused in RRE format.  */
-      *r1 = (insn[3] >> 4) & 0xf;
-      *r2 = insn[3] & 0xf;
-      return 1;
-    }
-  else
-    return 0;
-}
-
-
-static int
-is_rs (bfd_byte *insn, int op,
-       unsigned int *r1, unsigned int *r3, int *d2, unsigned int *b2)
-{
-  if (insn[0] == op)
-    {
-      *r1 = (insn[1] >> 4) & 0xf;
-      *r3 = insn[1] & 0xf;
-      *b2 = (insn[2] >> 4) & 0xf;
-      *d2 = ((insn[2] & 0xf) << 8) | insn[3];
-      return 1;
-    }
-  else
-    return 0;
-}
-
-
-static int
-is_rsy (bfd_byte *insn, int op1, int op2,
-	unsigned int *r1, unsigned int *r3, int *d2, unsigned int *b2)
-{
-  if (insn[0] == op1
-      && insn[5] == op2)
-    {
-      *r1 = (insn[1] >> 4) & 0xf;
-      *r3 = insn[1] & 0xf;
-      *b2 = (insn[2] >> 4) & 0xf;
-      /* The 'long displacement' is a 20-bit signed integer.  */
-      *d2 = ((((insn[2] & 0xf) << 8) | insn[3] | (insn[4] << 12))
-		^ 0x80000) - 0x80000;
-      return 1;
-    }
-  else
-    return 0;
-}
-
-
-static int
-is_rx (bfd_byte *insn, int op,
-       unsigned int *r1, int *d2, unsigned int *x2, unsigned int *b2)
-{
-  if (insn[0] == op)
-    {
-      *r1 = (insn[1] >> 4) & 0xf;
-      *x2 = insn[1] & 0xf;
-      *b2 = (insn[2] >> 4) & 0xf;
-      *d2 = ((insn[2] & 0xf) << 8) | insn[3];
-      return 1;
-    }
-  else
-    return 0;
-}
-
-
-static int
-is_rxy (bfd_byte *insn, int op1, int op2,
-	unsigned int *r1, int *d2, unsigned int *x2, unsigned int *b2)
-{
-  if (insn[0] == op1
-      && insn[5] == op2)
-    {
-      *r1 = (insn[1] >> 4) & 0xf;
-      *x2 = insn[1] & 0xf;
-      *b2 = (insn[2] >> 4) & 0xf;
-      /* The 'long displacement' is a 20-bit signed integer.  */
-      *d2 = ((((insn[2] & 0xf) << 8) | insn[3] | (insn[4] << 12))
-		^ 0x80000) - 0x80000;
-      return 1;
-    }
-  else
-    return 0;
-}
-
-
-/* Prologue analysis.  */
-
-#define S390_NUM_GPRS 16
-#define S390_NUM_FPRS 16
-
-struct s390_prologue_data {
-
-  /* The stack.  */
-  struct pv_area *stack;
-
-  /* The size and byte-order of a GPR or FPR.  */
-  int gpr_size;
-  int fpr_size;
-  enum bfd_endian byte_order;
-
-  /* The general-purpose registers.  */
-  pv_t gpr[S390_NUM_GPRS];
-
-  /* The floating-point registers.  */
-  pv_t fpr[S390_NUM_FPRS];
-
-  /* The offset relative to the CFA where the incoming GPR N was saved
-     by the function prologue.  0 if not saved or unknown.  */
-  int gpr_slot[S390_NUM_GPRS];
-
-  /* Likewise for FPRs.  */
-  int fpr_slot[S390_NUM_FPRS];
-
-  /* Nonzero if the backchain was saved.  This is assumed to be the
-     case when the incoming SP is saved at the current SP location.  */
-  int back_chain_saved_p;
-};
-
-/* Return the effective address for an X-style instruction, like:
-
-	L R1, D2(X2, B2)
-
-   Here, X2 and B2 are registers, and D2 is a signed 20-bit
-   constant; the effective address is the sum of all three.  If either
-   X2 or B2 are zero, then it doesn't contribute to the sum --- this
-   means that r0 can't be used as either X2 or B2.  */
-static pv_t
-s390_addr (struct s390_prologue_data *data,
-	   int d2, unsigned int x2, unsigned int b2)
-{
-  pv_t result;
-
-  result = pv_constant (d2);
-  if (x2)
-    result = pv_add (result, data->gpr[x2]);
-  if (b2)
-    result = pv_add (result, data->gpr[b2]);
-
-  return result;
-}
-
-/* Do a SIZE-byte store of VALUE to D2(X2,B2).  */
-static void
-s390_store (struct s390_prologue_data *data,
-	    int d2, unsigned int x2, unsigned int b2, CORE_ADDR size,
-	    pv_t value)
-{
-  pv_t addr = s390_addr (data, d2, x2, b2);
-  pv_t offset;
-
-  /* Check whether we are storing the backchain.  */
-  offset = pv_subtract (data->gpr[S390_SP_REGNUM - S390_R0_REGNUM], addr);
-
-  if (pv_is_constant (offset) && offset.k == 0)
-    if (size == data->gpr_size
-	&& pv_is_register_k (value, S390_SP_REGNUM, 0))
-      {
-	data->back_chain_saved_p = 1;
-	return;
-      }
-
-
-  /* Check whether we are storing a register into the stack.  */
-  if (!data->stack->store_would_trash (addr))
-    data->stack->store (addr, size, value);
-
-
-  /* Note: If this is some store we cannot identify, you might think we
-     should forget our cached values, as any of those might have been hit.
-
-     However, we make the assumption that the register save areas are only
-     ever stored to once in any given function, and we do recognize these
-     stores.  Thus every store we cannot recognize does not hit our data.  */
-}
-
-/* Do a SIZE-byte load from D2(X2,B2).  */
-static pv_t
-s390_load (struct s390_prologue_data *data,
-	   int d2, unsigned int x2, unsigned int b2, CORE_ADDR size)
-
-{
-  pv_t addr = s390_addr (data, d2, x2, b2);
-
-  /* If it's a load from an in-line constant pool, then we can
-     simulate that, under the assumption that the code isn't
-     going to change between the time the processor actually
-     executed it creating the current frame, and the time when
-     we're analyzing the code to unwind past that frame.  */
-  if (pv_is_constant (addr))
-    {
-      struct target_section *secp;
-      secp = target_section_by_addr (&current_target, addr.k);
-      if (secp != NULL
-	  && (bfd_get_section_flags (secp->the_bfd_section->owner,
-				     secp->the_bfd_section)
-	      & SEC_READONLY))
-	return pv_constant (read_memory_integer (addr.k, size,
-						 data->byte_order));
-    }
-
-  /* Check whether we are accessing one of our save slots.  */
-  return data->stack->fetch (addr, size);
-}
-
-/* Function for finding saved registers in a 'struct pv_area'; we pass
-   this to pv_area::scan.
-
-   If VALUE is a saved register, ADDR says it was saved at a constant
-   offset from the frame base, and SIZE indicates that the whole
-   register was saved, record its offset in the reg_offset table in
-   PROLOGUE_UNTYPED.  */
-static void
-s390_check_for_saved (void *data_untyped, pv_t addr,
-		      CORE_ADDR size, pv_t value)
-{
-  struct s390_prologue_data *data = (struct s390_prologue_data *) data_untyped;
-  int i, offset;
-
-  if (!pv_is_register (addr, S390_SP_REGNUM))
-    return;
-
-  offset = 16 * data->gpr_size + 32 - addr.k;
-
-  /* If we are storing the original value of a register, we want to
-     record the CFA offset.  If the same register is stored multiple
-     times, the stack slot with the highest address counts.  */
-
-  for (i = 0; i < S390_NUM_GPRS; i++)
-    if (size == data->gpr_size
-	&& pv_is_register_k (value, S390_R0_REGNUM + i, 0))
-      if (data->gpr_slot[i] == 0
-	  || data->gpr_slot[i] > offset)
-	{
-	  data->gpr_slot[i] = offset;
-	  return;
-	}
-
-  for (i = 0; i < S390_NUM_FPRS; i++)
-    if (size == data->fpr_size
-	&& pv_is_register_k (value, S390_F0_REGNUM + i, 0))
-      if (data->fpr_slot[i] == 0
-	  || data->fpr_slot[i] > offset)
-	{
-	  data->fpr_slot[i] = offset;
-	  return;
-	}
-}
-
-/* Analyze the prologue of the function starting at START_PC,
-   continuing at most until CURRENT_PC.  Initialize DATA to
-   hold all information we find out about the state of the registers
-   and stack slots.  Return the address of the instruction after
-   the last one that changed the SP, FP, or back chain; or zero
-   on error.  */
-static CORE_ADDR
-s390_analyze_prologue (struct gdbarch *gdbarch,
-		       CORE_ADDR start_pc,
-		       CORE_ADDR current_pc,
-		       struct s390_prologue_data *data)
-{
-  int word_size = gdbarch_ptr_bit (gdbarch) / 8;
-
-  /* Our return value:
-     The address of the instruction after the last one that changed
-     the SP, FP, or back chain;  zero if we got an error trying to
-     read memory.  */
-  CORE_ADDR result = start_pc;
-
-  /* The current PC for our abstract interpretation.  */
-  CORE_ADDR pc;
-
-  /* The address of the next instruction after that.  */
-  CORE_ADDR next_pc;
-
-  pv_area stack (S390_SP_REGNUM, gdbarch_addr_bit (gdbarch));
-  scoped_restore restore_stack = make_scoped_restore (&data->stack, &stack);
-
-  /* Set up everything's initial value.  */
-  {
-    int i;
-
-    /* For the purpose of prologue tracking, we consider the GPR size to
-       be equal to the ABI word size, even if it is actually larger
-       (i.e. when running a 32-bit binary under a 64-bit kernel).  */
-    data->gpr_size = word_size;
-    data->fpr_size = 8;
-    data->byte_order = gdbarch_byte_order (gdbarch);
-
-    for (i = 0; i < S390_NUM_GPRS; i++)
-      data->gpr[i] = pv_register (S390_R0_REGNUM + i, 0);
-
-    for (i = 0; i < S390_NUM_FPRS; i++)
-      data->fpr[i] = pv_register (S390_F0_REGNUM + i, 0);
-
-    for (i = 0; i < S390_NUM_GPRS; i++)
-      data->gpr_slot[i]  = 0;
-
-    for (i = 0; i < S390_NUM_FPRS; i++)
-      data->fpr_slot[i]  = 0;
-
-    data->back_chain_saved_p = 0;
-  }
-
-  /* Start interpreting instructions, until we hit the frame's
-     current PC or the first branch instruction.  */
-  for (pc = start_pc; pc > 0 && pc < current_pc; pc = next_pc)
-    {
-      bfd_byte insn[S390_MAX_INSTR_SIZE];
-      int insn_len = s390_readinstruction (insn, pc);
-
-      bfd_byte dummy[S390_MAX_INSTR_SIZE] = { 0 };
-      bfd_byte *insn32 = word_size == 4 ? insn : dummy;
-      bfd_byte *insn64 = word_size == 8 ? insn : dummy;
-
-      /* Fields for various kinds of instructions.  */
-      unsigned int b2, r1, r2, x2, r3;
-      int i2, d2;
-
-      /* The values of SP and FP before this instruction,
-	 for detecting instructions that change them.  */
-      pv_t pre_insn_sp, pre_insn_fp;
-      /* Likewise for the flag whether the back chain was saved.  */
-      int pre_insn_back_chain_saved_p;
-
-      /* If we got an error trying to read the instruction, report it.  */
-      if (insn_len < 0)
-	{
-	  result = 0;
-	  break;
-	}
-
-      next_pc = pc + insn_len;
-
-      pre_insn_sp = data->gpr[S390_SP_REGNUM - S390_R0_REGNUM];
-      pre_insn_fp = data->gpr[S390_FRAME_REGNUM - S390_R0_REGNUM];
-      pre_insn_back_chain_saved_p = data->back_chain_saved_p;
-
-
-      /* LHI r1, i2 --- load halfword immediate.  */
-      /* LGHI r1, i2 --- load halfword immediate (64-bit version).  */
-      /* LGFI r1, i2 --- load fullword immediate.  */
-      if (is_ri (insn32, op1_lhi, op2_lhi, &r1, &i2)
-	  || is_ri (insn64, op1_lghi, op2_lghi, &r1, &i2)
-	  || is_ril (insn, op1_lgfi, op2_lgfi, &r1, &i2))
-	data->gpr[r1] = pv_constant (i2);
-
-      /* LR r1, r2 --- load from register.  */
-      /* LGR r1, r2 --- load from register (64-bit version).  */
-      else if (is_rr (insn32, op_lr, &r1, &r2)
-	       || is_rre (insn64, op_lgr, &r1, &r2))
-	data->gpr[r1] = data->gpr[r2];
-
-      /* L r1, d2(x2, b2) --- load.  */
-      /* LY r1, d2(x2, b2) --- load (long-displacement version).  */
-      /* LG r1, d2(x2, b2) --- load (64-bit version).  */
-      else if (is_rx (insn32, op_l, &r1, &d2, &x2, &b2)
-	       || is_rxy (insn32, op1_ly, op2_ly, &r1, &d2, &x2, &b2)
-	       || is_rxy (insn64, op1_lg, op2_lg, &r1, &d2, &x2, &b2))
-	data->gpr[r1] = s390_load (data, d2, x2, b2, data->gpr_size);
-
-      /* ST r1, d2(x2, b2) --- store.  */
-      /* STY r1, d2(x2, b2) --- store (long-displacement version).  */
-      /* STG r1, d2(x2, b2) --- store (64-bit version).  */
-      else if (is_rx (insn32, op_st, &r1, &d2, &x2, &b2)
-	       || is_rxy (insn32, op1_sty, op2_sty, &r1, &d2, &x2, &b2)
-	       || is_rxy (insn64, op1_stg, op2_stg, &r1, &d2, &x2, &b2))
-	s390_store (data, d2, x2, b2, data->gpr_size, data->gpr[r1]);
-
-      /* STD r1, d2(x2,b2) --- store floating-point register.  */
-      else if (is_rx (insn, op_std, &r1, &d2, &x2, &b2))
-	s390_store (data, d2, x2, b2, data->fpr_size, data->fpr[r1]);
-
-      /* STM r1, r3, d2(b2) --- store multiple.  */
-      /* STMY r1, r3, d2(b2) --- store multiple (long-displacement
-	 version).  */
-      /* STMG r1, r3, d2(b2) --- store multiple (64-bit version).  */
-      else if (is_rs (insn32, op_stm, &r1, &r3, &d2, &b2)
-	       || is_rsy (insn32, op1_stmy, op2_stmy, &r1, &r3, &d2, &b2)
-	       || is_rsy (insn64, op1_stmg, op2_stmg, &r1, &r3, &d2, &b2))
-	{
-	  for (; r1 <= r3; r1++, d2 += data->gpr_size)
-	    s390_store (data, d2, 0, b2, data->gpr_size, data->gpr[r1]);
-	}
-
-      /* AHI r1, i2 --- add halfword immediate.  */
-      /* AGHI r1, i2 --- add halfword immediate (64-bit version).  */
-      /* AFI r1, i2 --- add fullword immediate.  */
-      /* AGFI r1, i2 --- add fullword immediate (64-bit version).  */
-      else if (is_ri (insn32, op1_ahi, op2_ahi, &r1, &i2)
-	       || is_ri (insn64, op1_aghi, op2_aghi, &r1, &i2)
-	       || is_ril (insn32, op1_afi, op2_afi, &r1, &i2)
-	       || is_ril (insn64, op1_agfi, op2_agfi, &r1, &i2))
-	data->gpr[r1] = pv_add_constant (data->gpr[r1], i2);
-
-      /* ALFI r1, i2 --- add logical immediate.  */
-      /* ALGFI r1, i2 --- add logical immediate (64-bit version).  */
-      else if (is_ril (insn32, op1_alfi, op2_alfi, &r1, &i2)
-	       || is_ril (insn64, op1_algfi, op2_algfi, &r1, &i2))
-	data->gpr[r1] = pv_add_constant (data->gpr[r1],
-					 (CORE_ADDR)i2 & 0xffffffff);
-
-      /* AR r1, r2 -- add register.  */
-      /* AGR r1, r2 -- add register (64-bit version).  */
-      else if (is_rr (insn32, op_ar, &r1, &r2)
-	       || is_rre (insn64, op_agr, &r1, &r2))
-	data->gpr[r1] = pv_add (data->gpr[r1], data->gpr[r2]);
-
-      /* A r1, d2(x2, b2) -- add.  */
-      /* AY r1, d2(x2, b2) -- add (long-displacement version).  */
-      /* AG r1, d2(x2, b2) -- add (64-bit version).  */
-      else if (is_rx (insn32, op_a, &r1, &d2, &x2, &b2)
-	       || is_rxy (insn32, op1_ay, op2_ay, &r1, &d2, &x2, &b2)
-	       || is_rxy (insn64, op1_ag, op2_ag, &r1, &d2, &x2, &b2))
-	data->gpr[r1] = pv_add (data->gpr[r1],
-				s390_load (data, d2, x2, b2, data->gpr_size));
-
-      /* SLFI r1, i2 --- subtract logical immediate.  */
-      /* SLGFI r1, i2 --- subtract logical immediate (64-bit version).  */
-      else if (is_ril (insn32, op1_slfi, op2_slfi, &r1, &i2)
-	       || is_ril (insn64, op1_slgfi, op2_slgfi, &r1, &i2))
-	data->gpr[r1] = pv_add_constant (data->gpr[r1],
-					 -((CORE_ADDR)i2 & 0xffffffff));
-
-      /* SR r1, r2 -- subtract register.  */
-      /* SGR r1, r2 -- subtract register (64-bit version).  */
-      else if (is_rr (insn32, op_sr, &r1, &r2)
-	       || is_rre (insn64, op_sgr, &r1, &r2))
-	data->gpr[r1] = pv_subtract (data->gpr[r1], data->gpr[r2]);
-
-      /* S r1, d2(x2, b2) -- subtract.  */
-      /* SY r1, d2(x2, b2) -- subtract (long-displacement version).  */
-      /* SG r1, d2(x2, b2) -- subtract (64-bit version).  */
-      else if (is_rx (insn32, op_s, &r1, &d2, &x2, &b2)
-	       || is_rxy (insn32, op1_sy, op2_sy, &r1, &d2, &x2, &b2)
-	       || is_rxy (insn64, op1_sg, op2_sg, &r1, &d2, &x2, &b2))
-	data->gpr[r1] = pv_subtract (data->gpr[r1],
-				s390_load (data, d2, x2, b2, data->gpr_size));
-
-      /* LA r1, d2(x2, b2) --- load address.  */
-      /* LAY r1, d2(x2, b2) --- load address (long-displacement version).  */
-      else if (is_rx (insn, op_la, &r1, &d2, &x2, &b2)
-	       || is_rxy (insn, op1_lay, op2_lay, &r1, &d2, &x2, &b2))
-	data->gpr[r1] = s390_addr (data, d2, x2, b2);
-
-      /* LARL r1, i2 --- load address relative long.  */
-      else if (is_ril (insn, op1_larl, op2_larl, &r1, &i2))
-	data->gpr[r1] = pv_constant (pc + i2 * 2);
-
-      /* BASR r1, 0 --- branch and save.
-	 Since r2 is zero, this saves the PC in r1, but doesn't branch.  */
-      else if (is_rr (insn, op_basr, &r1, &r2)
-	       && r2 == 0)
-	data->gpr[r1] = pv_constant (next_pc);
-
-      /* BRAS r1, i2 --- branch relative and save.  */
-      else if (is_ri (insn, op1_bras, op2_bras, &r1, &i2))
-	{
-	  data->gpr[r1] = pv_constant (next_pc);
-	  next_pc = pc + i2 * 2;
-
-	  /* We'd better not interpret any backward branches.  We'll
-	     never terminate.  */
-	  if (next_pc <= pc)
-	    break;
-	}
-
-      /* BRC/BRCL -- branch relative on condition.  Ignore "branch
-	 never", branch to following instruction, and "conditional
-	 trap" (BRC +2).  Otherwise terminate search.  */
-      else if (is_ri (insn, op1_brc, op2_brc, &r1, &i2))
-	{
-	  if (r1 != 0 && i2 != 1 && i2 != 2)
-	    break;
-	}
-      else if (is_ril (insn, op1_brcl, op2_brcl, &r1, &i2))
-	{
-	  if (r1 != 0 && i2 != 3)
-	    break;
-	}
-
-      /* Terminate search when hitting any other branch instruction.  */
-      else if (is_rr (insn, op_basr, &r1, &r2)
-	       || is_rx (insn, op_bas, &r1, &d2, &x2, &b2)
-	       || is_rr (insn, op_bcr, &r1, &r2)
-	       || is_rx (insn, op_bc, &r1, &d2, &x2, &b2)
-	       || is_ril (insn, op1_brasl, op2_brasl, &r2, &i2))
-	break;
-
-      else
-	{
-	  /* An instruction we don't know how to simulate.  The only
-	     safe thing to do would be to set every value we're tracking
-	     to 'unknown'.  Instead, we'll be optimistic: we assume that
-	     we *can* interpret every instruction that the compiler uses
-	     to manipulate any of the data we're interested in here --
-	     then we can just ignore anything else.  */
-	}
-
-      /* Record the address after the last instruction that changed
-	 the FP, SP, or backlink.  Ignore instructions that changed
-	 them back to their original values --- those are probably
-	 restore instructions.  (The back chain is never restored,
-	 just popped.)  */
-      {
-	pv_t sp = data->gpr[S390_SP_REGNUM - S390_R0_REGNUM];
-	pv_t fp = data->gpr[S390_FRAME_REGNUM - S390_R0_REGNUM];
-
-	if ((! pv_is_identical (pre_insn_sp, sp)
-	     && ! pv_is_register_k (sp, S390_SP_REGNUM, 0)
-	     && sp.kind != pvk_unknown)
-	    || (! pv_is_identical (pre_insn_fp, fp)
-		&& ! pv_is_register_k (fp, S390_FRAME_REGNUM, 0)
-		&& fp.kind != pvk_unknown)
-	    || pre_insn_back_chain_saved_p != data->back_chain_saved_p)
-	  result = next_pc;
-      }
-    }
-
-  /* Record where all the registers were saved.  */
-  data->stack->scan (s390_check_for_saved, data);
-
-  return result;
-}
-
-/* Advance PC across any function entry prologue instructions to reach
-   some "real" code.  */
-static CORE_ADDR
-s390_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
-{
-  struct s390_prologue_data data;
-  CORE_ADDR skip_pc, func_addr;
-
-  if (find_pc_partial_function (pc, NULL, &func_addr, NULL))
-    {
-      CORE_ADDR post_prologue_pc
-	= skip_prologue_using_sal (gdbarch, func_addr);
-      if (post_prologue_pc != 0)
-	return std::max (pc, post_prologue_pc);
-    }
-
-  skip_pc = s390_analyze_prologue (gdbarch, pc, (CORE_ADDR)-1, &data);
-  return skip_pc ? skip_pc : pc;
-}
-
-/* Implmement the stack_frame_destroyed_p gdbarch method.  */
-static int
-s390_stack_frame_destroyed_p (struct gdbarch *gdbarch, CORE_ADDR pc)
-{
-  int word_size = gdbarch_ptr_bit (gdbarch) / 8;
-
-  /* In frameless functions, there's not frame to destroy and thus
-     we don't care about the epilogue.
-
-     In functions with frame, the epilogue sequence is a pair of
-     a LM-type instruction that restores (amongst others) the
-     return register %r14 and the stack pointer %r15, followed
-     by a branch 'br %r14' --or equivalent-- that effects the
-     actual return.
-
-     In that situation, this function needs to return 'true' in
-     exactly one case: when pc points to that branch instruction.
-
-     Thus we try to disassemble the one instructions immediately
-     preceding pc and check whether it is an LM-type instruction
-     modifying the stack pointer.
-
-     Note that disassembling backwards is not reliable, so there
-     is a slight chance of false positives here ...  */
-
-  bfd_byte insn[6];
-  unsigned int r1, r3, b2;
-  int d2;
-
-  if (word_size == 4
-      && !target_read_memory (pc - 4, insn, 4)
-      && is_rs (insn, op_lm, &r1, &r3, &d2, &b2)
-      && r3 == S390_SP_REGNUM - S390_R0_REGNUM)
-    return 1;
-
-  if (word_size == 4
-      && !target_read_memory (pc - 6, insn, 6)
-      && is_rsy (insn, op1_lmy, op2_lmy, &r1, &r3, &d2, &b2)
-      && r3 == S390_SP_REGNUM - S390_R0_REGNUM)
-    return 1;
-
-  if (word_size == 8
-      && !target_read_memory (pc - 6, insn, 6)
-      && is_rsy (insn, op1_lmg, op2_lmg, &r1, &r3, &d2, &b2)
-      && r3 == S390_SP_REGNUM - S390_R0_REGNUM)
-    return 1;
-
-  return 0;
-}
-
-/* Displaced stepping.  */
-
-/* Return true if INSN is a non-branch RIL-b or RIL-c format
-   instruction.  */
-
-static int
-is_non_branch_ril (gdb_byte *insn)
-{
-  gdb_byte op1 = insn[0];
-
-  if (op1 == 0xc4)
-    {
-      gdb_byte op2 = insn[1] & 0x0f;
-
-      switch (op2)
-	{
-	case 0x02: /* llhrl */
-	case 0x04: /* lghrl */
-	case 0x05: /* lhrl */
-	case 0x06: /* llghrl */
-	case 0x07: /* sthrl */
-	case 0x08: /* lgrl */
-	case 0x0b: /* stgrl */
-	case 0x0c: /* lgfrl */
-	case 0x0d: /* lrl */
-	case 0x0e: /* llgfrl */
-	case 0x0f: /* strl */
-	  return 1;
-	}
-    }
-  else if (op1 == 0xc6)
-    {
-      gdb_byte op2 = insn[1] & 0x0f;
-
-      switch (op2)
-	{
-	case 0x00: /* exrl */
-	case 0x02: /* pfdrl */
-	case 0x04: /* cghrl */
-	case 0x05: /* chrl */
-	case 0x06: /* clghrl */
-	case 0x07: /* clhrl */
-	case 0x08: /* cgrl */
-	case 0x0a: /* clgrl */
-	case 0x0c: /* cgfrl */
-	case 0x0d: /* crl */
-	case 0x0e: /* clgfrl */
-	case 0x0f: /* clrl */
-	  return 1;
-	}
-    }
-
-  return 0;
-}
-
-typedef buf_displaced_step_closure s390_displaced_step_closure;
-
-/* Implementation of gdbarch_displaced_step_copy_insn.  */
-
-static struct displaced_step_closure *
-s390_displaced_step_copy_insn (struct gdbarch *gdbarch,
-			       CORE_ADDR from, CORE_ADDR to,
-			       struct regcache *regs)
-{
-  size_t len = gdbarch_max_insn_length (gdbarch);
-  std::unique_ptr<s390_displaced_step_closure> closure
-    (new s390_displaced_step_closure (len));
-  gdb_byte *buf = closure->buf.data ();
-
-  read_memory (from, buf, len);
-
-  /* Adjust the displacement field of PC-relative RIL instructions,
-     except branches.  The latter are handled in the fixup hook.  */
-  if (is_non_branch_ril (buf))
-    {
-      LONGEST offset;
-
-      offset = extract_signed_integer (buf + 2, 4, BFD_ENDIAN_BIG);
-      offset = (from - to + offset * 2) / 2;
-
-      /* If the instruction is too far from the jump pad, punt.  This
-	 will usually happen with instructions in shared libraries.
-	 We could probably support these by rewriting them to be
-	 absolute or fully emulating them.  */
-      if (offset < INT32_MIN || offset > INT32_MAX)
-	{
-	  /* Let the core fall back to stepping over the breakpoint
-	     in-line.  */
-	  if (debug_displaced)
-	    {
-	      fprintf_unfiltered (gdb_stdlog,
-				  "displaced: can't displaced step "
-				  "RIL instruction: offset %s out of range\n",
-				  plongest (offset));
-	    }
-
-	  return NULL;
-	}
-
-      store_signed_integer (buf + 2, 4, BFD_ENDIAN_BIG, offset);
-    }
-
-  write_memory (to, buf, len);
-
-  if (debug_displaced)
-    {
-      fprintf_unfiltered (gdb_stdlog, "displaced: copy %s->%s: ",
-                          paddress (gdbarch, from), paddress (gdbarch, to));
-      displaced_step_dump_bytes (gdb_stdlog, buf, len);
-    }
-
-  return closure.release ();
-}
-
-/* Fix up the state of registers and memory after having single-stepped
-   a displaced instruction.  */
-static void
-s390_displaced_step_fixup (struct gdbarch *gdbarch,
-			   struct displaced_step_closure *closure_,
-			   CORE_ADDR from, CORE_ADDR to,
-			   struct regcache *regs)
-{
-  /* Our closure is a copy of the instruction.  */
-  s390_displaced_step_closure *closure
-    = (s390_displaced_step_closure *) closure_;
-  gdb_byte *insn = closure->buf.data ();
-  static int s390_instrlen[] = { 2, 4, 4, 6 };
-  int insnlen = s390_instrlen[insn[0] >> 6];
-
-  /* Fields for various kinds of instructions.  */
-  unsigned int b2, r1, r2, x2, r3;
-  int i2, d2;
-
-  /* Get current PC and addressing mode bit.  */
-  CORE_ADDR pc = regcache_read_pc (regs);
-  ULONGEST amode = 0;
-
-  if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)
-    {
-      regcache_cooked_read_unsigned (regs, S390_PSWA_REGNUM, &amode);
-      amode &= 0x80000000;
-    }
-
-  if (debug_displaced)
-    fprintf_unfiltered (gdb_stdlog,
-			"displaced: (s390) fixup (%s, %s) pc %s len %d amode 0x%x\n",
-			paddress (gdbarch, from), paddress (gdbarch, to),
-			paddress (gdbarch, pc), insnlen, (int) amode);
-
-  /* Handle absolute branch and save instructions.  */
-  if (is_rr (insn, op_basr, &r1, &r2)
-      || is_rx (insn, op_bas, &r1, &d2, &x2, &b2))
-    {
-      /* Recompute saved return address in R1.  */
-      regcache_cooked_write_unsigned (regs, S390_R0_REGNUM + r1,
-				      amode | (from + insnlen));
-    }
-
-  /* Handle absolute branch instructions.  */
-  else if (is_rr (insn, op_bcr, &r1, &r2)
-	   || is_rx (insn, op_bc, &r1, &d2, &x2, &b2)
-	   || is_rr (insn, op_bctr, &r1, &r2)
-	   || is_rre (insn, op_bctgr, &r1, &r2)
-	   || is_rx (insn, op_bct, &r1, &d2, &x2, &b2)
-	   || is_rxy (insn, op1_bctg, op2_brctg, &r1, &d2, &x2, &b2)
-	   || is_rs (insn, op_bxh, &r1, &r3, &d2, &b2)
-	   || is_rsy (insn, op1_bxhg, op2_bxhg, &r1, &r3, &d2, &b2)
-	   || is_rs (insn, op_bxle, &r1, &r3, &d2, &b2)
-	   || is_rsy (insn, op1_bxleg, op2_bxleg, &r1, &r3, &d2, &b2))
-    {
-      /* Update PC iff branch was *not* taken.  */
-      if (pc == to + insnlen)
-	regcache_write_pc (regs, from + insnlen);
-    }
-
-  /* Handle PC-relative branch and save instructions.  */
-  else if (is_ri (insn, op1_bras, op2_bras, &r1, &i2)
-	   || is_ril (insn, op1_brasl, op2_brasl, &r1, &i2))
-    {
-      /* Update PC.  */
-      regcache_write_pc (regs, pc - to + from);
-      /* Recompute saved return address in R1.  */
-      regcache_cooked_write_unsigned (regs, S390_R0_REGNUM + r1,
-				      amode | (from + insnlen));
-    }
-
-  /* Handle LOAD ADDRESS RELATIVE LONG.  */
-  else if (is_ril (insn, op1_larl, op2_larl, &r1, &i2))
-    {
-      /* Update PC.  */
-      regcache_write_pc (regs, from + insnlen);
-      /* Recompute output address in R1.  */
-      regcache_cooked_write_unsigned (regs, S390_R0_REGNUM + r1,
-				      amode | (from + i2 * 2));
-    }
-
-  /* If we executed a breakpoint instruction, point PC right back at it.  */
-  else if (insn[0] == 0x0 && insn[1] == 0x1)
-    regcache_write_pc (regs, from);
-
-  /* For any other insn, adjust PC by negated displacement.  PC then
-     points right after the original instruction, except for PC-relative
-     branches, where it points to the adjusted branch target.  */
-  else
-    regcache_write_pc (regs, pc - to + from);
-
-  if (debug_displaced)
-    fprintf_unfiltered (gdb_stdlog,
-			"displaced: (s390) pc is now %s\n",
-			paddress (gdbarch, regcache_read_pc (regs)));
-}
-
-
-/* Helper routine to unwind pseudo registers.  */
-
-static struct value *
-s390_unwind_pseudo_register (struct frame_info *this_frame, int regnum)
-{
-  struct gdbarch *gdbarch = get_frame_arch (this_frame);
-  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
-  struct type *type = register_type (gdbarch, regnum);
-
-  /* Unwind PC via PSW address.  */
-  if (regnum == tdep->pc_regnum)
-    {
-      struct value *val;
-
-      val = frame_unwind_register_value (this_frame, S390_PSWA_REGNUM);
-      if (!value_optimized_out (val))
-	{
-	  LONGEST pswa = value_as_long (val);
-
-	  if (TYPE_LENGTH (type) == 4)
-	    return value_from_pointer (type, pswa & 0x7fffffff);
-	  else
-	    return value_from_pointer (type, pswa);
-	}
-    }
-
-  /* Unwind CC via PSW mask.  */
-  if (regnum == tdep->cc_regnum)
-    {
-      struct value *val;
-
-      val = frame_unwind_register_value (this_frame, S390_PSWM_REGNUM);
-      if (!value_optimized_out (val))
-	{
-	  LONGEST pswm = value_as_long (val);
-
-	  if (TYPE_LENGTH (type) == 4)
-	    return value_from_longest (type, (pswm >> 12) & 3);
-	  else
-	    return value_from_longest (type, (pswm >> 44) & 3);
-	}
-    }
-
-  /* Unwind full GPRs to show at least the lower halves (as the
-     upper halves are undefined).  */
-  if (regnum_is_gpr_full (tdep, regnum))
-    {
-      int reg = regnum - tdep->gpr_full_regnum;
-      struct value *val;
-
-      val = frame_unwind_register_value (this_frame, S390_R0_REGNUM + reg);
-      if (!value_optimized_out (val))
-	return value_cast (type, val);
-    }
-
-  return allocate_optimized_out_value (type);
-}
-
 static struct value *
 s390_trad_frame_prev_register (struct frame_info *this_frame,
 			       struct trad_frame_saved_reg saved_regs[],
@@ -3008,597 +1271,7 @@  static const struct frame_base s390_frame_base = {
   s390_local_base_address
 };
 
-static CORE_ADDR
-s390_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
-{
-  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
-  ULONGEST pc;
-  pc = frame_unwind_register_unsigned (next_frame, tdep->pc_regnum);
-  return gdbarch_addr_bits_remove (gdbarch, pc);
-}
-
-static CORE_ADDR
-s390_unwind_sp (struct gdbarch *gdbarch, struct frame_info *next_frame)
-{
-  ULONGEST sp;
-  sp = frame_unwind_register_unsigned (next_frame, S390_SP_REGNUM);
-  return gdbarch_addr_bits_remove (gdbarch, sp);
-}
-
-
-/* DWARF-2 frame support.  */
-
-static struct value *
-s390_dwarf2_prev_register (struct frame_info *this_frame, void **this_cache,
-			   int regnum)
-{
-  return s390_unwind_pseudo_register (this_frame, regnum);
-}
-
-static void
-s390_dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum,
-			    struct dwarf2_frame_state_reg *reg,
-			    struct frame_info *this_frame)
-{
-  /* The condition code (and thus PSW mask) is call-clobbered.  */
-  if (regnum == S390_PSWM_REGNUM)
-    reg->how = DWARF2_FRAME_REG_UNDEFINED;
-
-  /* The PSW address unwinds to the return address.  */
-  else if (regnum == S390_PSWA_REGNUM)
-    reg->how = DWARF2_FRAME_REG_RA;
-
-  /* Fixed registers are call-saved or call-clobbered
-     depending on the ABI in use.  */
-  else if (regnum < S390_NUM_REGS)
-    {
-      if (s390_register_call_saved (gdbarch, regnum))
-	reg->how = DWARF2_FRAME_REG_SAME_VALUE;
-      else
-	reg->how = DWARF2_FRAME_REG_UNDEFINED;
-    }
-
-  /* We install a special function to unwind pseudos.  */
-  else
-    {
-      reg->how = DWARF2_FRAME_REG_FN;
-      reg->loc.fn = s390_dwarf2_prev_register;
-    }
-}
-
-
-/* Dummy function calls.  */
-
-/* Unwrap any single-field structs in TYPE and return the effective
-   "inner" type.  E.g., yield "float" for all these cases:
-
-     float x;
-     struct { float x };
-     struct { struct { float x; } x; };
-     struct { struct { struct { float x; } x; } x; };
-
-   However, if an inner type is smaller than MIN_SIZE, abort the
-   unwrapping.  */
-
-static struct type *
-s390_effective_inner_type (struct type *type, unsigned int min_size)
-{
-  while (TYPE_CODE (type) == TYPE_CODE_STRUCT
-	 && TYPE_NFIELDS (type) == 1)
-    {
-      struct type *inner = check_typedef (TYPE_FIELD_TYPE (type, 0));
-
-      if (TYPE_LENGTH (inner) < min_size)
-	break;
-      type = inner;
-    }
-
-  return type;
-}
-
-/* Return non-zero if TYPE should be passed like "float" or
-   "double".  */
-
-static int
-s390_function_arg_float (struct type *type)
-{
-  /* Note that long double as well as complex types are intentionally
-     excluded. */
-  if (TYPE_LENGTH (type) > 8)
-    return 0;
-
-  /* A struct containing just a float or double is passed like a float
-     or double.  */
-  type = s390_effective_inner_type (type, 0);
-
-  return (TYPE_CODE (type) == TYPE_CODE_FLT
-	  || TYPE_CODE (type) == TYPE_CODE_DECFLOAT);
-}
-
-/* Return non-zero if TYPE should be passed like a vector.  */
-
-static int
-s390_function_arg_vector (struct type *type)
-{
-  if (TYPE_LENGTH (type) > 16)
-    return 0;
-
-  /* Structs containing just a vector are passed like a vector.  */
-  type = s390_effective_inner_type (type, TYPE_LENGTH (type));
-
-  return TYPE_CODE (type) == TYPE_CODE_ARRAY && TYPE_VECTOR (type);
-}
-
-/* Determine whether N is a power of two.  */
 
-static int
-is_power_of_two (unsigned int n)
-{
-  return n && ((n & (n - 1)) == 0);
-}
-
-/* For an argument whose type is TYPE and which is not passed like a
-   float or vector, return non-zero if it should be passed like "int"
-   or "long long".  */
-
-static int
-s390_function_arg_integer (struct type *type)
-{
-  enum type_code code = TYPE_CODE (type);
-
-  if (TYPE_LENGTH (type) > 8)
-    return 0;
-
-  if (code == TYPE_CODE_INT
-      || code == TYPE_CODE_ENUM
-      || code == TYPE_CODE_RANGE
-      || code == TYPE_CODE_CHAR
-      || code == TYPE_CODE_BOOL
-      || code == TYPE_CODE_PTR
-      || TYPE_IS_REFERENCE (type))
-    return 1;
-
-  return ((code == TYPE_CODE_UNION || code == TYPE_CODE_STRUCT)
-	  && is_power_of_two (TYPE_LENGTH (type)));
-}
-
-/* Argument passing state: Internal data structure passed to helper
-   routines of s390_push_dummy_call.  */
-
-struct s390_arg_state
-  {
-    /* Register cache, or NULL, if we are in "preparation mode".  */
-    struct regcache *regcache;
-    /* Next available general/floating-point/vector register for
-       argument passing.  */
-    int gr, fr, vr;
-    /* Current pointer to copy area (grows downwards).  */
-    CORE_ADDR copy;
-    /* Current pointer to parameter area (grows upwards).  */
-    CORE_ADDR argp;
-  };
-
-/* Prepare one argument ARG for a dummy call and update the argument
-   passing state AS accordingly.  If the regcache field in AS is set,
-   operate in "write mode" and write ARG into the inferior.  Otherwise
-   run "preparation mode" and skip all updates to the inferior.  */
-
-static void
-s390_handle_arg (struct s390_arg_state *as, struct value *arg,
-		 struct gdbarch_tdep *tdep, int word_size,
-		 enum bfd_endian byte_order, int is_unnamed)
-{
-  struct type *type = check_typedef (value_type (arg));
-  unsigned int length = TYPE_LENGTH (type);
-  int write_mode = as->regcache != NULL;
-
-  if (s390_function_arg_float (type))
-    {
-      /* The GNU/Linux for S/390 ABI uses FPRs 0 and 2 to pass
-	 arguments.  The GNU/Linux for zSeries ABI uses 0, 2, 4, and
-	 6.  */
-      if (as->fr <= (tdep->abi == ABI_LINUX_S390 ? 2 : 6))
-	{
-	  /* When we store a single-precision value in an FP register,
-	     it occupies the leftmost bits.  */
-	  if (write_mode)
-	    regcache_cooked_write_part (as->regcache,
-					S390_F0_REGNUM + as->fr,
-					0, length,
-					value_contents (arg));
-	  as->fr += 2;
-	}
-      else
-	{
-	  /* When we store a single-precision value in a stack slot,
-	     it occupies the rightmost bits.  */
-	  as->argp = align_up (as->argp + length, word_size);
-	  if (write_mode)
-	    write_memory (as->argp - length, value_contents (arg),
-			  length);
-	}
-    }
-  else if (tdep->vector_abi == S390_VECTOR_ABI_128
-	   && s390_function_arg_vector (type))
-    {
-      static const char use_vr[] = {24, 26, 28, 30, 25, 27, 29, 31};
-
-      if (!is_unnamed && as->vr < ARRAY_SIZE (use_vr))
-	{
-	  int regnum = S390_V24_REGNUM + use_vr[as->vr] - 24;
-
-	  if (write_mode)
-	    regcache_cooked_write_part (as->regcache, regnum,
-					0, length,
-					value_contents (arg));
-	  as->vr++;
-	}
-      else
-	{
-	  if (write_mode)
-	    write_memory (as->argp, value_contents (arg), length);
-	  as->argp = align_up (as->argp + length, word_size);
-	}
-    }
-  else if (s390_function_arg_integer (type) && length <= word_size)
-    {
-      /* Initialize it just to avoid a GCC false warning.  */
-      ULONGEST val = 0;
-
-      if (write_mode)
-	{
-	  /* Place value in least significant bits of the register or
-	     memory word and sign- or zero-extend to full word size.
-	     This also applies to a struct or union.  */
-	  val = TYPE_UNSIGNED (type)
-	    ? extract_unsigned_integer (value_contents (arg),
-					length, byte_order)
-	    : extract_signed_integer (value_contents (arg),
-				      length, byte_order);
-	}
-
-      if (as->gr <= 6)
-	{
-	  if (write_mode)
-	    regcache_cooked_write_unsigned (as->regcache,
-					    S390_R0_REGNUM + as->gr,
-					    val);
-	  as->gr++;
-	}
-      else
-	{
-	  if (write_mode)
-	    write_memory_unsigned_integer (as->argp, word_size,
-					   byte_order, val);
-	  as->argp += word_size;
-	}
-    }
-  else if (s390_function_arg_integer (type) && length == 8)
-    {
-      if (as->gr <= 5)
-	{
-	  if (write_mode)
-	    {
-	      regcache_cooked_write (as->regcache,
-				     S390_R0_REGNUM + as->gr,
-				     value_contents (arg));
-	      regcache_cooked_write (as->regcache,
-				     S390_R0_REGNUM + as->gr + 1,
-				     value_contents (arg) + word_size);
-	    }
-	  as->gr += 2;
-	}
-      else
-	{
-	  /* If we skipped r6 because we couldn't fit a DOUBLE_ARG
-	     in it, then don't go back and use it again later.  */
-	  as->gr = 7;
-
-	  if (write_mode)
-	    write_memory (as->argp, value_contents (arg), length);
-	  as->argp += length;
-	}
-    }
-  else
-    {
-      /* This argument type is never passed in registers.  Place the
-	 value in the copy area and pass a pointer to it.  Use 8-byte
-	 alignment as a conservative assumption.  */
-      as->copy = align_down (as->copy - length, 8);
-      if (write_mode)
-	write_memory (as->copy, value_contents (arg), length);
-
-      if (as->gr <= 6)
-	{
-	  if (write_mode)
-	    regcache_cooked_write_unsigned (as->regcache,
-					    S390_R0_REGNUM + as->gr,
-					    as->copy);
-	  as->gr++;
-	}
-      else
-	{
-	  if (write_mode)
-	    write_memory_unsigned_integer (as->argp, word_size,
-					   byte_order, as->copy);
-	  as->argp += word_size;
-	}
-    }
-}
-
-/* Put the actual parameter values pointed to by ARGS[0..NARGS-1] in
-   place to be passed to a function, as specified by the "GNU/Linux
-   for S/390 ELF Application Binary Interface Supplement".
-
-   SP is the current stack pointer.  We must put arguments, links,
-   padding, etc. whereever they belong, and return the new stack
-   pointer value.
-
-   If STRUCT_RETURN is non-zero, then the function we're calling is
-   going to return a structure by value; STRUCT_ADDR is the address of
-   a block we've allocated for it on the stack.
-
-   Our caller has taken care of any type promotions needed to satisfy
-   prototypes or the old K&R argument-passing rules.  */
-
-static CORE_ADDR
-s390_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
-		      struct regcache *regcache, CORE_ADDR bp_addr,
-		      int nargs, struct value **args, CORE_ADDR sp,
-		      int struct_return, CORE_ADDR struct_addr)
-{
-  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
-  int word_size = gdbarch_ptr_bit (gdbarch) / 8;
-  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
-  int i;
-  struct s390_arg_state arg_state, arg_prep;
-  CORE_ADDR param_area_start, new_sp;
-  struct type *ftype = check_typedef (value_type (function));
-
-  if (TYPE_CODE (ftype) == TYPE_CODE_PTR)
-    ftype = check_typedef (TYPE_TARGET_TYPE (ftype));
-
-  arg_prep.copy = sp;
-  arg_prep.gr = struct_return ? 3 : 2;
-  arg_prep.fr = 0;
-  arg_prep.vr = 0;
-  arg_prep.argp = 0;
-  arg_prep.regcache = NULL;
-
-  /* Initialize arg_state for "preparation mode".  */
-  arg_state = arg_prep;
-
-  /* Update arg_state.copy with the start of the reference-to-copy area
-     and arg_state.argp with the size of the parameter area.  */
-  for (i = 0; i < nargs; i++)
-    s390_handle_arg (&arg_state, args[i], tdep, word_size, byte_order,
-		     TYPE_VARARGS (ftype) && i >= TYPE_NFIELDS (ftype));
-
-  param_area_start = align_down (arg_state.copy - arg_state.argp, 8);
-
-  /* Allocate the standard frame areas: the register save area, the
-     word reserved for the compiler, and the back chain pointer.  */
-  new_sp = param_area_start - (16 * word_size + 32);
-
-  /* Now we have the final stack pointer.  Make sure we didn't
-     underflow; on 31-bit, this would result in addresses with the
-     high bit set, which causes confusion elsewhere.  Note that if we
-     error out here, stack and registers remain untouched.  */
-  if (gdbarch_addr_bits_remove (gdbarch, new_sp) != new_sp)
-    error (_("Stack overflow"));
-
-  /* Pass the structure return address in general register 2.  */
-  if (struct_return)
-    regcache_cooked_write_unsigned (regcache, S390_R2_REGNUM, struct_addr);
-
-  /* Initialize arg_state for "write mode".  */
-  arg_state = arg_prep;
-  arg_state.argp = param_area_start;
-  arg_state.regcache = regcache;
-
-  /* Write all parameters.  */
-  for (i = 0; i < nargs; i++)
-    s390_handle_arg (&arg_state, args[i], tdep, word_size, byte_order,
-		     TYPE_VARARGS (ftype) && i >= TYPE_NFIELDS (ftype));
-
-  /* Store return PSWA.  In 31-bit mode, keep addressing mode bit.  */
-  if (word_size == 4)
-    {
-      ULONGEST pswa;
-      regcache_cooked_read_unsigned (regcache, S390_PSWA_REGNUM, &pswa);
-      bp_addr = (bp_addr & 0x7fffffff) | (pswa & 0x80000000);
-    }
-  regcache_cooked_write_unsigned (regcache, S390_RETADDR_REGNUM, bp_addr);
-
-  /* Store updated stack pointer.  */
-  regcache_cooked_write_unsigned (regcache, S390_SP_REGNUM, new_sp);
-
-  /* We need to return the 'stack part' of the frame ID,
-     which is actually the top of the register save area.  */
-  return param_area_start;
-}
-
-/* Assuming THIS_FRAME is a dummy, return the frame ID of that
-   dummy frame.  The frame ID's base needs to match the TOS value
-   returned by push_dummy_call, and the PC match the dummy frame's
-   breakpoint.  */
-static struct frame_id
-s390_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
-{
-  int word_size = gdbarch_ptr_bit (gdbarch) / 8;
-  CORE_ADDR sp = get_frame_register_unsigned (this_frame, S390_SP_REGNUM);
-  sp = gdbarch_addr_bits_remove (gdbarch, sp);
-
-  return frame_id_build (sp + 16*word_size + 32,
-			 get_frame_pc (this_frame));
-}
-
-static CORE_ADDR
-s390_frame_align (struct gdbarch *gdbarch, CORE_ADDR addr)
-{
-  /* Both the 32- and 64-bit ABI's say that the stack pointer should
-     always be aligned on an eight-byte boundary.  */
-  return (addr & -8);
-}
-
-
-/* Helper for s390_return_value: Set or retrieve a function return
-   value if it resides in a register.  */
-
-static void
-s390_register_return_value (struct gdbarch *gdbarch, struct type *type,
-			    struct regcache *regcache,
-			    gdb_byte *out, const gdb_byte *in)
-{
-  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
-  int word_size = gdbarch_ptr_bit (gdbarch) / 8;
-  int length = TYPE_LENGTH (type);
-  int code = TYPE_CODE (type);
-
-  if (code == TYPE_CODE_FLT || code == TYPE_CODE_DECFLOAT)
-    {
-      /* Float-like value: left-aligned in f0.  */
-      if (in != NULL)
-	regcache_cooked_write_part (regcache, S390_F0_REGNUM,
-				    0, length, in);
-      else
-	regcache_cooked_read_part (regcache, S390_F0_REGNUM,
-				   0, length, out);
-    }
-  else if (code == TYPE_CODE_ARRAY)
-    {
-      /* Vector: left-aligned in v24.  */
-      if (in != NULL)
-	regcache_cooked_write_part (regcache, S390_V24_REGNUM,
-				    0, length, in);
-      else
-	regcache_cooked_read_part (regcache, S390_V24_REGNUM,
-				   0, length, out);
-    }
-  else if (length <= word_size)
-    {
-      /* Integer: zero- or sign-extended in r2.  */
-      if (out != NULL)
-	regcache_cooked_read_part (regcache, S390_R2_REGNUM,
-				   word_size - length, length, out);
-      else if (TYPE_UNSIGNED (type))
-	regcache_cooked_write_unsigned
-	  (regcache, S390_R2_REGNUM,
-	   extract_unsigned_integer (in, length, byte_order));
-      else
-	regcache_cooked_write_signed
-	  (regcache, S390_R2_REGNUM,
-	   extract_signed_integer (in, length, byte_order));
-    }
-  else if (length == 2 * word_size)
-    {
-      /* Double word: in r2 and r3.  */
-      if (in != NULL)
-	{
-	  regcache_cooked_write (regcache, S390_R2_REGNUM, in);
-	  regcache_cooked_write (regcache, S390_R3_REGNUM,
-				 in + word_size);
-	}
-      else
-	{
-	  regcache_cooked_read (regcache, S390_R2_REGNUM, out);
-	  regcache_cooked_read (regcache, S390_R3_REGNUM,
-				out + word_size);
-	}
-    }
-  else
-    internal_error (__FILE__, __LINE__, _("invalid return type"));
-}
-
-
-/* Implement the 'return_value' gdbarch method.  */
-
-static enum return_value_convention
-s390_return_value (struct gdbarch *gdbarch, struct value *function,
-		   struct type *type, struct regcache *regcache,
-		   gdb_byte *out, const gdb_byte *in)
-{
-  enum return_value_convention rvc;
-
-  type = check_typedef (type);
-
-  switch (TYPE_CODE (type))
-    {
-    case TYPE_CODE_STRUCT:
-    case TYPE_CODE_UNION:
-    case TYPE_CODE_COMPLEX:
-      rvc = RETURN_VALUE_STRUCT_CONVENTION;
-      break;
-    case TYPE_CODE_ARRAY:
-      rvc = (gdbarch_tdep (gdbarch)->vector_abi == S390_VECTOR_ABI_128
-	     && TYPE_LENGTH (type) <= 16 && TYPE_VECTOR (type))
-	? RETURN_VALUE_REGISTER_CONVENTION
-	: RETURN_VALUE_STRUCT_CONVENTION;
-      break;
-    default:
-      rvc = TYPE_LENGTH (type) <= 8
-	? RETURN_VALUE_REGISTER_CONVENTION
-	: RETURN_VALUE_STRUCT_CONVENTION;
-    }
-
-  if (in != NULL || out != NULL)
-    {
-      if (rvc == RETURN_VALUE_REGISTER_CONVENTION)
-	s390_register_return_value (gdbarch, type, regcache, out, in);
-      else if (in != NULL)
-	error (_("Cannot set function return value."));
-      else
-	error (_("Function return value unknown."));
-    }
-
-  return rvc;
-}
-
-
-/* Breakpoints.  */
-constexpr gdb_byte s390_break_insn[] = { 0x0, 0x1 };
-
-typedef BP_MANIPULATION (s390_break_insn) s390_breakpoint;
-
-/* Address handling.  */
-
-static CORE_ADDR
-s390_addr_bits_remove (struct gdbarch *gdbarch, CORE_ADDR addr)
-{
-  return addr & 0x7fffffff;
-}
-
-static int
-s390_address_class_type_flags (int byte_size, int dwarf2_addr_class)
-{
-  if (byte_size == 4)
-    return TYPE_INSTANCE_FLAG_ADDRESS_CLASS_1;
-  else
-    return 0;
-}
-
-static const char *
-s390_address_class_type_flags_to_name (struct gdbarch *gdbarch, int type_flags)
-{
-  if (type_flags & TYPE_INSTANCE_FLAG_ADDRESS_CLASS_1)
-    return "mode32";
-  else
-    return NULL;
-}
-
-static int
-s390_address_class_name_to_type_flags (struct gdbarch *gdbarch,
-				       const char *name,
-				       int *type_flags_ptr)
-{
-  if (strcmp (name, "mode32") == 0)
-    {
-      *type_flags_ptr = TYPE_INSTANCE_FLAG_ADDRESS_CLASS_1;
-      return 1;
-    }
-  else
-    return 0;
-}
 
 /* Implement gdbarch_gcc_target_options.  GCC does not know "-m32" or
    "-mcmodel=large".  */
@@ -7805,376 +5478,52 @@  s390_init_linux_record_tdep (struct linux_record_tdep *record_tdep,
   record_tdep->ioctl_FIOQSIZE = 0x545e;
 }
 
-/* Set up gdbarch struct.  */
+
+/* Set up GNU/Linux gdbarch.  Allocates struct gdbarch if needed.  */
 
 static struct gdbarch *
-s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
+s390_linux_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 {
   const struct target_desc *tdesc = info.target_desc;
-  struct tdesc_arch_data *tdesc_data = NULL;
-  struct gdbarch *gdbarch;
   struct gdbarch_tdep *tdep;
-  enum s390_abi_kind tdep_abi;
-  enum s390_vector_abi_kind vector_abi;
-  int have_upper = 0;
-  int have_linux_v1 = 0;
-  int have_linux_v2 = 0;
-  int have_tdb = 0;
-  int have_vx = 0;
-  int have_gs = 0;
-  int first_pseudo_reg, last_pseudo_reg;
-  static const char *const stap_register_prefixes[] = { "%", NULL };
-  static const char *const stap_register_indirection_prefixes[] = { "(",
-								    NULL };
-  static const char *const stap_register_indirection_suffixes[] = { ")",
-								    NULL };
-
-  /* Default ABI and register size.  */
-  switch (info.bfd_arch_info->mach)
-    {
-    case bfd_mach_s390_31:
-      tdep_abi = ABI_LINUX_S390;
-      break;
-
-    case bfd_mach_s390_64:
-      tdep_abi = ABI_LINUX_ZSERIES;
-      break;
-
-    default:
-      return NULL;
-    }
+  struct gdbarch *gdbarch;
 
   /* Use default target description if none provided by the target.  */
   if (!tdesc_has_registers (tdesc))
     {
-      if (tdep_abi == ABI_LINUX_S390)
+      if (info.bfd_arch_info->mach == bfd_mach_s390_31)
 	tdesc = tdesc_s390_linux32;
-      else
+      else if (info.bfd_arch_info->mach == bfd_mach_s390_64)
 	tdesc = tdesc_s390x_linux64;
-    }
-
-  /* Check any target description for validity.  */
-  if (tdesc_has_registers (tdesc))
-    {
-      static const char *const gprs[] = {
-	"r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
-	"r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15"
-      };
-      static const char *const fprs[] = {
-	"f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7",
-	"f8", "f9", "f10", "f11", "f12", "f13", "f14", "f15"
-      };
-      static const char *const acrs[] = {
-	"acr0", "acr1", "acr2", "acr3", "acr4", "acr5", "acr6", "acr7",
-	"acr8", "acr9", "acr10", "acr11", "acr12", "acr13", "acr14", "acr15"
-      };
-      static const char *const gprs_lower[] = {
-	"r0l", "r1l", "r2l", "r3l", "r4l", "r5l", "r6l", "r7l",
-	"r8l", "r9l", "r10l", "r11l", "r12l", "r13l", "r14l", "r15l"
-      };
-      static const char *const gprs_upper[] = {
-	"r0h", "r1h", "r2h", "r3h", "r4h", "r5h", "r6h", "r7h",
-	"r8h", "r9h", "r10h", "r11h", "r12h", "r13h", "r14h", "r15h"
-      };
-      static const char *const tdb_regs[] = {
-	"tdb0", "tac", "tct", "atia",
-	"tr0", "tr1", "tr2", "tr3", "tr4", "tr5", "tr6", "tr7",
-	"tr8", "tr9", "tr10", "tr11", "tr12", "tr13", "tr14", "tr15"
-      };
-      static const char *const vxrs_low[] = {
-	"v0l", "v1l", "v2l", "v3l", "v4l", "v5l", "v6l", "v7l", "v8l",
-	"v9l", "v10l", "v11l", "v12l", "v13l", "v14l", "v15l",
-      };
-      static const char *const vxrs_high[] = {
-	"v16", "v17", "v18", "v19", "v20", "v21", "v22", "v23", "v24",
-	"v25", "v26", "v27", "v28", "v29", "v30", "v31",
-      };
-      static const char *const gs_cb[] = {
-	"gsd", "gssm", "gsepla",
-      };
-      static const char *const gs_bc[] = {
-	"bc_gsd", "bc_gssm", "bc_gsepla",
-      };
-      const struct tdesc_feature *feature;
-      int i, valid_p = 1;
-
-      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.core");
-      if (feature == NULL)
-	return NULL;
-
-      tdesc_data = tdesc_data_alloc ();
-
-      valid_p &= tdesc_numbered_register (feature, tdesc_data,
-					  S390_PSWM_REGNUM, "pswm");
-      valid_p &= tdesc_numbered_register (feature, tdesc_data,
-					  S390_PSWA_REGNUM, "pswa");
-
-      if (tdesc_unnumbered_register (feature, "r0"))
-	{
-	  for (i = 0; i < 16; i++)
-	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
-						S390_R0_REGNUM + i, gprs[i]);
-	}
       else
-	{
-	  have_upper = 1;
-
-	  for (i = 0; i < 16; i++)
-	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
-						S390_R0_REGNUM + i,
-						gprs_lower[i]);
-	  for (i = 0; i < 16; i++)
-	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
-						S390_R0_UPPER_REGNUM + i,
-						gprs_upper[i]);
-	}
-
-      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.fpr");
-      if (feature == NULL)
-	{
-	  tdesc_data_cleanup (tdesc_data);
-	  return NULL;
-	}
-
-      valid_p &= tdesc_numbered_register (feature, tdesc_data,
-					  S390_FPC_REGNUM, "fpc");
-      for (i = 0; i < 16; i++)
-	valid_p &= tdesc_numbered_register (feature, tdesc_data,
-					    S390_F0_REGNUM + i, fprs[i]);
-
-      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.acr");
-      if (feature == NULL)
-	{
-	  tdesc_data_cleanup (tdesc_data);
-	  return NULL;
-	}
-
-      for (i = 0; i < 16; i++)
-	valid_p &= tdesc_numbered_register (feature, tdesc_data,
-					    S390_A0_REGNUM + i, acrs[i]);
-
-      /* Optional GNU/Linux-specific "registers".  */
-      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.linux");
-      if (feature)
-	{
-	  tdesc_numbered_register (feature, tdesc_data,
-				   S390_ORIG_R2_REGNUM, "orig_r2");
-
-	  if (tdesc_numbered_register (feature, tdesc_data,
-				       S390_LAST_BREAK_REGNUM, "last_break"))
-	    have_linux_v1 = 1;
-
-	  if (tdesc_numbered_register (feature, tdesc_data,
-				       S390_SYSTEM_CALL_REGNUM, "system_call"))
-	    have_linux_v2 = 1;
-
-	  if (have_linux_v2 > have_linux_v1)
-	    valid_p = 0;
-	}
-
-      /* Transaction diagnostic block.  */
-      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.tdb");
-      if (feature)
-	{
-	  for (i = 0; i < ARRAY_SIZE (tdb_regs); i++)
-	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
-						S390_TDB_DWORD0_REGNUM + i,
-						tdb_regs[i]);
-	  have_tdb = 1;
-	}
-
-      /* Vector registers.  */
-      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.vx");
-      if (feature)
-	{
-	  for (i = 0; i < 16; i++)
-	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
-						S390_V0_LOWER_REGNUM + i,
-						vxrs_low[i]);
-	  for (i = 0; i < 16; i++)
-	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
-						S390_V16_REGNUM + i,
-						vxrs_high[i]);
-	  have_vx = 1;
-	}
-
-      /* Guarded-storage registers.  */
-      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.gs");
-      if (feature)
-	{
-	  for (i = 0; i < 3; i++)
-	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
-						S390_GSD_REGNUM + i,
-						gs_cb[i]);
-	  have_gs = 1;
-	}
-
-      /* Guarded-storage broadcast control.  */
-      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.gsbc");
-      if (feature)
-	{
-	  valid_p &= have_gs;
-
-	  for (i = 0; i < 3; i++)
-	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
-						S390_BC_GSD_REGNUM + i,
-						gs_bc[i]);
-	}
-
-      if (!valid_p)
-	{
-	  tdesc_data_cleanup (tdesc_data);
-	  return NULL;
-	}
+	return NULL;
     }
 
-  /* Determine vector ABI.  */
-  vector_abi = S390_VECTOR_ABI_NONE;
-#ifdef HAVE_ELF
-  if (have_vx
-      && info.abfd != NULL
-      && info.abfd->format == bfd_object
-      && bfd_get_flavour (info.abfd) == bfd_target_elf_flavour
-      && bfd_elf_get_obj_attr_int (info.abfd, OBJ_ATTR_GNU,
-				   Tag_GNU_S390_ABI_Vector) == 2)
-    vector_abi = S390_VECTOR_ABI_128;
-#endif
-
-  /* Find a candidate among extant architectures.  */
-  for (arches = gdbarch_list_lookup_by_info (arches, &info);
-       arches != NULL;
-       arches = gdbarch_list_lookup_by_info (arches->next, &info))
-    {
-      tdep = gdbarch_tdep (arches->gdbarch);
-      if (!tdep)
-	continue;
-      if (tdep->abi != tdep_abi)
-	continue;
-      if (tdep->vector_abi != vector_abi)
-	continue;
-      if ((tdep->gpr_full_regnum != -1) != have_upper)
-	continue;
-      if (tdep->have_gs != have_gs)
-	continue;
-      if (tdesc_data != NULL)
-	tdesc_data_cleanup (tdesc_data);
-      return arches->gdbarch;
-    }
+  gdbarch = s390_gdbarch_init (info, arches, tdesc);
+  if (gdbarch == NULL)
+    return NULL;
 
-  /* Otherwise create a new gdbarch for the specified machine type.  */
-  tdep = XCNEW (struct gdbarch_tdep);
-  tdep->abi = tdep_abi;
-  tdep->vector_abi = vector_abi;
-  tdep->have_linux_v1 = have_linux_v1;
-  tdep->have_linux_v2 = have_linux_v2;
-  tdep->have_tdb = have_tdb;
-  tdep->have_gs = have_gs;
-  gdbarch = gdbarch_alloc (&info, tdep);
-
-  set_gdbarch_believe_pcc_promotion (gdbarch, 0);
-  set_gdbarch_char_signed (gdbarch, 0);
-
-  /* S/390 GNU/Linux uses either 64-bit or 128-bit long doubles.
-     We can safely let them default to 128-bit, since the debug info
-     will give the size of type actually used in each case.  */
-  set_gdbarch_long_double_bit (gdbarch, 128);
-  set_gdbarch_long_double_format (gdbarch, floatformats_ia64_quad);
-
-  /* Amount PC must be decremented by after a breakpoint.  This is
-     often the number of bytes returned by gdbarch_breakpoint_from_pc but not
-     always.  */
-  set_gdbarch_decr_pc_after_break (gdbarch, 2);
-  /* Stack grows downward.  */
-  set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
-  set_gdbarch_breakpoint_kind_from_pc (gdbarch, s390_breakpoint::kind_from_pc);
-  set_gdbarch_sw_breakpoint_from_kind (gdbarch, s390_breakpoint::bp_from_kind);
-  set_gdbarch_software_single_step (gdbarch, s390_software_single_step);
-  set_gdbarch_displaced_step_hw_singlestep (gdbarch, s390_displaced_step_hw_singlestep);
-  set_gdbarch_skip_prologue (gdbarch, s390_skip_prologue);
-  set_gdbarch_stack_frame_destroyed_p (gdbarch, s390_stack_frame_destroyed_p);
-
-  set_gdbarch_num_regs (gdbarch, S390_NUM_REGS);
-  set_gdbarch_sp_regnum (gdbarch, S390_SP_REGNUM);
-  set_gdbarch_fp0_regnum (gdbarch, S390_F0_REGNUM);
-  set_gdbarch_stab_reg_to_regnum (gdbarch, s390_dwarf_reg_to_regnum);
-  set_gdbarch_dwarf2_reg_to_regnum (gdbarch, s390_dwarf_reg_to_regnum);
-  set_gdbarch_value_from_register (gdbarch, s390_value_from_register);
+  tdep = gdbarch_tdep (gdbarch);
+  linux_init_abi (info, gdbarch);
+
+  /* Register handling.  */
   set_gdbarch_core_read_description (gdbarch, s390_core_read_description);
   set_gdbarch_iterate_over_regset_sections (gdbarch,
 					    s390_iterate_over_regset_sections);
-  set_gdbarch_cannot_store_register (gdbarch, s390_cannot_store_register);
-  set_gdbarch_write_pc (gdbarch, s390_write_pc);
   set_gdbarch_guess_tracepoint_registers (gdbarch, s390_guess_tracepoint_registers);
-  set_gdbarch_pseudo_register_read (gdbarch, s390_pseudo_register_read);
-  set_gdbarch_pseudo_register_write (gdbarch, s390_pseudo_register_write);
-  set_tdesc_pseudo_register_name (gdbarch, s390_pseudo_register_name);
-  set_tdesc_pseudo_register_type (gdbarch, s390_pseudo_register_type);
-  set_tdesc_pseudo_register_reggroup_p (gdbarch,
-					s390_pseudo_register_reggroup_p);
-  set_gdbarch_ax_pseudo_register_collect (gdbarch,
-					  s390_ax_pseudo_register_collect);
-  set_gdbarch_ax_pseudo_register_push_stack
-      (gdbarch, s390_ax_pseudo_register_push_stack);
-  set_gdbarch_gen_return_address (gdbarch, s390_gen_return_address);
-  tdesc_use_registers (gdbarch, tdesc, tdesc_data);
-  set_gdbarch_register_name (gdbarch, s390_register_name);
-
-  /* Assign pseudo register numbers.  */
-  first_pseudo_reg = gdbarch_num_regs (gdbarch);
-  last_pseudo_reg = first_pseudo_reg;
-  tdep->gpr_full_regnum = -1;
-  if (have_upper)
-    {
-      tdep->gpr_full_regnum = last_pseudo_reg;
-      last_pseudo_reg += 16;
-    }
-  tdep->v0_full_regnum = -1;
-  if (have_vx)
-    {
-      tdep->v0_full_regnum = last_pseudo_reg;
-      last_pseudo_reg += 16;
-    }
-  tdep->pc_regnum = last_pseudo_reg++;
-  tdep->cc_regnum = last_pseudo_reg++;
-  set_gdbarch_pc_regnum (gdbarch, tdep->pc_regnum);
-  set_gdbarch_num_pseudo_regs (gdbarch, last_pseudo_reg - first_pseudo_reg);
-
-  /* Inferior function calls.  */
-  set_gdbarch_push_dummy_call (gdbarch, s390_push_dummy_call);
-  set_gdbarch_dummy_id (gdbarch, s390_dummy_id);
-  set_gdbarch_frame_align (gdbarch, s390_frame_align);
-  set_gdbarch_return_value (gdbarch, s390_return_value);
 
   /* Syscall handling.  */
   set_gdbarch_get_syscall_number (gdbarch, s390_linux_get_syscall_number);
 
   /* Frame handling.  */
-  dwarf2_frame_set_init_reg (gdbarch, s390_dwarf2_frame_init_reg);
-  dwarf2_frame_set_adjust_regnum (gdbarch, s390_adjust_frame_regnum);
-  dwarf2_append_unwinders (gdbarch);
-  frame_base_append_sniffer (gdbarch, dwarf2_frame_base_sniffer);
   frame_unwind_append_unwinder (gdbarch, &s390_stub_frame_unwind);
   frame_unwind_append_unwinder (gdbarch, &s390_sigtramp_frame_unwind);
   frame_unwind_append_unwinder (gdbarch, &s390_frame_unwind);
   frame_base_set_default (gdbarch, &s390_frame_base);
-  set_gdbarch_unwind_pc (gdbarch, s390_unwind_pc);
-  set_gdbarch_unwind_sp (gdbarch, s390_unwind_sp);
-
-  /* Displaced stepping.  */
-  set_gdbarch_displaced_step_copy_insn (gdbarch,
-					s390_displaced_step_copy_insn);
-  set_gdbarch_displaced_step_fixup (gdbarch, s390_displaced_step_fixup);
-  set_gdbarch_displaced_step_location (gdbarch, linux_displaced_step_location);
-  set_gdbarch_max_insn_length (gdbarch, S390_MAX_INSTR_SIZE);
-
-  /* Note that GNU/Linux is the only OS supported on this
-     platform.  */
-  linux_init_abi (info, gdbarch);
 
   switch (tdep->abi)
     {
     case ABI_LINUX_S390:
-      set_gdbarch_addr_bits_remove (gdbarch, s390_addr_bits_remove);
       set_solib_svr4_fetch_link_map_offsets
 	(gdbarch, svr4_ilp32_fetch_link_map_offsets);
 
@@ -8182,17 +5531,8 @@  s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
       break;
 
     case ABI_LINUX_ZSERIES:
-      set_gdbarch_long_bit (gdbarch, 64);
-      set_gdbarch_long_long_bit (gdbarch, 64);
-      set_gdbarch_ptr_bit (gdbarch, 64);
       set_solib_svr4_fetch_link_map_offsets
 	(gdbarch, svr4_lp64_fetch_link_map_offsets);
-      set_gdbarch_address_class_type_flags (gdbarch,
-					    s390_address_class_type_flags);
-      set_gdbarch_address_class_type_flags_to_name (gdbarch,
-						    s390_address_class_type_flags_to_name);
-      set_gdbarch_address_class_name_to_type_flags (gdbarch,
-						    s390_address_class_name_to_type_flags);
       set_xml_syscall_file_name (gdbarch, XML_SYSCALL_FILENAME_S390X);
       break;
     }
@@ -8203,36 +5543,25 @@  s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   set_gdbarch_fetch_tls_load_module_address (gdbarch,
 					     svr4_fetch_objfile_link_map);
 
-  /* SystemTap functions.  */
-  set_gdbarch_stap_register_prefixes (gdbarch, stap_register_prefixes);
-  set_gdbarch_stap_register_indirection_prefixes (gdbarch,
-					  stap_register_indirection_prefixes);
-  set_gdbarch_stap_register_indirection_suffixes (gdbarch,
-					  stap_register_indirection_suffixes);
   set_gdbarch_stap_is_single_operand (gdbarch, s390_stap_is_single_operand);
   set_gdbarch_gcc_target_options (gdbarch, s390_gcc_target_options);
   set_gdbarch_gnu_triplet_regexp (gdbarch, s390_gnu_triplet_regexp);
 
   /* Support reverse debugging.  */
-
   set_gdbarch_process_record (gdbarch, s390_process_record);
   set_gdbarch_process_record_signal (gdbarch, s390_linux_record_signal);
 
   s390_init_linux_record_tdep (&s390_linux_record_tdep, ABI_LINUX_S390);
   s390_init_linux_record_tdep (&s390x_linux_record_tdep, ABI_LINUX_ZSERIES);
 
-  set_gdbarch_disassembler_options (gdbarch, &s390_disassembler_options);
-  set_gdbarch_valid_disassembler_options (gdbarch,
-					  disassembler_options_s390 ());
-
   return gdbarch;
 }
 
 void
-_initialize_s390_tdep (void)
+_initialize_s390_linux_tdep (void)
 {
   /* Hook us into the gdbarch mechanism.  */
-  register_gdbarch_init (bfd_arch_s390, s390_gdbarch_init);
+  register_gdbarch_init (bfd_arch_s390, s390_linux_gdbarch_init);
 
   /* Initialize the GNU/Linux target descriptions.  */
   initialize_tdesc_s390_linux32 ();
diff --git a/gdb/s390-linux-tdep.h b/gdb/s390-linux-tdep.h
index e8955300c5..50ecdb6189 100644
--- a/gdb/s390-linux-tdep.h
+++ b/gdb/s390-linux-tdep.h
@@ -1,4 +1,5 @@ 
-/* Target-dependent code for GDB, the GNU debugger.
+/* Target-dependent code for GNU/Linux on s390.
+
    Copyright (C) 2003-2017 Free Software Foundation, Inc.
 
    This file is part of GDB.
@@ -16,198 +17,15 @@ 
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-#ifndef S390_TDEP_H
-#define S390_TDEP_H
-
-/* Hardware capabilities. */
-
-#ifndef HWCAP_S390_HIGH_GPRS
-#define HWCAP_S390_HIGH_GPRS 512
-#endif
-
-#ifndef HWCAP_S390_TE
-#define HWCAP_S390_TE 1024
-#endif
-
-#ifndef HWCAP_S390_VX
-#define HWCAP_S390_VX 2048
-#endif
-
-#ifndef HWCAP_S390_GS
-#define HWCAP_S390_GS 16384
-#endif
-
-/* Register information.  */
-
-/* Program Status Word.  */
-#define S390_PSWM_REGNUM 0
-#define S390_PSWA_REGNUM 1
-/* General Purpose Registers.  */
-#define S390_R0_REGNUM 2
-#define S390_R1_REGNUM 3
-#define S390_R2_REGNUM 4
-#define S390_R3_REGNUM 5
-#define S390_R4_REGNUM 6
-#define S390_R5_REGNUM 7
-#define S390_R6_REGNUM 8
-#define S390_R7_REGNUM 9
-#define S390_R8_REGNUM 10
-#define S390_R9_REGNUM 11
-#define S390_R10_REGNUM 12
-#define S390_R11_REGNUM 13
-#define S390_R12_REGNUM 14
-#define S390_R13_REGNUM 15
-#define S390_R14_REGNUM 16
-#define S390_R15_REGNUM 17
-/* Access Registers.  */
-#define S390_A0_REGNUM 18
-#define S390_A1_REGNUM 19
-#define S390_A2_REGNUM 20
-#define S390_A3_REGNUM 21
-#define S390_A4_REGNUM 22
-#define S390_A5_REGNUM 23
-#define S390_A6_REGNUM 24
-#define S390_A7_REGNUM 25
-#define S390_A8_REGNUM 26
-#define S390_A9_REGNUM 27
-#define S390_A10_REGNUM 28
-#define S390_A11_REGNUM 29
-#define S390_A12_REGNUM 30
-#define S390_A13_REGNUM 31
-#define S390_A14_REGNUM 32
-#define S390_A15_REGNUM 33
-/* Floating Point Control Word.  */
-#define S390_FPC_REGNUM 34
-/* Floating Point Registers.  */
-#define S390_F0_REGNUM 35
-#define S390_F1_REGNUM 36
-#define S390_F2_REGNUM 37
-#define S390_F3_REGNUM 38
-#define S390_F4_REGNUM 39
-#define S390_F5_REGNUM 40
-#define S390_F6_REGNUM 41
-#define S390_F7_REGNUM 42
-#define S390_F8_REGNUM 43
-#define S390_F9_REGNUM 44
-#define S390_F10_REGNUM 45
-#define S390_F11_REGNUM 46
-#define S390_F12_REGNUM 47
-#define S390_F13_REGNUM 48
-#define S390_F14_REGNUM 49
-#define S390_F15_REGNUM 50
-/* General Purpose Register Upper Halves.  */
-#define S390_R0_UPPER_REGNUM 51
-#define S390_R1_UPPER_REGNUM 52
-#define S390_R2_UPPER_REGNUM 53
-#define S390_R3_UPPER_REGNUM 54
-#define S390_R4_UPPER_REGNUM 55
-#define S390_R5_UPPER_REGNUM 56
-#define S390_R6_UPPER_REGNUM 57
-#define S390_R7_UPPER_REGNUM 58
-#define S390_R8_UPPER_REGNUM 59
-#define S390_R9_UPPER_REGNUM 60
-#define S390_R10_UPPER_REGNUM 61
-#define S390_R11_UPPER_REGNUM 62
-#define S390_R12_UPPER_REGNUM 63
-#define S390_R13_UPPER_REGNUM 64
-#define S390_R14_UPPER_REGNUM 65
-#define S390_R15_UPPER_REGNUM 66
-/* GNU/Linux-specific optional registers.  */
-#define S390_ORIG_R2_REGNUM 67
-#define S390_LAST_BREAK_REGNUM 68
-#define S390_SYSTEM_CALL_REGNUM 69
-/* Transaction diagnostic block.  */
-#define S390_TDB_DWORD0_REGNUM 70
-#define S390_TDB_ABORT_CODE_REGNUM 71
-#define S390_TDB_CONFLICT_TOKEN_REGNUM 72
-#define S390_TDB_ATIA_REGNUM 73
-#define S390_TDB_R0_REGNUM 74
-#define S390_TDB_R1_REGNUM 75
-#define S390_TDB_R2_REGNUM 76
-#define S390_TDB_R3_REGNUM 77
-#define S390_TDB_R4_REGNUM 78
-#define S390_TDB_R5_REGNUM 79
-#define S390_TDB_R6_REGNUM 80
-#define S390_TDB_R7_REGNUM 81
-#define S390_TDB_R8_REGNUM 82
-#define S390_TDB_R9_REGNUM 83
-#define S390_TDB_R10_REGNUM 84
-#define S390_TDB_R11_REGNUM 85
-#define S390_TDB_R12_REGNUM 86
-#define S390_TDB_R13_REGNUM 87
-#define S390_TDB_R14_REGNUM 88
-#define S390_TDB_R15_REGNUM 89
-/* Vector registers.  */
-#define S390_V0_LOWER_REGNUM 90
-#define S390_V1_LOWER_REGNUM 91
-#define S390_V2_LOWER_REGNUM 92
-#define S390_V3_LOWER_REGNUM 93
-#define S390_V4_LOWER_REGNUM 94
-#define S390_V5_LOWER_REGNUM 95
-#define S390_V6_LOWER_REGNUM 96
-#define S390_V7_LOWER_REGNUM 97
-#define S390_V8_LOWER_REGNUM 98
-#define S390_V9_LOWER_REGNUM 99
-#define S390_V10_LOWER_REGNUM 100
-#define S390_V11_LOWER_REGNUM 101
-#define S390_V12_LOWER_REGNUM 102
-#define S390_V13_LOWER_REGNUM 103
-#define S390_V14_LOWER_REGNUM 104
-#define S390_V15_LOWER_REGNUM 105
-#define S390_V16_REGNUM 106
-#define S390_V17_REGNUM 107
-#define S390_V18_REGNUM 108
-#define S390_V19_REGNUM 109
-#define S390_V20_REGNUM 110
-#define S390_V21_REGNUM 111
-#define S390_V22_REGNUM 112
-#define S390_V23_REGNUM 113
-#define S390_V24_REGNUM 114
-#define S390_V25_REGNUM 115
-#define S390_V26_REGNUM 116
-#define S390_V27_REGNUM 117
-#define S390_V28_REGNUM 118
-#define S390_V29_REGNUM 119
-#define S390_V30_REGNUM 120
-#define S390_V31_REGNUM 121
-#define S390_GSD_REGNUM 122
-#define S390_GSSM_REGNUM 123
-#define S390_GSEPLA_REGNUM 124
-#define S390_BC_GSD_REGNUM 125
-#define S390_BC_GSSM_REGNUM 126
-#define S390_BC_GSEPLA_REGNUM 127
-/* Total.  */
-#define S390_NUM_REGS 128
-
-/* Special register usage.  */
-#define S390_SP_REGNUM S390_R15_REGNUM
-#define S390_RETADDR_REGNUM S390_R14_REGNUM
-#define S390_FRAME_REGNUM S390_R11_REGNUM
-
-#define S390_IS_GREGSET_REGNUM(i)					\
-  (((i) >= S390_PSWM_REGNUM && (i) <= S390_A15_REGNUM)			\
-   || ((i) >= S390_R0_UPPER_REGNUM && (i) <= S390_R15_UPPER_REGNUM)	\
-   || (i) == S390_ORIG_R2_REGNUM)
-
-#define S390_IS_FPREGSET_REGNUM(i)			\
-  ((i) >= S390_FPC_REGNUM && (i) <= S390_F15_REGNUM)
-
-#define S390_IS_TDBREGSET_REGNUM(i)				\
-  ((i) >= S390_TDB_DWORD0_REGNUM && (i) <= S390_TDB_R15_REGNUM)
+#ifndef S390_LINUX_TDEP_H
+#define S390_LINUX_TDEP_H
 
-/* Core file register sets, defined in s390-tdep.c.  */
-#define s390_sizeof_gregset 0x90
-#define s390x_sizeof_gregset 0xd8
-extern const struct regset s390_gregset;
-#define s390_sizeof_fpregset 0x88
-extern const struct regset s390_fpregset;
+/* Register sets, defined in s390-linux-tdep.c.  */
 extern const struct regset s390_last_break_regset;
 extern const struct regset s390x_last_break_regset;
 extern const struct regset s390_system_call_regset;
 extern const struct regset s390_tdb_regset;
 #define s390_sizeof_tdbregset 0x100
-extern const struct regset s390_vxrs_low_regset;
-extern const struct regset s390_vxrs_high_regset;
 extern const struct regset s390_gs_regset;
 extern const struct regset s390_gsbc_regset;
 
@@ -230,4 +48,4 @@  extern struct target_desc *tdesc_s390x_vx_linux64;
 extern struct target_desc *tdesc_s390x_tevx_linux64;
 extern struct target_desc *tdesc_s390x_gs_linux64;
 
-#endif
+#endif /* S390_LINUX_TDEP_H */
diff --git a/gdb/s390-tdep.c b/gdb/s390-tdep.c
new file mode 100644
index 0000000000..849ddc7cfa
--- /dev/null
+++ b/gdb/s390-tdep.c
@@ -0,0 +1,2607 @@ 
+/* Target-dependent code for s390.
+
+   Copyright (C) 2001-2017 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "defs.h"
+
+#include "arch-utils.h"
+#include "ax-gdb.h"
+#include "dis-asm.h"
+#include "dwarf2-frame.h"
+#include "elf/s390.h"
+#include "elf-bfd.h"
+#include "frame-base.h"
+#include "gdbarch.h"
+#include "gdbcore.h"
+#include "infrun.h"
+#include "linux-tdep.h"
+#include "record-full.h"
+#include "regcache.h"
+#include "reggroups.h"
+#include "regset.h"
+#include "s390-tdep.h"
+#include "target-descriptions.h"
+#include "value.h"
+
+/* Holds the current set of options to be passed to the disassembler.  */
+static char *s390_disassembler_options;
+
+/* Breakpoints.  */
+constexpr gdb_byte s390_break_insn[] = { 0x0, 0x1 };
+
+typedef BP_MANIPULATION (s390_break_insn) s390_breakpoint;
+
+/* Decoding S/390 instructions.  */
+
+/* See s390-tdep.h.  */
+
+int
+s390_readinstruction (bfd_byte instr[], CORE_ADDR at)
+{
+  static int s390_instrlen[] = { 2, 4, 4, 6 };
+  int instrlen;
+
+  if (target_read_memory (at, &instr[0], 2))
+    return -1;
+  instrlen = s390_instrlen[instr[0] >> 6];
+  if (instrlen > 2)
+    {
+      if (target_read_memory (at + 2, &instr[2], instrlen - 2))
+	return -1;
+    }
+  return instrlen;
+}
+
+/* The functions below are for recognizing and decoding S/390
+   instructions of various formats.  Each of them checks whether INSN
+   is an instruction of the given format, with the specified opcodes.
+   If it is, it sets the remaining arguments to the values of the
+   instruction's fields, and returns a non-zero value; otherwise, it
+   returns zero.
+
+   These functions' arguments appear in the order they appear in the
+   instruction, not in the machine-language form.  So, opcodes always
+   come first, even though they're sometimes scattered around the
+   instructions.  And displacements appear before base and extension
+   registers, as they do in the assembly syntax, not at the end, as
+   they do in the machine language.  */
+
+static int
+is_ri (bfd_byte *insn, int op1, int op2, unsigned int *r1, int *i2)
+{
+  if (insn[0] == op1 && (insn[1] & 0xf) == op2)
+    {
+      *r1 = (insn[1] >> 4) & 0xf;
+      /* i2 is a 16-bit signed quantity.  */
+      *i2 = (((insn[2] << 8) | insn[3]) ^ 0x8000) - 0x8000;
+      return 1;
+    }
+  else
+    return 0;
+}
+
+
+static int
+is_ril (bfd_byte *insn, int op1, int op2,
+	unsigned int *r1, int *i2)
+{
+  if (insn[0] == op1 && (insn[1] & 0xf) == op2)
+    {
+      *r1 = (insn[1] >> 4) & 0xf;
+      /* i2 is a signed quantity.  If the host 'int' is 32 bits long,
+	 no sign extension is necessary, but we don't want to assume
+	 that.  */
+      *i2 = (((insn[2] << 24)
+	      | (insn[3] << 16)
+	      | (insn[4] << 8)
+	      | (insn[5])) ^ 0x80000000) - 0x80000000;
+      return 1;
+    }
+  else
+    return 0;
+}
+
+
+static int
+is_rr (bfd_byte *insn, int op, unsigned int *r1, unsigned int *r2)
+{
+  if (insn[0] == op)
+    {
+      *r1 = (insn[1] >> 4) & 0xf;
+      *r2 = insn[1] & 0xf;
+      return 1;
+    }
+  else
+    return 0;
+}
+
+
+static int
+is_rre (bfd_byte *insn, int op, unsigned int *r1, unsigned int *r2)
+{
+  if (((insn[0] << 8) | insn[1]) == op)
+    {
+      /* Yes, insn[3].  insn[2] is unused in RRE format.  */
+      *r1 = (insn[3] >> 4) & 0xf;
+      *r2 = insn[3] & 0xf;
+      return 1;
+    }
+  else
+    return 0;
+}
+
+
+static int
+is_rs (bfd_byte *insn, int op,
+       unsigned int *r1, unsigned int *r3, int *d2, unsigned int *b2)
+{
+  if (insn[0] == op)
+    {
+      *r1 = (insn[1] >> 4) & 0xf;
+      *r3 = insn[1] & 0xf;
+      *b2 = (insn[2] >> 4) & 0xf;
+      *d2 = ((insn[2] & 0xf) << 8) | insn[3];
+      return 1;
+    }
+  else
+    return 0;
+}
+
+
+static int
+is_rsy (bfd_byte *insn, int op1, int op2,
+	unsigned int *r1, unsigned int *r3, int *d2, unsigned int *b2)
+{
+  if (insn[0] == op1
+      && insn[5] == op2)
+    {
+      *r1 = (insn[1] >> 4) & 0xf;
+      *r3 = insn[1] & 0xf;
+      *b2 = (insn[2] >> 4) & 0xf;
+      /* The 'long displacement' is a 20-bit signed integer.  */
+      *d2 = ((((insn[2] & 0xf) << 8) | insn[3] | (insn[4] << 12))
+		^ 0x80000) - 0x80000;
+      return 1;
+    }
+  else
+    return 0;
+}
+
+
+static int
+is_rx (bfd_byte *insn, int op,
+       unsigned int *r1, int *d2, unsigned int *x2, unsigned int *b2)
+{
+  if (insn[0] == op)
+    {
+      *r1 = (insn[1] >> 4) & 0xf;
+      *x2 = insn[1] & 0xf;
+      *b2 = (insn[2] >> 4) & 0xf;
+      *d2 = ((insn[2] & 0xf) << 8) | insn[3];
+      return 1;
+    }
+  else
+    return 0;
+}
+
+
+static int
+is_rxy (bfd_byte *insn, int op1, int op2,
+	unsigned int *r1, int *d2, unsigned int *x2, unsigned int *b2)
+{
+  if (insn[0] == op1
+      && insn[5] == op2)
+    {
+      *r1 = (insn[1] >> 4) & 0xf;
+      *x2 = insn[1] & 0xf;
+      *b2 = (insn[2] >> 4) & 0xf;
+      /* The 'long displacement' is a 20-bit signed integer.  */
+      *d2 = ((((insn[2] & 0xf) << 8) | insn[3] | (insn[4] << 12))
+		^ 0x80000) - 0x80000;
+      return 1;
+    }
+  else
+    return 0;
+}
+
+/* A helper for s390_software_single_step, decides if an instruction
+   is a partial-execution instruction that needs to be executed until
+   completion when in record mode.  If it is, returns 1 and writes
+   instruction length to a pointer.  */
+
+static int
+s390_is_partial_instruction (struct gdbarch *gdbarch, CORE_ADDR loc, int *len)
+{
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  uint16_t insn;
+
+  insn = read_memory_integer (loc, 2, byte_order);
+
+  switch (insn >> 8)
+    {
+    case 0xa8: /* MVCLE */
+      *len = 4;
+      return 1;
+
+    case 0xeb:
+      {
+	insn = read_memory_integer (loc + 4, 2, byte_order);
+	if ((insn & 0xff) == 0x8e)
+	  {
+	    /* MVCLU */
+	    *len = 6;
+	    return 1;
+	  }
+      }
+      break;
+    }
+
+  switch (insn)
+    {
+    case 0xb255: /* MVST */
+    case 0xb263: /* CMPSC */
+    case 0xb2a5: /* TRE */
+    case 0xb2a6: /* CU21 */
+    case 0xb2a7: /* CU12 */
+    case 0xb9b0: /* CU14 */
+    case 0xb9b1: /* CU24 */
+    case 0xb9b2: /* CU41 */
+    case 0xb9b3: /* CU42 */
+    case 0xb92a: /* KMF */
+    case 0xb92b: /* KMO */
+    case 0xb92f: /* KMC */
+    case 0xb92d: /* KMCTR */
+    case 0xb92e: /* KM */
+    case 0xb93c: /* PPNO */
+    case 0xb990: /* TRTT */
+    case 0xb991: /* TRTO */
+    case 0xb992: /* TROT */
+    case 0xb993: /* TROO */
+      *len = 4;
+      return 1;
+    }
+
+  return 0;
+}
+
+/* Implement the "software_single_step" gdbarch method, needed to single step
+   through instructions like MVCLE in record mode, to make sure they are
+   executed to completion.  Without that, record will save the full length
+   of destination buffer on every iteration, even though the CPU will only
+   process about 4kiB of it each time, leading to O(n**2) memory and time
+   complexity.  */
+
+static std::vector<CORE_ADDR>
+s390_software_single_step (struct regcache *regcache)
+{
+  struct gdbarch *gdbarch = regcache->arch ();
+  CORE_ADDR loc = regcache_read_pc (regcache);
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  int len;
+  uint16_t insn;
+
+  /* Special handling only if recording.  */
+  if (!record_full_is_used ())
+    return {};
+
+  /* First, match a partial instruction.  */
+  if (!s390_is_partial_instruction (gdbarch, loc, &len))
+    return {};
+
+  loc += len;
+
+  /* Second, look for a branch back to it.  */
+  insn = read_memory_integer (loc, 2, byte_order);
+  if (insn != 0xa714) /* BRC with mask 1 */
+    return {};
+
+  insn = read_memory_integer (loc + 2, 2, byte_order);
+  if (insn != (uint16_t) -(len / 2))
+    return {};
+
+  loc += 4;
+
+  /* Found it, step past the whole thing.  */
+  return {loc};
+}
+
+/* Displaced stepping.  */
+
+/* Return true if INSN is a non-branch RIL-b or RIL-c format
+   instruction.  */
+
+static int
+is_non_branch_ril (gdb_byte *insn)
+{
+  gdb_byte op1 = insn[0];
+
+  if (op1 == 0xc4)
+    {
+      gdb_byte op2 = insn[1] & 0x0f;
+
+      switch (op2)
+	{
+	case 0x02: /* llhrl */
+	case 0x04: /* lghrl */
+	case 0x05: /* lhrl */
+	case 0x06: /* llghrl */
+	case 0x07: /* sthrl */
+	case 0x08: /* lgrl */
+	case 0x0b: /* stgrl */
+	case 0x0c: /* lgfrl */
+	case 0x0d: /* lrl */
+	case 0x0e: /* llgfrl */
+	case 0x0f: /* strl */
+	  return 1;
+	}
+    }
+  else if (op1 == 0xc6)
+    {
+      gdb_byte op2 = insn[1] & 0x0f;
+
+      switch (op2)
+	{
+	case 0x00: /* exrl */
+	case 0x02: /* pfdrl */
+	case 0x04: /* cghrl */
+	case 0x05: /* chrl */
+	case 0x06: /* clghrl */
+	case 0x07: /* clhrl */
+	case 0x08: /* cgrl */
+	case 0x0a: /* clgrl */
+	case 0x0c: /* cgfrl */
+	case 0x0d: /* crl */
+	case 0x0e: /* clgfrl */
+	case 0x0f: /* clrl */
+	  return 1;
+	}
+    }
+
+  return 0;
+}
+
+typedef buf_displaced_step_closure s390_displaced_step_closure;
+
+/* Implementation of gdbarch_displaced_step_copy_insn.  */
+
+static struct displaced_step_closure *
+s390_displaced_step_copy_insn (struct gdbarch *gdbarch,
+			       CORE_ADDR from, CORE_ADDR to,
+			       struct regcache *regs)
+{
+  size_t len = gdbarch_max_insn_length (gdbarch);
+  std::unique_ptr<s390_displaced_step_closure> closure
+    (new s390_displaced_step_closure (len));
+  gdb_byte *buf = closure->buf.data ();
+
+  read_memory (from, buf, len);
+
+  /* Adjust the displacement field of PC-relative RIL instructions,
+     except branches.  The latter are handled in the fixup hook.  */
+  if (is_non_branch_ril (buf))
+    {
+      LONGEST offset;
+
+      offset = extract_signed_integer (buf + 2, 4, BFD_ENDIAN_BIG);
+      offset = (from - to + offset * 2) / 2;
+
+      /* If the instruction is too far from the jump pad, punt.  This
+	 will usually happen with instructions in shared libraries.
+	 We could probably support these by rewriting them to be
+	 absolute or fully emulating them.  */
+      if (offset < INT32_MIN || offset > INT32_MAX)
+	{
+	  /* Let the core fall back to stepping over the breakpoint
+	     in-line.  */
+	  if (debug_displaced)
+	    {
+	      fprintf_unfiltered (gdb_stdlog,
+				  "displaced: can't displaced step "
+				  "RIL instruction: offset %s out of range\n",
+				  plongest (offset));
+	    }
+
+	  return NULL;
+	}
+
+      store_signed_integer (buf + 2, 4, BFD_ENDIAN_BIG, offset);
+    }
+
+  write_memory (to, buf, len);
+
+  if (debug_displaced)
+    {
+      fprintf_unfiltered (gdb_stdlog, "displaced: copy %s->%s: ",
+			  paddress (gdbarch, from), paddress (gdbarch, to));
+      displaced_step_dump_bytes (gdb_stdlog, buf, len);
+    }
+
+  return closure.release ();
+}
+
+/* Fix up the state of registers and memory after having single-stepped
+   a displaced instruction.  */
+
+static void
+s390_displaced_step_fixup (struct gdbarch *gdbarch,
+			   struct displaced_step_closure *closure_,
+			   CORE_ADDR from, CORE_ADDR to,
+			   struct regcache *regs)
+{
+  /* Our closure is a copy of the instruction.  */
+  s390_displaced_step_closure *closure
+    = (s390_displaced_step_closure *) closure_;
+  gdb_byte *insn = closure->buf.data ();
+  static int s390_instrlen[] = { 2, 4, 4, 6 };
+  int insnlen = s390_instrlen[insn[0] >> 6];
+
+  /* Fields for various kinds of instructions.  */
+  unsigned int b2, r1, r2, x2, r3;
+  int i2, d2;
+
+  /* Get current PC and addressing mode bit.  */
+  CORE_ADDR pc = regcache_read_pc (regs);
+  ULONGEST amode = 0;
+
+  if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)
+    {
+      regcache_cooked_read_unsigned (regs, S390_PSWA_REGNUM, &amode);
+      amode &= 0x80000000;
+    }
+
+  if (debug_displaced)
+    fprintf_unfiltered (gdb_stdlog,
+			"displaced: (s390) fixup (%s, %s) pc %s len %d amode 0x%x\n",
+			paddress (gdbarch, from), paddress (gdbarch, to),
+			paddress (gdbarch, pc), insnlen, (int) amode);
+
+  /* Handle absolute branch and save instructions.  */
+  if (is_rr (insn, op_basr, &r1, &r2)
+      || is_rx (insn, op_bas, &r1, &d2, &x2, &b2))
+    {
+      /* Recompute saved return address in R1.  */
+      regcache_cooked_write_unsigned (regs, S390_R0_REGNUM + r1,
+				      amode | (from + insnlen));
+    }
+
+  /* Handle absolute branch instructions.  */
+  else if (is_rr (insn, op_bcr, &r1, &r2)
+	   || is_rx (insn, op_bc, &r1, &d2, &x2, &b2)
+	   || is_rr (insn, op_bctr, &r1, &r2)
+	   || is_rre (insn, op_bctgr, &r1, &r2)
+	   || is_rx (insn, op_bct, &r1, &d2, &x2, &b2)
+	   || is_rxy (insn, op1_bctg, op2_brctg, &r1, &d2, &x2, &b2)
+	   || is_rs (insn, op_bxh, &r1, &r3, &d2, &b2)
+	   || is_rsy (insn, op1_bxhg, op2_bxhg, &r1, &r3, &d2, &b2)
+	   || is_rs (insn, op_bxle, &r1, &r3, &d2, &b2)
+	   || is_rsy (insn, op1_bxleg, op2_bxleg, &r1, &r3, &d2, &b2))
+    {
+      /* Update PC iff branch was *not* taken.  */
+      if (pc == to + insnlen)
+	regcache_write_pc (regs, from + insnlen);
+    }
+
+  /* Handle PC-relative branch and save instructions.  */
+  else if (is_ri (insn, op1_bras, op2_bras, &r1, &i2)
+	   || is_ril (insn, op1_brasl, op2_brasl, &r1, &i2))
+    {
+      /* Update PC.  */
+      regcache_write_pc (regs, pc - to + from);
+      /* Recompute saved return address in R1.  */
+      regcache_cooked_write_unsigned (regs, S390_R0_REGNUM + r1,
+				      amode | (from + insnlen));
+    }
+
+  /* Handle LOAD ADDRESS RELATIVE LONG.  */
+  else if (is_ril (insn, op1_larl, op2_larl, &r1, &i2))
+    {
+      /* Update PC.  */
+      regcache_write_pc (regs, from + insnlen);
+      /* Recompute output address in R1.  */
+      regcache_cooked_write_unsigned (regs, S390_R0_REGNUM + r1,
+				      amode | (from + i2 * 2));
+    }
+
+  /* If we executed a breakpoint instruction, point PC right back at it.  */
+  else if (insn[0] == 0x0 && insn[1] == 0x1)
+    regcache_write_pc (regs, from);
+
+  /* For any other insn, adjust PC by negated displacement.  PC then
+     points right after the original instruction, except for PC-relative
+     branches, where it points to the adjusted branch target.  */
+  else
+    regcache_write_pc (regs, pc - to + from);
+
+  if (debug_displaced)
+    fprintf_unfiltered (gdb_stdlog,
+			"displaced: (s390) pc is now %s\n",
+			paddress (gdbarch, regcache_read_pc (regs)));
+}
+
+static int
+s390_displaced_step_hw_singlestep (struct gdbarch *gdbarch,
+				   struct displaced_step_closure *closure)
+{
+  return 1;
+}
+
+/* Prologue analysis.  */
+
+/* Return the effective address for an X-style instruction, like:
+
+	L R1, D2(X2, B2)
+
+   Here, X2 and B2 are registers, and D2 is a signed 20-bit
+   constant; the effective address is the sum of all three.  If either
+   X2 or B2 are zero, then it doesn't contribute to the sum --- this
+   means that r0 can't be used as either X2 or B2.  */
+
+static pv_t
+s390_addr (struct s390_prologue_data *data,
+	   int d2, unsigned int x2, unsigned int b2)
+{
+  pv_t result;
+
+  result = pv_constant (d2);
+  if (x2)
+    result = pv_add (result, data->gpr[x2]);
+  if (b2)
+    result = pv_add (result, data->gpr[b2]);
+
+  return result;
+}
+
+/* Do a SIZE-byte store of VALUE to D2(X2,B2).  */
+
+static void
+s390_store (struct s390_prologue_data *data,
+	    int d2, unsigned int x2, unsigned int b2, CORE_ADDR size,
+	    pv_t value)
+{
+  pv_t addr = s390_addr (data, d2, x2, b2);
+  pv_t offset;
+
+  /* Check whether we are storing the backchain.  */
+  offset = pv_subtract (data->gpr[S390_SP_REGNUM - S390_R0_REGNUM], addr);
+
+  if (pv_is_constant (offset) && offset.k == 0)
+    if (size == data->gpr_size
+	&& pv_is_register_k (value, S390_SP_REGNUM, 0))
+      {
+	data->back_chain_saved_p = 1;
+	return;
+      }
+
+  /* Check whether we are storing a register into the stack.  */
+  if (!data->stack->store_would_trash (addr))
+    data->stack->store (addr, size, value);
+
+  /* Note: If this is some store we cannot identify, you might think we
+     should forget our cached values, as any of those might have been hit.
+
+     However, we make the assumption that the register save areas are only
+     ever stored to once in any given function, and we do recognize these
+     stores.  Thus every store we cannot recognize does not hit our data.  */
+}
+
+/* Do a SIZE-byte load from D2(X2,B2).  */
+
+static pv_t
+s390_load (struct s390_prologue_data *data,
+	   int d2, unsigned int x2, unsigned int b2, CORE_ADDR size)
+
+{
+  pv_t addr = s390_addr (data, d2, x2, b2);
+
+  /* If it's a load from an in-line constant pool, then we can
+     simulate that, under the assumption that the code isn't
+     going to change between the time the processor actually
+     executed it creating the current frame, and the time when
+     we're analyzing the code to unwind past that frame.  */
+  if (pv_is_constant (addr))
+    {
+      struct target_section *secp;
+      secp = target_section_by_addr (&current_target, addr.k);
+      if (secp != NULL
+	  && (bfd_get_section_flags (secp->the_bfd_section->owner,
+				     secp->the_bfd_section)
+	      & SEC_READONLY))
+	return pv_constant (read_memory_integer (addr.k, size,
+						 data->byte_order));
+    }
+
+  /* Check whether we are accessing one of our save slots.  */
+  return data->stack->fetch (addr, size);
+}
+
+/* Function for finding saved registers in a 'struct pv_area'; we pass
+   this to pv_area::scan.
+
+   If VALUE is a saved register, ADDR says it was saved at a constant
+   offset from the frame base, and SIZE indicates that the whole
+   register was saved, record its offset in the reg_offset table in
+   PROLOGUE_UNTYPED.  */
+
+static void
+s390_check_for_saved (void *data_untyped, pv_t addr,
+		      CORE_ADDR size, pv_t value)
+{
+  struct s390_prologue_data *data = (struct s390_prologue_data *) data_untyped;
+  int i, offset;
+
+  if (!pv_is_register (addr, S390_SP_REGNUM))
+    return;
+
+  offset = 16 * data->gpr_size + 32 - addr.k;
+
+  /* If we are storing the original value of a register, we want to
+     record the CFA offset.  If the same register is stored multiple
+     times, the stack slot with the highest address counts.  */
+
+  for (i = 0; i < S390_NUM_GPRS; i++)
+    if (size == data->gpr_size
+	&& pv_is_register_k (value, S390_R0_REGNUM + i, 0))
+      if (data->gpr_slot[i] == 0
+	  || data->gpr_slot[i] > offset)
+	{
+	  data->gpr_slot[i] = offset;
+	  return;
+	}
+
+  for (i = 0; i < S390_NUM_FPRS; i++)
+    if (size == data->fpr_size
+	&& pv_is_register_k (value, S390_F0_REGNUM + i, 0))
+      if (data->fpr_slot[i] == 0
+	  || data->fpr_slot[i] > offset)
+	{
+	  data->fpr_slot[i] = offset;
+	  return;
+	}
+}
+
+/* See s390-tdep.h.  */
+
+CORE_ADDR
+s390_analyze_prologue (struct gdbarch *gdbarch,
+		       CORE_ADDR start_pc,
+		       CORE_ADDR current_pc,
+		       struct s390_prologue_data *data)
+{
+  int word_size = gdbarch_ptr_bit (gdbarch) / 8;
+
+  /* Our return value:
+     The address of the instruction after the last one that changed
+     the SP, FP, or back chain;  zero if we got an error trying to
+     read memory.  */
+  CORE_ADDR result = start_pc;
+
+  /* The current PC for our abstract interpretation.  */
+  CORE_ADDR pc;
+
+  /* The address of the next instruction after that.  */
+  CORE_ADDR next_pc;
+
+  pv_area stack (S390_SP_REGNUM, gdbarch_addr_bit (gdbarch));
+  scoped_restore restore_stack = make_scoped_restore (&data->stack, &stack);
+
+  /* Set up everything's initial value.  */
+  {
+    int i;
+
+    /* For the purpose of prologue tracking, we consider the GPR size to
+       be equal to the ABI word size, even if it is actually larger
+       (i.e. when running a 32-bit binary under a 64-bit kernel).  */
+    data->gpr_size = word_size;
+    data->fpr_size = 8;
+    data->byte_order = gdbarch_byte_order (gdbarch);
+
+    for (i = 0; i < S390_NUM_GPRS; i++)
+      data->gpr[i] = pv_register (S390_R0_REGNUM + i, 0);
+
+    for (i = 0; i < S390_NUM_FPRS; i++)
+      data->fpr[i] = pv_register (S390_F0_REGNUM + i, 0);
+
+    for (i = 0; i < S390_NUM_GPRS; i++)
+      data->gpr_slot[i]  = 0;
+
+    for (i = 0; i < S390_NUM_FPRS; i++)
+      data->fpr_slot[i]  = 0;
+
+    data->back_chain_saved_p = 0;
+  }
+
+  /* Start interpreting instructions, until we hit the frame's
+     current PC or the first branch instruction.  */
+  for (pc = start_pc; pc > 0 && pc < current_pc; pc = next_pc)
+    {
+      bfd_byte insn[S390_MAX_INSTR_SIZE];
+      int insn_len = s390_readinstruction (insn, pc);
+
+      bfd_byte dummy[S390_MAX_INSTR_SIZE] = { 0 };
+      bfd_byte *insn32 = word_size == 4 ? insn : dummy;
+      bfd_byte *insn64 = word_size == 8 ? insn : dummy;
+
+      /* Fields for various kinds of instructions.  */
+      unsigned int b2, r1, r2, x2, r3;
+      int i2, d2;
+
+      /* The values of SP and FP before this instruction,
+	 for detecting instructions that change them.  */
+      pv_t pre_insn_sp, pre_insn_fp;
+      /* Likewise for the flag whether the back chain was saved.  */
+      int pre_insn_back_chain_saved_p;
+
+      /* If we got an error trying to read the instruction, report it.  */
+      if (insn_len < 0)
+	{
+	  result = 0;
+	  break;
+	}
+
+      next_pc = pc + insn_len;
+
+      pre_insn_sp = data->gpr[S390_SP_REGNUM - S390_R0_REGNUM];
+      pre_insn_fp = data->gpr[S390_FRAME_REGNUM - S390_R0_REGNUM];
+      pre_insn_back_chain_saved_p = data->back_chain_saved_p;
+
+      /* LHI r1, i2 --- load halfword immediate.  */
+      /* LGHI r1, i2 --- load halfword immediate (64-bit version).  */
+      /* LGFI r1, i2 --- load fullword immediate.  */
+      if (is_ri (insn32, op1_lhi, op2_lhi, &r1, &i2)
+	  || is_ri (insn64, op1_lghi, op2_lghi, &r1, &i2)
+	  || is_ril (insn, op1_lgfi, op2_lgfi, &r1, &i2))
+	data->gpr[r1] = pv_constant (i2);
+
+      /* LR r1, r2 --- load from register.  */
+      /* LGR r1, r2 --- load from register (64-bit version).  */
+      else if (is_rr (insn32, op_lr, &r1, &r2)
+	       || is_rre (insn64, op_lgr, &r1, &r2))
+	data->gpr[r1] = data->gpr[r2];
+
+      /* L r1, d2(x2, b2) --- load.  */
+      /* LY r1, d2(x2, b2) --- load (long-displacement version).  */
+      /* LG r1, d2(x2, b2) --- load (64-bit version).  */
+      else if (is_rx (insn32, op_l, &r1, &d2, &x2, &b2)
+	       || is_rxy (insn32, op1_ly, op2_ly, &r1, &d2, &x2, &b2)
+	       || is_rxy (insn64, op1_lg, op2_lg, &r1, &d2, &x2, &b2))
+	data->gpr[r1] = s390_load (data, d2, x2, b2, data->gpr_size);
+
+      /* ST r1, d2(x2, b2) --- store.  */
+      /* STY r1, d2(x2, b2) --- store (long-displacement version).  */
+      /* STG r1, d2(x2, b2) --- store (64-bit version).  */
+      else if (is_rx (insn32, op_st, &r1, &d2, &x2, &b2)
+	       || is_rxy (insn32, op1_sty, op2_sty, &r1, &d2, &x2, &b2)
+	       || is_rxy (insn64, op1_stg, op2_stg, &r1, &d2, &x2, &b2))
+	s390_store (data, d2, x2, b2, data->gpr_size, data->gpr[r1]);
+
+      /* STD r1, d2(x2,b2) --- store floating-point register.  */
+      else if (is_rx (insn, op_std, &r1, &d2, &x2, &b2))
+	s390_store (data, d2, x2, b2, data->fpr_size, data->fpr[r1]);
+
+      /* STM r1, r3, d2(b2) --- store multiple.  */
+      /* STMY r1, r3, d2(b2) --- store multiple (long-displacement
+	 version).  */
+      /* STMG r1, r3, d2(b2) --- store multiple (64-bit version).  */
+      else if (is_rs (insn32, op_stm, &r1, &r3, &d2, &b2)
+	       || is_rsy (insn32, op1_stmy, op2_stmy, &r1, &r3, &d2, &b2)
+	       || is_rsy (insn64, op1_stmg, op2_stmg, &r1, &r3, &d2, &b2))
+	{
+	  for (; r1 <= r3; r1++, d2 += data->gpr_size)
+	    s390_store (data, d2, 0, b2, data->gpr_size, data->gpr[r1]);
+	}
+
+      /* AHI r1, i2 --- add halfword immediate.  */
+      /* AGHI r1, i2 --- add halfword immediate (64-bit version).  */
+      /* AFI r1, i2 --- add fullword immediate.  */
+      /* AGFI r1, i2 --- add fullword immediate (64-bit version).  */
+      else if (is_ri (insn32, op1_ahi, op2_ahi, &r1, &i2)
+	       || is_ri (insn64, op1_aghi, op2_aghi, &r1, &i2)
+	       || is_ril (insn32, op1_afi, op2_afi, &r1, &i2)
+	       || is_ril (insn64, op1_agfi, op2_agfi, &r1, &i2))
+	data->gpr[r1] = pv_add_constant (data->gpr[r1], i2);
+
+      /* ALFI r1, i2 --- add logical immediate.  */
+      /* ALGFI r1, i2 --- add logical immediate (64-bit version).  */
+      else if (is_ril (insn32, op1_alfi, op2_alfi, &r1, &i2)
+	       || is_ril (insn64, op1_algfi, op2_algfi, &r1, &i2))
+	data->gpr[r1] = pv_add_constant (data->gpr[r1],
+					 (CORE_ADDR)i2 & 0xffffffff);
+
+      /* AR r1, r2 -- add register.  */
+      /* AGR r1, r2 -- add register (64-bit version).  */
+      else if (is_rr (insn32, op_ar, &r1, &r2)
+	       || is_rre (insn64, op_agr, &r1, &r2))
+	data->gpr[r1] = pv_add (data->gpr[r1], data->gpr[r2]);
+
+      /* A r1, d2(x2, b2) -- add.  */
+      /* AY r1, d2(x2, b2) -- add (long-displacement version).  */
+      /* AG r1, d2(x2, b2) -- add (64-bit version).  */
+      else if (is_rx (insn32, op_a, &r1, &d2, &x2, &b2)
+	       || is_rxy (insn32, op1_ay, op2_ay, &r1, &d2, &x2, &b2)
+	       || is_rxy (insn64, op1_ag, op2_ag, &r1, &d2, &x2, &b2))
+	data->gpr[r1] = pv_add (data->gpr[r1],
+				s390_load (data, d2, x2, b2, data->gpr_size));
+
+      /* SLFI r1, i2 --- subtract logical immediate.  */
+      /* SLGFI r1, i2 --- subtract logical immediate (64-bit version).  */
+      else if (is_ril (insn32, op1_slfi, op2_slfi, &r1, &i2)
+	       || is_ril (insn64, op1_slgfi, op2_slgfi, &r1, &i2))
+	data->gpr[r1] = pv_add_constant (data->gpr[r1],
+					 -((CORE_ADDR)i2 & 0xffffffff));
+
+      /* SR r1, r2 -- subtract register.  */
+      /* SGR r1, r2 -- subtract register (64-bit version).  */
+      else if (is_rr (insn32, op_sr, &r1, &r2)
+	       || is_rre (insn64, op_sgr, &r1, &r2))
+	data->gpr[r1] = pv_subtract (data->gpr[r1], data->gpr[r2]);
+
+      /* S r1, d2(x2, b2) -- subtract.  */
+      /* SY r1, d2(x2, b2) -- subtract (long-displacement version).  */
+      /* SG r1, d2(x2, b2) -- subtract (64-bit version).  */
+      else if (is_rx (insn32, op_s, &r1, &d2, &x2, &b2)
+	       || is_rxy (insn32, op1_sy, op2_sy, &r1, &d2, &x2, &b2)
+	       || is_rxy (insn64, op1_sg, op2_sg, &r1, &d2, &x2, &b2))
+	data->gpr[r1] = pv_subtract (data->gpr[r1],
+				s390_load (data, d2, x2, b2, data->gpr_size));
+
+      /* LA r1, d2(x2, b2) --- load address.  */
+      /* LAY r1, d2(x2, b2) --- load address (long-displacement version).  */
+      else if (is_rx (insn, op_la, &r1, &d2, &x2, &b2)
+	       || is_rxy (insn, op1_lay, op2_lay, &r1, &d2, &x2, &b2))
+	data->gpr[r1] = s390_addr (data, d2, x2, b2);
+
+      /* LARL r1, i2 --- load address relative long.  */
+      else if (is_ril (insn, op1_larl, op2_larl, &r1, &i2))
+	data->gpr[r1] = pv_constant (pc + i2 * 2);
+
+      /* BASR r1, 0 --- branch and save.
+	 Since r2 is zero, this saves the PC in r1, but doesn't branch.  */
+      else if (is_rr (insn, op_basr, &r1, &r2)
+	       && r2 == 0)
+	data->gpr[r1] = pv_constant (next_pc);
+
+      /* BRAS r1, i2 --- branch relative and save.  */
+      else if (is_ri (insn, op1_bras, op2_bras, &r1, &i2))
+	{
+	  data->gpr[r1] = pv_constant (next_pc);
+	  next_pc = pc + i2 * 2;
+
+	  /* We'd better not interpret any backward branches.  We'll
+	     never terminate.  */
+	  if (next_pc <= pc)
+	    break;
+	}
+
+      /* BRC/BRCL -- branch relative on condition.  Ignore "branch
+	 never", branch to following instruction, and "conditional
+	 trap" (BRC +2).  Otherwise terminate search.  */
+      else if (is_ri (insn, op1_brc, op2_brc, &r1, &i2))
+	{
+	  if (r1 != 0 && i2 != 1 && i2 != 2)
+	    break;
+	}
+      else if (is_ril (insn, op1_brcl, op2_brcl, &r1, &i2))
+	{
+	  if (r1 != 0 && i2 != 3)
+	    break;
+	}
+
+      /* Terminate search when hitting any other branch instruction.  */
+      else if (is_rr (insn, op_basr, &r1, &r2)
+	       || is_rx (insn, op_bas, &r1, &d2, &x2, &b2)
+	       || is_rr (insn, op_bcr, &r1, &r2)
+	       || is_rx (insn, op_bc, &r1, &d2, &x2, &b2)
+	       || is_ril (insn, op1_brasl, op2_brasl, &r2, &i2))
+	break;
+
+      else
+	{
+	  /* An instruction we don't know how to simulate.  The only
+	     safe thing to do would be to set every value we're tracking
+	     to 'unknown'.  Instead, we'll be optimistic: we assume that
+	     we *can* interpret every instruction that the compiler uses
+	     to manipulate any of the data we're interested in here --
+	     then we can just ignore anything else.  */
+	}
+
+      /* Record the address after the last instruction that changed
+	 the FP, SP, or backlink.  Ignore instructions that changed
+	 them back to their original values --- those are probably
+	 restore instructions.  (The back chain is never restored,
+	 just popped.)  */
+      {
+	pv_t sp = data->gpr[S390_SP_REGNUM - S390_R0_REGNUM];
+	pv_t fp = data->gpr[S390_FRAME_REGNUM - S390_R0_REGNUM];
+
+	if ((! pv_is_identical (pre_insn_sp, sp)
+	     && ! pv_is_register_k (sp, S390_SP_REGNUM, 0)
+	     && sp.kind != pvk_unknown)
+	    || (! pv_is_identical (pre_insn_fp, fp)
+		&& ! pv_is_register_k (fp, S390_FRAME_REGNUM, 0)
+		&& fp.kind != pvk_unknown)
+	    || pre_insn_back_chain_saved_p != data->back_chain_saved_p)
+	  result = next_pc;
+      }
+    }
+
+  /* Record where all the registers were saved.  */
+  data->stack->scan (s390_check_for_saved, data);
+
+  return result;
+}
+
+/* Advance PC across any function entry prologue instructions to reach
+   some "real" code.  */
+
+static CORE_ADDR
+s390_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
+{
+  struct s390_prologue_data data;
+  CORE_ADDR skip_pc, func_addr;
+
+  if (find_pc_partial_function (pc, NULL, &func_addr, NULL))
+    {
+      CORE_ADDR post_prologue_pc
+	= skip_prologue_using_sal (gdbarch, func_addr);
+      if (post_prologue_pc != 0)
+	return std::max (pc, post_prologue_pc);
+    }
+
+  skip_pc = s390_analyze_prologue (gdbarch, pc, (CORE_ADDR)-1, &data);
+  return skip_pc ? skip_pc : pc;
+}
+
+/* Register handling.  */
+
+/* See s390-tdep.h.  */
+
+int
+s390_register_call_saved (struct gdbarch *gdbarch, int regnum)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  switch (tdep->abi)
+    {
+    case ABI_LINUX_S390:
+      if ((regnum >= S390_R6_REGNUM && regnum <= S390_R15_REGNUM)
+	  || regnum == S390_F4_REGNUM || regnum == S390_F6_REGNUM
+	  || regnum == S390_A0_REGNUM)
+	return 1;
+
+      break;
+
+    case ABI_LINUX_ZSERIES:
+      if ((regnum >= S390_R6_REGNUM && regnum <= S390_R15_REGNUM)
+	  || (regnum >= S390_F8_REGNUM && regnum <= S390_F15_REGNUM)
+	  || (regnum >= S390_A0_REGNUM && regnum <= S390_A1_REGNUM))
+	return 1;
+
+      break;
+    }
+
+  return 0;
+}
+
+/* Return the name of register REGNO.  Return the empty string for
+   registers that shouldn't be visible.  */
+
+static const char *
+s390_register_name (struct gdbarch *gdbarch, int regnum)
+{
+  if (regnum >= S390_V0_LOWER_REGNUM
+      && regnum <= S390_V15_LOWER_REGNUM)
+    return "";
+  return tdesc_register_name (gdbarch, regnum);
+}
+
+static int
+s390_cannot_store_register (struct gdbarch *gdbarch, int regnum)
+{
+  /* The last-break address is read-only.  */
+  return regnum == S390_LAST_BREAK_REGNUM;
+}
+
+static void
+s390_write_pc (struct regcache *regcache, CORE_ADDR pc)
+{
+  struct gdbarch *gdbarch = regcache->arch ();
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  regcache_cooked_write_unsigned (regcache, tdep->pc_regnum, pc);
+
+  /* Set special SYSTEM_CALL register to 0 to prevent the kernel from
+     messing with the PC we just installed, if we happen to be within
+     an interrupted system call that the kernel wants to restart.
+
+     Note that after we return from the dummy call, the SYSTEM_CALL and
+     ORIG_R2 registers will be automatically restored, and the kernel
+     continues to restart the system call at this point.  */
+  if (register_size (gdbarch, S390_SYSTEM_CALL_REGNUM) > 0)
+    regcache_cooked_write_unsigned (regcache, S390_SYSTEM_CALL_REGNUM, 0);
+}
+
+/* DWARF Register Mapping.  */
+
+static const short s390_dwarf_regmap[] =
+{
+  /* 0-15: General Purpose Registers.  */
+  S390_R0_REGNUM, S390_R1_REGNUM, S390_R2_REGNUM, S390_R3_REGNUM,
+  S390_R4_REGNUM, S390_R5_REGNUM, S390_R6_REGNUM, S390_R7_REGNUM,
+  S390_R8_REGNUM, S390_R9_REGNUM, S390_R10_REGNUM, S390_R11_REGNUM,
+  S390_R12_REGNUM, S390_R13_REGNUM, S390_R14_REGNUM, S390_R15_REGNUM,
+
+  /* 16-31: Floating Point Registers / Vector Registers 0-15. */
+  S390_F0_REGNUM, S390_F2_REGNUM, S390_F4_REGNUM, S390_F6_REGNUM,
+  S390_F1_REGNUM, S390_F3_REGNUM, S390_F5_REGNUM, S390_F7_REGNUM,
+  S390_F8_REGNUM, S390_F10_REGNUM, S390_F12_REGNUM, S390_F14_REGNUM,
+  S390_F9_REGNUM, S390_F11_REGNUM, S390_F13_REGNUM, S390_F15_REGNUM,
+
+  /* 32-47: Control Registers (not mapped).  */
+  -1, -1, -1, -1, -1, -1, -1, -1,
+  -1, -1, -1, -1, -1, -1, -1, -1,
+
+  /* 48-63: Access Registers.  */
+  S390_A0_REGNUM, S390_A1_REGNUM, S390_A2_REGNUM, S390_A3_REGNUM,
+  S390_A4_REGNUM, S390_A5_REGNUM, S390_A6_REGNUM, S390_A7_REGNUM,
+  S390_A8_REGNUM, S390_A9_REGNUM, S390_A10_REGNUM, S390_A11_REGNUM,
+  S390_A12_REGNUM, S390_A13_REGNUM, S390_A14_REGNUM, S390_A15_REGNUM,
+
+  /* 64-65: Program Status Word.  */
+  S390_PSWM_REGNUM,
+  S390_PSWA_REGNUM,
+
+  /* 66-67: Reserved.  */
+  -1, -1,
+
+  /* 68-83: Vector Registers 16-31.  */
+  S390_V16_REGNUM, S390_V18_REGNUM, S390_V20_REGNUM, S390_V22_REGNUM,
+  S390_V17_REGNUM, S390_V19_REGNUM, S390_V21_REGNUM, S390_V23_REGNUM,
+  S390_V24_REGNUM, S390_V26_REGNUM, S390_V28_REGNUM, S390_V30_REGNUM,
+  S390_V25_REGNUM, S390_V27_REGNUM, S390_V29_REGNUM, S390_V31_REGNUM,
+
+  /* End of "official" DWARF registers.  The remainder of the map is
+     for GDB internal use only.  */
+
+  /* GPR Lower Half Access.  */
+  S390_R0_REGNUM, S390_R1_REGNUM, S390_R2_REGNUM, S390_R3_REGNUM,
+  S390_R4_REGNUM, S390_R5_REGNUM, S390_R6_REGNUM, S390_R7_REGNUM,
+  S390_R8_REGNUM, S390_R9_REGNUM, S390_R10_REGNUM, S390_R11_REGNUM,
+  S390_R12_REGNUM, S390_R13_REGNUM, S390_R14_REGNUM, S390_R15_REGNUM,
+};
+
+enum { s390_dwarf_reg_r0l = ARRAY_SIZE (s390_dwarf_regmap) - 16 };
+
+/* Convert DWARF register number REG to the appropriate register
+   number used by GDB.  */
+
+static int
+s390_dwarf_reg_to_regnum (struct gdbarch *gdbarch, int reg)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  int gdb_reg = -1;
+
+  /* In a 32-on-64 debug scenario, debug info refers to the full
+     64-bit GPRs.  Note that call frame information still refers to
+     the 32-bit lower halves, because s390_adjust_frame_regnum uses
+     special register numbers to access GPRs.  */
+  if (tdep->gpr_full_regnum != -1 && reg >= 0 && reg < 16)
+    return tdep->gpr_full_regnum + reg;
+
+  if (reg >= 0 && reg < ARRAY_SIZE (s390_dwarf_regmap))
+    gdb_reg = s390_dwarf_regmap[reg];
+
+  if (tdep->v0_full_regnum == -1)
+    {
+      if (gdb_reg >= S390_V16_REGNUM && gdb_reg <= S390_V31_REGNUM)
+	gdb_reg = -1;
+    }
+  else
+    {
+      if (gdb_reg >= S390_F0_REGNUM && gdb_reg <= S390_F15_REGNUM)
+	gdb_reg = gdb_reg - S390_F0_REGNUM + tdep->v0_full_regnum;
+    }
+
+  return gdb_reg;
+}
+
+/* Pseudo register handling.  */
+
+static int
+regnum_is_gpr_full (struct gdbarch_tdep *tdep, int regnum)
+{
+  return (tdep->gpr_full_regnum != -1
+	  && regnum >= tdep->gpr_full_regnum
+	  && regnum <= tdep->gpr_full_regnum + 15);
+}
+
+/* Check whether REGNUM indicates a full vector register (v0-v15).
+   These pseudo-registers are composed of f0-f15 and v0l-v15l.  */
+
+static int
+regnum_is_vxr_full (struct gdbarch_tdep *tdep, int regnum)
+{
+  return (tdep->v0_full_regnum != -1
+	  && regnum >= tdep->v0_full_regnum
+	  && regnum <= tdep->v0_full_regnum + 15);
+}
+
+/* 'float' values are stored in the upper half of floating-point
+   registers, even though we are otherwise a big-endian platform.  The
+   same applies to a 'float' value within a vector.  */
+
+static struct value *
+s390_value_from_register (struct gdbarch *gdbarch, struct type *type,
+			  int regnum, struct frame_id frame_id)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  struct value *value = default_value_from_register (gdbarch, type,
+						     regnum, frame_id);
+  check_typedef (type);
+
+  if ((regnum >= S390_F0_REGNUM && regnum <= S390_F15_REGNUM
+       && TYPE_LENGTH (type) < 8)
+      || regnum_is_vxr_full (tdep, regnum)
+      || (regnum >= S390_V16_REGNUM && regnum <= S390_V31_REGNUM))
+    set_value_offset (value, 0);
+
+  return value;
+}
+
+static const char *
+s390_pseudo_register_name (struct gdbarch *gdbarch, int regnum)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  if (regnum == tdep->pc_regnum)
+    return "pc";
+
+  if (regnum == tdep->cc_regnum)
+    return "cc";
+
+  if (regnum_is_gpr_full (tdep, regnum))
+    {
+      static const char *full_name[] = {
+	"r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
+	"r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15"
+      };
+      return full_name[regnum - tdep->gpr_full_regnum];
+    }
+
+  if (regnum_is_vxr_full (tdep, regnum))
+    {
+      static const char *full_name[] = {
+	"v0", "v1", "v2", "v3", "v4", "v5", "v6", "v7",
+	"v8", "v9", "v10", "v11", "v12", "v13", "v14", "v15"
+      };
+      return full_name[regnum - tdep->v0_full_regnum];
+    }
+
+  internal_error (__FILE__, __LINE__, _("invalid regnum"));
+}
+
+static struct type *
+s390_pseudo_register_type (struct gdbarch *gdbarch, int regnum)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  if (regnum == tdep->pc_regnum)
+    return builtin_type (gdbarch)->builtin_func_ptr;
+
+  if (regnum == tdep->cc_regnum)
+    return builtin_type (gdbarch)->builtin_int;
+
+  if (regnum_is_gpr_full (tdep, regnum))
+    return builtin_type (gdbarch)->builtin_uint64;
+
+  if (regnum_is_vxr_full (tdep, regnum))
+    return tdesc_find_type (gdbarch, "vec128");
+
+  internal_error (__FILE__, __LINE__, _("invalid regnum"));
+}
+
+static enum register_status
+s390_pseudo_register_read (struct gdbarch *gdbarch, struct regcache *regcache,
+			   int regnum, gdb_byte *buf)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  int regsize = register_size (gdbarch, regnum);
+  ULONGEST val;
+
+  if (regnum == tdep->pc_regnum)
+    {
+      enum register_status status;
+
+      status = regcache_raw_read_unsigned (regcache, S390_PSWA_REGNUM, &val);
+      if (status == REG_VALID)
+	{
+	  if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)
+	    val &= 0x7fffffff;
+	  store_unsigned_integer (buf, regsize, byte_order, val);
+	}
+      return status;
+    }
+
+  if (regnum == tdep->cc_regnum)
+    {
+      enum register_status status;
+
+      status = regcache_raw_read_unsigned (regcache, S390_PSWM_REGNUM, &val);
+      if (status == REG_VALID)
+	{
+	  if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)
+	    val = (val >> 12) & 3;
+	  else
+	    val = (val >> 44) & 3;
+	  store_unsigned_integer (buf, regsize, byte_order, val);
+	}
+      return status;
+    }
+
+  if (regnum_is_gpr_full (tdep, regnum))
+    {
+      enum register_status status;
+      ULONGEST val_upper;
+
+      regnum -= tdep->gpr_full_regnum;
+
+      status = regcache_raw_read_unsigned (regcache, S390_R0_REGNUM + regnum, &val);
+      if (status == REG_VALID)
+	status = regcache_raw_read_unsigned (regcache, S390_R0_UPPER_REGNUM + regnum,
+					     &val_upper);
+      if (status == REG_VALID)
+	{
+	  val |= val_upper << 32;
+	  store_unsigned_integer (buf, regsize, byte_order, val);
+	}
+      return status;
+    }
+
+  if (regnum_is_vxr_full (tdep, regnum))
+    {
+      enum register_status status;
+
+      regnum -= tdep->v0_full_regnum;
+
+      status = regcache_raw_read (regcache, S390_F0_REGNUM + regnum, buf);
+      if (status == REG_VALID)
+	status = regcache_raw_read (regcache,
+				    S390_V0_LOWER_REGNUM + regnum, buf + 8);
+      return status;
+    }
+
+  internal_error (__FILE__, __LINE__, _("invalid regnum"));
+}
+
+static void
+s390_pseudo_register_write (struct gdbarch *gdbarch, struct regcache *regcache,
+			    int regnum, const gdb_byte *buf)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  int regsize = register_size (gdbarch, regnum);
+  ULONGEST val, psw;
+
+  if (regnum == tdep->pc_regnum)
+    {
+      val = extract_unsigned_integer (buf, regsize, byte_order);
+      if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)
+	{
+	  regcache_raw_read_unsigned (regcache, S390_PSWA_REGNUM, &psw);
+	  val = (psw & 0x80000000) | (val & 0x7fffffff);
+	}
+      regcache_raw_write_unsigned (regcache, S390_PSWA_REGNUM, val);
+      return;
+    }
+
+  if (regnum == tdep->cc_regnum)
+    {
+      val = extract_unsigned_integer (buf, regsize, byte_order);
+      regcache_raw_read_unsigned (regcache, S390_PSWM_REGNUM, &psw);
+      if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)
+	val = (psw & ~((ULONGEST)3 << 12)) | ((val & 3) << 12);
+      else
+	val = (psw & ~((ULONGEST)3 << 44)) | ((val & 3) << 44);
+      regcache_raw_write_unsigned (regcache, S390_PSWM_REGNUM, val);
+      return;
+    }
+
+  if (regnum_is_gpr_full (tdep, regnum))
+    {
+      regnum -= tdep->gpr_full_regnum;
+      val = extract_unsigned_integer (buf, regsize, byte_order);
+      regcache_raw_write_unsigned (regcache, S390_R0_REGNUM + regnum,
+				   val & 0xffffffff);
+      regcache_raw_write_unsigned (regcache, S390_R0_UPPER_REGNUM + regnum,
+				   val >> 32);
+      return;
+    }
+
+  if (regnum_is_vxr_full (tdep, regnum))
+    {
+      regnum -= tdep->v0_full_regnum;
+      regcache_raw_write (regcache, S390_F0_REGNUM + regnum, buf);
+      regcache_raw_write (regcache, S390_V0_LOWER_REGNUM + regnum, buf + 8);
+      return;
+    }
+
+  internal_error (__FILE__, __LINE__, _("invalid regnum"));
+}
+
+/* Register groups.  */
+
+static int
+s390_pseudo_register_reggroup_p (struct gdbarch *gdbarch, int regnum,
+				 struct reggroup *group)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+  /* We usually save/restore the whole PSW, which includes PC and CC.
+     However, some older gdbservers may not support saving/restoring
+     the whole PSW yet, and will return an XML register description
+     excluding those from the save/restore register groups.  In those
+     cases, we still need to explicitly save/restore PC and CC in order
+     to push or pop frames.  Since this doesn't hurt anything if we
+     already save/restore the whole PSW (it's just redundant), we add
+     PC and CC at this point unconditionally.  */
+  if (group == save_reggroup || group == restore_reggroup)
+    return regnum == tdep->pc_regnum || regnum == tdep->cc_regnum;
+
+  if (group == vector_reggroup)
+    return regnum_is_vxr_full (tdep, regnum);
+
+  if (group == general_reggroup && regnum_is_vxr_full (tdep, regnum))
+    return 0;
+
+  return default_register_reggroup_p (gdbarch, regnum, group);
+}
+
+/* The "ax_pseudo_register_collect" gdbarch method.  */
+
+static int
+s390_ax_pseudo_register_collect (struct gdbarch *gdbarch,
+				 struct agent_expr *ax, int regnum)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  if (regnum == tdep->pc_regnum)
+    {
+      ax_reg_mask (ax, S390_PSWA_REGNUM);
+    }
+  else if (regnum == tdep->cc_regnum)
+    {
+      ax_reg_mask (ax, S390_PSWM_REGNUM);
+    }
+  else if (regnum_is_gpr_full (tdep, regnum))
+    {
+      regnum -= tdep->gpr_full_regnum;
+      ax_reg_mask (ax, S390_R0_REGNUM + regnum);
+      ax_reg_mask (ax, S390_R0_UPPER_REGNUM + regnum);
+    }
+  else if (regnum_is_vxr_full (tdep, regnum))
+    {
+      regnum -= tdep->v0_full_regnum;
+      ax_reg_mask (ax, S390_F0_REGNUM + regnum);
+      ax_reg_mask (ax, S390_V0_LOWER_REGNUM + regnum);
+    }
+  else
+    {
+      internal_error (__FILE__, __LINE__, _("invalid regnum"));
+    }
+  return 0;
+}
+
+/* The "ax_pseudo_register_push_stack" gdbarch method.  */
+
+static int
+s390_ax_pseudo_register_push_stack (struct gdbarch *gdbarch,
+				    struct agent_expr *ax, int regnum)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  if (regnum == tdep->pc_regnum)
+    {
+      ax_reg (ax, S390_PSWA_REGNUM);
+      if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)
+	{
+	  ax_zero_ext (ax, 31);
+	}
+    }
+  else if (regnum == tdep->cc_regnum)
+    {
+      ax_reg (ax, S390_PSWM_REGNUM);
+      if (register_size (gdbarch, S390_PSWA_REGNUM) == 4)
+	ax_const_l (ax, 12);
+      else
+	ax_const_l (ax, 44);
+      ax_simple (ax, aop_rsh_unsigned);
+      ax_zero_ext (ax, 2);
+    }
+  else if (regnum_is_gpr_full (tdep, regnum))
+    {
+      regnum -= tdep->gpr_full_regnum;
+      ax_reg (ax, S390_R0_REGNUM + regnum);
+      ax_reg (ax, S390_R0_UPPER_REGNUM + regnum);
+      ax_const_l (ax, 32);
+      ax_simple (ax, aop_lsh);
+      ax_simple (ax, aop_bit_or);
+    }
+  else if (regnum_is_vxr_full (tdep, regnum))
+    {
+      /* Too large to stuff on the stack.  */
+      return 1;
+    }
+  else
+    {
+      internal_error (__FILE__, __LINE__, _("invalid regnum"));
+    }
+  return 0;
+}
+
+/* The "gen_return_address" gdbarch method.  Since this is supposed to be
+   just a best-effort method, and we don't really have the means to run
+   the full unwinder here, just collect the link register.  */
+
+static void
+s390_gen_return_address (struct gdbarch *gdbarch,
+			 struct agent_expr *ax, struct axs_value *value,
+			 CORE_ADDR scope)
+{
+  value->type = register_type (gdbarch, S390_R14_REGNUM);
+  value->kind = axs_lvalue_register;
+  value->u.reg = S390_R14_REGNUM;
+}
+
+/* Register maps & sets */
+
+static const struct regcache_map_entry s390_gregmap[] =
+  {
+    { 1, S390_PSWM_REGNUM },
+    { 1, S390_PSWA_REGNUM },
+    { 16, S390_R0_REGNUM },
+    { 16, S390_A0_REGNUM },
+    { 1, S390_ORIG_R2_REGNUM },
+    { 0 }
+  };
+
+static const struct regcache_map_entry s390_fpregmap[] =
+  {
+    { 1, S390_FPC_REGNUM, 8 },
+    { 16, S390_F0_REGNUM, 8 },
+    { 0 }
+  };
+
+static const struct regcache_map_entry s390_regmap_vxrs_low[] =
+  {
+    { 16, S390_V0_LOWER_REGNUM, 8 },
+    { 0 }
+  };
+
+static const struct regcache_map_entry s390_regmap_vxrs_high[] =
+  {
+    { 16, S390_V16_REGNUM, 16 },
+    { 0 }
+  };
+
+const struct regset s390_gregset = {
+  s390_gregmap,
+  regcache_supply_regset,
+  regcache_collect_regset
+};
+
+const struct regset s390_fpregset = {
+  s390_fpregmap,
+  regcache_supply_regset,
+  regcache_collect_regset
+};
+
+const struct regset s390_vxrs_low_regset = {
+  s390_regmap_vxrs_low,
+  regcache_supply_regset,
+  regcache_collect_regset
+};
+
+const struct regset s390_vxrs_high_regset = {
+  s390_regmap_vxrs_high,
+  regcache_supply_regset,
+  regcache_collect_regset
+};
+
+/* Address handling.  */
+
+static CORE_ADDR
+s390_addr_bits_remove (struct gdbarch *gdbarch, CORE_ADDR addr)
+{
+  return addr & 0x7fffffff;
+}
+
+static int
+s390_address_class_type_flags (int byte_size, int dwarf2_addr_class)
+{
+  if (byte_size == 4)
+    return TYPE_INSTANCE_FLAG_ADDRESS_CLASS_1;
+  else
+    return 0;
+}
+
+static const char *
+s390_address_class_type_flags_to_name (struct gdbarch *gdbarch, int type_flags)
+{
+  if (type_flags & TYPE_INSTANCE_FLAG_ADDRESS_CLASS_1)
+    return "mode32";
+  else
+    return NULL;
+}
+
+static int
+s390_address_class_name_to_type_flags (struct gdbarch *gdbarch,
+				       const char *name,
+				       int *type_flags_ptr)
+{
+  if (strcmp (name, "mode32") == 0)
+    {
+      *type_flags_ptr = TYPE_INSTANCE_FLAG_ADDRESS_CLASS_1;
+      return 1;
+    }
+  else
+    return 0;
+}
+
+/* Inferior function calls. */
+
+/* Dummy function calls.  */
+
+/* Unwrap any single-field structs in TYPE and return the effective
+   "inner" type.  E.g., yield "float" for all these cases:
+
+     float x;
+     struct { float x };
+     struct { struct { float x; } x; };
+     struct { struct { struct { float x; } x; } x; };
+
+   However, if an inner type is smaller than MIN_SIZE, abort the
+   unwrapping.  */
+
+static struct type *
+s390_effective_inner_type (struct type *type, unsigned int min_size)
+{
+  while (TYPE_CODE (type) == TYPE_CODE_STRUCT
+	 && TYPE_NFIELDS (type) == 1)
+    {
+      struct type *inner = check_typedef (TYPE_FIELD_TYPE (type, 0));
+
+      if (TYPE_LENGTH (inner) < min_size)
+	break;
+      type = inner;
+    }
+
+  return type;
+}
+
+/* Return non-zero if TYPE should be passed like "float" or
+   "double".  */
+
+static int
+s390_function_arg_float (struct type *type)
+{
+  /* Note that long double as well as complex types are intentionally
+     excluded. */
+  if (TYPE_LENGTH (type) > 8)
+    return 0;
+
+  /* A struct containing just a float or double is passed like a float
+     or double.  */
+  type = s390_effective_inner_type (type, 0);
+
+  return (TYPE_CODE (type) == TYPE_CODE_FLT
+	  || TYPE_CODE (type) == TYPE_CODE_DECFLOAT);
+}
+
+/* Return non-zero if TYPE should be passed like a vector.  */
+
+static int
+s390_function_arg_vector (struct type *type)
+{
+  if (TYPE_LENGTH (type) > 16)
+    return 0;
+
+  /* Structs containing just a vector are passed like a vector.  */
+  type = s390_effective_inner_type (type, TYPE_LENGTH (type));
+
+  return TYPE_CODE (type) == TYPE_CODE_ARRAY && TYPE_VECTOR (type);
+}
+
+/* Determine whether N is a power of two.  */
+
+static int
+is_power_of_two (unsigned int n)
+{
+  return n && ((n & (n - 1)) == 0);
+}
+
+/* For an argument whose type is TYPE and which is not passed like a
+   float or vector, return non-zero if it should be passed like "int"
+   or "long long".  */
+
+static int
+s390_function_arg_integer (struct type *type)
+{
+  enum type_code code = TYPE_CODE (type);
+
+  if (TYPE_LENGTH (type) > 8)
+    return 0;
+
+  if (code == TYPE_CODE_INT
+      || code == TYPE_CODE_ENUM
+      || code == TYPE_CODE_RANGE
+      || code == TYPE_CODE_CHAR
+      || code == TYPE_CODE_BOOL
+      || code == TYPE_CODE_PTR
+      || TYPE_IS_REFERENCE (type))
+    return 1;
+
+  return ((code == TYPE_CODE_UNION || code == TYPE_CODE_STRUCT)
+	  && is_power_of_two (TYPE_LENGTH (type)));
+}
+
+/* Argument passing state: Internal data structure passed to helper
+   routines of s390_push_dummy_call.  */
+
+struct s390_arg_state
+  {
+    /* Register cache, or NULL, if we are in "preparation mode".  */
+    struct regcache *regcache;
+    /* Next available general/floating-point/vector register for
+       argument passing.  */
+    int gr, fr, vr;
+    /* Current pointer to copy area (grows downwards).  */
+    CORE_ADDR copy;
+    /* Current pointer to parameter area (grows upwards).  */
+    CORE_ADDR argp;
+  };
+
+/* Prepare one argument ARG for a dummy call and update the argument
+   passing state AS accordingly.  If the regcache field in AS is set,
+   operate in "write mode" and write ARG into the inferior.  Otherwise
+   run "preparation mode" and skip all updates to the inferior.  */
+
+static void
+s390_handle_arg (struct s390_arg_state *as, struct value *arg,
+		 struct gdbarch_tdep *tdep, int word_size,
+		 enum bfd_endian byte_order, int is_unnamed)
+{
+  struct type *type = check_typedef (value_type (arg));
+  unsigned int length = TYPE_LENGTH (type);
+  int write_mode = as->regcache != NULL;
+
+  if (s390_function_arg_float (type))
+    {
+      /* The GNU/Linux for S/390 ABI uses FPRs 0 and 2 to pass
+	 arguments.  The GNU/Linux for zSeries ABI uses 0, 2, 4, and
+	 6.  */
+      if (as->fr <= (tdep->abi == ABI_LINUX_S390 ? 2 : 6))
+	{
+	  /* When we store a single-precision value in an FP register,
+	     it occupies the leftmost bits.  */
+	  if (write_mode)
+	    regcache_cooked_write_part (as->regcache,
+					S390_F0_REGNUM + as->fr,
+					0, length,
+					value_contents (arg));
+	  as->fr += 2;
+	}
+      else
+	{
+	  /* When we store a single-precision value in a stack slot,
+	     it occupies the rightmost bits.  */
+	  as->argp = align_up (as->argp + length, word_size);
+	  if (write_mode)
+	    write_memory (as->argp - length, value_contents (arg),
+			  length);
+	}
+    }
+  else if (tdep->vector_abi == S390_VECTOR_ABI_128
+	   && s390_function_arg_vector (type))
+    {
+      static const char use_vr[] = {24, 26, 28, 30, 25, 27, 29, 31};
+
+      if (!is_unnamed && as->vr < ARRAY_SIZE (use_vr))
+	{
+	  int regnum = S390_V24_REGNUM + use_vr[as->vr] - 24;
+
+	  if (write_mode)
+	    regcache_cooked_write_part (as->regcache, regnum,
+					0, length,
+					value_contents (arg));
+	  as->vr++;
+	}
+      else
+	{
+	  if (write_mode)
+	    write_memory (as->argp, value_contents (arg), length);
+	  as->argp = align_up (as->argp + length, word_size);
+	}
+    }
+  else if (s390_function_arg_integer (type) && length <= word_size)
+    {
+      /* Initialize it just to avoid a GCC false warning.  */
+      ULONGEST val = 0;
+
+      if (write_mode)
+	{
+	  /* Place value in least significant bits of the register or
+	     memory word and sign- or zero-extend to full word size.
+	     This also applies to a struct or union.  */
+	  val = TYPE_UNSIGNED (type)
+	    ? extract_unsigned_integer (value_contents (arg),
+					length, byte_order)
+	    : extract_signed_integer (value_contents (arg),
+				      length, byte_order);
+	}
+
+      if (as->gr <= 6)
+	{
+	  if (write_mode)
+	    regcache_cooked_write_unsigned (as->regcache,
+					    S390_R0_REGNUM + as->gr,
+					    val);
+	  as->gr++;
+	}
+      else
+	{
+	  if (write_mode)
+	    write_memory_unsigned_integer (as->argp, word_size,
+					   byte_order, val);
+	  as->argp += word_size;
+	}
+    }
+  else if (s390_function_arg_integer (type) && length == 8)
+    {
+      if (as->gr <= 5)
+	{
+	  if (write_mode)
+	    {
+	      regcache_cooked_write (as->regcache,
+				     S390_R0_REGNUM + as->gr,
+				     value_contents (arg));
+	      regcache_cooked_write (as->regcache,
+				     S390_R0_REGNUM + as->gr + 1,
+				     value_contents (arg) + word_size);
+	    }
+	  as->gr += 2;
+	}
+      else
+	{
+	  /* If we skipped r6 because we couldn't fit a DOUBLE_ARG
+	     in it, then don't go back and use it again later.  */
+	  as->gr = 7;
+
+	  if (write_mode)
+	    write_memory (as->argp, value_contents (arg), length);
+	  as->argp += length;
+	}
+    }
+  else
+    {
+      /* This argument type is never passed in registers.  Place the
+	 value in the copy area and pass a pointer to it.  Use 8-byte
+	 alignment as a conservative assumption.  */
+      as->copy = align_down (as->copy - length, 8);
+      if (write_mode)
+	write_memory (as->copy, value_contents (arg), length);
+
+      if (as->gr <= 6)
+	{
+	  if (write_mode)
+	    regcache_cooked_write_unsigned (as->regcache,
+					    S390_R0_REGNUM + as->gr,
+					    as->copy);
+	  as->gr++;
+	}
+      else
+	{
+	  if (write_mode)
+	    write_memory_unsigned_integer (as->argp, word_size,
+					   byte_order, as->copy);
+	  as->argp += word_size;
+	}
+    }
+}
+
+/* Put the actual parameter values pointed to by ARGS[0..NARGS-1] in
+   place to be passed to a function, as specified by the "GNU/Linux
+   for S/390 ELF Application Binary Interface Supplement".
+
+   SP is the current stack pointer.  We must put arguments, links,
+   padding, etc. whereever they belong, and return the new stack
+   pointer value.
+
+   If STRUCT_RETURN is non-zero, then the function we're calling is
+   going to return a structure by value; STRUCT_ADDR is the address of
+   a block we've allocated for it on the stack.
+
+   Our caller has taken care of any type promotions needed to satisfy
+   prototypes or the old K&R argument-passing rules.  */
+
+static CORE_ADDR
+s390_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
+		      struct regcache *regcache, CORE_ADDR bp_addr,
+		      int nargs, struct value **args, CORE_ADDR sp,
+		      int struct_return, CORE_ADDR struct_addr)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  int word_size = gdbarch_ptr_bit (gdbarch) / 8;
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  int i;
+  struct s390_arg_state arg_state, arg_prep;
+  CORE_ADDR param_area_start, new_sp;
+  struct type *ftype = check_typedef (value_type (function));
+
+  if (TYPE_CODE (ftype) == TYPE_CODE_PTR)
+    ftype = check_typedef (TYPE_TARGET_TYPE (ftype));
+
+  arg_prep.copy = sp;
+  arg_prep.gr = struct_return ? 3 : 2;
+  arg_prep.fr = 0;
+  arg_prep.vr = 0;
+  arg_prep.argp = 0;
+  arg_prep.regcache = NULL;
+
+  /* Initialize arg_state for "preparation mode".  */
+  arg_state = arg_prep;
+
+  /* Update arg_state.copy with the start of the reference-to-copy area
+     and arg_state.argp with the size of the parameter area.  */
+  for (i = 0; i < nargs; i++)
+    s390_handle_arg (&arg_state, args[i], tdep, word_size, byte_order,
+		     TYPE_VARARGS (ftype) && i >= TYPE_NFIELDS (ftype));
+
+  param_area_start = align_down (arg_state.copy - arg_state.argp, 8);
+
+  /* Allocate the standard frame areas: the register save area, the
+     word reserved for the compiler, and the back chain pointer.  */
+  new_sp = param_area_start - (16 * word_size + 32);
+
+  /* Now we have the final stack pointer.  Make sure we didn't
+     underflow; on 31-bit, this would result in addresses with the
+     high bit set, which causes confusion elsewhere.  Note that if we
+     error out here, stack and registers remain untouched.  */
+  if (gdbarch_addr_bits_remove (gdbarch, new_sp) != new_sp)
+    error (_("Stack overflow"));
+
+  /* Pass the structure return address in general register 2.  */
+  if (struct_return)
+    regcache_cooked_write_unsigned (regcache, S390_R2_REGNUM, struct_addr);
+
+  /* Initialize arg_state for "write mode".  */
+  arg_state = arg_prep;
+  arg_state.argp = param_area_start;
+  arg_state.regcache = regcache;
+
+  /* Write all parameters.  */
+  for (i = 0; i < nargs; i++)
+    s390_handle_arg (&arg_state, args[i], tdep, word_size, byte_order,
+		     TYPE_VARARGS (ftype) && i >= TYPE_NFIELDS (ftype));
+
+  /* Store return PSWA.  In 31-bit mode, keep addressing mode bit.  */
+  if (word_size == 4)
+    {
+      ULONGEST pswa;
+      regcache_cooked_read_unsigned (regcache, S390_PSWA_REGNUM, &pswa);
+      bp_addr = (bp_addr & 0x7fffffff) | (pswa & 0x80000000);
+    }
+  regcache_cooked_write_unsigned (regcache, S390_RETADDR_REGNUM, bp_addr);
+
+  /* Store updated stack pointer.  */
+  regcache_cooked_write_unsigned (regcache, S390_SP_REGNUM, new_sp);
+
+  /* We need to return the 'stack part' of the frame ID,
+     which is actually the top of the register save area.  */
+  return param_area_start;
+}
+
+/* Assuming THIS_FRAME is a dummy, return the frame ID of that
+   dummy frame.  The frame ID's base needs to match the TOS value
+   returned by push_dummy_call, and the PC match the dummy frame's
+   breakpoint.  */
+static struct frame_id
+s390_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
+{
+  int word_size = gdbarch_ptr_bit (gdbarch) / 8;
+  CORE_ADDR sp = get_frame_register_unsigned (this_frame, S390_SP_REGNUM);
+  sp = gdbarch_addr_bits_remove (gdbarch, sp);
+
+  return frame_id_build (sp + 16*word_size + 32,
+			 get_frame_pc (this_frame));
+}
+
+static CORE_ADDR
+s390_frame_align (struct gdbarch *gdbarch, CORE_ADDR addr)
+{
+  /* Both the 32- and 64-bit ABI's say that the stack pointer should
+     always be aligned on an eight-byte boundary.  */
+  return (addr & -8);
+}
+
+/* Helper for s390_return_value: Set or retrieve a function return
+   value if it resides in a register.  */
+
+static void
+s390_register_return_value (struct gdbarch *gdbarch, struct type *type,
+			    struct regcache *regcache,
+			    gdb_byte *out, const gdb_byte *in)
+{
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  int word_size = gdbarch_ptr_bit (gdbarch) / 8;
+  int length = TYPE_LENGTH (type);
+  int code = TYPE_CODE (type);
+
+  if (code == TYPE_CODE_FLT || code == TYPE_CODE_DECFLOAT)
+    {
+      /* Float-like value: left-aligned in f0.  */
+      if (in != NULL)
+	regcache_cooked_write_part (regcache, S390_F0_REGNUM,
+				    0, length, in);
+      else
+	regcache_cooked_read_part (regcache, S390_F0_REGNUM,
+				   0, length, out);
+    }
+  else if (code == TYPE_CODE_ARRAY)
+    {
+      /* Vector: left-aligned in v24.  */
+      if (in != NULL)
+	regcache_cooked_write_part (regcache, S390_V24_REGNUM,
+				    0, length, in);
+      else
+	regcache_cooked_read_part (regcache, S390_V24_REGNUM,
+				   0, length, out);
+    }
+  else if (length <= word_size)
+    {
+      /* Integer: zero- or sign-extended in r2.  */
+      if (out != NULL)
+	regcache_cooked_read_part (regcache, S390_R2_REGNUM,
+				   word_size - length, length, out);
+      else if (TYPE_UNSIGNED (type))
+	regcache_cooked_write_unsigned
+	  (regcache, S390_R2_REGNUM,
+	   extract_unsigned_integer (in, length, byte_order));
+      else
+	regcache_cooked_write_signed
+	  (regcache, S390_R2_REGNUM,
+	   extract_signed_integer (in, length, byte_order));
+    }
+  else if (length == 2 * word_size)
+    {
+      /* Double word: in r2 and r3.  */
+      if (in != NULL)
+	{
+	  regcache_cooked_write (regcache, S390_R2_REGNUM, in);
+	  regcache_cooked_write (regcache, S390_R3_REGNUM,
+				 in + word_size);
+	}
+      else
+	{
+	  regcache_cooked_read (regcache, S390_R2_REGNUM, out);
+	  regcache_cooked_read (regcache, S390_R3_REGNUM,
+				out + word_size);
+	}
+    }
+  else
+    internal_error (__FILE__, __LINE__, _("invalid return type"));
+}
+
+/* Implement the 'return_value' gdbarch method.  */
+
+static enum return_value_convention
+s390_return_value (struct gdbarch *gdbarch, struct value *function,
+		   struct type *type, struct regcache *regcache,
+		   gdb_byte *out, const gdb_byte *in)
+{
+  enum return_value_convention rvc;
+
+  type = check_typedef (type);
+
+  switch (TYPE_CODE (type))
+    {
+    case TYPE_CODE_STRUCT:
+    case TYPE_CODE_UNION:
+    case TYPE_CODE_COMPLEX:
+      rvc = RETURN_VALUE_STRUCT_CONVENTION;
+      break;
+    case TYPE_CODE_ARRAY:
+      rvc = (gdbarch_tdep (gdbarch)->vector_abi == S390_VECTOR_ABI_128
+	     && TYPE_LENGTH (type) <= 16 && TYPE_VECTOR (type))
+	? RETURN_VALUE_REGISTER_CONVENTION
+	: RETURN_VALUE_STRUCT_CONVENTION;
+      break;
+    default:
+      rvc = TYPE_LENGTH (type) <= 8
+	? RETURN_VALUE_REGISTER_CONVENTION
+	: RETURN_VALUE_STRUCT_CONVENTION;
+    }
+
+  if (in != NULL || out != NULL)
+    {
+      if (rvc == RETURN_VALUE_REGISTER_CONVENTION)
+	s390_register_return_value (gdbarch, type, regcache, out, in);
+      else if (in != NULL)
+	error (_("Cannot set function return value."));
+      else
+	error (_("Function return value unknown."));
+    }
+
+  return rvc;
+}
+
+/* Frame unwinding.  */
+
+/* See s390-tdep.h.  */
+
+int
+s390_stack_frame_destroyed_p (struct gdbarch *gdbarch, CORE_ADDR pc)
+{
+  int word_size = gdbarch_ptr_bit (gdbarch) / 8;
+
+  /* In frameless functions, there's not frame to destroy and thus
+     we don't care about the epilogue.
+
+     In functions with frame, the epilogue sequence is a pair of
+     a LM-type instruction that restores (amongst others) the
+     return register %r14 and the stack pointer %r15, followed
+     by a branch 'br %r14' --or equivalent-- that effects the
+     actual return.
+
+     In that situation, this function needs to return 'true' in
+     exactly one case: when pc points to that branch instruction.
+
+     Thus we try to disassemble the one instructions immediately
+     preceding pc and check whether it is an LM-type instruction
+     modifying the stack pointer.
+
+     Note that disassembling backwards is not reliable, so there
+     is a slight chance of false positives here ...  */
+
+  bfd_byte insn[6];
+  unsigned int r1, r3, b2;
+  int d2;
+
+  if (word_size == 4
+      && !target_read_memory (pc - 4, insn, 4)
+      && is_rs (insn, op_lm, &r1, &r3, &d2, &b2)
+      && r3 == S390_SP_REGNUM - S390_R0_REGNUM)
+    return 1;
+
+  if (word_size == 4
+      && !target_read_memory (pc - 6, insn, 6)
+      && is_rsy (insn, op1_lmy, op2_lmy, &r1, &r3, &d2, &b2)
+      && r3 == S390_SP_REGNUM - S390_R0_REGNUM)
+    return 1;
+
+  if (word_size == 8
+      && !target_read_memory (pc - 6, insn, 6)
+      && is_rsy (insn, op1_lmg, op2_lmg, &r1, &r3, &d2, &b2)
+      && r3 == S390_SP_REGNUM - S390_R0_REGNUM)
+    return 1;
+
+  return 0;
+}
+
+static CORE_ADDR
+s390_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
+{
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  ULONGEST pc;
+  pc = frame_unwind_register_unsigned (next_frame, tdep->pc_regnum);
+  return gdbarch_addr_bits_remove (gdbarch, pc);
+}
+
+static CORE_ADDR
+s390_unwind_sp (struct gdbarch *gdbarch, struct frame_info *next_frame)
+{
+  ULONGEST sp;
+  sp = frame_unwind_register_unsigned (next_frame, S390_SP_REGNUM);
+  return gdbarch_addr_bits_remove (gdbarch, sp);
+}
+
+/* See s390-tdep.h.  */
+
+struct value *
+s390_unwind_pseudo_register (struct frame_info *this_frame, int regnum)
+{
+  struct gdbarch *gdbarch = get_frame_arch (this_frame);
+  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+  struct type *type = register_type (gdbarch, regnum);
+
+  /* Unwind PC via PSW address.  */
+  if (regnum == tdep->pc_regnum)
+    {
+      struct value *val;
+
+      val = frame_unwind_register_value (this_frame, S390_PSWA_REGNUM);
+      if (!value_optimized_out (val))
+	{
+	  LONGEST pswa = value_as_long (val);
+
+	  if (TYPE_LENGTH (type) == 4)
+	    return value_from_pointer (type, pswa & 0x7fffffff);
+	  else
+	    return value_from_pointer (type, pswa);
+	}
+    }
+
+  /* Unwind CC via PSW mask.  */
+  if (regnum == tdep->cc_regnum)
+    {
+      struct value *val;
+
+      val = frame_unwind_register_value (this_frame, S390_PSWM_REGNUM);
+      if (!value_optimized_out (val))
+	{
+	  LONGEST pswm = value_as_long (val);
+
+	  if (TYPE_LENGTH (type) == 4)
+	    return value_from_longest (type, (pswm >> 12) & 3);
+	  else
+	    return value_from_longest (type, (pswm >> 44) & 3);
+	}
+    }
+
+  /* Unwind full GPRs to show at least the lower halves (as the
+     upper halves are undefined).  */
+  if (regnum_is_gpr_full (tdep, regnum))
+    {
+      int reg = regnum - tdep->gpr_full_regnum;
+      struct value *val;
+
+      val = frame_unwind_register_value (this_frame, S390_R0_REGNUM + reg);
+      if (!value_optimized_out (val))
+	return value_cast (type, val);
+    }
+
+  return allocate_optimized_out_value (type);
+}
+
+/* Translate a .eh_frame register to DWARF register, or adjust a
+   .debug_frame register.  */
+
+static int
+s390_adjust_frame_regnum (struct gdbarch *gdbarch, int num, int eh_frame_p)
+{
+  /* See s390_dwarf_reg_to_regnum for comments.  */
+  return (num >= 0 && num < 16) ? num + s390_dwarf_reg_r0l : num;
+}
+
+/* DWARF2 frame unwinding.  */
+
+static struct value *
+s390_dwarf2_prev_register (struct frame_info *this_frame, void **this_cache,
+			   int regnum)
+{
+  return s390_unwind_pseudo_register (this_frame, regnum);
+}
+
+static void
+s390_dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum,
+			    struct dwarf2_frame_state_reg *reg,
+			    struct frame_info *this_frame)
+{
+  /* The condition code (and thus PSW mask) is call-clobbered.  */
+  if (regnum == S390_PSWM_REGNUM)
+    reg->how = DWARF2_FRAME_REG_UNDEFINED;
+
+  /* The PSW address unwinds to the return address.  */
+  else if (regnum == S390_PSWA_REGNUM)
+    reg->how = DWARF2_FRAME_REG_RA;
+
+  /* Fixed registers are call-saved or call-clobbered
+     depending on the ABI in use.  */
+  else if (regnum < S390_NUM_REGS)
+    {
+      if (s390_register_call_saved (gdbarch, regnum))
+	reg->how = DWARF2_FRAME_REG_SAME_VALUE;
+      else
+	reg->how = DWARF2_FRAME_REG_UNDEFINED;
+    }
+
+  /* We install a special function to unwind pseudos.  */
+  else
+    {
+      reg->how = DWARF2_FRAME_REG_FN;
+      reg->loc.fn = s390_dwarf2_prev_register;
+    }
+}
+
+/* See s390-tdep.h.  */
+
+struct gdbarch *
+s390_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches,
+		   const struct target_desc *tdesc)
+{
+  struct tdesc_arch_data *tdesc_data = NULL;
+  struct gdbarch *gdbarch;
+  struct gdbarch_tdep *tdep;
+  enum s390_abi_kind tdep_abi;
+  enum s390_vector_abi_kind vector_abi;
+  int have_upper = 0;
+  int have_linux_v1 = 0;
+  int have_linux_v2 = 0;
+  int have_tdb = 0;
+  int have_vx = 0;
+  int have_gs = 0;
+  int first_pseudo_reg, last_pseudo_reg;
+  static const char *const stap_register_prefixes[] = { "%", NULL };
+  static const char *const stap_register_indirection_prefixes[] = { "(",
+								    NULL };
+  static const char *const stap_register_indirection_suffixes[] = { ")",
+								    NULL };
+
+  /* Default ABI and register size.  */
+  switch (info.bfd_arch_info->mach)
+    {
+    case bfd_mach_s390_31:
+      tdep_abi = ABI_LINUX_S390;
+      break;
+
+    case bfd_mach_s390_64:
+      tdep_abi = ABI_LINUX_ZSERIES;
+      break;
+
+    default:
+      return NULL;
+    }
+
+  /* Check any target description for validity.  */
+  if (tdesc_has_registers (tdesc))
+    {
+      static const char *const gprs[] = {
+	"r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
+	"r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15"
+      };
+      static const char *const fprs[] = {
+	"f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7",
+	"f8", "f9", "f10", "f11", "f12", "f13", "f14", "f15"
+      };
+      static const char *const acrs[] = {
+	"acr0", "acr1", "acr2", "acr3", "acr4", "acr5", "acr6", "acr7",
+	"acr8", "acr9", "acr10", "acr11", "acr12", "acr13", "acr14", "acr15"
+      };
+      static const char *const gprs_lower[] = {
+	"r0l", "r1l", "r2l", "r3l", "r4l", "r5l", "r6l", "r7l",
+	"r8l", "r9l", "r10l", "r11l", "r12l", "r13l", "r14l", "r15l"
+      };
+      static const char *const gprs_upper[] = {
+	"r0h", "r1h", "r2h", "r3h", "r4h", "r5h", "r6h", "r7h",
+	"r8h", "r9h", "r10h", "r11h", "r12h", "r13h", "r14h", "r15h"
+      };
+      static const char *const tdb_regs[] = {
+	"tdb0", "tac", "tct", "atia",
+	"tr0", "tr1", "tr2", "tr3", "tr4", "tr5", "tr6", "tr7",
+	"tr8", "tr9", "tr10", "tr11", "tr12", "tr13", "tr14", "tr15"
+      };
+      static const char *const vxrs_low[] = {
+	"v0l", "v1l", "v2l", "v3l", "v4l", "v5l", "v6l", "v7l", "v8l",
+	"v9l", "v10l", "v11l", "v12l", "v13l", "v14l", "v15l",
+      };
+      static const char *const vxrs_high[] = {
+	"v16", "v17", "v18", "v19", "v20", "v21", "v22", "v23", "v24",
+	"v25", "v26", "v27", "v28", "v29", "v30", "v31",
+      };
+      static const char *const gs_cb[] = {
+	"gsd", "gssm", "gsepla",
+      };
+      static const char *const gs_bc[] = {
+	"bc_gsd", "bc_gssm", "bc_gsepla",
+      };
+      const struct tdesc_feature *feature;
+      int i, valid_p = 1;
+
+      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.core");
+      if (feature == NULL)
+	return NULL;
+
+      tdesc_data = tdesc_data_alloc ();
+
+      valid_p &= tdesc_numbered_register (feature, tdesc_data,
+					  S390_PSWM_REGNUM, "pswm");
+      valid_p &= tdesc_numbered_register (feature, tdesc_data,
+					  S390_PSWA_REGNUM, "pswa");
+
+      if (tdesc_unnumbered_register (feature, "r0"))
+	{
+	  for (i = 0; i < 16; i++)
+	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
+						S390_R0_REGNUM + i, gprs[i]);
+	}
+      else
+	{
+	  have_upper = 1;
+
+	  for (i = 0; i < 16; i++)
+	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
+						S390_R0_REGNUM + i,
+						gprs_lower[i]);
+	  for (i = 0; i < 16; i++)
+	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
+						S390_R0_UPPER_REGNUM + i,
+						gprs_upper[i]);
+	}
+
+      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.fpr");
+      if (feature == NULL)
+	{
+	  tdesc_data_cleanup (tdesc_data);
+	  return NULL;
+	}
+
+      valid_p &= tdesc_numbered_register (feature, tdesc_data,
+					  S390_FPC_REGNUM, "fpc");
+      for (i = 0; i < 16; i++)
+	valid_p &= tdesc_numbered_register (feature, tdesc_data,
+					    S390_F0_REGNUM + i, fprs[i]);
+
+      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.acr");
+      if (feature == NULL)
+	{
+	  tdesc_data_cleanup (tdesc_data);
+	  return NULL;
+	}
+
+      for (i = 0; i < 16; i++)
+	valid_p &= tdesc_numbered_register (feature, tdesc_data,
+					    S390_A0_REGNUM + i, acrs[i]);
+
+      /* Optional GNU/Linux-specific "registers".  */
+      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.linux");
+      if (feature)
+	{
+	  tdesc_numbered_register (feature, tdesc_data,
+				   S390_ORIG_R2_REGNUM, "orig_r2");
+
+	  if (tdesc_numbered_register (feature, tdesc_data,
+				       S390_LAST_BREAK_REGNUM, "last_break"))
+	    have_linux_v1 = 1;
+
+	  if (tdesc_numbered_register (feature, tdesc_data,
+				       S390_SYSTEM_CALL_REGNUM, "system_call"))
+	    have_linux_v2 = 1;
+
+	  if (have_linux_v2 > have_linux_v1)
+	    valid_p = 0;
+	}
+
+      /* Transaction diagnostic block.  */
+      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.tdb");
+      if (feature)
+	{
+	  for (i = 0; i < ARRAY_SIZE (tdb_regs); i++)
+	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
+						S390_TDB_DWORD0_REGNUM + i,
+						tdb_regs[i]);
+	  have_tdb = 1;
+	}
+
+      /* Vector registers.  */
+      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.vx");
+      if (feature)
+	{
+	  for (i = 0; i < 16; i++)
+	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
+						S390_V0_LOWER_REGNUM + i,
+						vxrs_low[i]);
+	  for (i = 0; i < 16; i++)
+	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
+						S390_V16_REGNUM + i,
+						vxrs_high[i]);
+	  have_vx = 1;
+	}
+
+      /* Guarded-storage registers.  */
+      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.gs");
+      if (feature)
+	{
+	  for (i = 0; i < 3; i++)
+	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
+						S390_GSD_REGNUM + i,
+						gs_cb[i]);
+	  have_gs = 1;
+	}
+
+      /* Guarded-storage broadcast control.  */
+      feature = tdesc_find_feature (tdesc, "org.gnu.gdb.s390.gsbc");
+      if (feature)
+	{
+	  valid_p &= have_gs;
+
+	  for (i = 0; i < 3; i++)
+	    valid_p &= tdesc_numbered_register (feature, tdesc_data,
+						S390_BC_GSD_REGNUM + i,
+						gs_bc[i]);
+	}
+
+      if (!valid_p)
+	{
+	  tdesc_data_cleanup (tdesc_data);
+	  return NULL;
+	}
+    }
+
+  /* Determine vector ABI.  */
+  vector_abi = S390_VECTOR_ABI_NONE;
+#ifdef HAVE_ELF
+  if (have_vx
+      && info.abfd != NULL
+      && info.abfd->format == bfd_object
+      && bfd_get_flavour (info.abfd) == bfd_target_elf_flavour
+      && bfd_elf_get_obj_attr_int (info.abfd, OBJ_ATTR_GNU,
+				   Tag_GNU_S390_ABI_Vector) == 2)
+    vector_abi = S390_VECTOR_ABI_128;
+#endif
+
+  /* Find a candidate among extant architectures.  */
+  for (arches = gdbarch_list_lookup_by_info (arches, &info);
+       arches != NULL;
+       arches = gdbarch_list_lookup_by_info (arches->next, &info))
+    {
+      tdep = gdbarch_tdep (arches->gdbarch);
+      if (!tdep)
+	continue;
+      if (tdep->abi != tdep_abi)
+	continue;
+      if (tdep->vector_abi != vector_abi)
+	continue;
+      if ((tdep->gpr_full_regnum != -1) != have_upper)
+	continue;
+      if (tdep->have_gs != have_gs)
+	continue;
+      if (tdesc_data != NULL)
+	tdesc_data_cleanup (tdesc_data);
+      return arches->gdbarch;
+    }
+
+  /* Otherwise create a new gdbarch for the specified machine type.  */
+  tdep = XCNEW (struct gdbarch_tdep);
+  tdep->abi = tdep_abi;
+  tdep->vector_abi = vector_abi;
+  tdep->have_linux_v1 = have_linux_v1;
+  tdep->have_linux_v2 = have_linux_v2;
+  tdep->have_tdb = have_tdb;
+  tdep->have_gs = have_gs;
+  gdbarch = gdbarch_alloc (&info, tdep);
+
+  set_gdbarch_believe_pcc_promotion (gdbarch, 0);
+  set_gdbarch_char_signed (gdbarch, 0);
+
+  /* S/390 GNU/Linux uses either 64-bit or 128-bit long doubles.
+     We can safely let them default to 128-bit, since the debug info
+     will give the size of type actually used in each case.  */
+  set_gdbarch_long_double_bit (gdbarch, 128);
+  set_gdbarch_long_double_format (gdbarch, floatformats_ia64_quad);
+
+  /* Breakpoints.  */
+  /* Amount PC must be decremented by after a breakpoint.  This is
+     often the number of bytes returned by gdbarch_breakpoint_from_pc but not
+     always.  */
+  set_gdbarch_decr_pc_after_break (gdbarch, 2);
+  set_gdbarch_breakpoint_kind_from_pc (gdbarch, s390_breakpoint::kind_from_pc);
+  set_gdbarch_sw_breakpoint_from_kind (gdbarch, s390_breakpoint::bp_from_kind);
+
+  /* Displaced stepping.  */
+  set_gdbarch_displaced_step_copy_insn (gdbarch,
+					s390_displaced_step_copy_insn);
+  set_gdbarch_displaced_step_fixup (gdbarch, s390_displaced_step_fixup);
+  set_gdbarch_displaced_step_location (gdbarch, linux_displaced_step_location);
+  set_gdbarch_displaced_step_hw_singlestep (gdbarch, s390_displaced_step_hw_singlestep);
+  set_gdbarch_software_single_step (gdbarch, s390_software_single_step);
+  set_gdbarch_max_insn_length (gdbarch, S390_MAX_INSTR_SIZE);
+
+  /* Prologue analysis.  */
+  set_gdbarch_skip_prologue (gdbarch, s390_skip_prologue);
+
+  /* Register handling.  */
+  set_gdbarch_num_regs (gdbarch, S390_NUM_REGS);
+  set_gdbarch_sp_regnum (gdbarch, S390_SP_REGNUM);
+  set_gdbarch_fp0_regnum (gdbarch, S390_F0_REGNUM);
+  set_gdbarch_register_name (gdbarch, s390_register_name);
+  set_gdbarch_cannot_store_register (gdbarch, s390_cannot_store_register);
+  set_gdbarch_write_pc (gdbarch, s390_write_pc);
+  set_gdbarch_stab_reg_to_regnum (gdbarch, s390_dwarf_reg_to_regnum);
+  set_gdbarch_dwarf2_reg_to_regnum (gdbarch, s390_dwarf_reg_to_regnum);
+  set_gdbarch_value_from_register (gdbarch, s390_value_from_register);
+
+  /* Pseudo registers.  */
+  set_gdbarch_pseudo_register_read (gdbarch, s390_pseudo_register_read);
+  set_gdbarch_pseudo_register_write (gdbarch, s390_pseudo_register_write);
+  set_tdesc_pseudo_register_name (gdbarch, s390_pseudo_register_name);
+  set_tdesc_pseudo_register_type (gdbarch, s390_pseudo_register_type);
+  set_tdesc_pseudo_register_reggroup_p (gdbarch,
+					s390_pseudo_register_reggroup_p);
+  set_gdbarch_ax_pseudo_register_collect (gdbarch,
+					  s390_ax_pseudo_register_collect);
+  set_gdbarch_ax_pseudo_register_push_stack
+      (gdbarch, s390_ax_pseudo_register_push_stack);
+  set_gdbarch_gen_return_address (gdbarch, s390_gen_return_address);
+  tdesc_use_registers (gdbarch, tdesc, tdesc_data);
+
+  /* Assign pseudo register numbers.  */
+  first_pseudo_reg = gdbarch_num_regs (gdbarch);
+  last_pseudo_reg = first_pseudo_reg;
+  tdep->gpr_full_regnum = -1;
+  if (have_upper)
+    {
+      tdep->gpr_full_regnum = last_pseudo_reg;
+      last_pseudo_reg += 16;
+    }
+  tdep->v0_full_regnum = -1;
+  if (have_vx)
+    {
+      tdep->v0_full_regnum = last_pseudo_reg;
+      last_pseudo_reg += 16;
+    }
+  tdep->pc_regnum = last_pseudo_reg++;
+  tdep->cc_regnum = last_pseudo_reg++;
+  set_gdbarch_pc_regnum (gdbarch, tdep->pc_regnum);
+  set_gdbarch_num_pseudo_regs (gdbarch, last_pseudo_reg - first_pseudo_reg);
+
+  /* Inferior function calls.  */
+  set_gdbarch_push_dummy_call (gdbarch, s390_push_dummy_call);
+  set_gdbarch_dummy_id (gdbarch, s390_dummy_id);
+  set_gdbarch_frame_align (gdbarch, s390_frame_align);
+  set_gdbarch_return_value (gdbarch, s390_return_value);
+
+  /* Frame handling.  */
+  /* Stack grows downward.  */
+  set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
+  set_gdbarch_stack_frame_destroyed_p (gdbarch, s390_stack_frame_destroyed_p);
+  dwarf2_frame_set_init_reg (gdbarch, s390_dwarf2_frame_init_reg);
+  dwarf2_frame_set_adjust_regnum (gdbarch, s390_adjust_frame_regnum);
+  dwarf2_append_unwinders (gdbarch);
+  frame_base_append_sniffer (gdbarch, dwarf2_frame_base_sniffer);
+  set_gdbarch_unwind_pc (gdbarch, s390_unwind_pc);
+  set_gdbarch_unwind_sp (gdbarch, s390_unwind_sp);
+
+  switch (tdep->abi)
+    {
+    case ABI_LINUX_S390:
+      set_gdbarch_addr_bits_remove (gdbarch, s390_addr_bits_remove);
+      break;
+
+    case ABI_LINUX_ZSERIES:
+      set_gdbarch_long_bit (gdbarch, 64);
+      set_gdbarch_long_long_bit (gdbarch, 64);
+      set_gdbarch_ptr_bit (gdbarch, 64);
+      set_gdbarch_address_class_type_flags (gdbarch,
+					    s390_address_class_type_flags);
+      set_gdbarch_address_class_type_flags_to_name (gdbarch,
+						    s390_address_class_type_flags_to_name);
+      set_gdbarch_address_class_name_to_type_flags (gdbarch,
+						    s390_address_class_name_to_type_flags);
+      break;
+    }
+
+  /* SystemTap functions.  */
+  set_gdbarch_stap_register_prefixes (gdbarch, stap_register_prefixes);
+  set_gdbarch_stap_register_indirection_prefixes (gdbarch,
+						  stap_register_indirection_prefixes);
+  set_gdbarch_stap_register_indirection_suffixes (gdbarch,
+						  stap_register_indirection_suffixes);
+
+  set_gdbarch_disassembler_options (gdbarch, &s390_disassembler_options);
+  set_gdbarch_valid_disassembler_options (gdbarch,
+					  disassembler_options_s390 ());
+
+  return gdbarch;
+}
diff --git a/gdb/s390-tdep.h b/gdb/s390-tdep.h
new file mode 100644
index 0000000000..57ff2294d1
--- /dev/null
+++ b/gdb/s390-tdep.h
@@ -0,0 +1,386 @@ 
+/* Target-dependent code for s390.
+
+   Copyright (C) 2003-2017 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef S390_TDEP_H
+#define S390_TDEP_H
+
+#include "prologue-value.h"
+
+enum s390_abi_kind
+{
+  ABI_LINUX_S390,
+  ABI_LINUX_ZSERIES
+};
+
+enum s390_vector_abi_kind
+{
+  S390_VECTOR_ABI_NONE,
+  S390_VECTOR_ABI_128
+};
+
+/* The tdep structure.  */
+
+struct gdbarch_tdep
+{
+  /* ABI version.  */
+  enum s390_abi_kind abi;
+
+  /* Vector ABI.  */
+  enum s390_vector_abi_kind vector_abi;
+
+  /* Pseudo register numbers.  */
+  int gpr_full_regnum;
+  int pc_regnum;
+  int cc_regnum;
+  int v0_full_regnum;
+
+  int have_linux_v1;
+  int have_linux_v2;
+  int have_tdb;
+  bool have_gs;
+};
+
+/* Decoding S/390 instructions.  */
+
+/* Named opcode values for the S/390 instructions we recognize.  Some
+   instructions have their opcode split across two fields; those are the
+   op1_* and op2_* enums.  */
+
+enum
+  {
+    op1_lhi  = 0xa7,   op2_lhi  = 0x08,
+    op1_lghi = 0xa7,   op2_lghi = 0x09,
+    op1_lgfi = 0xc0,   op2_lgfi = 0x01,
+    op_lr    = 0x18,
+    op_lgr   = 0xb904,
+    op_l     = 0x58,
+    op1_ly   = 0xe3,   op2_ly   = 0x58,
+    op1_lg   = 0xe3,   op2_lg   = 0x04,
+    op_lm    = 0x98,
+    op1_lmy  = 0xeb,   op2_lmy  = 0x98,
+    op1_lmg  = 0xeb,   op2_lmg  = 0x04,
+    op_st    = 0x50,
+    op1_sty  = 0xe3,   op2_sty  = 0x50,
+    op1_stg  = 0xe3,   op2_stg  = 0x24,
+    op_std   = 0x60,
+    op_stm   = 0x90,
+    op1_stmy = 0xeb,   op2_stmy = 0x90,
+    op1_stmg = 0xeb,   op2_stmg = 0x24,
+    op1_aghi = 0xa7,   op2_aghi = 0x0b,
+    op1_ahi  = 0xa7,   op2_ahi  = 0x0a,
+    op1_agfi = 0xc2,   op2_agfi = 0x08,
+    op1_afi  = 0xc2,   op2_afi  = 0x09,
+    op1_algfi= 0xc2,   op2_algfi= 0x0a,
+    op1_alfi = 0xc2,   op2_alfi = 0x0b,
+    op_ar    = 0x1a,
+    op_agr   = 0xb908,
+    op_a     = 0x5a,
+    op1_ay   = 0xe3,   op2_ay   = 0x5a,
+    op1_ag   = 0xe3,   op2_ag   = 0x08,
+    op1_slgfi= 0xc2,   op2_slgfi= 0x04,
+    op1_slfi = 0xc2,   op2_slfi = 0x05,
+    op_sr    = 0x1b,
+    op_sgr   = 0xb909,
+    op_s     = 0x5b,
+    op1_sy   = 0xe3,   op2_sy   = 0x5b,
+    op1_sg   = 0xe3,   op2_sg   = 0x09,
+    op_nr    = 0x14,
+    op_ngr   = 0xb980,
+    op_la    = 0x41,
+    op1_lay  = 0xe3,   op2_lay  = 0x71,
+    op1_larl = 0xc0,   op2_larl = 0x00,
+    op_basr  = 0x0d,
+    op_bas   = 0x4d,
+    op_bcr   = 0x07,
+    op_bc    = 0x0d,
+    op_bctr  = 0x06,
+    op_bctgr = 0xb946,
+    op_bct   = 0x46,
+    op1_bctg = 0xe3,   op2_bctg = 0x46,
+    op_bxh   = 0x86,
+    op1_bxhg = 0xeb,   op2_bxhg = 0x44,
+    op_bxle  = 0x87,
+    op1_bxleg= 0xeb,   op2_bxleg= 0x45,
+    op1_bras = 0xa7,   op2_bras = 0x05,
+    op1_brasl= 0xc0,   op2_brasl= 0x05,
+    op1_brc  = 0xa7,   op2_brc  = 0x04,
+    op1_brcl = 0xc0,   op2_brcl = 0x04,
+    op1_brct = 0xa7,   op2_brct = 0x06,
+    op1_brctg= 0xa7,   op2_brctg= 0x07,
+    op_brxh  = 0x84,
+    op1_brxhg= 0xec,   op2_brxhg= 0x44,
+    op_brxle = 0x85,
+    op1_brxlg= 0xec,   op2_brxlg= 0x45,
+    op_svc   = 0x0a,
+  };
+
+/* Hardware capabilities. */
+
+#ifndef HWCAP_S390_HIGH_GPRS
+#define HWCAP_S390_HIGH_GPRS 512
+#endif
+
+#ifndef HWCAP_S390_TE
+#define HWCAP_S390_TE 1024
+#endif
+
+#ifndef HWCAP_S390_VX
+#define HWCAP_S390_VX 2048
+#endif
+
+#ifndef HWCAP_S390_GS
+#define HWCAP_S390_GS 16384
+#endif
+
+/* Register information.  */
+
+/* Program Status Word.  */
+#define S390_PSWM_REGNUM 0
+#define S390_PSWA_REGNUM 1
+/* General Purpose Registers.  */
+#define S390_R0_REGNUM 2
+#define S390_R1_REGNUM 3
+#define S390_R2_REGNUM 4
+#define S390_R3_REGNUM 5
+#define S390_R4_REGNUM 6
+#define S390_R5_REGNUM 7
+#define S390_R6_REGNUM 8
+#define S390_R7_REGNUM 9
+#define S390_R8_REGNUM 10
+#define S390_R9_REGNUM 11
+#define S390_R10_REGNUM 12
+#define S390_R11_REGNUM 13
+#define S390_R12_REGNUM 14
+#define S390_R13_REGNUM 15
+#define S390_R14_REGNUM 16
+#define S390_R15_REGNUM 17
+/* Access Registers.  */
+#define S390_A0_REGNUM 18
+#define S390_A1_REGNUM 19
+#define S390_A2_REGNUM 20
+#define S390_A3_REGNUM 21
+#define S390_A4_REGNUM 22
+#define S390_A5_REGNUM 23
+#define S390_A6_REGNUM 24
+#define S390_A7_REGNUM 25
+#define S390_A8_REGNUM 26
+#define S390_A9_REGNUM 27
+#define S390_A10_REGNUM 28
+#define S390_A11_REGNUM 29
+#define S390_A12_REGNUM 30
+#define S390_A13_REGNUM 31
+#define S390_A14_REGNUM 32
+#define S390_A15_REGNUM 33
+/* Floating Point Control Word.  */
+#define S390_FPC_REGNUM 34
+/* Floating Point Registers.  */
+#define S390_F0_REGNUM 35
+#define S390_F1_REGNUM 36
+#define S390_F2_REGNUM 37
+#define S390_F3_REGNUM 38
+#define S390_F4_REGNUM 39
+#define S390_F5_REGNUM 40
+#define S390_F6_REGNUM 41
+#define S390_F7_REGNUM 42
+#define S390_F8_REGNUM 43
+#define S390_F9_REGNUM 44
+#define S390_F10_REGNUM 45
+#define S390_F11_REGNUM 46
+#define S390_F12_REGNUM 47
+#define S390_F13_REGNUM 48
+#define S390_F14_REGNUM 49
+#define S390_F15_REGNUM 50
+/* General Purpose Register Upper Halves.  */
+#define S390_R0_UPPER_REGNUM 51
+#define S390_R1_UPPER_REGNUM 52
+#define S390_R2_UPPER_REGNUM 53
+#define S390_R3_UPPER_REGNUM 54
+#define S390_R4_UPPER_REGNUM 55
+#define S390_R5_UPPER_REGNUM 56
+#define S390_R6_UPPER_REGNUM 57
+#define S390_R7_UPPER_REGNUM 58
+#define S390_R8_UPPER_REGNUM 59
+#define S390_R9_UPPER_REGNUM 60
+#define S390_R10_UPPER_REGNUM 61
+#define S390_R11_UPPER_REGNUM 62
+#define S390_R12_UPPER_REGNUM 63
+#define S390_R13_UPPER_REGNUM 64
+#define S390_R14_UPPER_REGNUM 65
+#define S390_R15_UPPER_REGNUM 66
+/* GNU/Linux-specific optional registers.  */
+#define S390_ORIG_R2_REGNUM 67
+#define S390_LAST_BREAK_REGNUM 68
+#define S390_SYSTEM_CALL_REGNUM 69
+/* Transaction diagnostic block.  */
+#define S390_TDB_DWORD0_REGNUM 70
+#define S390_TDB_ABORT_CODE_REGNUM 71
+#define S390_TDB_CONFLICT_TOKEN_REGNUM 72
+#define S390_TDB_ATIA_REGNUM 73
+#define S390_TDB_R0_REGNUM 74
+#define S390_TDB_R1_REGNUM 75
+#define S390_TDB_R2_REGNUM 76
+#define S390_TDB_R3_REGNUM 77
+#define S390_TDB_R4_REGNUM 78
+#define S390_TDB_R5_REGNUM 79
+#define S390_TDB_R6_REGNUM 80
+#define S390_TDB_R7_REGNUM 81
+#define S390_TDB_R8_REGNUM 82
+#define S390_TDB_R9_REGNUM 83
+#define S390_TDB_R10_REGNUM 84
+#define S390_TDB_R11_REGNUM 85
+#define S390_TDB_R12_REGNUM 86
+#define S390_TDB_R13_REGNUM 87
+#define S390_TDB_R14_REGNUM 88
+#define S390_TDB_R15_REGNUM 89
+/* Vector registers.  */
+#define S390_V0_LOWER_REGNUM 90
+#define S390_V1_LOWER_REGNUM 91
+#define S390_V2_LOWER_REGNUM 92
+#define S390_V3_LOWER_REGNUM 93
+#define S390_V4_LOWER_REGNUM 94
+#define S390_V5_LOWER_REGNUM 95
+#define S390_V6_LOWER_REGNUM 96
+#define S390_V7_LOWER_REGNUM 97
+#define S390_V8_LOWER_REGNUM 98
+#define S390_V9_LOWER_REGNUM 99
+#define S390_V10_LOWER_REGNUM 100
+#define S390_V11_LOWER_REGNUM 101
+#define S390_V12_LOWER_REGNUM 102
+#define S390_V13_LOWER_REGNUM 103
+#define S390_V14_LOWER_REGNUM 104
+#define S390_V15_LOWER_REGNUM 105
+#define S390_V16_REGNUM 106
+#define S390_V17_REGNUM 107
+#define S390_V18_REGNUM 108
+#define S390_V19_REGNUM 109
+#define S390_V20_REGNUM 110
+#define S390_V21_REGNUM 111
+#define S390_V22_REGNUM 112
+#define S390_V23_REGNUM 113
+#define S390_V24_REGNUM 114
+#define S390_V25_REGNUM 115
+#define S390_V26_REGNUM 116
+#define S390_V27_REGNUM 117
+#define S390_V28_REGNUM 118
+#define S390_V29_REGNUM 119
+#define S390_V30_REGNUM 120
+#define S390_V31_REGNUM 121
+#define S390_GSD_REGNUM 122
+#define S390_GSSM_REGNUM 123
+#define S390_GSEPLA_REGNUM 124
+#define S390_BC_GSD_REGNUM 125
+#define S390_BC_GSSM_REGNUM 126
+#define S390_BC_GSEPLA_REGNUM 127
+/* Total.  */
+#define S390_NUM_REGS 128
+#define S390_NUM_GPRS 16
+#define S390_NUM_FPRS 16
+
+#define S390_MAX_INSTR_SIZE 6
+
+/* Special register usage.  */
+#define S390_SP_REGNUM S390_R15_REGNUM
+#define S390_RETADDR_REGNUM S390_R14_REGNUM
+#define S390_FRAME_REGNUM S390_R11_REGNUM
+
+#define S390_IS_GREGSET_REGNUM(i)					\
+  (((i) >= S390_PSWM_REGNUM && (i) <= S390_A15_REGNUM)			\
+   || ((i) >= S390_R0_UPPER_REGNUM && (i) <= S390_R15_UPPER_REGNUM)	\
+   || (i) == S390_ORIG_R2_REGNUM)
+
+#define S390_IS_FPREGSET_REGNUM(i)			\
+  ((i) >= S390_FPC_REGNUM && (i) <= S390_F15_REGNUM)
+
+#define S390_IS_TDBREGSET_REGNUM(i)				\
+  ((i) >= S390_TDB_DWORD0_REGNUM && (i) <= S390_TDB_R15_REGNUM)
+
+/* Core file register sets, defined in s390-tdep.c.  */
+#define s390_sizeof_gregset 0x90
+#define s390x_sizeof_gregset 0xd8
+extern const struct regset s390_gregset;
+#define s390_sizeof_fpregset 0x88
+extern const struct regset s390_fpregset;
+extern const struct regset s390_vxrs_low_regset;
+extern const struct regset s390_vxrs_high_regset;
+
+/* Decoding S/390 instructions.  */
+
+/* Read a single instruction from address AT.  */
+extern int s390_readinstruction (bfd_byte instr[], CORE_ADDR at);
+
+/* Prologue analysis.  */
+
+struct s390_prologue_data {
+
+  /* The stack.  */
+  struct pv_area *stack;
+
+  /* The size and byte-order of a GPR or FPR.  */
+  int gpr_size;
+  int fpr_size;
+  enum bfd_endian byte_order;
+
+  /* The general-purpose registers.  */
+  pv_t gpr[S390_NUM_GPRS];
+
+  /* The floating-point registers.  */
+  pv_t fpr[S390_NUM_FPRS];
+
+  /* The offset relative to the CFA where the incoming GPR N was saved
+     by the function prologue.  0 if not saved or unknown.  */
+  int gpr_slot[S390_NUM_GPRS];
+
+  /* Likewise for FPRs.  */
+  int fpr_slot[S390_NUM_FPRS];
+
+  /* Nonzero if the backchain was saved.  This is assumed to be the
+     case when the incoming SP is saved at the current SP location.  */
+  int back_chain_saved_p;
+};
+
+/* Analyze the prologue of the function starting at START_PC, continuing at
+   most until CURRENT_PC.  Initialize DATA to hold all information we find
+   out about the state of the registers and stack slots.  Return the address
+   of the instruction after the last one that changed the SP, FP, or back
+   chain; or zero on error.  */
+extern CORE_ADDR s390_analyze_prologue (struct gdbarch *gdbarch,
+					CORE_ADDR start_pc,
+					CORE_ADDR current_pc,
+					struct s390_prologue_data *data);
+
+/* Register handling.  */
+
+/* ABI call-saved register information.  */
+extern int s390_register_call_saved (struct gdbarch *gdbarch, int regnum);
+
+/* Frame unwinding.  */
+
+/* Implmement the stack_frame_destroyed_p gdbarch method.  */
+extern int s390_stack_frame_destroyed_p (struct gdbarch *gdbarch, CORE_ADDR pc);
+
+/* Helper routine to unwind pseudo registers.  */
+extern struct value *s390_unwind_pseudo_register (struct frame_info *this_frame,
+						  int regnum);
+
+/* Initialize common gdbarch features.  Allocates new gdbarch if needed.  */
+extern struct gdbarch *s390_gdbarch_init (struct gdbarch_info info,
+					  struct gdbarch_list *arches,
+					  const struct target_desc *tdesc);
+
+#endif /* S390_TDEP_H */