diff mbox

[2/3] Add FreeBSD/mips architecture.

Message ID 20161123205902.90995-3-jhb@FreeBSD.org
State New
Headers show

Commit Message

John Baldwin Nov. 23, 2016, 8:59 p.m. UTC
This has been tested for the n64 and o32 ABIs.  Signal frame unwinders for
both ABIs are provided.  FreeBSD/mips requires custom linkmap offsets since
it contains an additional l_off member in 'struct link_map' that other
FreeBSD platforms do not have.  Support for collecting and supplying
general purpose and floating point register sets are provided.  Common
routines for working with native format register sets are exported for
use by the native target.

gdb/ChangeLog:

	* Makefile.in (ALL_TARGET_OBS): Add mips-fbsd-tdep.o.
	(ALLDEPFILES): Add mips-fbsd-tdep.c.
	* configure.tgt: Add mips*-*-freebsd*.
	* mips-fbsd-tdep.c: New file.
	* mips-fbsd-tdep.h: New file.
---
 gdb/ChangeLog        |   8 +
 gdb/Makefile.in      |   2 +
 gdb/configure.tgt    |   5 +
 gdb/mips-fbsd-tdep.c | 541 +++++++++++++++++++++++++++++++++++++++++++++++++++
 gdb/mips-fbsd-tdep.h |  28 +++
 5 files changed, 584 insertions(+)
 create mode 100644 gdb/mips-fbsd-tdep.c
 create mode 100644 gdb/mips-fbsd-tdep.h

Comments

Luis Machado Nov. 25, 2016, 10:52 p.m. UTC | #1
Code looks good. I have a few comments on other things.

On 11/23/2016 02:59 PM, John Baldwin wrote:
> @@ -0,0 +1,541 @@
> +/* Target-dependent code for FreeBSD/mips.
> +
> +   Copyright (C) 2016 Free Software Foundation, Inc.
> +
> +   This software was developed by SRI International and the University
> +   of Cambridge Computer Laboratory under DARPA/AFRL contract
> +   FA8750-10-C-0237 ("CTSRD"), as part of the DARPA CRASH research
> +   programme.
> +
> +   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 "osabi.h"
> +#include "regset.h"
> +#include "trad-frame.h"
> +#include "tramp-frame.h"
> +
> +#include "fbsd-tdep.h"
> +#include "mips-tdep.h"
> +#include "mips-fbsd-tdep.h"
> +
> +#include "solib-svr4.h"
> +
> +/* Shorthand for some register numbers used below.  */
> +#define MIPS_PC_REGNUM  MIPS_EMBED_PC_REGNUM
> +#define MIPS_FP0_REGNUM MIPS_EMBED_FP0_REGNUM
> +#define MIPS_FSR_REGNUM MIPS_EMBED_FP0_REGNUM + 32
> +
> +/* Core file support. */
> +
> +/* Number of registers in `struct reg' from <machine/reg.h>.  The
> +   first 38 follow the standard MIPS layout.  The 39th holds
> +   IC_INT_REG on RM7K and RM9K processors.  The 40th is a dummy for
> +   padding.  */
> +#define MIPSFBSD_NUM_GREGS	40
> +
> +/* Number of registers in `struct fpreg' from <machine/reg.h>.  The
> +   first 32 hold floating point registers.  33 holds the FSR.  The
> +   34th is a dummy for padding.  */
> +#define MIPSFBSD_NUM_FPREGS	34

Should all the above defines be moved to the header file mips-fbsd-tdep.h?

> +
> +/* Supply a single register.  If the source register size matches the
> +   size the regcache expects, this can use regcache_raw_supply().  If
> +   they are different, this copies the source register into a buffer
> +   that can be passed to regcache_raw_supply().  */
> +
> +static void
> +mipsfbsd_supply_reg (struct regcache *regcache, int regnum, const void *addr,
> +		     size_t len)

How about mips_fbsd_* for the function names? Multiple occurrences of this.

> +{
> +  struct gdbarch *gdbarch = get_regcache_arch (regcache);
> +
> +  if (register_size (gdbarch, regnum) == len)
> +    {
> +      regcache_raw_supply (regcache, regnum, addr);
> +    }

No need for curly braces for single-statement blocks. Multiple 
occurrences of this.

> +/* Supply the floating-point registers stored in FPREGS to REGCACHE.
> +   Each floating-point register in FPREGS is REGSIZE bytes in
> +   length.  */
> +
> +void
> +mipsfbsd_supply_fpregs (struct regcache *regcache, int regnum,
> +			const void *fpregs, size_t regsize)
> +{
> +  const char *regs = (const char *) fpregs;

Should these const char * types be const gdb_byte * types instead? 
Multiple occurrences.

> +/* FreeBSD/mips register sets.  */
> +
> +static const struct regset mipsfbsd_gregset =
> +{
> +  NULL,
> +  mipsfbsd_supply_gregset,
> +  mipsfbsd_collect_gregset,
> +};
> +
> +static const struct regset mipsfbsd_fpregset =
> +{
> +  NULL,
> +  mipsfbsd_supply_fpregset,
> +  mipsfbsd_collect_fpregset,
> +};
> +
> +/* Iterate over core file register note sections.  */
> +
> +static void
> +mipsfbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
> +				       iterate_over_regset_sections_cb *cb,
> +				       void *cb_data,
> +				       const struct regcache *regcache)
> +{
> +  size_t regsize = mips_abi_regsize (gdbarch);
> +
> +  cb (".reg", MIPSFBSD_NUM_GREGS * regsize, &mipsfbsd_gregset,
> +      NULL, cb_data);
> +  cb (".reg2", MIPSFBSD_NUM_FPREGS * regsize, &mipsfbsd_fpregset,
> +      NULL, cb_data);
> +}
> +
> +/* Signal trampoline support.  */
> +
> +static void
> +mipsfbsd_sigframe_init (const struct tramp_frame *self,
> +			  struct frame_info *this_frame,
> +			  struct trad_frame_cache *cache,
> +			  CORE_ADDR func)
> +{
> +  struct gdbarch *gdbarch = get_frame_arch (this_frame);
> +  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
> +  CORE_ADDR sp, ucontext_addr, addr;
> +  int regnum;
> +  gdb_byte buf[4];
> +
> +  /* We find the appropriate instance of `ucontext_t' at a
> +     fixed offset in the signal frame.  */
> +  sp = get_frame_register_signed (this_frame,
> +				  MIPS_SP_REGNUM + gdbarch_num_regs (gdbarch));
> +  ucontext_addr = sp + 16;

We should make the fixed offset a constant with a #define. Maybe move 
those to the header file as well.

> +
> +  /* PC.  */
> +  regnum = mips_regnum (gdbarch)->pc;
> +  trad_frame_set_reg_addr (cache,
> +			   regnum + gdbarch_num_regs (gdbarch),
> +			    ucontext_addr + 20);

Same here for the PC offset.

> +
> +  /* GPRs.  */
> +  for (regnum = MIPS_AT_REGNUM, addr = ucontext_addr + 28;

Same here for all the other GPR's, and so on for the other fixed offsets.

> +       regnum <= MIPS_RA_REGNUM; regnum++, addr += 4)
> +    trad_frame_set_reg_addr (cache,
> +			     regnum + gdbarch_num_regs (gdbarch),
> +			     addr);
> +
> +  regnum = MIPS_PS_REGNUM;
> +  trad_frame_set_reg_addr (cache,
> +			   regnum + gdbarch_num_regs (gdbarch),
> +			   ucontext_addr + 152);

Here.

> +
> +  /* HI and LO.  */
> +  regnum = mips_regnum (gdbarch)->lo;
> +  trad_frame_set_reg_addr (cache,
> +			   regnum + gdbarch_num_regs (gdbarch),
> +			   ucontext_addr + 156);

Here.

> +  regnum = mips_regnum (gdbarch)->hi;
> +  trad_frame_set_reg_addr (cache,
> +			   regnum + gdbarch_num_regs (gdbarch),
> +			   ucontext_addr + 160);
> +

Here.

> +  if (target_read_memory (ucontext_addr + 164, buf, 4) == 0 &&

And here. More occurrences throughout the patch.

> +      extract_unsigned_integer (buf, 4, byte_order) != 0)
> +    {
> +      for (regnum = 0, addr = ucontext_addr + 168;
> +	   regnum < 32; regnum++, addr += 8)
> +	trad_frame_set_reg_addr (cache,
> +				 regnum + gdbarch_fp0_regnum (gdbarch),
> +				 addr);
> +      trad_frame_set_reg_addr (cache, mips_regnum (gdbarch)->fp_control_status,
> +			       addr);
> +    }
> +
> +  trad_frame_set_id (cache, frame_id_build (sp, func));
> +}
> +

> +static const struct tramp_frame mipsfbsd_sigframe =
> +{
> +  SIGTRAMP_FRAME,
> +  MIPS_INSN32_SIZE,
> +  {
> +    { 0x27a40010, -1 },		/* addiu   a0, sp, SIGF_UC */
> +    { 0x240201a1, -1 },		/* li      v0, SYS_sigreturn */
> +    { 0x0000000c, -1 },		/* syscall */
> +    { 0x0000000d, -1 },		/* break */
> +    { TRAMP_SENTINEL_INSN, -1 }
> +  },
> +  mipsfbsd_sigframe_init

These hex constants should be set with a #define. See mips-linux-tdep.c. 
More occurrences throughout the patch.


> +static void
> +mipsfbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
> +{
> +  enum mips_abi abi = mips_abi (gdbarch);
> +
> +  /* Generic FreeBSD support.  */
> +  fbsd_init_abi (info, gdbarch);
> +
> +  set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
> +
> +  switch (abi)
> +    {
> +      case MIPS_ABI_O32:
> +	tramp_frame_prepend_unwinder (gdbarch, &mipsfbsd_sigframe);
> +	break;
> +      case MIPS_ABI_N32:
> +	/* Float formats similar to Linux?  */

Is it similar? If so, then it should make it explicit.

> +	break;
> +      case MIPS_ABI_N64:
> +	/* Float formats similar to Linux?  */

Same here.

> +	tramp_frame_prepend_unwinder (gdbarch, &mips64fbsd_sigframe);
> +	break;
> +    }
> +
> +  /* TODO: set_gdbarch_longjmp_target  */
> +

I think we're fine without the TODO here. It can be addressed later.

Thanks,
Luis
John Baldwin Nov. 28, 2016, 10:31 p.m. UTC | #2
On Friday, November 25, 2016 04:52:31 PM Luis Machado wrote:
> On 11/23/2016 02:59 PM, John Baldwin wrote:
> > +/* Shorthand for some register numbers used below.  */
> > +#define MIPS_PC_REGNUM  MIPS_EMBED_PC_REGNUM
> > +#define MIPS_FP0_REGNUM MIPS_EMBED_FP0_REGNUM
> > +#define MIPS_FSR_REGNUM MIPS_EMBED_FP0_REGNUM + 32
> > +
> > +/* Core file support. */
> > +
> > +/* Number of registers in `struct reg' from <machine/reg.h>.  The
> > +   first 38 follow the standard MIPS layout.  The 39th holds
> > +   IC_INT_REG on RM7K and RM9K processors.  The 40th is a dummy for
> > +   padding.  */
> > +#define MIPSFBSD_NUM_GREGS	40
> > +
> > +/* Number of registers in `struct fpreg' from <machine/reg.h>.  The
> > +   first 32 hold floating point registers.  33 holds the FSR.  The
> > +   34th is a dummy for padding.  */
> > +#define MIPSFBSD_NUM_FPREGS	34
> 
> Should all the above defines be moved to the header file mips-fbsd-tdep.h?

They are only used in this file by virtue of the callbacks being exported for
use by the native target.  I wasn't inclined to export more to the header
than is necessary.  (This matches the approach used in mips-nbsd-tdep.* FWIW.)

> > +
> > +/* Supply a single register.  If the source register size matches the
> > +   size the regcache expects, this can use regcache_raw_supply().  If
> > +   they are different, this copies the source register into a buffer
> > +   that can be passed to regcache_raw_supply().  */
> > +
> > +static void
> > +mipsfbsd_supply_reg (struct regcache *regcache, int regnum, const void *addr,
> > +		     size_t len)
> 
> How about mips_fbsd_* for the function names? Multiple occurrences of this.

The reason it uses the current scheme is to match other *BSD targets (both
mipsnbsd_* and mips64obsd_*, but also other platforms such as x86bsd_* and
amd64bsd_*, etc.)  On the other hand, Simon just renamed all the BSD target
files to add a - between the architecture and OS, so that pattern might be
an old one.  I'm fine using mips_* for new code if that is generally desired.

> > +{
> > +  struct gdbarch *gdbarch = get_regcache_arch (regcache);
> > +
> > +  if (register_size (gdbarch, regnum) == len)
> > +    {
> > +      regcache_raw_supply (regcache, regnum, addr);
> > +    }
> 
> No need for curly braces for single-statement blocks. Multiple 
> occurrences of this.

Ok.  (Too many different style guides to juggle in one's head) 

> > +/* Supply the floating-point registers stored in FPREGS to REGCACHE.
> > +   Each floating-point register in FPREGS is REGSIZE bytes in
> > +   length.  */
> > +
> > +void
> > +mipsfbsd_supply_fpregs (struct regcache *regcache, int regnum,
> > +			const void *fpregs, size_t regsize)
> > +{
> > +  const char *regs = (const char *) fpregs;
> 
> Should these const char * types be const gdb_byte * types instead? 
> Multiple occurrences.

Hmm, perhaps?  The NetBSD/mips target I used as a template uses 'char',
but other places use gdb_byte (e.g. amd64_collect_*).  I'll go ahead
and switch it.

> > +/* Signal trampoline support.  */
> > +
> > +static void
> > +mipsfbsd_sigframe_init (const struct tramp_frame *self,
> > +			  struct frame_info *this_frame,
> > +			  struct trad_frame_cache *cache,
> > +			  CORE_ADDR func)
> > +{
> > +  struct gdbarch *gdbarch = get_frame_arch (this_frame);
> > +  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
> > +  CORE_ADDR sp, ucontext_addr, addr;
> > +  int regnum;
> > +  gdb_byte buf[4];
> > +
> > +  /* We find the appropriate instance of `ucontext_t' at a
> > +     fixed offset in the signal frame.  */
> > +  sp = get_frame_register_signed (this_frame,
> > +				  MIPS_SP_REGNUM + gdbarch_num_regs (gdbarch));
> > +  ucontext_addr = sp + 16;
> 
> We should make the fixed offset a constant with a #define. Maybe move 
> those to the header file as well.

FWIW, mips64-obsd just used magic numbers (which is what I used as my
template for the signal frame bits), but I can add constants for the
layout of ucontext_t, etc.  I'm inclined to keep them in the C file
as they won't be used outside of it.

> > +static const struct tramp_frame mipsfbsd_sigframe =
> > +{
> > +  SIGTRAMP_FRAME,
> > +  MIPS_INSN32_SIZE,
> > +  {
> > +    { 0x27a40010, -1 },		/* addiu   a0, sp, SIGF_UC */
> > +    { 0x240201a1, -1 },		/* li      v0, SYS_sigreturn */
> > +    { 0x0000000c, -1 },		/* syscall */
> > +    { 0x0000000d, -1 },		/* break */
> > +    { TRAMP_SENTINEL_INSN, -1 }
> > +  },
> > +  mipsfbsd_sigframe_init
> 
> These hex constants should be set with a #define. See mips-linux-tdep.c. 
> More occurrences throughout the patch.

Will fix.  As above, this was copied from the mips64-obsd target.

> > +static void
> > +mipsfbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
> > +{
> > +  enum mips_abi abi = mips_abi (gdbarch);
> > +
> > +  /* Generic FreeBSD support.  */
> > +  fbsd_init_abi (info, gdbarch);
> > +
> > +  set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
> > +
> > +  switch (abi)
> > +    {
> > +      case MIPS_ABI_O32:
> > +	tramp_frame_prepend_unwinder (gdbarch, &mipsfbsd_sigframe);
> > +	break;
> > +      case MIPS_ABI_N32:
> > +	/* Float formats similar to Linux?  */
> 
> Is it similar? If so, then it should make it explicit.

I don't know yet.  I have another pending patch to do so, but I think
FreeBSD/mips is currently using long double == double on n32 and n64
rather than 128-bit long doubles (as Linux, NetBSD, and OpenBSD all
seem to do).

> > +	tramp_frame_prepend_unwinder (gdbarch, &mips64fbsd_sigframe);
> > +	break;
> > +    }
> > +
> > +  /* TODO: set_gdbarch_longjmp_target  */
> > +
> 
> I think we're fine without the TODO here. It can be addressed later.

I left it as a reminder for myself, but I can axe it.
diff mbox

Patch

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index a2a11e2..092ca9e 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,11 @@ 
+2016-11-23  John Baldwin  <jhb@FreeBSD.org>
+
+	* Makefile.in (ALL_TARGET_OBS): Add mips-fbsd-tdep.o.
+	(ALLDEPFILES): Add mips-fbsd-tdep.c.
+	* configure.tgt: Add mips*-*-freebsd*.
+	* mips-fbsd-tdep.c: New file.
+	* mips-fbsd-tdep.h: New file.
+
 2016-11-23  Pedro Alves  <palves@redhat.com>
 
 	* Makefile.in (SFILES): Add common/run-time-clock.c.
diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 44a743e..d89a17f 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -817,6 +817,7 @@  ALL_TARGET_OBS = \
 	mep-tdep.o \
 	microblaze-linux-tdep.o \
 	microblaze-tdep.o \
+	mips-fbsd-tdep.o \
 	mips-linux-tdep.o \
 	mips-nbsd-tdep.o \
 	mips-sde-tdep.o \
@@ -2541,6 +2542,7 @@  ALLDEPFILES = \
 	microblaze-linux-tdep.c \
 	microblaze-tdep.c \
 	mingw-hdep.c \
+	mips-fbsd-tdep.c \
 	mips-linux-nat.c \
 	mips-linux-tdep.c \
 	mips-nbsd-nat.c \
diff --git a/gdb/configure.tgt b/gdb/configure.tgt
index 3a1ea6f..1a43604 100644
--- a/gdb/configure.tgt
+++ b/gdb/configure.tgt
@@ -369,6 +369,11 @@  mips*-*-netbsd* | mips*-*-knetbsd*-gnu)
 	gdb_target_obs="mips-tdep.o mips-nbsd-tdep.o solib-svr4.o nbsd-tdep.o"
 	gdb_sim=../sim/mips/libsim.a
 	;;
+mips*-*-freebsd*)
+	# Target: MIPS running FreeBSD
+	gdb_target_obs="mips-tdep.o mips-fbsd-tdep.o solib-svr4.o fbsd-tdep.o"
+	gdb_sim=../sim/mips/libsim.a
+	;;
 mips64*-*-openbsd*)
 	# Target: OpenBSD/mips64
 	gdb_target_obs="mips-tdep.o mips64-obsd-tdep.o obsd-tdep.o solib-svr4.o"
diff --git a/gdb/mips-fbsd-tdep.c b/gdb/mips-fbsd-tdep.c
new file mode 100644
index 0000000..424eb95
--- /dev/null
+++ b/gdb/mips-fbsd-tdep.c
@@ -0,0 +1,541 @@ 
+/* Target-dependent code for FreeBSD/mips.
+
+   Copyright (C) 2016 Free Software Foundation, Inc.
+
+   This software was developed by SRI International and the University
+   of Cambridge Computer Laboratory under DARPA/AFRL contract
+   FA8750-10-C-0237 ("CTSRD"), as part of the DARPA CRASH research
+   programme.
+
+   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 "osabi.h"
+#include "regset.h"
+#include "trad-frame.h"
+#include "tramp-frame.h"
+
+#include "fbsd-tdep.h"
+#include "mips-tdep.h"
+#include "mips-fbsd-tdep.h"
+
+#include "solib-svr4.h"
+
+/* Shorthand for some register numbers used below.  */
+#define MIPS_PC_REGNUM  MIPS_EMBED_PC_REGNUM
+#define MIPS_FP0_REGNUM MIPS_EMBED_FP0_REGNUM
+#define MIPS_FSR_REGNUM MIPS_EMBED_FP0_REGNUM + 32
+
+/* Core file support. */
+
+/* Number of registers in `struct reg' from <machine/reg.h>.  The
+   first 38 follow the standard MIPS layout.  The 39th holds
+   IC_INT_REG on RM7K and RM9K processors.  The 40th is a dummy for
+   padding.  */
+#define MIPSFBSD_NUM_GREGS	40
+
+/* Number of registers in `struct fpreg' from <machine/reg.h>.  The
+   first 32 hold floating point registers.  33 holds the FSR.  The
+   34th is a dummy for padding.  */
+#define MIPSFBSD_NUM_FPREGS	34
+
+/* Supply a single register.  If the source register size matches the
+   size the regcache expects, this can use regcache_raw_supply().  If
+   they are different, this copies the source register into a buffer
+   that can be passed to regcache_raw_supply().  */
+
+static void
+mipsfbsd_supply_reg (struct regcache *regcache, int regnum, const void *addr,
+		     size_t len)
+{
+  struct gdbarch *gdbarch = get_regcache_arch (regcache);
+
+  if (register_size (gdbarch, regnum) == len)
+    {
+      regcache_raw_supply (regcache, regnum, addr);
+    }
+  else
+    {
+      enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+      gdb_byte buf[MAX_REGISTER_SIZE];
+      LONGEST val;
+
+      val = extract_signed_integer ((const gdb_byte *) addr, len, byte_order);
+      store_signed_integer (buf, register_size (gdbarch, regnum), byte_order,
+			    val);
+      regcache_raw_supply (regcache, regnum, buf);
+    }
+}
+
+/* Collect a single register.  If the destination register size
+   matches the size the regcache expects, this can use
+   regcache_raw_supply().  If they are different, this fetches the
+   register via regcache_raw_supply() into a buffer and then copies it
+   into the final destination.  */
+
+static void
+mipsfbsd_collect_reg (const struct regcache *regcache, int regnum, void *addr,
+		      size_t len)
+{
+  struct gdbarch *gdbarch = get_regcache_arch (regcache);
+
+  if (register_size (gdbarch, regnum) == len)
+    {
+      regcache_raw_collect (regcache, regnum, addr);
+    }
+  else
+    {
+      enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+      gdb_byte buf[MAX_REGISTER_SIZE];
+      LONGEST val;
+
+      regcache_raw_collect (regcache, regnum, buf);
+      val = extract_signed_integer (buf, register_size (gdbarch, regnum),
+				    byte_order);
+      store_signed_integer ((gdb_byte *) addr, len, byte_order, val);
+    }
+}
+
+/* Supply the floating-point registers stored in FPREGS to REGCACHE.
+   Each floating-point register in FPREGS is REGSIZE bytes in
+   length.  */
+
+void
+mipsfbsd_supply_fpregs (struct regcache *regcache, int regnum,
+			const void *fpregs, size_t regsize)
+{
+  const char *regs = (const char *) fpregs;
+  int i;
+
+  for (i = MIPS_FP0_REGNUM; i <= MIPS_FSR_REGNUM; i++)
+    {
+      if (regnum == i || regnum == -1)
+	mipsfbsd_supply_reg (regcache, i,
+			     regs + (i - MIPS_FP0_REGNUM) * regsize, regsize);
+    }
+}
+
+/* Supply the general-purpose registers stored in GREGS to REGCACHE.
+   Each general-purpose register in GREGS is REGSIZE bytes in
+   length.  */
+
+void
+mipsfbsd_supply_gregs (struct regcache *regcache, int regnum,
+		       const void *gregs, size_t regsize)
+{
+  const char *regs = (const char *) gregs;
+  int i;
+
+  for (i = 0; i <= MIPS_PC_REGNUM; i++)
+    {
+      if (regnum == i || regnum == -1)
+	mipsfbsd_supply_reg (regcache, i, regs + i * regsize, regsize);
+    }
+}
+
+/* Collect the floating-point registers from REGCACHE and store them
+   in FPREGS.  Each floating-point register in FPREGS is REGSIZE bytes
+   in length.  */
+
+void
+mipsfbsd_collect_fpregs (const struct regcache *regcache, int regnum,
+			 void *fpregs, size_t regsize)
+{
+  char *regs = (char *) fpregs;
+  int i;
+
+  for (i = MIPS_FP0_REGNUM; i <= MIPS_FSR_REGNUM; i++)
+    {
+      if (regnum == i || regnum == -1)
+	mipsfbsd_collect_reg (regcache, i,
+			     regs + (i - MIPS_FP0_REGNUM) * regsize, regsize);
+    }
+}
+
+/* Collect the general-purpose registers from REGCACHE and store them
+   in GREGS.  Each general-purpose register in GREGS is REGSIZE bytes
+   in length.  */
+
+void
+mipsfbsd_collect_gregs (const struct regcache *regcache, int regnum,
+			void *gregs, size_t regsize)
+{
+  char *regs = (char *) gregs;
+  int i;
+
+  for (i = 0; i <= MIPS_PC_REGNUM; i++)
+    {
+      if (regnum == i || regnum == -1)
+	mipsfbsd_collect_reg (regcache, i, regs + i * regsize, regsize);
+    }
+}
+
+/* Supply register REGNUM from the buffer specified by FPREGS and LEN
+   in the floating-point register set REGSET to register cache
+   REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
+
+static void
+mipsfbsd_supply_fpregset (const struct regset *regset,
+			  struct regcache *regcache,
+			  int regnum, const void *fpregs, size_t len)
+{
+  size_t regsize = mips_abi_regsize (get_regcache_arch (regcache));
+
+  gdb_assert (len >= MIPSFBSD_NUM_FPREGS * regsize);
+
+  mipsfbsd_supply_fpregs (regcache, regnum, fpregs, regsize);
+}
+
+/* Collect register REGNUM from the register cache REGCACHE and store
+   it in the buffer specified by FPREGS and LEN in the floating-point
+   register set REGSET.  If REGNUM is -1, do this for all registers in
+   REGSET.  */
+
+static void
+mipsfbsd_collect_fpregset (const struct regset *regset,
+			   const struct regcache *regcache,
+			   int regnum, void *fpregs, size_t len)
+{
+  size_t regsize = mips_abi_regsize (get_regcache_arch (regcache));
+
+  gdb_assert (len >= MIPSFBSD_NUM_FPREGS * regsize);
+
+  mipsfbsd_collect_fpregs (regcache, regnum, fpregs, regsize);
+}
+
+/* Supply register REGNUM from the buffer specified by GREGS and LEN
+   in the general-purpose register set REGSET to register cache
+   REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
+
+static void
+mipsfbsd_supply_gregset (const struct regset *regset,
+			 struct regcache *regcache, int regnum,
+			 const void *gregs, size_t len)
+{
+  size_t regsize = mips_abi_regsize (get_regcache_arch (regcache));
+
+  gdb_assert (len >= MIPSFBSD_NUM_GREGS * regsize);
+
+  mipsfbsd_supply_gregs (regcache, regnum, gregs, regsize);
+}
+
+/* Collect register REGNUM from the register cache REGCACHE and store
+   it in the buffer specified by GREGS and LEN in the general-purpose
+   register set REGSET.  If REGNUM is -1, do this for all registers in
+   REGSET.  */
+
+static void
+mipsfbsd_collect_gregset (const struct regset *regset,
+			  const struct regcache *regcache,
+			  int regnum, void *gregs, size_t len)
+{
+  size_t regsize = mips_abi_regsize (get_regcache_arch (regcache));
+
+  gdb_assert (len >= MIPSFBSD_NUM_GREGS * regsize);
+
+  mipsfbsd_collect_gregs (regcache, regnum, gregs, regsize);
+}
+
+/* FreeBSD/mips register sets.  */
+
+static const struct regset mipsfbsd_gregset =
+{
+  NULL,
+  mipsfbsd_supply_gregset,
+  mipsfbsd_collect_gregset,
+};
+
+static const struct regset mipsfbsd_fpregset =
+{
+  NULL,
+  mipsfbsd_supply_fpregset,
+  mipsfbsd_collect_fpregset,
+};
+
+/* Iterate over core file register note sections.  */
+
+static void
+mipsfbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
+				       iterate_over_regset_sections_cb *cb,
+				       void *cb_data,
+				       const struct regcache *regcache)
+{
+  size_t regsize = mips_abi_regsize (gdbarch);
+
+  cb (".reg", MIPSFBSD_NUM_GREGS * regsize, &mipsfbsd_gregset,
+      NULL, cb_data);
+  cb (".reg2", MIPSFBSD_NUM_FPREGS * regsize, &mipsfbsd_fpregset,
+      NULL, cb_data);
+}
+
+/* Signal trampoline support.  */
+
+static void
+mipsfbsd_sigframe_init (const struct tramp_frame *self,
+			  struct frame_info *this_frame,
+			  struct trad_frame_cache *cache,
+			  CORE_ADDR func)
+{
+  struct gdbarch *gdbarch = get_frame_arch (this_frame);
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  CORE_ADDR sp, ucontext_addr, addr;
+  int regnum;
+  gdb_byte buf[4];
+
+  /* We find the appropriate instance of `ucontext_t' at a
+     fixed offset in the signal frame.  */
+  sp = get_frame_register_signed (this_frame,
+				  MIPS_SP_REGNUM + gdbarch_num_regs (gdbarch));
+  ucontext_addr = sp + 16;
+
+  /* PC.  */
+  regnum = mips_regnum (gdbarch)->pc;
+  trad_frame_set_reg_addr (cache,
+			   regnum + gdbarch_num_regs (gdbarch),
+			    ucontext_addr + 20);
+
+  /* GPRs.  */
+  for (regnum = MIPS_AT_REGNUM, addr = ucontext_addr + 28;
+       regnum <= MIPS_RA_REGNUM; regnum++, addr += 4)
+    trad_frame_set_reg_addr (cache,
+			     regnum + gdbarch_num_regs (gdbarch),
+			     addr);
+
+  regnum = MIPS_PS_REGNUM;
+  trad_frame_set_reg_addr (cache,
+			   regnum + gdbarch_num_regs (gdbarch),
+			   ucontext_addr + 152);
+
+  /* HI and LO.  */
+  regnum = mips_regnum (gdbarch)->lo;
+  trad_frame_set_reg_addr (cache,
+			   regnum + gdbarch_num_regs (gdbarch),
+			   ucontext_addr + 156);
+  regnum = mips_regnum (gdbarch)->hi;
+  trad_frame_set_reg_addr (cache,
+			   regnum + gdbarch_num_regs (gdbarch),
+			   ucontext_addr + 160);
+
+  if (target_read_memory (ucontext_addr + 164, buf, 4) == 0 &&
+      extract_unsigned_integer (buf, 4, byte_order) != 0)
+    {
+      for (regnum = 0, addr = ucontext_addr + 168;
+	   regnum < 32; regnum++, addr += 8)
+	trad_frame_set_reg_addr (cache,
+				 regnum + gdbarch_fp0_regnum (gdbarch),
+				 addr);
+      trad_frame_set_reg_addr (cache, mips_regnum (gdbarch)->fp_control_status,
+			       addr);
+    }
+
+  trad_frame_set_id (cache, frame_id_build (sp, func));
+}
+
+static const struct tramp_frame mipsfbsd_sigframe =
+{
+  SIGTRAMP_FRAME,
+  MIPS_INSN32_SIZE,
+  {
+    { 0x27a40010, -1 },		/* addiu   a0, sp, SIGF_UC */
+    { 0x240201a1, -1 },		/* li      v0, SYS_sigreturn */
+    { 0x0000000c, -1 },		/* syscall */
+    { 0x0000000d, -1 },		/* break */
+    { TRAMP_SENTINEL_INSN, -1 }
+  },
+  mipsfbsd_sigframe_init
+};
+
+static void
+mips64fbsd_sigframe_init (const struct tramp_frame *self,
+			  struct frame_info *this_frame,
+			  struct trad_frame_cache *cache,
+			  CORE_ADDR func)
+{
+  struct gdbarch *gdbarch = get_frame_arch (this_frame);
+  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+  CORE_ADDR sp, ucontext_addr, addr;
+  int regnum;
+  gdb_byte buf[4];
+
+  /* We find the appropriate instance of `ucontext_t' at a
+     fixed offset in the signal frame.  */
+  sp = get_frame_register_signed (this_frame,
+				  MIPS_SP_REGNUM + gdbarch_num_regs (gdbarch));
+  ucontext_addr = sp + 32;
+
+  /* PC.  */
+  regnum = mips_regnum (gdbarch)->pc;
+  trad_frame_set_reg_addr (cache,
+			   regnum + gdbarch_num_regs (gdbarch),
+			    ucontext_addr + 24);
+
+  /* GPRs.  */
+  for (regnum = MIPS_AT_REGNUM, addr = ucontext_addr + 40;
+       regnum <= MIPS_RA_REGNUM; regnum++, addr += 8)
+    trad_frame_set_reg_addr (cache,
+			     regnum + gdbarch_num_regs (gdbarch),
+			     addr);
+
+  regnum = MIPS_PS_REGNUM;
+  trad_frame_set_reg_addr (cache,
+			   regnum + gdbarch_num_regs (gdbarch),
+			   ucontext_addr + 288);
+
+  /* HI and LO.  */
+  regnum = mips_regnum (gdbarch)->lo;
+  trad_frame_set_reg_addr (cache,
+			   regnum + gdbarch_num_regs (gdbarch),
+			   ucontext_addr + 296);
+  regnum = mips_regnum (gdbarch)->hi;
+  trad_frame_set_reg_addr (cache,
+			   regnum + gdbarch_num_regs (gdbarch),
+			   ucontext_addr + 304);
+
+  if (target_read_memory (ucontext_addr + 312, buf, 4) == 0 &&
+      extract_unsigned_integer (buf, 4, byte_order) != 0)
+    {
+      for (regnum = 0, addr = ucontext_addr + 320;
+	   regnum < 32; regnum++, addr += 8)
+	trad_frame_set_reg_addr (cache,
+				 regnum + gdbarch_fp0_regnum (gdbarch),
+				 addr);
+      trad_frame_set_reg_addr (cache, mips_regnum (gdbarch)->fp_control_status,
+			       addr);
+    }
+
+  trad_frame_set_id (cache, frame_id_build (sp, func));
+}
+
+static const struct tramp_frame mips64fbsd_sigframe =
+{
+  SIGTRAMP_FRAME,
+  MIPS_INSN32_SIZE,
+  {
+    { 0x67a40020, -1 },		/* daddiu  a0, sp, SIGF_UC */
+    { 0x240201a1, -1 },		/* li      v0, SYS_sigreturn */
+    { 0x0000000c, -1 },		/* syscall */
+    { 0x0000000d, -1 },		/* break */
+    { TRAMP_SENTINEL_INSN, -1 }
+  },
+  mips64fbsd_sigframe_init
+};
+
+/* Shared library support.  */
+
+/* FreeBSD/mips uses a slightly different `struct link_map' than the
+   other FreeBSD platforms as it includes an additional `l_off'
+   member.  */
+
+static struct link_map_offsets *
+mipsfbsd_ilp32_fetch_link_map_offsets (void)
+{
+  static struct link_map_offsets lmo;
+  static struct link_map_offsets *lmp = NULL;
+
+  if (lmp == NULL) 
+    {
+      lmp = &lmo;
+
+      lmo.r_version_offset = 0;
+      lmo.r_version_size = 4;
+      lmo.r_map_offset = 4;
+      lmo.r_brk_offset = 8;
+      lmo.r_ldsomap_offset = -1;
+
+      lmo.link_map_size = 24;
+      lmo.l_addr_offset = 0;
+      lmo.l_name_offset = 8;
+      lmo.l_ld_offset = 12;
+      lmo.l_next_offset = 16;
+      lmo.l_prev_offset = 20;
+    }
+
+  return lmp;
+}
+
+static struct link_map_offsets *
+mipsfbsd_lp64_fetch_link_map_offsets (void)
+{
+  static struct link_map_offsets lmo;
+  static struct link_map_offsets *lmp = NULL;
+
+  if (lmp == NULL)
+    {
+      lmp = &lmo;
+
+      lmo.r_version_offset = 0;
+      lmo.r_version_size = 4;
+      lmo.r_map_offset = 8;
+      lmo.r_brk_offset = 16;
+      lmo.r_ldsomap_offset = -1;
+
+      lmo.link_map_size = 48;
+      lmo.l_addr_offset = 0;
+      lmo.l_name_offset = 16; 
+      lmo.l_ld_offset = 24;
+      lmo.l_next_offset = 32;
+      lmo.l_prev_offset = 40;
+    }
+
+  return lmp;
+}
+
+static void
+mipsfbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+  enum mips_abi abi = mips_abi (gdbarch);
+
+  /* Generic FreeBSD support.  */
+  fbsd_init_abi (info, gdbarch);
+
+  set_gdbarch_software_single_step (gdbarch, mips_software_single_step);
+
+  switch (abi)
+    {
+      case MIPS_ABI_O32:
+	tramp_frame_prepend_unwinder (gdbarch, &mipsfbsd_sigframe);
+	break;
+      case MIPS_ABI_N32:
+	/* Float formats similar to Linux?  */
+	break;
+      case MIPS_ABI_N64:
+	/* Float formats similar to Linux?  */
+	tramp_frame_prepend_unwinder (gdbarch, &mips64fbsd_sigframe);
+	break;
+    }
+
+  /* TODO: set_gdbarch_longjmp_target  */
+
+  set_gdbarch_iterate_over_regset_sections
+    (gdbarch, mipsfbsd_iterate_over_regset_sections);
+
+  /* FreeBSD/mips has SVR4-style shared libraries.  */
+  set_solib_svr4_fetch_link_map_offsets
+    (gdbarch, (gdbarch_ptr_bit (gdbarch) == 32 ?
+	       mipsfbsd_ilp32_fetch_link_map_offsets :
+	       mipsfbsd_lp64_fetch_link_map_offsets));
+}
+
+
+/* Provide a prototype to silence -Wmissing-prototypes.  */
+void _initialize_mipsfbsd_tdep (void);
+
+void
+_initialize_mipsfbsd_tdep (void)
+{
+  gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_FREEBSD_ELF,
+			  mipsfbsd_init_abi);
+}
diff --git a/gdb/mips-fbsd-tdep.h b/gdb/mips-fbsd-tdep.h
new file mode 100644
index 0000000..dd344f3
--- /dev/null
+++ b/gdb/mips-fbsd-tdep.h
@@ -0,0 +1,28 @@ 
+/* Common target dependent code for GDB on MIPS systems running FreeBSD.
+
+   Copyright (C) 2016 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 MIPS_FBSD_TDEP_H
+#define MIPS_FBSD_TDEP_H
+
+void mipsfbsd_supply_fpregs (struct regcache *, int, const void *, size_t);
+void mipsfbsd_supply_gregs (struct regcache *, int, const void *, size_t);
+void mipsfbsd_collect_fpregs (const struct regcache *, int, void *, size_t);
+void mipsfbsd_collect_gregs (const struct regcache *, int, void *, size_t);
+
+#endif /* MIPS_FBSD_TDEP_H */