[3/4] Add FreeBSD/arm architecture.
Commit Message
Support for collecting and supplying general purpose and floating
point registers is provided along with signal frame unwinding. While
FreeBSD/arm kernels do populate NT_FPREGSET notes, they are always
zero-filled, so this implementation ignores them. Recent FreeBSD/arm
kernels generate NT_ARM_VFP notes which are used to supply
floating-point registers. As with Linux, the AT_HWCAP feature flags
are used to determine the correct target description.
gdb/ChangeLog:
* Makefile.in (ALL_TARGET_OBS): Add arm-fbsd-tdep.o.
(ALLDEPFILES): Add arm-fbsd-tdep.c.
* NEWS: Mention new FreeBSD/arm target.
* configure.tgt: Add arm*-*-freebsd*.
* arm-fbsd-tdep.c: New file.
* arm-fbsd-tdep.h: New file.
---
gdb/ChangeLog | 9 ++
gdb/Makefile.in | 2 +
gdb/NEWS | 1 +
gdb/arm-fbsd-tdep.c | 258 ++++++++++++++++++++++++++++++++++++++++++++++++++++
gdb/arm-fbsd-tdep.h | 39 ++++++++
gdb/configure.tgt | 5 +
6 files changed, 314 insertions(+)
create mode 100644 gdb/arm-fbsd-tdep.c
create mode 100644 gdb/arm-fbsd-tdep.h
Comments
On 09/14/2017 04:18 PM, John Baldwin wrote:
> Support for collecting and supplying general purpose and floating
> point registers is provided along with signal frame unwinding. While
> FreeBSD/arm kernels do populate NT_FPREGSET notes, they are always
> zero-filled, so this implementation ignores them. Recent FreeBSD/arm
> kernels generate NT_ARM_VFP notes which are used to supply
> floating-point registers. As with Linux, the AT_HWCAP feature flags
> are used to determine the correct target description.
>
Hi John. FWIW, this looks good to me. I'm comfortable with
you self-approving this as FreeBSD maintainer after a
period, BTW. A few minor nits below.
> diff --git a/gdb/NEWS b/gdb/NEWS
> index 2e6d48c016..f33b7ac49f 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -105,6 +105,7 @@ FreeBSD/aarch64 aarch64*-*-freebsd*
> * New targets
>
> FreeBSD/aarch64 aarch64*-*-freebsd*
> +FreeBSD/arm arm*-*-freebsd*
It'd be nice to update the hosts table at:
https://sourceware.org/gdb/wiki/Systems
(I've added a notes column now, thinking that we'd start
saying something like "since GDB 8.1". We could rename
the column too.)
> +#define ARM_MCONTEXT_REG_SIZE 4
> +#define ARM_MCONTEXT_VFP_REG_SIZE 8
> +#define ARM_SIGFRAME_UCONTEXT_OFFSET 64
> +#define ARM_UCONTEXT_MCONTEXT_OFFSET 16
> +#define ARM_MCONTEXT_VFP_PTR_OFFSET 72
Space vs tab after #define in the last line above.
> +
> +/* Implement the "init" method of struct tramp_frame. */
> +
> +static void
> +arm_fbsd_sigframe_init (const struct tramp_frame *self,
> + struct frame_info *this_frame,
> + struct trad_frame_cache *this_cache,
> + CORE_ADDR func)
> +{
> + struct gdbarch *gdbarch = get_frame_arch (this_frame);
> + enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
> + CORE_ADDR sp = get_frame_register_unsigned (this_frame, ARM_SP_REGNUM);
> + CORE_ADDR mcontext_addr =
> + sp
> + + ARM_SIGFRAME_UCONTEXT_OFFSET
> + + ARM_UCONTEXT_MCONTEXT_OFFSET;
= goes on next line. Then per GNU standards (because that's
what Emacs likes), to line up the multiple lines, wrap in parens:
CORE_ADDR mcontext_addr
= (sp
+ ARM_SIGFRAME_UCONTEXT_OFFSET
+ ARM_UCONTEXT_MCONTEXT_OFFSET);
Thought this would fit too, and is shorter:
CORE_ADDR mcontext_addr = (sp
+ ARM_SIGFRAME_UCONTEXT_OFFSET
+ ARM_UCONTEXT_MCONTEXT_OFFSET);
> + CORE_ADDR mcontext_vfp_addr;
> + gdb_byte buf[4];
> + int i;
> +
> + for (i = 0; i < 16; i++)
Suggest writing:
for (int i = 0; i < 16; i++)
> + {
> + trad_frame_set_reg_addr (this_cache,
> + ARM_A1_REGNUM + i,
> + mcontext_addr + i * ARM_MCONTEXT_REG_SIZE);
> + }
> + trad_frame_set_reg_addr (this_cache, ARM_PS_REGNUM,
> + mcontext_addr + 16 * ARM_MCONTEXT_REG_SIZE);
> +
> + mcontext_vfp_addr = 0;
> + if (target_read_memory (mcontext_addr + ARM_MCONTEXT_VFP_PTR_OFFSET, buf,
> + 4) == 0)
> + mcontext_vfp_addr = extract_unsigned_integer (buf, 4, byte_order);
I mildly wonder whether this be:
if (safe_read_memory_unsigned_integer (mcontext_addr + ARM_MCONTEXT_VFP_PTR_OFFSET, 4,
byte_order, &mcontext_vfp_addr)
{
for (i = 0; i < 32; i++)
....
I'd convey intention and avoid the "= 0" initialization + "!= 0" check
(unless you need it anyway).
Thanks,
Pedro Alves
On Wednesday, October 11, 2017 12:05:35 PM Pedro Alves wrote:
> On 09/14/2017 04:18 PM, John Baldwin wrote:
> > Support for collecting and supplying general purpose and floating
> > point registers is provided along with signal frame unwinding. While
> > FreeBSD/arm kernels do populate NT_FPREGSET notes, they are always
> > zero-filled, so this implementation ignores them. Recent FreeBSD/arm
> > kernels generate NT_ARM_VFP notes which are used to supply
> > floating-point registers. As with Linux, the AT_HWCAP feature flags
> > are used to determine the correct target description.
> >
>
> Hi John. FWIW, this looks good to me. I'm comfortable with
> you self-approving this as FreeBSD maintainer after a
> period, BTW. A few minor nits below.
>
> > diff --git a/gdb/NEWS b/gdb/NEWS
> > index 2e6d48c016..f33b7ac49f 100644
> > --- a/gdb/NEWS
> > +++ b/gdb/NEWS
> > @@ -105,6 +105,7 @@ FreeBSD/aarch64 aarch64*-*-freebsd*
> > * New targets
> >
> > FreeBSD/aarch64 aarch64*-*-freebsd*
> > +FreeBSD/arm arm*-*-freebsd*
>
> It'd be nice to update the hosts table at:
> https://sourceware.org/gdb/wiki/Systems
>
> (I've added a notes column now, thinking that we'd start
> saying something like "since GDB 8.1". We could rename
> the column too.)
>
> > +#define ARM_MCONTEXT_REG_SIZE 4
> > +#define ARM_MCONTEXT_VFP_REG_SIZE 8
> > +#define ARM_SIGFRAME_UCONTEXT_OFFSET 64
> > +#define ARM_UCONTEXT_MCONTEXT_OFFSET 16
> > +#define ARM_MCONTEXT_VFP_PTR_OFFSET 72
>
> Space vs tab after #define in the last line above.
Fixed.
> > +
> > +/* Implement the "init" method of struct tramp_frame. */
> > +
> > +static void
> > +arm_fbsd_sigframe_init (const struct tramp_frame *self,
> > + struct frame_info *this_frame,
> > + struct trad_frame_cache *this_cache,
> > + CORE_ADDR func)
> > +{
> > + struct gdbarch *gdbarch = get_frame_arch (this_frame);
> > + enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
> > + CORE_ADDR sp = get_frame_register_unsigned (this_frame, ARM_SP_REGNUM);
> > + CORE_ADDR mcontext_addr =
> > + sp
> > + + ARM_SIGFRAME_UCONTEXT_OFFSET
> > + + ARM_UCONTEXT_MCONTEXT_OFFSET;
>
> = goes on next line. Then per GNU standards (because that's
> what Emacs likes), to line up the multiple lines, wrap in parens:
>
> CORE_ADDR mcontext_addr
> = (sp
> + ARM_SIGFRAME_UCONTEXT_OFFSET
> + ARM_UCONTEXT_MCONTEXT_OFFSET);
>
> Thought this would fit too, and is shorter:
>
> CORE_ADDR mcontext_addr = (sp
> + ARM_SIGFRAME_UCONTEXT_OFFSET
> + ARM_UCONTEXT_MCONTEXT_OFFSET);
Ok, the second looks better to me.
> > + CORE_ADDR mcontext_vfp_addr;
> > + gdb_byte buf[4];
> > + int i;
> > +
> > + for (i = 0; i < 16; i++)
>
> Suggest writing:
>
> for (int i = 0; i < 16; i++)
Done.
> > + {
> > + trad_frame_set_reg_addr (this_cache,
> > + ARM_A1_REGNUM + i,
> > + mcontext_addr + i * ARM_MCONTEXT_REG_SIZE);
> > + }
> > + trad_frame_set_reg_addr (this_cache, ARM_PS_REGNUM,
> > + mcontext_addr + 16 * ARM_MCONTEXT_REG_SIZE);
> > +
> > + mcontext_vfp_addr = 0;
> > + if (target_read_memory (mcontext_addr + ARM_MCONTEXT_VFP_PTR_OFFSET, buf,
> > + 4) == 0)
> > + mcontext_vfp_addr = extract_unsigned_integer (buf, 4, byte_order);
>
> I mildly wonder whether this be:
>
> if (safe_read_memory_unsigned_integer (mcontext_addr + ARM_MCONTEXT_VFP_PTR_OFFSET, 4,
> byte_order, &mcontext_vfp_addr)
> {
> for (i = 0; i < 32; i++)
> ....
>
> I'd convey intention and avoid the "= 0" initialization + "!= 0" check
> (unless you need it anyway).
I do need the != 0 check, but safe_read_memory_unsigned_integer does indeed
look nicer.
BTW, while working on the arm and aarch64 FreeBSD backends I've really liked
having the arrays of 'struct regcache_map_entry' objects. I think I'd like
to add a similar type of 'map' array for work with trad_frame used for
signal frames as then one can just define a structure to describe the layout
and perhaps give a starting CORE_ADDR and the 'map' array as args to a
trad_frame function that would handle calling trad_frame_set_reg_addr().
@@ -1,5 +1,14 @@
2017-09-14 John Baldwin <jhb@FreeBSD.org>
+ * Makefile.in (ALL_TARGET_OBS): Add arm-fbsd-tdep.o.
+ (ALLDEPFILES): Add arm-fbsd-tdep.c.
+ * NEWS: Mention new FreeBSD/arm target.
+ * configure.tgt: Add arm*-*-freebsd*.
+ * arm-fbsd-tdep.c: New file.
+ * arm-fbsd-tdep.h: New file.
+
+2017-09-14 John Baldwin <jhb@FreeBSD.org>
+
* fbsd-tdep.c (fbsd_print_auxv_entry): Handle AT_EHDRFLAGS and
AT_HWCAP.
@@ -790,6 +790,7 @@ ALL_TARGET_OBS = \
arc-tdep.o \
arm.o \
arm-bsd-tdep.o \
+ arm-fbsd-tdep.o \
arm-get-next-pcs.o \
arm-linux.o \
arm-linux-tdep.o \
@@ -2529,6 +2530,7 @@ ALLDEPFILES = \
arc-tdep.c \
arm.c \
arm-bsd-tdep.c \
+ arm-fbsd-tdep.c \
arm-get-next-pcs.c \
arm-linux.c \
arm-linux-nat.c \
@@ -105,6 +105,7 @@ FreeBSD/aarch64 aarch64*-*-freebsd*
* New targets
FreeBSD/aarch64 aarch64*-*-freebsd*
+FreeBSD/arm arm*-*-freebsd*
*** Changes in GDB 8.0
new file mode 100644
@@ -0,0 +1,258 @@
+/* Target-dependent code for FreeBSD/arm.
+
+ Copyright (C) 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 "elf/common.h"
+#include "arm-tdep.h"
+#include "arm-fbsd-tdep.h"
+#include "auxv.h"
+#include "fbsd-tdep.h"
+#include "osabi.h"
+#include "solib-svr4.h"
+#include "target.h"
+#include "trad-frame.h"
+#include "tramp-frame.h"
+
+/* In a signal frame, sp points to a 'struct sigframe' which is
+ defined as:
+
+ struct sigframe {
+ siginfo_t sf_si;
+ ucontext_t sf_uc;
+ mcontext_vfp_t sf_vfp;
+ };
+
+ ucontext_t is defined as:
+
+ struct __ucontext {
+ sigset_t uc_sigmask;
+ mcontext_t uc_mcontext;
+ ...
+ };
+
+ mcontext_t is defined as:
+
+ struct {
+ unsigned int __gregs[17];
+ size_t mc_vfp_size;
+ void *mc_vfp_ptr;
+ ...
+ };
+
+ mcontext_vfp_t is defined as:
+
+ struct {
+ uint64_t mcv_reg[32];
+ uint32_t mcv_fpscr;
+ };
+
+ If the VFP state is valid, then mc_vfp_ptr will point to sf_vfp in
+ the sigframe, otherwise it is NULL. There is no non-VFP floating
+ point register state saved in the signal frame. */
+
+#define ARM_MCONTEXT_REG_SIZE 4
+#define ARM_MCONTEXT_VFP_REG_SIZE 8
+#define ARM_SIGFRAME_UCONTEXT_OFFSET 64
+#define ARM_UCONTEXT_MCONTEXT_OFFSET 16
+#define ARM_MCONTEXT_VFP_PTR_OFFSET 72
+
+/* Implement the "init" method of struct tramp_frame. */
+
+static void
+arm_fbsd_sigframe_init (const struct tramp_frame *self,
+ struct frame_info *this_frame,
+ struct trad_frame_cache *this_cache,
+ CORE_ADDR func)
+{
+ struct gdbarch *gdbarch = get_frame_arch (this_frame);
+ enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+ CORE_ADDR sp = get_frame_register_unsigned (this_frame, ARM_SP_REGNUM);
+ CORE_ADDR mcontext_addr =
+ sp
+ + ARM_SIGFRAME_UCONTEXT_OFFSET
+ + ARM_UCONTEXT_MCONTEXT_OFFSET;
+ CORE_ADDR mcontext_vfp_addr;
+ gdb_byte buf[4];
+ int i;
+
+ for (i = 0; i < 16; i++)
+ {
+ trad_frame_set_reg_addr (this_cache,
+ ARM_A1_REGNUM + i,
+ mcontext_addr + i * ARM_MCONTEXT_REG_SIZE);
+ }
+ trad_frame_set_reg_addr (this_cache, ARM_PS_REGNUM,
+ mcontext_addr + 16 * ARM_MCONTEXT_REG_SIZE);
+
+ mcontext_vfp_addr = 0;
+ if (target_read_memory (mcontext_addr + ARM_MCONTEXT_VFP_PTR_OFFSET, buf,
+ 4) == 0)
+ mcontext_vfp_addr = extract_unsigned_integer (buf, 4, byte_order);
+ if (mcontext_vfp_addr != 0)
+ {
+ for (i = 0; i < 32; i++)
+ {
+ trad_frame_set_reg_addr (this_cache, ARM_D0_REGNUM + i,
+ mcontext_vfp_addr
+ + i * ARM_MCONTEXT_VFP_REG_SIZE);
+ }
+ trad_frame_set_reg_addr (this_cache, ARM_FPSCR_REGNUM,
+ mcontext_vfp_addr
+ + 32 * ARM_MCONTEXT_VFP_REG_SIZE);
+ }
+
+ trad_frame_set_id (this_cache, frame_id_build (sp, func));
+}
+
+static const struct tramp_frame arm_fbsd_sigframe =
+{
+ SIGTRAMP_FRAME,
+ 4,
+ {
+ {0xe1a0000d, -1}, /* mov r0, sp */
+ {0xe2800040, -1}, /* add r0, r0, #SIGF_UC */
+ {0xe59f700c, -1}, /* ldr r7, [pc, #12] */
+ {0xef0001a1, -1}, /* swi SYS_sigreturn */
+ {TRAMP_SENTINEL_INSN, -1}
+ },
+ arm_fbsd_sigframe_init
+};
+
+/* Register maps. */
+
+static const struct regcache_map_entry arm_fbsd_gregmap[] =
+ {
+ { 13, ARM_A1_REGNUM, 4 }, /* r0 ... r12 */
+ { 1, ARM_SP_REGNUM, 4 },
+ { 1, ARM_LR_REGNUM, 4 },
+ { 1, ARM_PC_REGNUM, 4 },
+ { 1, ARM_PS_REGNUM, 4 },
+ { 0 }
+ };
+
+static const struct regcache_map_entry arm_fbsd_vfpregmap[] =
+ {
+ { 32, ARM_D0_REGNUM, 8 }, /* d0 ... d31 */
+ { 1, ARM_FPSCR_REGNUM, 4 },
+ { 0 }
+ };
+
+/* Register set definitions. */
+
+const struct regset arm_fbsd_gregset =
+ {
+ arm_fbsd_gregmap,
+ regcache_supply_regset, regcache_collect_regset
+ };
+
+const struct regset arm_fbsd_vfpregset =
+ {
+ arm_fbsd_vfpregmap,
+ regcache_supply_regset, regcache_collect_regset
+ };
+
+/* Implement the "regset_from_core_section" gdbarch method. */
+
+static void
+arm_fbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
+ iterate_over_regset_sections_cb *cb,
+ void *cb_data,
+ const struct regcache *regcache)
+{
+ struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+ cb (".reg", ARM_FBSD_SIZEOF_GREGSET, &arm_fbsd_gregset, NULL, cb_data);
+
+ /* While FreeBSD/arm cores do contain a NT_FPREGSET / ".reg2"
+ register set, it is not populated with register values by the
+ kernel but just contains all zeroes. */
+ if (tdep->vfp_register_count > 0)
+ cb (".reg-arm-vfp", ARM_FBSD_SIZEOF_VFPREGSET, &arm_fbsd_vfpregset,
+ "VFP floating-point", cb_data);
+}
+
+/* Lookup a target description from a target's AT_HWCAP auxiliary
+ vector. */
+
+const struct target_desc *
+arm_fbsd_read_description_auxv (struct target_ops *target)
+{
+ CORE_ADDR arm_hwcap = 0;
+
+ if (target_auxv_search (target, AT_FREEBSD_HWCAP, &arm_hwcap) != 1)
+ return NULL;
+
+ if (arm_hwcap & HWCAP_VFP)
+ {
+ if ((arm_hwcap & (HWCAP_VFPv3 | HWCAP_VFPD32))
+ == (HWCAP_VFPv3 | HWCAP_VFPD32))
+ return tdesc_arm_with_vfpv3;
+ else
+ return tdesc_arm_with_vfpv2;
+ }
+
+ return NULL;
+}
+
+/* Implement the "core_read_description" gdbarch method. */
+
+static const struct target_desc *
+arm_fbsd_core_read_description (struct gdbarch *gdbarch,
+ struct target_ops *target,
+ bfd *abfd)
+{
+ return arm_fbsd_read_description_auxv (target);
+}
+
+/* Implement the 'init_osabi' method of struct gdb_osabi_handler. */
+
+static void
+arm_fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
+{
+ struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
+
+ /* Generic FreeBSD support. */
+ fbsd_init_abi (info, gdbarch);
+
+ if (tdep->fp_model == ARM_FLOAT_AUTO)
+ tdep->fp_model = ARM_FLOAT_SOFT_VFP;
+
+ tramp_frame_prepend_unwinder (gdbarch, &arm_fbsd_sigframe);
+
+ set_solib_svr4_fetch_link_map_offsets
+ (gdbarch, svr4_ilp32_fetch_link_map_offsets);
+
+ tdep->jb_pc = 24;
+ tdep->jb_elt_size = 4;
+
+ set_gdbarch_iterate_over_regset_sections
+ (gdbarch, arm_fbsd_iterate_over_regset_sections);
+ set_gdbarch_core_read_description (gdbarch, arm_fbsd_core_read_description);
+
+ /* Single stepping. */
+ set_gdbarch_software_single_step (gdbarch, arm_software_single_step);
+}
+
+void
+_initialize_arm_fbsd_tdep (void)
+{
+ gdbarch_register_osabi (bfd_arch_arm, 0, GDB_OSABI_FREEBSD,
+ arm_fbsd_init_abi);
+}
new file mode 100644
@@ -0,0 +1,39 @@
+/* FreeBSD/arm target support, prototypes.
+
+ Copyright (C) 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 "regset.h"
+
+/* The general-purpose regset consists of 13 R registers, plus SP, LR,
+ PC, and CPSR registers. */
+#define ARM_FBSD_SIZEOF_GREGSET (17 * 4)
+
+/* The VFP regset consists of 32 D registers plus FPSCR, and the whole
+ structure is padded to 64-bit alignment. */
+#define ARM_FBSD_SIZEOF_VFPREGSET (33 * 8)
+
+extern const struct regset arm_fbsd_gregset;
+extern const struct regset arm_fbsd_vfpregset;
+
+/* Flags passed in AT_HWCAP. */
+#define HWCAP_VFP 0x00000040
+#define HWCAP_VFPv3 0x00000200
+#define HWCAP_VFPD32 0x00080000
+
+extern const struct target_desc *
+arm_fbsd_read_description_auxv (struct target_ops *target);
@@ -109,6 +109,11 @@ arm*-*-linux*)
solib-svr4.o symfile-mem.o linux-tdep.o linux-record.o"
build_gdbserver=yes
;;
+arm*-*-freebsd*)
+ # Target: FreeBSD/arm
+ gdb_target_obs="arm.o arm-get-next-pcs.o arm-tdep.o arm-fbsd-tdep.o \
+ fbsd-tdep.o solib-svr4.o"
+ ;;
arm*-*-netbsd* | arm*-*-knetbsd*-gnu)
# Target: NetBSD/arm
gdb_target_obs="arm.o arm-get-next-pcs.o arm-tdep.o arm-nbsd-tdep.o \