[PATCH v6 06/15] gdb: Update x86 FreeBSD architectures to support XSAVE layouts.

John Baldwin
2023-07-14T15:57:21Z

Refactor i386fbsd_core_read_xcr0 to fetch and return a corresponding
x86_xsave_layout as well as xcr0 using the size of an existing
NT_X86_XSTATE core dump to determine the offsets via
i387_set_xsave_layout. Use this to add an implementation of
gdbarch_core_xfer_x86_xsave_layout.

Use tdep->xsave_layout.sizeof_xsave as the size of the XSTATE register
set and only fetch/store the register set if this size is non-zero.
---
gdb/amd64-fbsd-tdep.c | 12 ++++++--
gdb/i386-fbsd-tdep.c | 72 ++++++++++++++++++++++++-------------------
gdb/i386-fbsd-tdep.h | 14 +++++++--
3 files changed, 62 insertions(+), 36 deletions(-)

diff --git a/gdb/amd64-fbsd-tdep.c b/gdb/amd64-fbsd-tdep.c
index 0d5ce004fb1..5dc519d7d6e 100644
--- a/gdb/amd64-fbsd-tdep.c
+++ b/gdb/amd64-fbsd-tdep.c
@@ -224,7 +224,9 @@ amd64fbsd_core_read_description (struct gdbarch *gdbarch,
struct target_ops *target,
bfd *abfd)
{
- return amd64_target_description (i386fbsd_core_read_xcr0 (abfd), true);
+ x86_xsave_layout layout;
+ return amd64_target_description (i386_fbsd_core_read_xsave_info (abfd, layout),
+ true);
}

/* Similar to amd64_supply_fpregset, but use XSAVE extended state. */
@@ -271,8 +273,10 @@ amd64fbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
cb (".reg-x86-segbases", AMD64_FBSD_SIZEOF_SEGBASES_REGSET,
AMD64_FBSD_SIZEOF_SEGBASES_REGSET, &amd64_fbsd_segbases_regset,
"segment bases", cb_data);
- cb (".reg-xstate", X86_XSTATE_SIZE (tdep->xcr0), X86_XSTATE_SIZE (tdep->xcr0),
- &amd64fbsd_xstateregset, "XSAVE extended state", cb_data);
+ if (tdep->xsave_layout.sizeof_xsave != 0)
+ cb (".reg-xstate", tdep->xsave_layout.sizeof_xsave,
+ tdep->xsave_layout.sizeof_xsave, &amd64fbsd_xstateregset,
+ "XSAVE extended state", cb_data);
}

/* Implement the get_thread_local_address gdbarch method. */
@@ -313,6 +317,8 @@ amd64fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
tramp_frame_prepend_unwinder (gdbarch, &amd64_fbsd_sigframe);

tdep->xsave_xcr0_offset = I386_FBSD_XSAVE_XCR0_OFFSET;
+ set_gdbarch_core_read_x86_xsave_layout
+ (gdbarch, i386_fbsd_core_read_x86_xsave_layout);

/* Iterate over core file register note sections. */
set_gdbarch_iterate_over_regset_sections
diff --git a/gdb/i386-fbsd-tdep.c b/gdb/i386-fbsd-tdep.c
index fb9030413ab..df842f16bfc 100644
--- a/gdb/i386-fbsd-tdep.c
+++ b/gdb/i386-fbsd-tdep.c
@@ -18,13 +18,13 @@
along with this program. If not, see <http://www.gnu.org/licenses/>. */

#include "defs.h"
+#include "gdbcore.h"
#include "osabi.h"
#include "regcache.h"
#include "regset.h"
#include "trad-frame.h"
#include "tramp-frame.h"
#include "i386-fbsd-tdep.h"
-#include "gdbsupport/x86-xstate.h"

#include "i386-tdep.h"
#include "i387-tdep.h"
@@ -241,43 +241,49 @@ static const struct tramp_frame i386_fbsd64_sigframe =
i386_fbsd_sigframe_init
};

-/* Get XSAVE extended state xcr0 from core dump. */
+/* See i386-fbsd-tdep.h. */

uint64_t
-i386fbsd_core_read_xcr0 (bfd *abfd)
+i386_fbsd_core_read_xsave_info (bfd *abfd, x86_xsave_layout &layout)
{
asection *xstate = bfd_get_section_by_name (abfd, ".reg-xstate");
- uint64_t xcr0;
+ if (xstate == nullptr)
+ return X86_XSTATE_SSE_MASK;

- if (xstate)
+ /* Check extended state size. */
+ size_t size = bfd_section_size (xstate);
+ if (size < X86_XSTATE_AVX_SIZE)
+ return X86_XSTATE_SSE_MASK;
+
+ char contents[8];
+ if (! bfd_get_section_contents (abfd, xstate, contents,
+ I386_FBSD_XSAVE_XCR0_OFFSET, 8))
{
- size_t size = bfd_section_size (xstate);
-
- /* Check extended state size. */
- if (size < X86_XSTATE_AVX_SIZE)
- xcr0 = X86_XSTATE_SSE_MASK;
- else
- {
- char contents[8];
-
- if (! bfd_get_section_contents (abfd, xstate, contents,
- I386_FBSD_XSAVE_XCR0_OFFSET,
- 8))
- {
- warning (_("Couldn't read `xcr0' bytes from "
- "`.reg-xstate' section in core file."));
- return X86_XSTATE_SSE_MASK;
- }
-
- xcr0 = bfd_get_64 (abfd, contents);
- }
+ warning (_("Couldn't read `xcr0' bytes from "
+ "`.reg-xstate' section in core file."));
+ return X86_XSTATE_SSE_MASK;
}
- else
- xcr0 = X86_XSTATE_SSE_MASK;
+
+ uint64_t xcr0 = bfd_get_64 (abfd, contents);
+
+ if (!i387_set_xsave_layout (xcr0, size, layout))
+ return X86_XSTATE_SSE_MASK;

return xcr0;
}

+/* Implement the core_read_x86_xsave_layout gdbarch method. */
+
+bool
+i386_fbsd_core_read_x86_xsave_layout (struct gdbarch *gdbarch,
+ x86_xsave_layout &layout)
+{
+ if (i386_fbsd_core_read_xsave_info (core_bfd, layout) == X86_XSTATE_SSE_MASK)
+ return false;
+
+ return true;
+}
+
/* Implement the core_read_description gdbarch method. */

static const struct target_desc *
@@ -285,7 +291,9 @@ i386fbsd_core_read_description (struct gdbarch *gdbarch,
struct target_ops *target,
bfd *abfd)
{
- return i386_target_description (i386fbsd_core_read_xcr0 (abfd), true);
+ x86_xsave_layout layout;
+ return i386_target_description (i386_fbsd_core_read_xsave_info (abfd, layout),
+ true);
}

/* Similar to i386_supply_fpregset, but use XSAVE extended state. */
@@ -335,9 +343,9 @@ i386fbsd_iterate_over_regset_sections (struct gdbarch *gdbarch,
I386_FBSD_SIZEOF_SEGBASES_REGSET, &i386_fbsd_segbases_regset,
"segment bases", cb_data);

- if (tdep->xcr0 & X86_XSTATE_AVX)
- cb (".reg-xstate", X86_XSTATE_SIZE (tdep->xcr0),
- X86_XSTATE_SIZE (tdep->xcr0), &i386fbsd_xstateregset,
+ if (tdep->xsave_layout.sizeof_xsave != 0)
+ cb (".reg-xstate", tdep->xsave_layout.sizeof_xsave,
+ tdep->xsave_layout.sizeof_xsave, &i386fbsd_xstateregset,
"XSAVE extended state", cb_data);
}

@@ -386,6 +394,8 @@ i386fbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
i386_elf_init_abi (info, gdbarch);

tdep->xsave_xcr0_offset = I386_FBSD_XSAVE_XCR0_OFFSET;
+ set_gdbarch_core_read_x86_xsave_layout
+ (gdbarch, i386_fbsd_core_read_x86_xsave_layout);

/* Iterate over core file register note sections. */
set_gdbarch_iterate_over_regset_sections
diff --git a/gdb/i386-fbsd-tdep.h b/gdb/i386-fbsd-tdep.h
index cb991af9e49..cc2af4a0600 100644
--- a/gdb/i386-fbsd-tdep.h
+++ b/gdb/i386-fbsd-tdep.h
@@ -20,10 +20,20 @@
#ifndef I386_FBSD_TDEP_H
#define I386_FBSD_TDEP_H

+#include "gdbsupport/x86-xstate.h"
#include "regset.h"

-/* Get XSAVE extended state xcr0 from core dump. */
-extern uint64_t i386fbsd_core_read_xcr0 (bfd *abfd);
+/* Read the XSAVE extended state xcr0 value from the ABFD core file.
+ If it appears to be valid, return it and fill LAYOUT with values
+ inferred from that value.
+
+ Otherwise, return X86_XSTATE_SSE_MASK as a fallback and leave
+ LAYOUT untouched. */
+uint64_t i386_fbsd_core_read_xsave_info (bfd *abfd, x86_xsave_layout &layout);
+
+/* Implement the core_read_x86_xsave_layout gdbarch method. */
+bool i386_fbsd_core_read_x86_xsave_layout (struct gdbarch *gdbarch,
+ x86_xsave_layout &layout);

/* The format of the XSAVE extended area is determined by hardware.
Cores store the XSAVE extended area in a NT_X86_XSTATE note that
--
2.40.0