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* [binutils-gdb] [gdb/tdep] Add amd64/i386 epilogue override unwinders
@ 2023-02-20 11:20 Tom de Vries
0 siblings, 0 replies; only message in thread
From: Tom de Vries @ 2023-02-20 11:20 UTC (permalink / raw)
To: gdb-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=5aca7eaa2be78b5bb9f993b901b32acef51e5c45
commit 5aca7eaa2be78b5bb9f993b901b32acef51e5c45
Author: Tom de Vries <tdevries@suse.de>
Date: Mon Feb 20 12:20:14 2023 +0100
[gdb/tdep] Add amd64/i386 epilogue override unwinders
For amd64 the current frame-unwinders are:
...
$ gdb -q -batch -ex "set arch i386:x86-64" -ex "maint info frame-unwinders"
The target architecture is set to "i386:x86-64".
dummy DUMMY_FRAME
dwarf2 tailcall TAILCALL_FRAME
inline INLINE_FRAME
python NORMAL_FRAME
amd64 epilogue NORMAL_FRAME
dwarf2 NORMAL_FRAME
dwarf2 signal SIGTRAMP_FRAME
amd64 sigtramp SIGTRAMP_FRAME
amd64 prologue NORMAL_FRAME
...
For a -g0 -fasynchronous-unwind-tables exec (without .debug_info but with
.eh_frame section), we'd like to start using the dwarf2 unwinder instead of
the "amd64 epilogue" unwinder, by returning true in
compunit_epilogue_unwind_valid for cust == nullptr.
But we'd run into the following problem for a -g0
-fno-asynchronous-unwind-tables (without .debug_info and .eh_frame section)
exec:
- the "amd64 epilogue" unwinder would not run
(because compunit_epilogue_unwind_valid () == true)
- the dwarf2 unwinder would also not run
(because there's no .eh_frame info).
Fix this by:
- renaming the "amd64 epilogue" unwinder to "amd64 epilogue override", and
- adding a fallback "amd64 epilogue" after the dwarf unwinders,
while making sure that only one of the two is active. Likewise for i386. NFC.
For amd64, this results in this change:
...
$ gdb -q -batch -ex "set arch i386:x86-64" -ex "maint info frame-unwinders"
The target architecture is set to "i386:x86-64".
dummy DUMMY_FRAME
dwarf2 tailcall TAILCALL_FRAME
inline INLINE_FRAME
python NORMAL_FRAME
-amd64 epilogue NORMAL_FRAME
+amd64 epilogue override NORMAL_FRAME
dwarf2 NORMAL_FRAME
dwarf2 signal SIGTRAMP_FRAME
+amd64 epilogue NORMAL_FRAME
amd64 sigtramp SIGTRAMP_FRAME
amd64 prologue NORMAL_FRAME
...
And for i386:
...
$ gdb -q -batch -ex "set arch i386" -ex "maint info frame-unwinders"
The target architecture is set to "i386".
dummy DUMMY_FRAME
dwarf2 tailcall TAILCALL_FRAME
iline INLINE_FRAME
-i386 epilogue NORMAL_FRAME
+i386 epilogue override NORMAL_FRAME
dwarf2 NORMAL_FRAME
dwarf2 signal SIGTRAMP_FRAME
+i386 epilogue NORMAL_FRAME
i386 stack tramp NORMAL_FRAME
i386 sigtramp SIGTRAMP_FRAME
i386 prologue NORMAL_FRAME
...
Diff:
---
gdb/amd64-tdep.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++-------
gdb/i386-tdep.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++++-------
2 files changed, 103 insertions(+), 14 deletions(-)
diff --git a/gdb/amd64-tdep.c b/gdb/amd64-tdep.c
index 75ab1b23ccf..0ae09dc7bfb 100644
--- a/gdb/amd64-tdep.c
+++ b/gdb/amd64-tdep.c
@@ -2913,9 +2913,9 @@ amd64_stack_frame_destroyed_p (struct gdbarch *gdbarch, CORE_ADDR pc)
}
static int
-amd64_epilogue_frame_sniffer (const struct frame_unwind *self,
- frame_info_ptr this_frame,
- void **this_prologue_cache)
+amd64_epilogue_frame_sniffer_1 (const struct frame_unwind *self,
+ frame_info_ptr this_frame,
+ void **this_prologue_cache, bool override_p)
{
struct gdbarch *gdbarch = get_frame_arch (this_frame);
CORE_ADDR pc = get_frame_pc (this_frame);
@@ -2924,14 +2924,45 @@ amd64_epilogue_frame_sniffer (const struct frame_unwind *self,
/* We're not in the inner frame, so assume we're not in an epilogue. */
return 0;
- if (compunit_epilogue_unwind_valid (find_pc_compunit_symtab (pc)))
- /* Don't override the symtab unwinders. */
- return 0;
+ bool unwind_valid_p
+ = compunit_epilogue_unwind_valid (find_pc_compunit_symtab (pc));
+ if (override_p)
+ {
+ if (unwind_valid_p)
+ /* Don't override the symtab unwinders, skip
+ "amd64 epilogue override". */
+ return 0;
+ }
+ else
+ {
+ if (!unwind_valid_p)
+ /* "amd64 epilogue override" unwinder already ran, skip
+ "amd64 epilogue". */
+ return 0;
+ }
/* Check whether we're in an epilogue. */
return amd64_stack_frame_destroyed_p (gdbarch, pc);
}
+static int
+amd64_epilogue_override_frame_sniffer (const struct frame_unwind *self,
+ frame_info_ptr this_frame,
+ void **this_prologue_cache)
+{
+ return amd64_epilogue_frame_sniffer_1 (self, this_frame, this_prologue_cache,
+ true);
+}
+
+static int
+amd64_epilogue_frame_sniffer (const struct frame_unwind *self,
+ frame_info_ptr this_frame,
+ void **this_prologue_cache)
+{
+ return amd64_epilogue_frame_sniffer_1 (self, this_frame, this_prologue_cache,
+ false);
+}
+
static struct amd64_frame_cache *
amd64_epilogue_frame_cache (frame_info_ptr this_frame, void **this_cache)
{
@@ -3000,6 +3031,17 @@ amd64_epilogue_frame_this_id (frame_info_ptr this_frame,
(*this_id) = frame_id_build (cache->base + 16, cache->pc);
}
+static const struct frame_unwind amd64_epilogue_override_frame_unwind =
+{
+ "amd64 epilogue override",
+ NORMAL_FRAME,
+ amd64_epilogue_frame_unwind_stop_reason,
+ amd64_epilogue_frame_this_id,
+ amd64_frame_prev_register,
+ NULL,
+ amd64_epilogue_override_frame_sniffer
+};
+
static const struct frame_unwind amd64_epilogue_frame_unwind =
{
"amd64 epilogue",
@@ -3257,7 +3299,9 @@ amd64_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch,
/* Hook the function epilogue frame unwinder. This unwinder is
appended to the list first, so that it supercedes the other
unwinders in function epilogues. */
- frame_unwind_prepend_unwinder (gdbarch, &amd64_epilogue_frame_unwind);
+ frame_unwind_prepend_unwinder (gdbarch, &amd64_epilogue_override_frame_unwind);
+
+ frame_unwind_append_unwinder (gdbarch, &amd64_epilogue_frame_unwind);
/* Hook the prologue-based frame unwinders. */
frame_unwind_append_unwinder (gdbarch, &amd64_sigtramp_frame_unwind);
diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index 032fcc4dd76..476d17f1efd 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -2229,9 +2229,9 @@ i386_stack_frame_destroyed_p (struct gdbarch *gdbarch, CORE_ADDR pc)
}
static int
-i386_epilogue_frame_sniffer (const struct frame_unwind *self,
- frame_info_ptr this_frame,
- void **this_prologue_cache)
+i386_epilogue_frame_sniffer_1 (const struct frame_unwind *self,
+ frame_info_ptr this_frame,
+ void **this_prologue_cache, bool override_p)
{
struct gdbarch *gdbarch = get_frame_arch (this_frame);
CORE_ADDR pc = get_frame_pc (this_frame);
@@ -2240,14 +2240,45 @@ i386_epilogue_frame_sniffer (const struct frame_unwind *self,
/* We're not in the inner frame, so assume we're not in an epilogue. */
return 0;
- if (compunit_epilogue_unwind_valid (find_pc_compunit_symtab (pc)))
- /* Don't override the symtab unwinders. */
- return 0;
+ bool unwind_valid_p
+ = compunit_epilogue_unwind_valid (find_pc_compunit_symtab (pc));
+ if (override_p)
+ {
+ if (unwind_valid_p)
+ /* Don't override the symtab unwinders, skip
+ "i386 epilogue override". */
+ return 0;
+ }
+ else
+ {
+ if (!unwind_valid_p)
+ /* "i386 epilogue override" unwinder already ran, skip
+ "i386 epilogue". */
+ return 0;
+ }
/* Check whether we're in an epilogue. */
return i386_stack_frame_destroyed_p (gdbarch, pc);
}
+static int
+i386_epilogue_override_frame_sniffer (const struct frame_unwind *self,
+ frame_info_ptr this_frame,
+ void **this_prologue_cache)
+{
+ return i386_epilogue_frame_sniffer_1 (self, this_frame, this_prologue_cache,
+ true);
+}
+
+static int
+i386_epilogue_frame_sniffer (const struct frame_unwind *self,
+ frame_info_ptr this_frame,
+ void **this_prologue_cache)
+{
+ return i386_epilogue_frame_sniffer_1 (self, this_frame, this_prologue_cache,
+ false);
+}
+
static struct i386_frame_cache *
i386_epilogue_frame_cache (frame_info_ptr this_frame, void **this_cache)
{
@@ -2320,6 +2351,17 @@ i386_epilogue_frame_prev_register (frame_info_ptr this_frame,
return i386_frame_prev_register (this_frame, this_cache, regnum);
}
+static const struct frame_unwind i386_epilogue_override_frame_unwind =
+{
+ "i386 epilogue override",
+ NORMAL_FRAME,
+ i386_epilogue_frame_unwind_stop_reason,
+ i386_epilogue_frame_this_id,
+ i386_epilogue_frame_prev_register,
+ NULL,
+ i386_epilogue_override_frame_sniffer
+};
+
static const struct frame_unwind i386_epilogue_frame_unwind =
{
"i386 epilogue",
@@ -8618,13 +8660,16 @@ i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
unwinder in function epilogues (where the DWARF unwinder
currently fails). */
if (info.bfd_arch_info->bits_per_word == 32)
- frame_unwind_append_unwinder (gdbarch, &i386_epilogue_frame_unwind);
+ frame_unwind_append_unwinder (gdbarch, &i386_epilogue_override_frame_unwind);
/* Hook in the DWARF CFI frame unwinder. This unwinder is appended
to the list before the prologue-based unwinders, so that DWARF
CFI info will be used if it is available. */
dwarf2_append_unwinders (gdbarch);
+ if (info.bfd_arch_info->bits_per_word == 32)
+ frame_unwind_append_unwinder (gdbarch, &i386_epilogue_frame_unwind);
+
frame_base_set_default (gdbarch, &i386_frame_base);
/* Pseudo registers may be changed by amd64_init_abi. */
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2023-02-20 11:20 [binutils-gdb] [gdb/tdep] Add amd64/i386 epilogue override unwinders Tom de Vries
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