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From: "vries at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>
To: gdb-prs@sourceware.org
Subject: [Bug tdep/30102] New: [gdb/tdep, amd64] Disable i386 unwinders
Date: Thu, 09 Feb 2023 14:24:36 +0000 [thread overview]
Message-ID: <bug-30102-4717@http.sourceware.org/bugzilla/> (raw)
https://sourceware.org/bugzilla/show_bug.cgi?id=30102
Bug ID: 30102
Summary: [gdb/tdep, amd64] Disable i386 unwinders
Product: gdb
Version: HEAD
Status: NEW
Severity: minor
Priority: P2
Component: tdep
Assignee: unassigned at sourceware dot org
Reporter: vries at gcc dot gnu.org
Target Milestone: ---
As mentioned here (
https://sourceware.org/pipermail/gdb-patches/2023-February/196724.html ), for
i386 we have these unwinders:
...
$ 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
inline INLINE_FRAME
i386 epilogue NORMAL_FRAME
dwarf2 NORMAL_FRAME
dwarf2 signal SIGTRAMP_FRAME
i386 stack tramp NORMAL_FRAME
i386 sigtramp SIGTRAMP_FRAME
i386 prologue NORMAL_FRAME
...
and for amd64:
...
$ 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
i386 epilogue NORMAL_FRAME
dwarf2 NORMAL_FRAME
dwarf2 signal SIGTRAMP_FRAME
amd64 sigtramp SIGTRAMP_FRAME
amd64 prologue NORMAL_FRAME
i386 stack tramp NORMAL_FRAME
i386 sigtramp SIGTRAMP_FRAME
i386 prologue NORMAL_FRAME
...
So, why are the i386 unwinders there for amd64?
I recently played around with disabling or moving the "amd64 epilogue"
unwinder, and while investigating the effect of that, I came across a failure
that was due to the "i386 epilogue" unwinder becoming active and giving the
wrong answer, which suggest that the i386 unwinders shouldn't be there for
amd64.
Using this tentative patch:
...
diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index 580664d2ce5..8dccae633f7 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -8613,7 +8613,8 @@ i386_gdbarch_init (struct gdbarch_info info, struct
gdbarch_list *arc
hes)
appended to the list first, so that it supercedes the DWARF
unwinder in function epilogues (where the DWARF unwinder
currently fails). */
- frame_unwind_append_unwinder (gdbarch, &i386_epilogue_frame_unwind);
+ if (info.bfd_arch_info->bits_per_word == 32)
+ frame_unwind_append_unwinder (gdbarch, &i386_epilogue_frame_unwind);
/* Hook in the DWARF CFI frame unwinder. This unwinder is appended
to the list before the prologue-based unwinders, so that DWARF
@@ -8792,9 +8793,12 @@ i386_gdbarch_init (struct gdbarch_info info, struct
gdbarch_list *ar
ches)
tdep-> bnd0_regnum = -1;
/* Hook in the legacy prologue-based unwinders last (fallback). */
- frame_unwind_append_unwinder (gdbarch, &i386_stack_tramp_frame_unwind);
- frame_unwind_append_unwinder (gdbarch, &i386_sigtramp_frame_unwind);
- frame_unwind_append_unwinder (gdbarch, &i386_frame_unwind);
+ if (info.bfd_arch_info->bits_per_word == 32)
+ {
+ frame_unwind_append_unwinder (gdbarch, &i386_stack_tramp_frame_unwind);
+ frame_unwind_append_unwinder (gdbarch, &i386_sigtramp_frame_unwind);
+ frame_unwind_append_unwinder (gdbarch, &i386_frame_unwind);
+ }
/* If we have a register mapping, enable the generic core file
support, unless it has already been enabled. */
...
we have for i386 as before, and for amd64:
...
$ 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
...
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next reply other threads:[~2023-02-09 14:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-09 14:24 vries at gcc dot gnu.org [this message]
2023-02-09 15:21 ` [Bug tdep/30102] " vries at gcc dot gnu.org
2023-02-09 22:02 ` vries at gcc dot gnu.org
2023-02-10 12:56 ` vries at gcc dot gnu.org
2023-02-11 8:04 ` cvs-commit at gcc dot gnu.org
2023-02-11 8:05 ` vries at gcc dot gnu.org
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