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authorMichael Snyder <msnyder@vmware.com>2009-07-12 17:46:21 +0000
committerMichael Snyder <msnyder@vmware.com>2009-07-12 17:46:21 +0000
commit06da04c61051b251f9bb5427a091c7cfa27bdb6d (patch)
tree5dfd472eb4ccb4dab945853c1f22d377b901ed4a /gdb/i386-tdep.c
parent6a8b86150e2ad521822b63f1839b320a749335ac (diff)
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2009-07-12 Michael Snyder <msnyder@vmware.com>
* i386-tdep.c: Add a frame unwinder for function epilogues. (i386_in_function_epilogue_p): New function. (i386_epilogue_frame_sniffer): New function. (i386_epilogue_frame_cache): New function. (i386_epilogue_frame_this_id): New function. (i386_epilogue_frame_unwind): New struct frame_unwind. (i386_gdbarch_init): Hook the new unwinder.
Diffstat (limited to 'gdb/i386-tdep.c')
-rw-r--r--gdb/i386-tdep.c94
1 files changed, 93 insertions, 1 deletions
diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index bf3a844..2d73785 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -1487,6 +1487,89 @@ static const struct frame_unwind i386_frame_unwind =
NULL,
default_frame_sniffer
};
+
+/* Normal frames, but in a function epilogue. */
+
+/* The epilogue is defined here as the 'ret' instruction, which will
+ follow any instruction such as 'leave' or 'pop %ebp' that destroys
+ the function's stack frame. */
+
+static int
+i386_in_function_epilogue_p (struct gdbarch *gdbarch, CORE_ADDR pc)
+{
+ gdb_byte insn;
+
+ if (target_read_memory (pc, &insn, 1))
+ return 0; /* Can't read memory at pc. */
+
+ if (insn != 0xc3) /* 'ret' instruction. */
+ return 0;
+
+ return 1;
+}
+
+static int
+i386_epilogue_frame_sniffer (const struct frame_unwind *self,
+ struct frame_info *this_frame,
+ void **this_prologue_cache)
+{
+ if (frame_relative_level (this_frame) == 0)
+ return i386_in_function_epilogue_p (get_frame_arch (this_frame),
+ get_frame_pc (this_frame));
+ else
+ return 0;
+}
+
+static struct i386_frame_cache *
+i386_epilogue_frame_cache (struct frame_info *this_frame, void **this_cache)
+{
+ struct gdbarch *gdbarch = get_frame_arch (this_frame);
+ enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+ struct i386_frame_cache *cache;
+ gdb_byte buf[4];
+
+ if (*this_cache)
+ return *this_cache;
+
+ cache = i386_alloc_frame_cache ();
+ *this_cache = cache;
+
+ /* Cache base will be %esp plus cache->sp_offset (-4). */
+ get_frame_register (this_frame, I386_ESP_REGNUM, buf);
+ cache->base = extract_unsigned_integer (buf, 4,
+ byte_order) + cache->sp_offset;
+
+ /* Cache pc will be the frame func. */
+ cache->pc = get_frame_pc (this_frame);
+
+ /* The saved %esp will be at cache->base plus 8. */
+ cache->saved_sp = cache->base + 8;
+
+ /* The saved %eip will be at cache->base plus 4. */
+ cache->saved_regs[I386_EIP_REGNUM] = cache->base + 4;
+
+ return cache;
+}
+
+static void
+i386_epilogue_frame_this_id (struct frame_info *this_frame,
+ void **this_cache,
+ struct frame_id *this_id)
+{
+ struct i386_frame_cache *cache = i386_epilogue_frame_cache (this_frame,
+ this_cache);
+
+ (*this_id) = frame_id_build (cache->base + 8, cache->pc);
+}
+
+static const struct frame_unwind i386_epilogue_frame_unwind =
+{
+ NORMAL_FRAME,
+ i386_epilogue_frame_this_id,
+ i386_frame_prev_register,
+ NULL,
+ i386_epilogue_frame_sniffer
+};
/* Signal trampolines. */
@@ -5329,7 +5412,15 @@ i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
/* Helper for function argument information. */
set_gdbarch_fetch_pointer_argument (gdbarch, i386_fetch_pointer_argument);
- /* Hook in the DWARF CFI frame unwinder. */
+ /* Hook the function epilogue frame unwinder. This unwinder is
+ 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);
+
+ /* 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);
frame_base_set_default (gdbarch, &i386_frame_base);
@@ -5337,6 +5428,7 @@ i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
/* Hook in ABI-specific overrides, if they have been registered. */
gdbarch_init_osabi (info, gdbarch);
+ /* Hook in the legacy prologue-based unwinders last (fallback). */
frame_unwind_append_unwinder (gdbarch, &i386_sigtramp_frame_unwind);
frame_unwind_append_unwinder (gdbarch, &i386_frame_unwind);