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Re: [RFA] Add epilogue unwinder for AMD64


With this patch and amd64-1.txt, all the reverse testsuite pass.
It's so great!

Thanks for you keep work in this part.  Thank you very much.

Hui

On Mon, Aug 17, 2009 at 08:18, Michael Snyder<msnyder@vmware.com> wrote:
> This patch corresponds to the similar one in i386-tdep.c, and
> corrects for a gcc issue with elf/dwarf debug info in function
> epilogues. ?It is needed in order to make reverse-step and next
> work properly for stepping backward through a return.
>
> No testsuite regressions.
>
> OK to commit?
>
>
> 2009-08-16 ?Michael Snyder ?<msnyder@vmware.com>
>
> ? ? ? ?* amd64-tdep.c: Add a frame unwinder for function epilogues.
> ? ? ? ?(amd64_in_function_epilogue_p): New function.
> ? ? ? ?(amd64_epilogue_frame_sniffer): New function.
> ? ? ? ?(amd64_epilogue_frame_cache): New function.
> ? ? ? ?(amd64_epilogue_frame_this_id): New function.
> ? ? ? ?(amd64_epilogue_frame_unwind): New struct frame_unwind.
> ? ? ? ?(amd64_init_abi): Hook the new unwinder.
>
> Index: amd64-tdep.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/amd64-tdep.c,v
> retrieving revision 1.64
> diff -u -p -r1.64 amd64-tdep.c
> --- amd64-tdep.c ? ? ? ?10 Aug 2009 03:02:39 -0000 ? ? ?1.64
> +++ amd64-tdep.c ? ? ? ?16 Aug 2009 23:12:25 -0000
> @@ -1887,6 +1887,89 @@ static const struct frame_base amd64_fra
> ? amd64_frame_base_address
> ?};
>
> +/* 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
> +amd64_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
> +amd64_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 amd64_in_function_epilogue_p (get_frame_arch (this_frame),
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?get_frame_pc (this_frame));
> + ?else
> + ? ?return 0;
> +}
> +
> +static struct amd64_frame_cache *
> +amd64_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 amd64_frame_cache *cache;
> + ?gdb_byte buf[4];
> +
> + ?if (*this_cache)
> + ? ?return *this_cache;
> +
> + ?cache = amd64_alloc_frame_cache ();
> + ?*this_cache = cache;
> +
> + ?/* Cache base will be %esp plus cache->sp_offset (-8). ?*/
> + ?get_frame_register (this_frame, AMD64_RSP_REGNUM, buf);
> + ?cache->base = extract_unsigned_integer (buf, 8,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 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 16. ?*/
> + ?cache->saved_sp = cache->base + 16;
> +
> + ?/* The saved %eip will be at cache->base plus 8. ?*/
> + ?cache->saved_regs[AMD64_RIP_REGNUM] = cache->base + 8;
> +
> + ?return cache;
> +}
> +
> +static void
> +amd64_epilogue_frame_this_id (struct frame_info *this_frame,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? void **this_cache,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? struct frame_id *this_id)
> +{
> + ?struct amd64_frame_cache *cache = amd64_epilogue_frame_cache (this_frame,
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?this_cache);
> +
> + ?(*this_id) = frame_id_build (cache->base + 8, cache->pc);
> +}
> +
> +static const struct frame_unwind amd64_epilogue_frame_unwind =
> +{
> + ?NORMAL_FRAME,
> + ?amd64_epilogue_frame_this_id,
> + ?amd64_frame_prev_register,
> + ?NULL,
> + ?amd64_epilogue_frame_sniffer
> +};
> +
> ?static struct frame_id
> ?amd64_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
> ?{
> @@ -2065,6 +2148,12 @@ amd64_init_abi (struct gdbarch_info info
>
> ? set_gdbarch_dummy_id (gdbarch, amd64_dummy_id);
>
> + ?/* 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);
> +
> + ?/* Hook the prologue-based frame unwinders. ?*/
> ? frame_unwind_append_unwinder (gdbarch, &amd64_sigtramp_frame_unwind);
> ? frame_unwind_append_unwinder (gdbarch, &amd64_frame_unwind);
> ? frame_base_set_default (gdbarch, &amd64_frame_base);
>
>


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