On Tue, Feb 14, 2012 at 8:39 AM, Uros Bizjak <ubiz...@gmail.com> wrote:
>>>> - cfi_register(%rip, %rdx)
>>>> + cfi_offset(%rip, 56)
>>>
>>> Hm, we just defined new CFA as rcx+0, so we should define location of
>>> rip relative to new CFA. Since CFA points to stack slot just before
>>> return address was pushed, new rip lies at CFA-8 for 64bit resp. CFA-4
>>> for x86_32. Did I get these .cfi directives correctly?
>>
>> No. The value at %rcx-8 is total garbage. There no guarantee that
>> the call stack leading to this abort has anything in common with the
>> call stack that created the jmpbuf, except *above* %rcx, the new CFA.
>>
>> The new rip is at rsi+56. You can see that in that you jump to it.
>
> Thanks for the explanation, I will commit the patch with your suggested
> change.
Now with the patch attached... (please also note that rip is now
defined with offset to old CFA, before CFA is updated to new
register).
Uros.
Index: ChangeLog
===================================================================
--- ChangeLog (revision 184197)
+++ ChangeLog (working copy)
@@ -1,3 +1,7 @@
+2012-02-15 Uros Bizjak <ubiz...@gmail.com>
+
+ * config/x86/target.h (GTM_longjmp): Jump indirect from memory address.
+
2012-02-13 Eric Botcazou <ebotca...@adacore.com>
* configure.tgt (target_cpu): Handle sparc and sparc64 & sparcv9.
Index: config/x86/sjlj.S
===================================================================
--- config/x86/sjlj.S (revision 184150)
+++ config/x86/sjlj.S (working copy)
@@ -119,23 +119,21 @@
movq 32(%rsi), %r13
movq 40(%rsi), %r14
movq 48(%rsi), %r15
- movq 56(%rsi), %rdx
movl %edi, %eax
+ cfi_offset(%rip, 56)
cfi_def_cfa(%rcx, 0)
- cfi_register(%rip, %rdx)
movq %rcx, %rsp
- jmp *%rdx
+ jmp *56(%rsi)
#else
movl (%edx), %ecx
movl 4(%edx), %ebx
movl 8(%edx), %esi
movl 12(%edx), %edi
movl 16(%edx), %ebp
- movl 20(%edx), %edx
+ cfi_offset(%eip, 20)
cfi_def_cfa(%ecx, 0)
- cfi_register(%eip, %edx)
movl %ecx, %esp
- jmp *%edx
+ jmp *20(%edx)
#endif
cfi_endproc
