Re: [PATCH, libitm]: GTM_longjmp: Jump indirect from memory address
On Tue, Feb 14, 2012 at 8:52 PM, Richard Henderson r...@redhat.com wrote: On 02/14/2012 10:26 AM, Uros Bizjak wrote: #ifdef __x86_64__ + cfi_def_cfa(%rsi, 0) movq (%rsi), %rcx movq 8(%rsi), %rbx movq 16(%rsi), %rbp @@ -119,20 +120,21 @@ movq 32(%rsi), %r13 movq 40(%rsi), %r14 movq 48(%rsi), %r15 + cfi_offset(%rip, 56) movl %edi, %eax - cfi_offset(%rip, 56) - cfi_def_cfa(%rcx, 0) movq %rcx, %rsp + cfi_register(%rsp, %rcx) jmp *56(%rsi) No, your changes are incorrect. All three markers needed to be together in order to provide a consistent and coherent unwind. What you committed was much worse than simply not describing anything at all. Fixed as below. Committed. Thanks! Uros.
Re: [PATCH, libitm]: GTM_longjmp: Jump indirect from memory address
On 02/13/2012 11:54 PM, Uros Bizjak wrote: movq48(%rsi), %r15 - movq56(%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) I'm sorry, I was mistaken earlier. The rip value is not at CFA+56, it's at RSI+56. The way to describe this is cfi_def_cfa(%rsi, 0) cfi_offset(%rip, 56) cfi_register(%rsp, %rcx) r~
Re: [PATCH, libitm]: GTM_longjmp: Jump indirect from memory address
On Tue, Feb 14, 2012 at 7:07 PM, Richard Henderson r...@redhat.com wrote:
On 02/13/2012 11:54 PM, Uros Bizjak wrote:
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)
I'm sorry, I was mistaken earlier. The rip value is not at CFA+56, it's at
RSI+56.
The way to describe this is
cfi_def_cfa(%rsi, 0)
cfi_offset(%rip, 56)
cfi_register(%rsp, %rcx)
Yes, IMO this now describes correct CFA handling. Following follow-on
patch corrects this issue (and also puts .cfi directions to the place
where they make most sense, mainly a cosmetic change).
Re-tested on x86_64-pc-linux-gnu {,-m32} and committed.
Thanks,
Uros.
Index: config/x86/sjlj.S
===
--- config/x86/sjlj.S (revision 184213)
+++ config/x86/sjlj.S (working copy)
@@ -112,6 +112,7 @@
SYM(GTM_longjmp):
cfi_startproc
#ifdef __x86_64__
+ cfi_def_cfa(%rsi, 0)
movq(%rsi), %rcx
movq8(%rsi), %rbx
movq16(%rsi), %rbp
@@ -119,20 +120,21 @@
movq32(%rsi), %r13
movq40(%rsi), %r14
movq48(%rsi), %r15
+ cfi_offset(%rip, 56)
movl%edi, %eax
- cfi_offset(%rip, 56)
- cfi_def_cfa(%rcx, 0)
movq%rcx, %rsp
+ cfi_register(%rsp, %rcx)
jmp *56(%rsi)
#else
+ cfi_def_cfa(%edx, 0)
movl(%edx), %ecx
movl4(%edx), %ebx
movl8(%edx), %esi
movl12(%edx), %edi
movl16(%edx), %ebp
cfi_offset(%eip, 20)
- cfi_def_cfa(%ecx, 0)
movl%ecx, %esp
+ cfi_register(%esp, %ecx)
jmp *20(%edx)
#endif
cfi_endproc
[PATCH, libitm]: GTM_longjmp: Jump indirect from memory address
Hello!
We can jump indirect from memory address, sparing a couple of cycles.
2012-02-14 Uros Bizjak ubiz...@gmail.com
* config/x86/target.h (GTM_longjmp): Jump indirect from memory address.
Tested on x86_64-pc-linux-gnu {,-m32}.
OK for mainline?
Uros.
Index: config/x86/sjlj.S
===
--- config/x86/sjlj.S (revision 184177)
+++ config/x86/sjlj.S (working copy)
@@ -119,23 +119,19 @@ SYM(GTM_longjmp):
movq32(%rsi), %r13
movq40(%rsi), %r14
movq48(%rsi), %r15
- movq56(%rsi), %rdx
movl%edi, %eax
cfi_def_cfa(%rcx, 0)
- cfi_register(%rip, %rdx)
movq%rcx, %rsp
- jmp *%rdx
+ jmp *56(%rsi)
#else
movl(%edx), %ecx
movl4(%edx), %ebx
movl8(%edx), %esi
movl12(%edx), %edi
movl16(%edx), %ebp
- movl20(%edx), %edx
cfi_def_cfa(%ecx, 0)
- cfi_register(%eip, %edx)
movl%ecx, %esp
- jmp *%edx
+ jmp *20(%edx)
#endif
cfi_endproc
Re: [PATCH, libitm]: GTM_longjmp: Jump indirect from memory address
On 02/13/2012 02:54 PM, Uros Bizjak wrote: - movq56(%rsi), %rdx movl%edi, %eax cfi_def_cfa(%rcx, 0) - cfi_register(%rip, %rdx) movq%rcx, %rsp - jmp *%rdx + jmp *56(%rsi) If you're going to do that, the correct fix for the unwind info is - cfi_register(%rip, %rdx) + cfi_offset(%rip, 56) Otherwise ok. r~
Re: [PATCH, libitm]: GTM_longjmp: Jump indirect from memory address
On Mon, Feb 13, 2012 at 11:57 PM, Richard Henderson r...@redhat.com wrote: On 02/13/2012 02:54 PM, Uros Bizjak wrote: - movq 56(%rsi), %rdx movl %edi, %eax cfi_def_cfa(%rcx, 0) - cfi_register(%rip, %rdx) movq %rcx, %rsp - jmp *%rdx + jmp *56(%rsi) If you're going to do that, the correct fix for the unwind info is - 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? SYM(GTM_longjmp): cfi_startproc #ifdef __x86_64__ movq(%rsi), %rcx movq8(%rsi), %rbx movq16(%rsi), %rbp movq24(%rsi), %r12 movq32(%rsi), %r13 movq40(%rsi), %r14 movq48(%rsi), %r15 movl%edi, %eax cfi_def_cfa(%rcx, 0) cfi_offset(%rip, -8) movq%rcx, %rsp jmp *56(%rsi) #else movl(%edx), %ecx movl4(%edx), %ebx movl8(%edx), %esi movl12(%edx), %edi movl16(%edx), %ebp cfi_def_cfa(%ecx, 0) cfi_offset(%eip, -4) movl%ecx, %esp jmp *20(%edx) #endif cfi_endproc Uros.
Re: [PATCH, libitm]: GTM_longjmp: Jump indirect from memory address
On 02/13/2012 04:09 PM, Uros Bizjak wrote: On Mon, Feb 13, 2012 at 11:57 PM, Richard Henderson r...@redhat.com wrote: On 02/13/2012 02:54 PM, Uros Bizjak wrote: - movq56(%rsi), %rdx movl%edi, %eax cfi_def_cfa(%rcx, 0) - cfi_register(%rip, %rdx) movq%rcx, %rsp - jmp *%rdx + jmp *56(%rsi) If you're going to do that, the correct fix for the unwind info is - 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. r~
Re: [PATCH, libitm]: GTM_longjmp: Jump indirect from memory address
On Tue, Feb 14, 2012 at 1:15 AM, Richard Henderson r...@redhat.com wrote: - movq 56(%rsi), %rdx movl %edi, %eax cfi_def_cfa(%rcx, 0) - cfi_register(%rip, %rdx) movq %rcx, %rsp - jmp *%rdx + jmp *56(%rsi) If you're going to do that, the correct fix for the unwind info is - 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. Uros.
Re: [PATCH, libitm]: GTM_longjmp: Jump indirect from memory address
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 @@ movq32(%rsi), %r13 movq40(%rsi), %r14 movq48(%rsi), %r15 - movq56(%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 movl4(%edx), %ebx movl8(%edx), %esi movl12(%edx), %edi movl16(%edx), %ebp - movl20(%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
