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authorJan Beulich <jbeulich@novell.com>2006-09-26 10:52:41 +0200
committerAndi Kleen <andi@basil.nowhere.org>2006-09-26 10:52:41 +0200
commitadf1423698f00d00b267f7dca8231340ce7d65ef (patch)
treeec2e28a32d467cc3c618c8ee0cedd3d1a49f9c43 /arch/x86_64/ia32/ia32entry.S
parentab2e0b46cb9a197fab7d98e147cac7cd41a14047 (diff)
[PATCH] i386/x86-64: Work around gcc bug with noreturn functions in unwinder
Current gcc generates calls not jumps to noreturn functions. When that happens the return address can point to the next function, which confuses the unwinder. This patch works around it by marking asynchronous exception frames in contrast normal call frames in the unwind information. Then teach the unwinder to decode this. For normal call frames the unwinder now subtracts one from the address which avoids this problem. The standard libgcc unwinder uses the same trick. It doesn't include adjustment of the printed address (i.e. for the original example, it'd still be kernel_math_error+0 that gets displayed, but the unwinder wouldn't get confused anymore. This only works with binutils 2.6.17+ and some versions of H.J.Lu's 2.6.16 unfortunately because earlier binutils don't support .cfi_signal_frame [AK: added automatic detection of the new binutils and wrote description] Signed-off-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Andi Kleen <ak@suse.de>
Diffstat (limited to 'arch/x86_64/ia32/ia32entry.S')
-rw-r--r--arch/x86_64/ia32/ia32entry.S4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86_64/ia32/ia32entry.S b/arch/x86_64/ia32/ia32entry.S
index 32fd32bea07..b4aa875e175 100644
--- a/arch/x86_64/ia32/ia32entry.S
+++ b/arch/x86_64/ia32/ia32entry.S
@@ -71,6 +71,7 @@
*/
ENTRY(ia32_sysenter_target)
CFI_STARTPROC32 simple
+ CFI_SIGNAL_FRAME
CFI_DEF_CFA rsp,0
CFI_REGISTER rsp,rbp
swapgs
@@ -186,6 +187,7 @@ ENDPROC(ia32_sysenter_target)
*/
ENTRY(ia32_cstar_target)
CFI_STARTPROC32 simple
+ CFI_SIGNAL_FRAME
CFI_DEF_CFA rsp,PDA_STACKOFFSET
CFI_REGISTER rip,rcx
/*CFI_REGISTER rflags,r11*/
@@ -293,6 +295,7 @@ ia32_badarg:
ENTRY(ia32_syscall)
CFI_STARTPROC simple
+ CFI_SIGNAL_FRAME
CFI_DEF_CFA rsp,SS+8-RIP
/*CFI_REL_OFFSET ss,SS-RIP*/
CFI_REL_OFFSET rsp,RSP-RIP
@@ -370,6 +373,7 @@ ENTRY(ia32_ptregs_common)
popq %r11
CFI_ENDPROC
CFI_STARTPROC32 simple
+ CFI_SIGNAL_FRAME
CFI_DEF_CFA rsp,SS+8-ARGOFFSET
CFI_REL_OFFSET rax,RAX-ARGOFFSET
CFI_REL_OFFSET rcx,RCX-ARGOFFSET