From adf1423698f00d00b267f7dca8231340ce7d65ef Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Tue, 26 Sep 2006 10:52:41 +0200 Subject: [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 Signed-off-by: Andi Kleen --- arch/x86_64/Makefile | 4 ++++ arch/x86_64/ia32/ia32entry.S | 4 ++++ arch/x86_64/kernel/entry.S | 4 ++++ 3 files changed, 12 insertions(+) (limited to 'arch/x86_64') diff --git a/arch/x86_64/Makefile b/arch/x86_64/Makefile index 2b8d07c7010..1c0f18d4f88 100644 --- a/arch/x86_64/Makefile +++ b/arch/x86_64/Makefile @@ -58,6 +58,10 @@ cflags-y += $(call cc-option,-mno-sse -mno-mmx -mno-sse2 -mno-3dnow,) cflags-y += $(call as-instr,.cfi_startproc\n.cfi_endproc,-DCONFIG_AS_CFI=1,) AFLAGS += $(call as-instr,.cfi_startproc\n.cfi_endproc,-DCONFIG_AS_CFI=1,) +# is .cfi_signal_frame supported too? +cflags-y += $(call as-instr,.cfi_startproc\n.cfi_signal_frame\n.cfi_endproc,-DCONFIG_AS_CFI_SIGNAL_FRAME=1,) +AFLAGS += $(call as-instr,.cfi_startproc\n.cfi_signal_frame\n.cfi_endproc,-DCONFIG_AS_CFI_SIGNAL_FRAME=1,) + cflags-$(CONFIG_CC_STACKPROTECTOR) += $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) -fstack-protector ) cflags-$(CONFIG_CC_STACKPROTECTOR_ALL) += $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) -fstack-protector-all ) 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 diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S index ea32688386f..4cbc65290ae 100644 --- a/arch/x86_64/kernel/entry.S +++ b/arch/x86_64/kernel/entry.S @@ -123,6 +123,7 @@ .macro CFI_DEFAULT_STACK start=1 .if \start CFI_STARTPROC simple + CFI_SIGNAL_FRAME CFI_DEF_CFA rsp,SS+8 .else CFI_DEF_CFA_OFFSET SS+8 @@ -207,6 +208,7 @@ END(ret_from_fork) ENTRY(system_call) CFI_STARTPROC simple + CFI_SIGNAL_FRAME CFI_DEF_CFA rsp,PDA_STACKOFFSET CFI_REGISTER rip,rcx /*CFI_REGISTER rflags,r11*/ @@ -324,6 +326,7 @@ END(system_call) */ ENTRY(int_ret_from_sys_call) CFI_STARTPROC simple + CFI_SIGNAL_FRAME CFI_DEF_CFA rsp,SS+8-ARGOFFSET /*CFI_REL_OFFSET ss,SS-ARGOFFSET*/ CFI_REL_OFFSET rsp,RSP-ARGOFFSET @@ -484,6 +487,7 @@ END(stub_rt_sigreturn) */ .macro _frame ref CFI_STARTPROC simple + CFI_SIGNAL_FRAME CFI_DEF_CFA rsp,SS+8-\ref /*CFI_REL_OFFSET ss,SS-\ref*/ CFI_REL_OFFSET rsp,RSP-\ref -- cgit v1.2.3