From: Jan Beulich Date: Tue, 26 Sep 2006 08:52:41 +0000 (+0200) Subject: [PATCH] i386/x86-64: Work around gcc bug with noreturn functions in unwinder X-Git-Tag: v2.6.19-rc1~1077^2~11 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=adf1423698f00d00b267f7dca8231340ce7d65ef;p=linux-2.6 [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 --- diff --git a/arch/i386/Makefile b/arch/i386/Makefile index 508cdbeb3a..7cc0b189b8 100644 --- a/arch/i386/Makefile +++ b/arch/i386/Makefile @@ -50,6 +50,10 @@ CFLAGS += $(shell if [ $(call cc-version) -lt 0400 ] ; then echo $(call cc-op 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_endproc,-DCONFIG_AS_CFI=1,) +AFLAGS += $(call as-instr,.cfi_startproc\n.cfi_endproc,-DCONFIG_AS_CFI=1,) + CFLAGS += $(cflags-y) # Default subarch .c files diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S index 284f2e908a..5a63d6fdb7 100644 --- a/arch/i386/kernel/entry.S +++ b/arch/i386/kernel/entry.S @@ -183,18 +183,21 @@ VM_MASK = 0x00020000 #define RING0_INT_FRAME \ CFI_STARTPROC simple;\ + CFI_SIGNAL_FRAME;\ CFI_DEF_CFA esp, 3*4;\ /*CFI_OFFSET cs, -2*4;*/\ CFI_OFFSET eip, -3*4 #define RING0_EC_FRAME \ CFI_STARTPROC simple;\ + CFI_SIGNAL_FRAME;\ CFI_DEF_CFA esp, 4*4;\ /*CFI_OFFSET cs, -2*4;*/\ CFI_OFFSET eip, -3*4 #define RING0_PTREGS_FRAME \ CFI_STARTPROC simple;\ + CFI_SIGNAL_FRAME;\ CFI_DEF_CFA esp, OLDESP-EBX;\ /*CFI_OFFSET cs, CS-OLDESP;*/\ CFI_OFFSET eip, EIP-OLDESP;\ @@ -275,6 +278,7 @@ need_resched: # sysenter call handler stub ENTRY(sysenter_entry) CFI_STARTPROC simple + CFI_SIGNAL_FRAME CFI_DEF_CFA esp, 0 CFI_REGISTER esp, ebp movl TSS_sysenter_esp0(%esp),%esp diff --git a/arch/x86_64/Makefile b/arch/x86_64/Makefile index 2b8d07c701..1c0f18d4f8 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 32fd32bea0..b4aa875e17 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 ea32688386..4cbc65290a 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 diff --git a/include/asm-i386/dwarf2.h b/include/asm-i386/dwarf2.h index 5d1a8db5a9..6d66398a30 100644 --- a/include/asm-i386/dwarf2.h +++ b/include/asm-i386/dwarf2.h @@ -28,6 +28,12 @@ #define CFI_RESTORE_STATE .cfi_restore_state #define CFI_UNDEFINED .cfi_undefined +#ifdef CONFIG_AS_CFI_SIGNAL_FRAME +#define CFI_SIGNAL_FRAME .cfi_signal_frame +#else +#define CFI_SIGNAL_FRAME +#endif + #else /* Due to the structure of pre-exisiting code, don't use assembler line @@ -48,6 +54,7 @@ #define CFI_REMEMBER_STATE ignore #define CFI_RESTORE_STATE ignore #define CFI_UNDEFINED ignore +#define CFI_SIGNAL_FRAME ignore #endif diff --git a/include/asm-i386/unwind.h b/include/asm-i386/unwind.h index f0ac399bae..5031d693b8 100644 --- a/include/asm-i386/unwind.h +++ b/include/asm-i386/unwind.h @@ -18,6 +18,7 @@ struct unwind_frame_info { struct pt_regs regs; struct task_struct *task; + unsigned call_frame:1; }; #define UNW_PC(frame) (frame)->regs.eip @@ -44,6 +45,10 @@ struct unwind_frame_info PTREGS_INFO(edi), \ PTREGS_INFO(eip) +#define UNW_DEFAULT_RA(raItem, dataAlign) \ + ((raItem).where == Memory && \ + !((raItem).value * (dataAlign) + 4)) + static inline void arch_unw_init_frame_info(struct unwind_frame_info *info, /*const*/ struct pt_regs *regs) { diff --git a/include/asm-x86_64/dwarf2.h b/include/asm-x86_64/dwarf2.h index 2b9368365f..eedc08526b 100644 --- a/include/asm-x86_64/dwarf2.h +++ b/include/asm-x86_64/dwarf2.h @@ -28,6 +28,11 @@ #define CFI_REMEMBER_STATE .cfi_remember_state #define CFI_RESTORE_STATE .cfi_restore_state #define CFI_UNDEFINED .cfi_undefined +#ifdef CONFIG_AS_CFI_SIGNAL_FRAME +#define CFI_SIGNAL_FRAME .cfi_signal_frame +#else +#define CFI_SIGNAL_FRAME +#endif #else @@ -45,6 +50,7 @@ #define CFI_REMEMBER_STATE # #define CFI_RESTORE_STATE # #define CFI_UNDEFINED # +#define CFI_SIGNAL_FRAME # #endif diff --git a/include/asm-x86_64/unwind.h b/include/asm-x86_64/unwind.h index 1f6e9bfb56..b8fa5cb7ff 100644 --- a/include/asm-x86_64/unwind.h +++ b/include/asm-x86_64/unwind.h @@ -18,6 +18,7 @@ struct unwind_frame_info { struct pt_regs regs; struct task_struct *task; + unsigned call_frame:1; }; #define UNW_PC(frame) (frame)->regs.rip @@ -57,6 +58,10 @@ struct unwind_frame_info PTREGS_INFO(r15), \ PTREGS_INFO(rip) +#define UNW_DEFAULT_RA(raItem, dataAlign) \ + ((raItem).where == Memory && \ + !((raItem).value * (dataAlign) + 8)) + static inline void arch_unw_init_frame_info(struct unwind_frame_info *info, /*const*/ struct pt_regs *regs) { diff --git a/kernel/unwind.c b/kernel/unwind.c index f69c804c8e..3430475fcd 100644 --- a/kernel/unwind.c +++ b/kernel/unwind.c @@ -603,6 +603,7 @@ int unwind(struct unwind_frame_info *frame) #define FRAME_REG(r, t) (((t *)frame)[reg_info[r].offs]) const u32 *fde = NULL, *cie = NULL; const u8 *ptr = NULL, *end = NULL; + unsigned long pc = UNW_PC(frame) - frame->call_frame; unsigned long startLoc = 0, endLoc = 0, cfa; unsigned i; signed ptrType = -1; @@ -612,7 +613,7 @@ int unwind(struct unwind_frame_info *frame) if (UNW_PC(frame) == 0) return -EINVAL; - if ((table = find_table(UNW_PC(frame))) != NULL + if ((table = find_table(pc)) != NULL && !(table->size & (sizeof(*fde) - 1))) { unsigned long tableSize = table->size; @@ -647,7 +648,7 @@ int unwind(struct unwind_frame_info *frame) ptrType & DW_EH_PE_indirect ? ptrType : ptrType & (DW_EH_PE_FORM|DW_EH_PE_signed)); - if (UNW_PC(frame) >= startLoc && UNW_PC(frame) < endLoc) + if (pc >= startLoc && pc < endLoc) break; cie = NULL; } @@ -657,16 +658,28 @@ int unwind(struct unwind_frame_info *frame) state.cieEnd = ptr; /* keep here temporarily */ ptr = (const u8 *)(cie + 2); end = (const u8 *)(cie + 1) + *cie; + frame->call_frame = 1; if ((state.version = *ptr) != 1) cie = NULL; /* unsupported version */ else if (*++ptr) { /* check if augmentation size is first (and thus present) */ if (*ptr == 'z') { - /* check for ignorable (or already handled) - * nul-terminated augmentation string */ - while (++ptr < end && *ptr) - if (strchr("LPR", *ptr) == NULL) + while (++ptr < end && *ptr) { + switch(*ptr) { + /* check for ignorable (or already handled) + * nul-terminated augmentation string */ + case 'L': + case 'P': + case 'R': + continue; + case 'S': + frame->call_frame = 0; + continue; + default: break; + } + break; + } } if (ptr >= end || *ptr) cie = NULL; @@ -755,7 +768,7 @@ int unwind(struct unwind_frame_info *frame) state.org = startLoc; memcpy(&state.cfa, &badCFA, sizeof(state.cfa)); /* process instructions */ - if (!processCFI(ptr, end, UNW_PC(frame), ptrType, &state) + if (!processCFI(ptr, end, pc, ptrType, &state) || state.loc > endLoc || state.regs[retAddrReg].where == Nowhere || state.cfa.reg >= ARRAY_SIZE(reg_info) @@ -763,6 +776,11 @@ int unwind(struct unwind_frame_info *frame) || state.cfa.offs % sizeof(unsigned long)) return -EIO; /* update frame */ +#ifndef CONFIG_AS_CFI_SIGNAL_FRAME + if(frame->call_frame + && !UNW_DEFAULT_RA(state.regs[retAddrReg], state.dataAlign)) + frame->call_frame = 0; +#endif cfa = FRAME_REG(state.cfa.reg, unsigned long) + state.cfa.offs; startLoc = min((unsigned long)UNW_SP(frame), cfa); endLoc = max((unsigned long)UNW_SP(frame), cfa); @@ -866,6 +884,7 @@ int unwind_init_frame_info(struct unwind_frame_info *info, /*const*/ struct pt_regs *regs) { info->task = tsk; + info->call_frame = 0; arch_unw_init_frame_info(info, regs); return 0; @@ -879,6 +898,7 @@ int unwind_init_blocked(struct unwind_frame_info *info, struct task_struct *tsk) { info->task = tsk; + info->call_frame = 0; arch_unw_init_blocked(info); return 0; @@ -894,6 +914,7 @@ int unwind_init_running(struct unwind_frame_info *info, void *arg) { info->task = current; + info->call_frame = 0; return arch_unwind_init_running(info, callback, arg); } diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index 7adef12a0c..4f5ff19b99 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -66,8 +66,8 @@ as-option = $(shell if $(CC) $(CFLAGS) $(1) -Wa,-Z -c -o /dev/null \ # as-instr # Usage: cflags-y += $(call as-instr, instr, option1, option2) -as-instr = $(shell if echo -e "$(1)" | $(AS) -Z -o astest$$$$.out \ - 2>&1 >/dev/null ; then echo "$(2)"; else echo "$(3)"; fi; \ +as-instr = $(shell if echo -e "$(1)" | $(AS) >/dev/null 2>&1 -W -Z -o astest$$$$.out ; \ + then echo "$(2)"; else echo "$(3)"; fi; \ rm -f astest$$$$.out) # cc-option