>>> Andi Kleen <[email protected]> 30.08.06 17:40 >>>
>On Wednesday 30 August 2006 17:28, Jan Beulich wrote:
>> >Hmm, yes. Sigh, so it's either gcc changes or binutils changes, and none
>> >of that can be relied upon, except someone has a better idea to identify
>> >signal frames with high enough assurance to be sensible for debugging.
>>
>> The only alternative idea I have is to take into consideration the location
>> of the return address: if it's at the default location (top of call frame),
>> then assume this is a normal frame, in all other cases assume it's an
>> interrupt/exception one. This will probably get a few cases wrong
>> (where the return address is being played with), but it might be better
>> than the current situation. Andi?
>
>Fine by me.
>
>At least it will likely be less controversal than changing all the noreturns :)
Here's a patch, including all that I think is necessary once we selectively
enable (auto-detect) CONFIG_AS_CFI_SIGNAL_FRAME for newer binutils.
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.
Signed-off-by: Jan Beulich <[email protected]>
--- linux-2.6.18-rc6/arch/i386/kernel/entry.S 2006-09-11 17:18:19.000000000 +0200
+++ 2.6.18-rc6-unwind-adjust-caller-pc/arch/i386/kernel/entry.S 2006-09-11 15:26:14.000000000 +0200
@@ -176,18 +176,21 @@ 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;\
@@ -263,6 +266,7 @@ 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
--- linux-2.6.18-rc6/arch/x86_64/ia32/ia32entry.S 2006-09-11 17:18:24.000000000 +0200
+++ 2.6.18-rc6-unwind-adjust-caller-pc/arch/x86_64/ia32/ia32entry.S 2006-09-11 15:28:10.000000000 +0200
@@ -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
--- linux-2.6.18-rc6/arch/x86_64/kernel/entry.S 2006-09-11 17:18:24.000000000 +0200
+++ 2.6.18-rc6-unwind-adjust-caller-pc/arch/x86_64/kernel/entry.S 2006-09-11 15:26:47.000000000 +0200
@@ -115,6 +115,7 @@
.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
@@ -199,6 +200,7 @@ 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*/
@@ -316,6 +318,7 @@ 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
@@ -476,6 +479,7 @@ 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
--- linux-2.6.18-rc6/include/asm-i386/dwarf2.h 2006-09-11 17:18:42.000000000 +0200
+++ 2.6.18-rc6-unwind-adjust-caller-pc/include/asm-i386/dwarf2.h 2006-09-11 15:16:45.000000000 +0200
@@ -28,6 +28,11 @@
#define CFI_RESTORE .cfi_restore
#define CFI_REMEMBER_STATE .cfi_remember_state
#define CFI_RESTORE_STATE .cfi_restore_state
+#ifdef CONFIG_AS_CFI_SIGNAL_FRAME
+#define CFI_SIGNAL_FRAME .cfi_signal_frame
+#else
+#define CFI_SIGNAL_FRAME
+#endif
#else
@@ -48,6 +53,7 @@
#define CFI_RESTORE ignore
#define CFI_REMEMBER_STATE ignore
#define CFI_RESTORE_STATE ignore
+#define CFI_SIGNAL_FRAME ignore
#endif
--- linux-2.6.18-rc6/include/asm-i386/unwind.h 2006-09-11 17:18:42.000000000 +0200
+++ 2.6.18-rc6-unwind-adjust-caller-pc/include/asm-i386/unwind.h 2006-09-11 16:10:20.000000000 +0200
@@ -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
@@ -42,6 +43,10 @@ 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)
{
--- linux-2.6.18-rc6/include/asm-x86_64/dwarf2.h 2006-09-11 17:18:44.000000000 +0200
+++ 2.6.18-rc6-unwind-adjust-caller-pc/include/asm-x86_64/dwarf2.h 2006-09-11 15:17:13.000000000 +0200
@@ -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
--- linux-2.6.18-rc6/include/asm-x86_64/unwind.h 2006-09-11 17:18:44.000000000 +0200
+++ 2.6.18-rc6-unwind-adjust-caller-pc/include/asm-x86_64/unwind.h 2006-09-11 16:10:29.000000000 +0200
@@ -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)
{
--- linux-2.6.18-rc6/kernel/unwind.c 2006-09-11 17:18:46.000000000 +0200
+++ 2.6.18-rc6-unwind-adjust-caller-pc/kernel/unwind.c 2006-09-11 16:44:02.000000000 +0200
@@ -603,6 +603,7 @@ int unwind(struct unwind_frame_info *fra
#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 *fra
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 *fra
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 *fra
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 *fra
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 *fra
|| 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
/*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_fr
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_fr
void *arg)
{
info->task = current;
+ info->call_frame = 0;
return arch_unwind_init_running(info, callback, arg);
}
-
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