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[PATCH] x86_64: Dump leftover backtrace entries when dwarf2 unwinder got stuck

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The dwarf2 unwinder currently often gets stuck because a lot
of assembly code doesn't have proper dwarf2 annotiation yet.

This currently often happens with __down. Should fix this by
adding proper dwarf2 annotation to all inline assembly. However
until that's done we need a quick fix for 2.6.18 to avoid
incomplete backtraces.

So when this happens dump the rest of the stack with the old unwinder
instead of silently not dumping it. There was already a optional
"both" mode that dumped both, but that was too ugly.

I also clarified the headers for the different backtraces a bit.

Also add a clear error message for missing dwarf2
annotation that people can work on.

And I removed a dead variable left over from Ingo's changes.

Cc: mingo@elte.hu
Cc: jbeulich@novell.com
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Andi Kleen 2006-07-28 14:44:51 +02:00 committed by Linus Torvalds
parent a4045dff78
commit b13761ecd1
1 changed files with 16 additions and 6 deletions
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22
arch/x86_64/kernel/traps.c
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@ -254,7 +254,6 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
{
const unsigned cpu = safe_smp_processor_id();
unsigned long *irqstack_end = (unsigned long *)cpu_pda(cpu)->irqstackptr;
int i = 11;
unsigned used = 0;
printk("\nCall Trace:\n");
@ -275,11 +274,20 @@ void show_trace(struct task_struct *tsk, struct pt_regs *regs, unsigned long * s
if (unwind_init_blocked(&info, tsk) == 0)
unw_ret = show_trace_unwind(&info, NULL);
}
if (unw_ret > 0) {
if (call_trace > 0)
if (unw_ret > 0 && !arch_unw_user_mode(&info)) {
#ifdef CONFIG_STACK_UNWIND
unsigned long rip = info.regs.rip;
print_symbol("DWARF2 unwinder stuck at %s\n", rip);
if (call_trace == 1) {
printk("Leftover inexact backtrace:\n");
stack = (unsigned long *)info.regs.rsp;
} else if (call_trace > 1)
return;
printk("Legacy call trace:");
i = 18;
else
printk("Full inexact backtrace again:\n");
#else
printk("Inexact backtrace:\n");
#endif
}
}
@ -1118,8 +1126,10 @@ static int __init call_trace_setup(char *s)
call_trace = -1;
else if (strcmp(s, "both") == 0)
call_trace = 0;
else if (strcmp(s, "new") == 0)
else if (strcmp(s, "newfallback") == 0)
call_trace = 1;
else if (strcmp(s, "new") == 0)
call_trace = 2;
return 1;
}
__setup("call_trace=", call_trace_setup);