[PATCH] x86_64: Dump leftover backtrace entries when dwarf2 unwinder got stuck (b13761ec) · Commits · 戴 / test

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>

arch/x86_64/kernel/traps.c

+16 −6

Original line number	Diff line number	Diff line
		@@ -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);

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