[PATCH] i386/x86-64: fall back to old-style call trace if no unwinding
If no unwinding is possible at all for a certain exception instance,
fall back to the old style call trace instead of not showing any trace
at all.
Also, allow setting the stack trace mode at the command line.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index eb1534f..bd0891f 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -107,6 +107,7 @@
}
static int kstack_depth_to_print = 10;
+static int call_trace = 1;
#ifdef CONFIG_KALLSYMS
#include <linux/kallsyms.h>
@@ -190,11 +191,12 @@
return NULL;
}
-static void show_trace_unwind(struct unwind_frame_info *info, void *context)
+static int show_trace_unwind(struct unwind_frame_info *info, void *context)
{
- int i = 11;
+ int i = 11, n = 0;
while (unwind(info) == 0 && UNW_PC(info)) {
+ ++n;
if (i > 50) {
printk("\n ");
i = 7;
@@ -205,6 +207,7 @@
break;
}
printk("\n");
+ return n;
}
/*
@@ -218,27 +221,32 @@
{
const unsigned cpu = safe_smp_processor_id();
unsigned long *irqstack_end = (unsigned long *)cpu_pda(cpu)->irqstackptr;
- int i;
+ int i = 11;
unsigned used = 0;
- struct unwind_frame_info info;
printk("\nCall Trace:");
if (!tsk)
tsk = current;
- if (regs) {
- if (unwind_init_frame_info(&info, tsk, regs) == 0) {
- show_trace_unwind(&info, NULL);
- return;
+ if (call_trace >= 0) {
+ int unw_ret = 0;
+ struct unwind_frame_info info;
+
+ if (regs) {
+ if (unwind_init_frame_info(&info, tsk, regs) == 0)
+ unw_ret = show_trace_unwind(&info, NULL);
+ } else if (tsk == current)
+ unw_ret = unwind_init_running(&info, show_trace_unwind, NULL);
+ else {
+ if (unwind_init_blocked(&info, tsk) == 0)
+ unw_ret = show_trace_unwind(&info, NULL);
}
- } else if (tsk == current) {
- if (unwind_init_running(&info, show_trace_unwind, NULL) == 0)
- return;
- } else {
- if (unwind_init_blocked(&info, tsk) == 0) {
- show_trace_unwind(&info, NULL);
- return;
+ if (unw_ret > 0) {
+ if (call_trace > 0)
+ return;
+ printk("Legacy call trace:");
+ i = 18;
}
}
@@ -264,7 +272,7 @@
} \
} while (0)
- for(i = 11; ; ) {
+ for(; ; ) {
const char *id;
unsigned long *estack_end;
estack_end = in_exception_stack(cpu, (unsigned long)stack,
@@ -1052,3 +1060,14 @@
}
__setup("kstack=", kstack_setup);
+static int __init call_trace_setup(char *s)
+{
+ if (strcmp(s, "old") == 0)
+ call_trace = -1;
+ else if (strcmp(s, "both") == 0)
+ call_trace = 0;
+ else if (strcmp(s, "new") == 0)
+ call_trace = 1;
+ return 1;
+}
+__setup("call_trace=", call_trace_setup);