ftrace/sysprof: don't trace the user stack if we are a kernel thread.
Check that current->mm is non-NULL before attempting to trace the user
stack.
Also take depth of the kernel stack into account when comparing
against sample_max_depth.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/trace/trace_sysprof.c b/kernel/trace/trace_sysprof.c
index fe23d6d..2301e1e 100644
--- a/kernel/trace/trace_sysprof.c
+++ b/kernel/trace/trace_sysprof.c
@@ -95,13 +95,12 @@
.address = backtrace_address,
};
-static struct pt_regs *
+static int
trace_kernel(struct pt_regs *regs, struct trace_array *tr,
struct trace_array_cpu *data)
{
struct backtrace_info info;
unsigned long bp;
- char *user_stack;
char *stack;
info.tr = tr;
@@ -119,10 +118,7 @@
dump_trace(NULL, regs, (void *)stack, bp, &backtrace_ops, &info);
- /* Now trace the user stack */
- user_stack = ((char *)current->thread.sp0 - sizeof(struct pt_regs));
-
- return (struct pt_regs *)user_stack;
+ return info.pos;
}
static void timer_notify(struct pt_regs *regs, int cpu)
@@ -150,32 +146,44 @@
__trace_special(tr, data, 0, 0, current->pid);
if (!is_user)
- regs = trace_kernel(regs, tr, data);
+ i = trace_kernel(regs, tr, data);
+ else
+ i = 0;
- fp = (void __user *)regs->bp;
+ /*
+ * Trace user stack if we are not a kernel thread
+ */
+ if (current->mm && i < sample_max_depth) {
+ regs = (struct pt_regs *)current->thread.sp0 - 1;
- __trace_special(tr, data, 2, regs->ip, 0);
+ fp = (void __user *)regs->bp;
- for (i = 0; i < sample_max_depth; i++) {
- frame.next_fp = 0;
- frame.return_address = 0;
- if (!copy_stack_frame(fp, &frame))
- break;
- if ((unsigned long)fp < regs->sp)
- break;
+ __trace_special(tr, data, 2, regs->ip, 0);
- __trace_special(tr, data, 2, frame.return_address,
- (unsigned long)fp);
- fp = frame.next_fp;
+ while (i < sample_max_depth) {
+ frame.next_fp = 0;
+ frame.return_address = 0;
+ if (!copy_stack_frame(fp, &frame))
+ break;
+ if ((unsigned long)fp < regs->sp)
+ break;
+
+ __trace_special(tr, data, 2, frame.return_address,
+ (unsigned long)fp);
+ fp = frame.next_fp;
+
+ i++;
+ }
+
}
- __trace_special(tr, data, 3, current->pid, i);
-
/*
* Special trace entry if we overflow the max depth:
*/
if (i == sample_max_depth)
__trace_special(tr, data, -1, -1, -1);
+
+ __trace_special(tr, data, 3, current->pid, i);
}
static enum hrtimer_restart stack_trace_timer_fn(struct hrtimer *hrtimer)
