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Commit cf3271a7 authored by Soeren Sandmann's avatar Soeren Sandmann Committed by Thomas Gleixner
Browse files

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: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 8a9e94c1

kernel/trace/trace_sysprof.c

+29 −21
Original line number Diff line number Diff line
@@ -95,13 +95,12 @@ const static struct stacktrace_ops backtrace_ops = { 
	.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 @@ trace_kernel(struct pt_regs *regs, struct trace_array *tr, 


	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)
@@ -150,13 +146,21 @@ static void timer_notify(struct pt_regs *regs, int cpu) 
	__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;



	/*

	 * 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;



		fp = (void __user *)regs->bp;



		__trace_special(tr, data, 2, regs->ip, 0);



	for (i = 0; i < sample_max_depth; i++) {

		while (i < sample_max_depth) {

			frame.next_fp = 0;

			frame.return_address = 0;

			if (!copy_stack_frame(fp, &frame))
@@ -167,15 +171,19 @@ static void timer_notify(struct pt_regs *regs, int cpu) 
			__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)