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Commit 2ee5b92a authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
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tracing: Update stack trace skipping for ORC unwinder 



With the addition of ORC unwinder and FRAME POINTER unwinder, the stack
trace skipping requirements have changed.

I went through the tracing stack trace dumps with ORC and with frame
pointers and recalculated the proper values.

Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 6be7fa3c

kernel/trace/trace.c

+20 −14
Original line number Diff line number Diff line
@@ -2374,6 +2374,15 @@ void trace_event_buffer_commit(struct trace_event_buffer *fbuffer) 
}

EXPORT_SYMBOL_GPL(trace_event_buffer_commit);



/*

 * Skip 3:

 *

 *   trace_buffer_unlock_commit_regs()

 *   trace_event_buffer_commit()

 *   trace_event_raw_event_xxx()

*/

# define STACK_SKIP 3



void trace_buffer_unlock_commit_regs(struct trace_array *tr,

				     struct ring_buffer *buffer,

				     struct ring_buffer_event *event,
@@ -2383,16 +2392,12 @@ void trace_buffer_unlock_commit_regs(struct trace_array *tr, 
	__buffer_unlock_commit(buffer, event);



	/*

	 * If regs is not set, then skip the following callers:

	 *   trace_buffer_unlock_commit_regs

	 *   event_trigger_unlock_commit

	 *   trace_event_buffer_commit

	 *   trace_event_raw_event_sched_switch

	 * If regs is not set, then skip the necessary functions.

	 * Note, we can still get here via blktrace, wakeup tracer

	 * and mmiotrace, but that's ok if they lose a function or

	 * two. They are that meaningful.

	 * two. They are not that meaningful.

	 */

	ftrace_trace_stack(tr, buffer, flags, regs ? 0 : 4, pc, regs);

	ftrace_trace_stack(tr, buffer, flags, regs ? 0 : STACK_SKIP, pc, regs);

	ftrace_trace_userstack(buffer, flags, pc);

}
@@ -2579,11 +2584,13 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer, 
	trace.skip		= skip;



	/*

	 * Add two, for this function and the call to save_stack_trace()

	 * Add one, for this function and the call to save_stack_trace()

	 * If regs is set, then these functions will not be in the way.

	 */

#ifndef CONFIG_UNWINDER_ORC

	if (!regs)

		trace.skip += 2;

		trace.skip++;

#endif



	/*

	 * Since events can happen in NMIs there's no safe way to
@@ -2711,11 +2718,10 @@ void trace_dump_stack(int skip) 


	local_save_flags(flags);



	/*

	 * Skip 3 more, seems to get us at the caller of

	 * this function.

	 */

	skip += 3;

#ifndef CONFIG_UNWINDER_ORC

	/* Skip 1 to skip this function. */

	skip++;

#endif

	__ftrace_trace_stack(global_trace.trace_buffer.buffer,

			     flags, skip, preempt_count(), NULL);

}

kernel/trace/trace_events_trigger.c

+11 −2
Original line number Diff line number Diff line
@@ -1123,13 +1123,22 @@ static __init int register_trigger_snapshot_cmd(void) { return 0; } 
#endif /* CONFIG_TRACER_SNAPSHOT */



#ifdef CONFIG_STACKTRACE

#ifdef CONFIG_UNWINDER_ORC

/* Skip 2:

 *   event_triggers_post_call()

 *   trace_event_raw_event_xxx()

 */

# define STACK_SKIP 2

#else

/*

 * Skip 3:

 * Skip 4:

 *   stacktrace_trigger()

 *   event_triggers_post_call()

 *   trace_event_buffer_commit()

 *   trace_event_raw_event_xxx()

 */

#define STACK_SKIP 3

#define STACK_SKIP 4

#endif



static void

stacktrace_trigger(struct event_trigger_data *data, void *rec)

kernel/trace/trace_functions.c

+36 −13
Original line number Diff line number Diff line
@@ -154,6 +154,24 @@ function_trace_call(unsigned long ip, unsigned long parent_ip, 
	preempt_enable_notrace();

}



#ifdef CONFIG_UNWINDER_ORC

/*

 * Skip 2:

 *

 *   function_stack_trace_call()

 *   ftrace_call()

 */

#define STACK_SKIP 2

#else

/*

 * Skip 3:

 *   __trace_stack()

 *   function_stack_trace_call()

 *   ftrace_call()

 */

#define STACK_SKIP 3

#endif



static void

function_stack_trace_call(unsigned long ip, unsigned long parent_ip,

			  struct ftrace_ops *op, struct pt_regs *pt_regs)
@@ -180,15 +198,7 @@ function_stack_trace_call(unsigned long ip, unsigned long parent_ip, 
	if (likely(disabled == 1)) {

		pc = preempt_count();

		trace_function(tr, ip, parent_ip, flags, pc);

		/*

		 * skip over 5 funcs:

		 *    __ftrace_trace_stack,

		 *    __trace_stack,

		 *    function_stack_trace_call

		 *    ftrace_list_func

		 *    ftrace_call

		 */

		__trace_stack(tr, flags, 5, pc);

		__trace_stack(tr, flags, STACK_SKIP, pc);

	}



	atomic_dec(&data->disabled);
@@ -367,14 +377,27 @@ ftrace_traceoff(unsigned long ip, unsigned long parent_ip, 
	tracer_tracing_off(tr);

}



#ifdef CONFIG_UNWINDER_ORC

/*

 * Skip 4:

 * Skip 3:

 *

 *   function_trace_probe_call()

 *   ftrace_ops_assist_func()

 *   ftrace_call()

 */

#define FTRACE_STACK_SKIP 3

#else

/*

 * Skip 5:

 *

 *   __trace_stack()

 *   ftrace_stacktrace()

 *   function_trace_probe_call()

 *   ftrace_ops_list_func()

 *   ftrace_ops_assist_func()

 *   ftrace_call()

 */

#define STACK_SKIP 4

#define FTRACE_STACK_SKIP 5

#endif



static __always_inline void trace_stack(struct trace_array *tr)

{
@@ -384,7 +407,7 @@ static __always_inline void trace_stack(struct trace_array *tr) 
	local_save_flags(flags);

	pc = preempt_count();



	__trace_stack(tr, flags, STACK_SKIP, pc);

	__trace_stack(tr, flags, FTRACE_STACK_SKIP, pc);

}



static void