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Commit 781d0624 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt
Browse files

ftrace: Do not test frame pointers if -mfentry is used 

The function graph has a test to check if the frame pointer is
corrupted, which can happen with various options of gcc with mcount.
But this is not an issue with -mfentry as -mfentry does not need nor use
frame pointers for function graph tracing.

Link: http://lkml.kernel.org/r/20120807194059.773895870@goodmis.org



Acked-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
Acked-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent a2546fae

kernel/trace/trace_functions_graph.c

+4 −1
Original line number Diff line number Diff line
@@ -143,7 +143,7 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret, 
		return;

	}



#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST

#if defined(CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST) && !defined(CC_USING_FENTRY)

	/*

	 * The arch may choose to record the frame pointer used

	 * and check it here to make sure that it is what we expect it
@@ -154,6 +154,9 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret, 
	 *

	 * Currently, x86_32 with optimize for size (-Os) makes the latest

	 * gcc do the above.

	 *

	 * Note, -mfentry does not use frame pointers, and this test

	 *  is not needed if CC_USING_FENTRY is set.

	 */

	if (unlikely(current->ret_stack[index].fp != frame_pointer)) {

		ftrace_graph_stop();