Messages in this thread Patch in this message | | | Date | Mon, 27 Aug 2012 10:05:23 -0700 | From | tip-bot for Steven Rostedt <> | Subject | [tip:perf/core] ftrace: Do not test frame pointers if -mfentry is used |
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Commit-ID: 781d06248234e221edb560a18461d65808a8a942 Gitweb: http://git.kernel.org/tip/781d06248234e221edb560a18461d65808a8a942 Author: Steven Rostedt <srostedt@redhat.com> AuthorDate: Wed, 9 Feb 2011 13:27:22 -0500 Committer: Steven Rostedt <rostedt@goodmis.org> CommitDate: Thu, 23 Aug 2012 11:25:29 -0400
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: H. Peter Anvin <hpa@linux.intel.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> --- kernel/trace/trace_functions_graph.c | 5 ++++- 1 files changed, 4 insertions(+), 1 deletions(-)
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index ce27c8b..99b4378 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -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();
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