From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@elte.hu>,
Andrew Morton <akpm@linux-foundation.org>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
"H. Peter Anvin" <hpa@linux.intel.com>,
Ingo Molnar <mingo@kernel.org>, Andi Kleen <andi@firstfloor.org>
Subject: [PATCH 3/4] ftrace: Do not test frame pointers if -mfentry is used
Date: Thu, 23 Aug 2012 14:15:40 -0400 [thread overview]
Message-ID: <20120823181659.584532686@goodmis.org> (raw)
In-Reply-To: 20120823181537.510961094@goodmis.org
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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 file changed, 4 insertions(+), 1 deletion(-)
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();
--
1.7.10.4
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next prev parent reply other threads:[~2012-08-23 18:17 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-23 18:15 [PATCH 0/4] [GIT PULL] ftrace: Use of __fentry__ Steven Rostedt
2012-08-23 18:15 ` [PATCH 1/4] ftrace: Make recordmcount.c handle __fentry__ Steven Rostedt
2012-08-23 18:47 ` Andi Kleen
2012-08-23 18:15 ` [PATCH 2/4] ftrace: Add -mfentry to Makefile on function tracer Steven Rostedt
2012-08-23 18:15 ` Steven Rostedt [this message]
2012-08-23 18:15 ` [PATCH 4/4] ftrace/x86: Add support for -mfentry to x86_64 Steven Rostedt
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