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authorSteven Rostedt <srostedt@redhat.com>2011-02-09 13:15:59 -0500
committerSteven Rostedt <rostedt@goodmis.org>2012-08-23 11:25:02 -0400
commita2546fae01124fb8063747439300fcf39bac033a (patch)
treebd6b8e31532045c1bf88b2c119ce58c4863ec9ac /kernel/trace
parent48bb5dc6cd9d30fe0d594947563da1f8bd9abada (diff)
ftrace: Add -mfentry to Makefile on function tracer
Thanks to Andi Kleen, gcc 4.6.0 now supports -mfentry for x86 (and hopefully soon for other archs). What this does is to have the function profiler start at the beginning of the function instead of after the stack is set up. As plain -pg (mcount) is called after the stack is set up, and in some cases can have issues with the function graph tracer. It also requires frame pointers to be enabled. The -mfentry now calls __fentry__ at the beginning of the function. This allows for compiling without frame pointers and even has the ability to access parameters if needed. If the architecture and the compiler both support -mfentry then use that instead. Link: http://lkml.kernel.org/r/20120807194059.392617243@goodmis.org Acked-by: H. Peter Anvin <hpa@linux.intel.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Michal Marek <mmarek@suse.cz> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/Kconfig5
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 8c4c07071cc..9301a0e35e0 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -49,6 +49,11 @@ config HAVE_SYSCALL_TRACEPOINTS
help
See Documentation/trace/ftrace-design.txt
+config HAVE_FENTRY
+ bool
+ help
+ Arch supports the gcc options -pg with -mfentry
+
config HAVE_C_RECORDMCOUNT
bool
help