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| author | Steven Rostedt <srostedt@redhat.com> | 2011-02-09 13:15:59 -0500 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2012-08-23 11:25:02 -0400 |
| commit | a2546fae01124fb8063747439300fcf39bac033a (patch) | |
| tree | bd6b8e31532045c1bf88b2c119ce58c4863ec9ac /kernel/trace/Kconfig | |
| parent | 48bb5dc6cd9d30fe0d594947563da1f8bd9abada (diff) | |
| download | lwn-a2546fae01124fb8063747439300fcf39bac033a.tar.gz lwn-a2546fae01124fb8063747439300fcf39bac033a.zip | |
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/Kconfig')
| -rw-r--r-- | kernel/trace/Kconfig | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 8c4c07071cc5..9301a0e35e0c 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 |