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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 /Makefile
parent48bb5dc6cd9d30fe0d594947563da1f8bd9abada (diff)
downloadvexpress-lsk-a2546fae01124fb8063747439300fcf39bac033a.tar.gz
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 'Makefile')
-rw-r--r--Makefile6
1 files changed, 5 insertions, 1 deletions
diff --git a/Makefile b/Makefile
index ddf5be952e4..e7ca93f1785 100644
--- a/Makefile
+++ b/Makefile
@@ -609,7 +609,11 @@ KBUILD_CFLAGS += $(call cc-option, -femit-struct-debug-baseonly)
endif
ifdef CONFIG_FUNCTION_TRACER
-KBUILD_CFLAGS += -pg
+ifdef CONFIG_HAVE_FENTRY
+CC_USING_FENTRY := $(call cc-option, -mfentry -DCC_USING_FENTRY)
+endif
+KBUILD_CFLAGS += -pg $(CC_USING_FENTRY)
+KBUILD_AFLAGS += $(CC_USING_FENTRY)
ifdef CONFIG_DYNAMIC_FTRACE
ifdef CONFIG_HAVE_C_RECORDMCOUNT
BUILD_C_RECORDMCOUNT := y