From: Andi Kleen <a...@linux.intel.com>
gcc 5 supports a new -mcount-record option to generate ftrace
tables directly. This avoids the need to run record_mcount
manually.
Use this option when available.
It also has a -mcount-nop option to generate the mcount calls
as nops. So far that is not implemented, but it could be used
to optimize patching at boot up.
Signed-off-by: Andi Kleen <a...@linux.intel.com>
---
scripts/Makefile.build | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index de46ab03f063..2d7467076411 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -212,6 +212,11 @@ cmd_modversions =
\
endif
ifdef CONFIG_FTRACE_MCOUNT_RECORD
+# gcc 5 supports generating the mcount tables directly
+ifneq ($(call cc-option,-mrecord-mcount,y),y)
+ KBUILD_CFLAGS += -mrecord-mcount
+else
+# else do it all manually
ifdef BUILD_C_RECORDMCOUNT
ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
RECORDMCOUNT_FLAGS = -w
@@ -241,6 +246,7 @@ cmd_record_mcount =
\
$(sub_cmd_record_mcount) \
fi;
endif
+endif
ifdef CONFIG_STACK_VALIDATION
ifneq ($(SKIP_STACK_VALIDATION),1)
--
2.5.5
