tracing: Handle CC_FLAGS_FTRACE more accurately

CC_FLAGS_FTRACE is exported and later used to remove ftrace relevant
build flags from files which should be built without ftrace support.
For that reason add -mfentry to CC_FLAGS_FTRACE as well. That fixes
a problem with vdso32 build on s390, where -mfentry could not be used
together with -m31 flag.

At the same time flags like -pg and -mfentry are not relevant for asm
files, so avoid adding them to KBUILD_AFLAGS.

Introduce CC_FLAGS_USING instead of CC_USING_FENTRY to collect
-DCC_USING_FENTRY (and future alike) which are relevant for both
KBUILD_CFLAGS and KBUILD_AFLAGS.

Link: http://lkml.kernel.org/r/patch-1.thread-aa7b8d.git-42971afe87de.your-ad-here.call-01533557518-ext-9465@work.hours

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files changed, 7 insertions, 4 deletions

diff --git a/Makefile b/Makefile
index 67d9d20f8564..489de42d30c7 100644
--- a/Makefile
+++ b/Makefile
@@ -743,12 +743,15 @@ ifdef CONFIG_FUNCTION_TRACER
 ifndef CC_FLAGS_FTRACE
 CC_FLAGS_FTRACE := -pg
 endif
-export CC_FLAGS_FTRACE
 ifdef CONFIG_HAVE_FENTRY
-CC_USING_FENTRY := $(call cc-option, -mfentry -DCC_USING_FENTRY)
+  ifeq ($(call cc-option-yn, -mfentry),y)
+    CC_FLAGS_FTRACE     += -mfentry
+    CC_FLAGS_USING      += -DCC_USING_FENTRY
+  endif
 endif
-KBUILD_CFLAGS   += $(CC_FLAGS_FTRACE) $(CC_USING_FENTRY)
-KBUILD_AFLAGS   += $(CC_USING_FENTRY)
+export CC_FLAGS_FTRACE
+KBUILD_CFLAGS   += $(CC_FLAGS_FTRACE) $(CC_FLAGS_USING)
+KBUILD_AFLAGS   += $(CC_FLAGS_USING)
 ifdef CONFIG_DYNAMIC_FTRACE
         ifdef CONFIG_HAVE_C_RECORDMCOUNT
                 BUILD_C_RECORDMCOUNT := y