[PATCH 4.9 38/49] tracing: Avoid calling cc-option -mrecord-mcount for every Makefile

Greg Kroah-Hartman
2021-02-22T13:52:12Z

From: Vasily Gorbik <gor@linux.ibm.com>

commit 07d0408120216b60625c9a5b8012d1c3a907984d upstream.

Currently if CONFIG_FTRACE_MCOUNT_RECORD is enabled -mrecord-mcount
compiler flag support is tested for every Makefile.

Top 4 cc-option usages:
511 -mrecord-mcount
11 -fno-stack-protector
9 -Wno-override-init
2 -fsched-pressure

To address that move cc-option from scripts/Makefile.build to top Makefile
and export CC_USING_RECORD_MCOUNT to be used in original place.

While doing that also add -mrecord-mcount to CC_FLAGS_FTRACE (if gcc
actually supports it).

Link: http://lkml.kernel.org/r/patch-2.thread-aa7b8d.git-de935bace15a.your-ad-here.call-01533557518-ext-9465@work.hours

Acked-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Makefile | 7 +++++++
scripts/Makefile.build | 9 +++------
2 files changed, 10 insertions(+), 6 deletions(-)

--- a/Makefile
+++ b/Makefile
@@ -762,6 +762,13 @@ ifdef CONFIG_FUNCTION_TRACER
ifndef CC_FLAGS_FTRACE
CC_FLAGS_FTRACE := -pg
endif
+ifdef CONFIG_FTRACE_MCOUNT_RECORD
+ # gcc 5 supports generating the mcount tables directly
+ ifeq ($(call cc-option-yn,-mrecord-mcount),y)
+ CC_FLAGS_FTRACE += -mrecord-mcount
+ export CC_USING_RECORD_MCOUNT := 1
+ endif
+endif
export CC_FLAGS_FTRACE
ifdef CONFIG_HAVE_FENTRY
CC_USING_FENTRY := $(call cc-option, -mfentry -DCC_USING_FENTRY)
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -222,11 +222,8 @@ cmd_modversions_c = \
endif

ifdef CONFIG_FTRACE_MCOUNT_RECORD
-# gcc 5 supports generating the mcount tables directly
-ifneq ($(call cc-option,-mrecord-mcount,y),y)
-KBUILD_CFLAGS += -mrecord-mcount
-else
-# else do it all manually
+ifndef CC_USING_RECORD_MCOUNT
+# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
ifdef BUILD_C_RECORDMCOUNT
ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
RECORDMCOUNT_FLAGS = -w
@@ -255,7 +252,7 @@ cmd_record_mcount = \
"$(CC_FLAGS_FTRACE)" ]; then \
$(sub_cmd_record_mcount) \
fi;
-endif # -record-mcount
+endif # CC_USING_RECORD_MCOUNT
endif

ifdef CONFIG_STACK_VALIDATION