ftrace: allow architectures to specify ftrace compile options

If the kernel is compiled with function tracer support the -pg compile option
is passed to gcc to generate extra code into the prologue of each function.

This patch replaces the "open-coded" -pg compile flag with a CC_FLAGS_FTRACE
makefile variable which architectures can override if a different option
should be used for code generation.

Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Makefile

@@ -724,10 +724,14 @@ KBUILD_CFLAGS 	+= $(call cc-option, -femit-struct-debug-baseonly) \
 endif
 
 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)
 endif
-KBUILD_CFLAGS	+= -pg $(CC_USING_FENTRY)
+KBUILD_CFLAGS	+= $(CC_FLAGS_FTRACE) $(CC_USING_FENTRY)
 KBUILD_AFLAGS	+= $(CC_USING_FENTRY)
 ifdef CONFIG_DYNAMIC_FTRACE
 	ifdef CONFIG_HAVE_C_RECORDMCOUNT

kernel/Makefile

@@ -13,8 +13,8 @@ obj-y     = fork.o exec_domain.o panic.o \
 
 ifdef CONFIG_FUNCTION_TRACER
 # Do not trace debug files and internal ftrace files
-CFLAGS_REMOVE_cgroup-debug.o = -pg
+CFLAGS_REMOVE_cgroup-debug.o = $(CC_FLAGS_FTRACE)
-CFLAGS_REMOVE_irq_work.o = -pg
+CFLAGS_REMOVE_irq_work.o = $(CC_FLAGS_FTRACE)
 endif
 
 # cond_syscall is currently not LTO compatible

kernel/events/Makefile

@@ -1,5 +1,5 @@
 ifdef CONFIG_FUNCTION_TRACER
-CFLAGS_REMOVE_core.o = -pg
+CFLAGS_REMOVE_core.o = $(CC_FLAGS_FTRACE)
 endif
 
 obj-y := core.o ring_buffer.o callchain.o

kernel/locking/Makefile

@@ -2,10 +2,10 @@
 obj-y += mutex.o semaphore.o rwsem.o mcs_spinlock.o
 
 ifdef CONFIG_FUNCTION_TRACER
-CFLAGS_REMOVE_lockdep.o = -pg
+CFLAGS_REMOVE_lockdep.o = $(CC_FLAGS_FTRACE)
-CFLAGS_REMOVE_lockdep_proc.o = -pg
+CFLAGS_REMOVE_lockdep_proc.o = $(CC_FLAGS_FTRACE)
-CFLAGS_REMOVE_mutex-debug.o = -pg
+CFLAGS_REMOVE_mutex-debug.o = $(CC_FLAGS_FTRACE)
-CFLAGS_REMOVE_rtmutex-debug.o = -pg
+CFLAGS_REMOVE_rtmutex-debug.o = $(CC_FLAGS_FTRACE)
 endif
 
 obj-$(CONFIG_DEBUG_MUTEXES) += mutex-debug.o

kernel/sched/Makefile

@@ -1,5 +1,5 @@
 ifdef CONFIG_FUNCTION_TRACER
-CFLAGS_REMOVE_clock.o = -pg
+CFLAGS_REMOVE_clock.o = $(CC_FLAGS_FTRACE)
 endif
 
 ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y)

kernel/trace/Makefile

@@ -3,11 +3,11 @@
 
 ifdef CONFIG_FUNCTION_TRACER
 ORIG_CFLAGS := $(KBUILD_CFLAGS)
-KBUILD_CFLAGS = $(subst -pg,,$(ORIG_CFLAGS))
+KBUILD_CFLAGS = $(subst $(CC_FLAGS_FTRACE),,$(ORIG_CFLAGS))
 
 ifdef CONFIG_FTRACE_SELFTEST
 # selftest needs instrumentation
-CFLAGS_trace_selftest_dynamic.o = -pg
+CFLAGS_trace_selftest_dynamic.o = $(CC_FLAGS_FTRACE)
 obj-y += trace_selftest_dynamic.o
 endif
 endif

lib/Makefile

@@ -4,7 +4,7 @@
 
 ifdef CONFIG_FUNCTION_TRACER
 ORIG_CFLAGS := $(KBUILD_CFLAGS)
-KBUILD_CFLAGS = $(subst -pg,,$(ORIG_CFLAGS))
+KBUILD_CFLAGS = $(subst $(CC_FLAGS_FTRACE),,$(ORIG_CFLAGS))
 endif
 
 lib-y := ctype.o string.o vsprintf.o cmdline.o \

scripts/Makefile.build

@@ -234,8 +234,9 @@ sub_cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH
 	"$(if $(part-of-module),1,0)" "$(@)";
 recordmcount_source := $(srctree)/scripts/recordmcount.pl
 endif
-cmd_record_mcount = 						\
+cmd_record_mcount =						\
-	if [ "$(findstring -pg,$(_c_flags))" = "-pg" ]; then	\
+	if [ "$(findstring $(CC_FLAGS_FTRACE),$(_c_flags))" =	\
+	     "$(CC_FLAGS_FTRACE)" ]; then			\
 		$(sub_cmd_record_mcount)			\
 	fi;
 endif