ftrace: do not profile lib/string.o

Most archs define the string and memory compare functions in assembly.
Some do not. But these functions may be used in some archs at early
boot up.

Since most archs define this code in assembly and they are not usually
traced, there's no need to trace them when they are not defined in
assembly.

This patch removes the -pg from the CFLAGS for lib/string.o.
This prevents the string functions use in either vdso or early bootup
from crashing the system.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/lib/Makefile b/lib/Makefile
index 74b0cfb1fcc3c0eb009648484a368116d0681f88..6ca9e6ee1e338b82254eee1dfbe3bde025575d78 100644 (file)
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -8,6 +8,14 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
         sha1.o irq_regs.o reciprocal_div.o argv_split.o \
         proportions.o prio_heap.o ratelimit.o
 
+ifdef CONFIG_FTRACE
+# Do not profile string.o, since it may be used in early boot or vdso
+ORIG_CFLAGS := $(KBUILD_CFLAGS)
+KBUILD_CFLAGS = $(if $(subst string,,$(basename $(notdir $@))), \
+       $(ORIG_CFLAGS), \
+       $(subst -pg,,$(ORIG_CFLAGS)))
+endif
+
 lib-$(CONFIG_MMU) += ioremap.o
 lib-$(CONFIG_SMP) += cpumask.o