From 3594136ad67a54d77bcb2547e70011754a2f91d5 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <srostedt@redhat.com>
Date: Mon, 12 May 2008 21:20:50 +0200
Subject: [PATCH] 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>
---
 lib/Makefile | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/lib/Makefile b/lib/Makefile
index 74b0cfb1fcc3..6ca9e6ee1e33 100644
--- 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
 
-- 
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