From 6447facba36e3fff77ab4c68f46297a5dab024c8 Mon Sep 17 00:00:00 2001
From: Andy Lutomirski <luto@MIT.EDU>
Date: Mon, 23 May 2011 09:31:29 -0400
Subject: [PATCH] x86-64: Turn off -pg and turn on -foptimize-sibling-calls for
 vDSO

The vDSO isn't part of the kernel, so profiling and kernel
backtraces don't really matter.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Borislav Petkov <bp@amd64.org>
Link: http://lkml.kernel.org/r/%3C23087b738c037342abb53f2f07b9bef89ceaeea3.1306156808.git.luto%40mit.edu%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/vdso/Makefile | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile
index a651861..bef0bc9 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -37,11 +37,24 @@ $(obj)/%.so: OBJCOPYFLAGS := -S
 $(obj)/%.so: $(obj)/%.so.dbg FORCE
 	$(call if_changed,objcopy)
 
+#
+# Don't omit frame pointers for ease of userspace debugging, but do
+# optimize sibling calls.
+#
 CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64 \
-       $(filter -g%,$(KBUILD_CFLAGS)) $(call cc-option, -fno-stack-protector)
+       $(filter -g%,$(KBUILD_CFLAGS)) $(call cc-option, -fno-stack-protector) \
+       -fno-omit-frame-pointer -foptimize-sibling-calls
 
 $(vobjs): KBUILD_CFLAGS += $(CFL)
 
+#
+# vDSO code runs in userspace and -pg doesn't help with profiling anyway.
+#
+CFLAGS_REMOVE_vdso-note.o = -pg
+CFLAGS_REMOVE_vclock_gettime.o = -pg
+CFLAGS_REMOVE_vgetcpu.o = -pg
+CFLAGS_REMOVE_vvar.o = -pg
+
 targets += vdso-syms.lds
 obj-$(VDSO64-y)			+= vdso-syms.lds
 
-- 
2.7.4