[tip:x86/asm] x86: Pack function addresses tightly as well

tip-bot for Ingo Molnar
2015-05-15T09:41:10Z

Commit-ID: 4874fe1eeb40b403a8c9d0ddeb4d166cab3f37ba
Gitweb: http://git.kernel.org/tip/4874fe1eeb40b403a8c9d0ddeb4d166cab3f37ba
Author: Ingo Molnar <mingo@kernel.org>
AuthorDate: Fri, 10 Apr 2015 14:18:08 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 15 May 2015 11:05:21 +0200

x86: Pack function addresses tightly as well

So as per the arguments laid out in:

be6cb02779ca ("x86: Align jump targets to 1-byte boundaries")

We can pack function addresses tightly as well:

text data bss dec filename
12566391 1617840 1089536 15273767 vmlinux.align.16-byte
12224951 1617840 1089536 14932327 vmlinux.align.1-byte
11976567 1617840 1089536 14683943 vmlinux.align.1-byte.funcs-1-byte

Which brings another 2% reduction in the defconfig kernel's
code size.

Acked-by: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Low <jason.low2@hp.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Link: http://lkml.kernel.org/r/20150410121808.GA19918@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/Makefile | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index ca17e5f..5c7edf9 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -80,6 +80,9 @@ else
# Align jump targets to 1 byte, not the default 16 bytes:
KBUILD_CFLAGS += -falign-jumps=1

+ # Pack functions tightly as well:
+ KBUILD_CFLAGS += -falign-functions=1
+
# Don't autogenerate traditional x87 instructions
KBUILD_CFLAGS += $(call cc-option,-mno-80387)
KBUILD_CFLAGS += $(call cc-option,-mno-fp-ret-in-387)