linux-kernel - [RFC] x86: setup code_bytes - use mask to restrict it's size

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Date:	Sun, 3 Feb 2008 01:12:11 +0300
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Andi Kleen <ak@...e.de>, "H. Peter Anvin" <hpa@...or.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: [RFC] x86: setup code_bytes - use mask to restrict it's size

This patch strips off 8 bytes from text section. Not a really
big advantage (especially for __init section). It seems 8192
bytes of disassembled code is rare used anyway.

before:
	text    data     bss     dec     hex filename
	9900     176      20   10096    2770 arch/x86/kernel/traps_64.o.old
after:
	text    data     bss     dec     hex filename
	9892     176      20   10088    2768 arch/x86/kernel/traps_64.o

Signed-off-by: Cyrill Gorcunov <gorcunov@...il.com>
---

If there is no benefit at all - just drop the patch.
Any comments are welcome ;)

Index: linux-2.6.git/arch/x86/kernel/traps_32.c
===================================================================
--- linux-2.6.git.orig/arch/x86/kernel/traps_32.c	2008-02-02 23:52:16.000000000 +0300
+++ linux-2.6.git/arch/x86/kernel/traps_32.c	2008-02-03 00:39:58.000000000 +0300
@@ -1229,8 +1229,9 @@ __setup("kstack=", kstack_setup);
 static int __init code_bytes_setup(char *s)
 {
 	code_bytes = simple_strtoul(s, NULL, 0);
-	if (code_bytes > 8192)
-		code_bytes = 8192;
+
+	/* we don't want too long code-dump */
+	code_bytes &= 8191;
 
 	return 1;
 }
Index: linux-2.6.git/arch/x86/kernel/traps_64.c
===================================================================
--- linux-2.6.git.orig/arch/x86/kernel/traps_64.c	2008-02-02 23:52:16.000000000 +0300
+++ linux-2.6.git/arch/x86/kernel/traps_64.c	2008-02-03 00:38:10.000000000 +0300
@@ -1196,8 +1196,9 @@ early_param("kstack", kstack_setup);
 static int __init code_bytes_setup(char *s)
 {
 	code_bytes = simple_strtoul(s, NULL, 0);
-	if (code_bytes > 8192)
-		code_bytes = 8192;
+
+	/* we don't want too long code-dump */
+	code_bytes &= 8191;
 
 	return 1;
 }
--
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