linux-kernel - [PATCH v2 02/36] x86/uaccess: __chk_range_not

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Date:	Mon,  5 Oct 2015 17:47:50 -0700
From:	Andy Lutomirski <luto@...nel.org>
To:	x86@...nel.org, linux-kernel@...r.kernel.org
Cc:	Brian Gerst <brgerst@...il.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Borislav Petkov <bp@...en8.de>,
	Andy Lutomirski <luto@...nel.org>
Subject: [PATCH v2 02/36] x86/uaccess: __chk_range_not_ok is unlikely to return true

This should improve code quality a bit.  It also shrinks the kernel
text.

Before:
   text	   data	    bss	    dec	    hex	filename
21828379	5194760	1277952	28301091	1afd723 vmlinux
   text	   data	    bss	    dec	    hex	filename
21827997	5194760	1277952	28300709	1afd5a5	vmlinux

Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
 arch/x86/include/asm/uaccess.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 3e911c68876e..09b1b0ab94b7 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -51,13 +51,13 @@ static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, un
 	 * limit, not add it to the address).
 	 */
 	if (__builtin_constant_p(size))
-		return addr > limit - size;
+		return unlikely(addr > limit - size);
 
 	/* Arbitrary sizes? Be careful about overflow */
 	addr += size;
-	if (addr < size)
+	if (unlikely(addr < size))
 		return true;
-	return addr > limit;
+	return unlikely(addr > limit);
 }
 
 #define __range_not_ok(addr, size, limit)				\
-- 
2.4.3

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