From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753437AbaATNxF (ORCPT ); Mon, 20 Jan 2014 08:53:05 -0500 Received: from mail-ea0-f172.google.com ([209.85.215.172]:37684 "EHLO mail-ea0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753013AbaATNxC (ORCPT ); Mon, 20 Jan 2014 08:53:02 -0500 Date: Mon, 20 Jan 2014 14:52:58 +0100 From: Ingo Molnar To: Linus Torvalds Cc: linux-kernel@vger.kernel.org, "H. Peter Anvin" , Thomas Gleixner , Andrew Morton Subject: [GIT PULL] x86/asm changes for v3.14 Message-ID: <20140120135258.GA12476@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linus, Please pull the latest x86-asm-for-linus git tree from: git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-asm-for-linus # HEAD: a740576a4abf933de8f50787f24f24456cebd761 x86: Slightly tweak the access_ok() C variant for better code Misc optimizations. Thanks, Ingo ------------------> Fenghua Yu (1): x86-64, copy_user: Remove zero byte check before copy user buffer. H. Peter Anvin (2): x86-64, copy_user: Use leal to produce 32-bit results x86: Slightly tweak the access_ok() C variant for better code Linus Torvalds (1): x86: Replace assembly access_ok() with a C variant arch/x86/include/asm/uaccess.h | 32 ++++++++++++++++++++------------ arch/x86/lib/copy_user_64.S | 12 ++++-------- 2 files changed, 24 insertions(+), 20 deletions(-) diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 8ec57c0..6f1bb74 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -40,22 +40,30 @@ /* * Test whether a block of memory is a valid user space address. * Returns 0 if the range is valid, nonzero otherwise. - * - * This is equivalent to the following test: - * (u33)addr + (u33)size > (u33)current->addr_limit.seg (u65 for x86_64) - * - * This needs 33-bit (65-bit for x86_64) arithmetic. We have a carry... */ +static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit) +{ + /* + * If we have used "sizeof()" for the size, + * we know it won't overflow the limit (but + * it might overflow the 'addr', so it's + * important to subtract the size from the + * limit, not add it to the address). + */ + if (__builtin_constant_p(size)) + return addr > limit - size; + + /* Arbitrary sizes? Be careful about overflow */ + addr += size; + if (addr < size) + return true; + return addr > limit; +} #define __range_not_ok(addr, size, limit) \ ({ \ - unsigned long flag, roksum; \ __chk_user_ptr(addr); \ - asm("add %3,%1 ; sbb %0,%0 ; cmp %1,%4 ; sbb $0,%0" \ - : "=&r" (flag), "=r" (roksum) \ - : "1" (addr), "g" ((long)(size)), \ - "rm" (limit)); \ - flag; \ + __chk_range_not_ok((unsigned long __force)(addr), size, limit); \ }) /** @@ -78,7 +86,7 @@ * this function, memory access functions may still return -EFAULT. */ #define access_ok(type, addr, size) \ - (likely(__range_not_ok(addr, size, user_addr_max()) == 0)) + likely(!__range_not_ok(addr, size, user_addr_max())) /* * The exception table consists of pairs of addresses relative to the diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S index a30ca15..dee945d 100644 --- a/arch/x86/lib/copy_user_64.S +++ b/arch/x86/lib/copy_user_64.S @@ -186,7 +186,7 @@ ENTRY(copy_user_generic_unrolled) 30: shll $6,%ecx addl %ecx,%edx jmp 60f -40: lea (%rdx,%rcx,8),%rdx +40: leal (%rdx,%rcx,8),%edx jmp 60f 50: movl %ecx,%edx 60: jmp copy_user_handle_tail /* ecx is zerorest also */ @@ -236,8 +236,6 @@ ENDPROC(copy_user_generic_unrolled) ENTRY(copy_user_generic_string) CFI_STARTPROC ASM_STAC - andl %edx,%edx - jz 4f cmpl $8,%edx jb 2f /* less than 8 bytes, go to byte copy loop */ ALIGN_DESTINATION @@ -249,12 +247,12 @@ ENTRY(copy_user_generic_string) 2: movl %edx,%ecx 3: rep movsb -4: xorl %eax,%eax + xorl %eax,%eax ASM_CLAC ret .section .fixup,"ax" -11: lea (%rdx,%rcx,8),%rcx +11: leal (%rdx,%rcx,8),%ecx 12: movl %ecx,%edx /* ecx is zerorest also */ jmp copy_user_handle_tail .previous @@ -279,12 +277,10 @@ ENDPROC(copy_user_generic_string) ENTRY(copy_user_enhanced_fast_string) CFI_STARTPROC ASM_STAC - andl %edx,%edx - jz 2f movl %edx,%ecx 1: rep movsb -2: xorl %eax,%eax + xorl %eax,%eax ASM_CLAC ret