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avoid reading from out of range that may cause access fault.

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This commit is contained in:
ryo 2018-07-09 06:07:06 +00:00
parent 9ab5372263
commit 6c83813761
1 changed files with 8 additions and 6 deletions
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14
common/lib/libc/arch/aarch64/string/memcmp.S
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@ -1,4 +1,4 @@
/* $NetBSD: memcmp.S,v 1.2 2018/02/04 21:52:16 skrll Exp $ */ /* $NetBSD: memcmp.S,v 1.3 2018/07/09 06:07:06 ryo Exp $ */
/*- /*-
* Copyright (c) 2014 The NetBSD Foundation, Inc. * Copyright (c) 2014 The NetBSD Foundation, Inc.
@ -31,7 +31,7 @@
#include <machine/asm.h> #include <machine/asm.h>
RCSID("$NetBSD: memcmp.S,v 1.2 2018/02/04 21:52:16 skrll Exp $") RCSID("$NetBSD: memcmp.S,v 1.3 2018/07/09 06:07:06 ryo Exp $")
ENTRY(memcmp) ENTRY(memcmp)
mov x9, x0 mov x9, x0
@ -55,17 +55,19 @@ ENTRY(memcmp)
sub x2, x2, #8 /* now subtract a dword */ sub x2, x2, #8 /* now subtract a dword */
sub x9, x9, x3 /* dword align src1 */ sub x9, x9, x3 /* dword align src1 */
sub x10, x10, x3 /* adjust src2 */
ldr x6, [x10], #8 /* load dword from src2 */
sub x10, x10, x3 /* src2 -= x3 */
lsl x3, x3, #3 /* convert bytes to bits */ lsl x3, x3, #3 /* convert bytes to bits */
ldr x4, [x9], #8 /* load dword from src1 */ ldr x4, [x9], #8 /* load dword from src1 */
ldr x6, [x10], #8 /* load dword from src2 */
#ifdef __AARCH64EB__ #ifdef __AARCH64EB__
lsl x4, x4, x3 /* discard leading bytes from data1 */ lsl x4, x4, x3 /* discard leading bytes from data1 */
lsl x6, x6, x3 /* discard leading bytes from data2 */ lsr x6, x6, x3 /* discard leading bytes from data2 */
lsl x6, x6, x3 /* get back bit position */
#else #else
lsr x4, x4, x3 /* discard leading bytes from data1 */ lsr x4, x4, x3 /* discard leading bytes from data1 */
lsr x6, x6, x3 /* discard leading bytes from data2 */ lsl x6, x6, x3 /* discard leading bytes from data2 */
lsr x6, x6, x3 /* get back bit position */
#endif #endif
subs x0, x4, x6 /* compare data */ subs x0, x4, x6 /* compare data */
b.ne .Lmemcmp_last_compare /* difference. find it */ b.ne .Lmemcmp_last_compare /* difference. find it */