From: Jakub Jelinek <jakub@redhat.com>
To: Ulrich Drepper <drepper@redhat.com>
Cc: Glibc hackers <libc-hacker@sources.redhat.com>
Subject: [PATCH] Fix x86-64 memchr
Date: Tue, 16 Jun 2009 17:13:00 -0000 [thread overview]
Message-ID: <20090616171301.GO3101@sunsite.ms.mff.cuni.cz> (raw)
Hi!
As the testcase shows, if length passed to memchr is above half of address
space length, memchr will return NULL instead of the correct result.
2009-06-16 Jakub Jelinek <jakub@redhat.com>
* sysdeps/x86_64/memchr.S (memchr): Use unsigned instead of signed
comparisons.
* string/test-memchr.c (do_random_tests): Test very large lengths
as well.
--- libc/sysdeps/x86_64/memchr.S.jj 2009-05-16 19:23:47.000000000 +0200
+++ libc/sysdeps/x86_64/memchr.S 2009-06-16 19:04:08.000000000 +0200
@@ -41,7 +41,7 @@ ENTRY (memchr)
movl $16, %esi
jnz 1f
cmpq %rsi, %rdx
- jle 3f
+ jbe 3f
2: movdqa (%rdi,%rsi), %xmm0
leaq 16(%rsi), %rsi
@@ -50,7 +50,7 @@ ENTRY (memchr)
testl %ecx, %ecx
jnz 1f
cmpq %rsi, %rdx
- jg 2b
+ ja 2b
3: xorl %eax, %eax
ret
@@ -60,7 +60,7 @@ ENTRY (memchr)
addq %rcx, %rax
leaq -16(%rsi,%rcx), %rsi
cmpq %rsi, %rdx
- jle 3b
+ jbe 3b
ret
END (memchr)
--- libc/string/test-memchr.c.jj 2009-05-16 19:23:37.000000000 +0200
+++ libc/string/test-memchr.c 2009-06-16 18:48:34.000000000 +0200
@@ -1,5 +1,5 @@
/* Test and measure memchr functions.
- Copyright (C) 1999, 2002, 2003, 2005 Free Software Foundation, Inc.
+ Copyright (C) 1999, 2002, 2003, 2005, 2009 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Written by Jakub Jelinek <jakub@redhat.com>, 1999.
@@ -144,7 +144,12 @@ do_random_tests (void)
}
if (pos < len)
- result = (char *) (p + pos + align);
+ {
+ size_t r = random ();
+ if ((r & 31) == 0)
+ len = ~(uintptr_t) (p + align) - ((r >> 5) & 31);
+ result = (char *) (p + pos + align);
+ }
else
result = NULL;
Jakub
reply other threads:[~2009-06-16 17:13 UTC|newest]
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