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glibc/string/test-memcmp.c
Florian Weimer 3ec7c02cc3 x86-64: memcmp-avx2-movbe.S needs saturating subtraction [BZ #21662] 
This code:

L(between_2_3):
	/* Load as big endian with overlapping loads and bswap to avoid
	   branches.  */
	movzwl	-2(%rdi, %rdx), %eax
	movzwl	-2(%rsi, %rdx), %ecx
	shll	$16, %eax
	shll	$16, %ecx
	movzwl	(%rdi), %edi
	movzwl	(%rsi), %esi
	orl	%edi, %eax
	orl	%esi, %ecx
	bswap	%eax
	bswap	%ecx
	subl	%ecx, %eax
	ret

needs a saturating subtract because the full register is used.
With this commit, only the lower 24 bits of the register are used,
so a regular subtraction suffices.

The test case change adds coverage for these kinds of bugs.
2017-06-23 17:24:40 +02:00

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/* Test and measure memcmp functions.
Copyright (C) 1999-2017 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Written by Jakub Jelinek <jakub@redhat.com>, 1999.
Added wmemcmp support by Liubov Dmitrieva <liubov.dmitrieva@gmail.com>, 2011.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#define TEST_MAIN
#ifdef WIDE
# define TEST_NAME "wmemcmp"
#else
# define TEST_NAME "memcmp"
#endif
#include "test-string.h"
#ifdef WIDE
# include <inttypes.h>
# include <wchar.h>
# define MEMCMP wmemcmp
# define MEMCPY wmemcpy
# define SIMPLE_MEMCMP simple_wmemcmp
# define CHAR wchar_t
# define UCHAR wchar_t
# define CHARBYTES 4
# define CHAR__MIN WCHAR_MIN
# define CHAR__MAX WCHAR_MAX
int
simple_wmemcmp (const wchar_t *s1, const wchar_t *s2, size_t n)
{
int ret = 0;
/* Warning!
wmemcmp has to use SIGNED comparison for elements.
memcmp has to use UNSIGNED comparison for elemnts.
*/
while (n-- && (ret = *s1 < *s2 ? -1 : *s1 == *s2 ? 0 : 1) == 0) {s1++; s2++;}
return ret;
}
#else
# include <limits.h>
# define MEMCMP memcmp
# define MEMCPY memcpy
# define SIMPLE_MEMCMP simple_memcmp
# define CHAR char
# define MAX_CHAR 255
# define UCHAR unsigned char
# define CHARBYTES 1
# define CHAR__MIN CHAR_MIN
# define CHAR__MAX CHAR_MAX
int
simple_memcmp (const char *s1, const char *s2, size_t n)
{
int ret = 0;
while (n-- && (ret = *(unsigned char *) s1++ - *(unsigned char *) s2++) == 0);
return ret;
}
#endif
typedef int (*proto_t) (const CHAR *, const CHAR *, size_t);
IMPL (SIMPLE_MEMCMP, 0)
IMPL (MEMCMP, 1)
static int
check_result (impl_t *impl, const CHAR *s1, const CHAR *s2, size_t len,
int exp_result)
{
int result = CALL (impl, s1, s2, len);
if ((exp_result == 0 && result != 0)
|| (exp_result < 0 && result >= 0)
|| (exp_result > 0 && result <= 0))
{
error (0, 0, "Wrong result in function %s %d %d", impl->name,
result, exp_result);
ret = 1;
return -1;
}
return 0;
}
static void
do_one_test (impl_t *impl, const CHAR *s1, const CHAR *s2, size_t len,
int exp_result)
{
if (check_result (impl, s1, s2, len, exp_result) < 0)
return;
}
static void
do_test (size_t align1, size_t align2, size_t len, int exp_result)
{
size_t i;
CHAR *s1, *s2;
if (len == 0)
return;
align1 &= 63;
if (align1 + (len + 1) * CHARBYTES >= page_size)
return;
align2 &= 63;
if (align2 + (len + 1) * CHARBYTES >= page_size)
return;
s1 = (CHAR *) (buf1 + align1);
s2 = (CHAR *) (buf2 + align2);
for (i = 0; i < len; i++)
s1[i] = s2[i] = 1 + (23 << ((CHARBYTES - 1) * 8)) * i % CHAR__MAX;
s1[len] = align1;
s2[len] = align2;
s2[len - 1] -= exp_result;
FOR_EACH_IMPL (impl, 0)
do_one_test (impl, s1, s2, len, exp_result);
}
static void
do_random_tests (void)
{
size_t i, j, n, align1, align2, pos, len;
int result;
long r;
UCHAR *p1 = (UCHAR *) (buf1 + page_size - 512 * CHARBYTES);
UCHAR *p2 = (UCHAR *) (buf2 + page_size - 512 * CHARBYTES);
for (n = 0; n < ITERATIONS; n++)
{
align1 = random () & 31;
if (random () & 1)
align2 = random () & 31;
else
align2 = align1 + (random () & 24);
pos = random () & 511;
j = align1;
if (align2 > j)
j = align2;
if (pos + j >= 512)
pos = 511 - j - (random () & 7);
len = random () & 511;
if (len + j >= 512)
len = 511 - j - (random () & 7);
j = len + align1 + 64;
if (j > 512) j = 512;
for (i = 0; i < j; ++i)
p1[i] = random () & 255;
for (i = 0; i < j; ++i)
p2[i] = random () & 255;
result = 0;
if (pos >= len)
MEMCPY ((CHAR *) p2 + align2, (const CHAR *) p1 + align1, len);
else
{
MEMCPY ((CHAR *) p2 + align2, (const CHAR *) p1 + align1, pos);
if (p2[align2 + pos] == p1[align1 + pos])
{
p2[align2 + pos] = random () & 255;
if (p2[align2 + pos] == p1[align1 + pos])
p2[align2 + pos] = p1[align1 + pos] + 3 + (random () & 127);
}
if (p1[align1 + pos] < p2[align2 + pos])
result = -1;
else
result = 1;
}
FOR_EACH_IMPL (impl, 1)
{
r = CALL (impl, (CHAR *) p1 + align1, (const CHAR *) p2 + align2,
len);
if ((r == 0 && result)
|| (r < 0 && result >= 0)
|| (r > 0 && result <= 0))
{
error (0, 0, "Iteration %zd - wrong result in function %s (%zd, %zd, %zd, %zd) %ld != %d, p1 %p p2 %p",
n, impl->name, align1 * CHARBYTES & 63, align2 * CHARBYTES & 63, len, pos, r, result, p1, p2);
ret = 1;
}
}
}
}
static void
check1 (void)
{
CHAR s1[116], s2[116];
int n, exp_result;
s1[0] = -108;
s2[0] = -108;
s1[1] = 99;
s2[1] = 99;
s1[2] = -113;
s2[2] = -113;
s1[3] = 1;
s2[3] = 1;
s1[4] = 116;
s2[4] = 116;
s1[5] = 99;
s2[5] = 99;
s1[6] = -113;
s2[6] = -113;
s1[7] = 1;
s2[7] = 1;
s1[8] = 84;
s2[8] = 84;
s1[9] = 99;
s2[9] = 99;
s1[10] = -113;
s2[10] = -113;
s1[11] = 1;
s2[11] = 1;
s1[12] = 52;
s2[12] = 52;
s1[13] = 99;
s2[13] = 99;
s1[14] = -113;
s2[14] = -113;
s1[15] = 1;
s2[15] = 1;
s1[16] = -76;
s2[16] = -76;
s1[17] = -14;
s2[17] = -14;
s1[18] = -109;
s2[18] = -109;
s1[19] = 1;
s2[19] = 1;
s1[20] = -108;
s2[20] = -108;
s1[21] = -14;
s2[21] = -14;
s1[22] = -109;
s2[22] = -109;
s1[23] = 1;
s2[23] = 1;
s1[24] = 84;
s2[24] = 84;
s1[25] = -15;
s2[25] = -15;
s1[26] = -109;
s2[26] = -109;
s1[27] = 1;
s2[27] = 1;
s1[28] = 52;
s2[28] = 52;
s1[29] = -15;
s2[29] = -15;
s1[30] = -109;
s2[30] = -109;
s1[31] = 1;
s2[31] = 1;
s1[32] = 20;
s2[32] = 20;
s1[33] = -15;
s2[33] = -15;
s1[34] = -109;
s2[34] = -109;
s1[35] = 1;
s2[35] = 1;
s1[36] = 20;
s2[36] = 20;
s1[37] = -14;
s2[37] = -14;
s1[38] = -109;
s2[38] = -109;
s1[39] = 1;
s2[39] = 1;
s1[40] = 52;
s2[40] = 52;
s1[41] = -14;
s2[41] = -14;
s1[42] = -109;
s2[42] = -109;
s1[43] = 1;
s2[43] = 1;
s1[44] = 84;
s2[44] = 84;
s1[45] = -14;
s2[45] = -14;
s1[46] = -109;
s2[46] = -109;
s1[47] = 1;
s2[47] = 1;
s1[48] = 116;
s2[48] = 116;
s1[49] = -14;
s2[49] = -14;
s1[50] = -109;
s2[50] = -109;
s1[51] = 1;
s2[51] = 1;
s1[52] = 116;
s2[52] = 116;
s1[53] = -15;
s2[53] = -15;
s1[54] = -109;
s2[54] = -109;
s1[55] = 1;
s2[55] = 1;
s1[56] = -44;
s2[56] = -44;
s1[57] = -14;
s2[57] = -14;
s1[58] = -109;
s2[58] = -109;
s1[59] = 1;
s2[59] = 1;
s1[60] = -108;
s2[60] = -108;
s1[61] = -15;
s2[61] = -15;
s1[62] = -109;
s2[62] = -109;
s1[63] = 1;
s2[63] = 1;
s1[64] = -76;
s2[64] = -76;
s1[65] = -15;
s2[65] = -15;
s1[66] = -109;
s2[66] = -109;
s1[67] = 1;
s2[67] = 1;
s1[68] = -44;
s2[68] = -44;
s1[69] = -15;
s2[69] = -15;
s1[70] = -109;
s2[70] = -109;
s1[71] = 1;
s2[71] = 1;
s1[72] = -12;
s2[72] = -12;
s1[73] = -15;
s2[73] = -15;
s1[74] = -109;
s2[74] = -109;
s1[75] = 1;
s2[75] = 1;
s1[76] = -12;
s2[76] = -12;
s1[77] = -14;
s2[77] = -14;
s1[78] = -109;
s2[78] = -109;
s1[79] = 1;
s2[79] = 1;
s1[80] = 20;
s2[80] = -68;
s1[81] = -12;
s2[81] = 64;
s1[82] = -109;
s2[82] = -106;
s1[83] = 1;
s2[83] = 1;
s1[84] = -12;
s2[84] = -12;
s1[85] = -13;
s2[85] = -13;
s1[86] = -109;
s2[86] = -109;
s1[87] = 1;
s2[87] = 1;
s1[88] = -44;
s2[88] = -44;
s1[89] = -13;
s2[89] = -13;
s1[90] = -109;
s2[90] = -109;
s1[91] = 1;
s2[91] = 1;
s1[92] = -76;
s2[92] = -76;
s1[93] = -13;
s2[93] = -13;
s1[94] = -109;
s2[94] = -109;
s1[95] = 1;
s2[95] = 1;
s1[96] = -108;
s2[96] = -108;
s1[97] = -13;
s2[97] = -13;
s1[98] = -109;
s2[98] = -109;
s1[99] = 1;
s2[99] = 1;
s1[100] = 116;
s2[100] = 116;
s1[101] = CHAR__MIN;
s2[101] = CHAR__MAX;
s1[102] = -109;
s2[102] = -109;
s1[103] = 1;
s2[103] = 1;
s1[104] = 84;
s2[104] = 84;
s1[105] = -13;
s2[105] = -13;
s1[106] = -109;
s2[106] = -109;
s1[107] = 1;
s2[107] = 1;
s1[108] = 52;
s2[108] = 52;
s1[109] = -13;
s2[109] = -13;
s1[110] = -109;
s2[110] = -109;
s1[111] = 1;
s2[111] = 1;
s1[112] = CHAR__MAX;
s2[112] = CHAR__MIN;
s1[113] = -13;
s2[113] = -13;
s1[114] = -109;
s2[114] = -109;
s1[115] = 1;
s2[115] = 1;
n = 116;
for (size_t i = 0; i < n; i++)
for (size_t len = 0; len <= n - i; ++len)
{
exp_result = SIMPLE_MEMCMP (s1 + i, s2 + i, len);
FOR_EACH_IMPL (impl, 0)
check_result (impl, s1 + i, s2 + i, len, exp_result);
}
}
/* This test checks that memcmp doesn't overrun buffers. */
static void
check2 (void)
{
size_t max_length = page_size / sizeof (CHAR);
/* Initialize buf2 to the same values as buf1. The bug requires the
last compared byte to be different. */
memcpy (buf2, buf1, page_size);
((char *) buf2)[page_size - 1] ^= 0x11;
for (size_t length = 1; length < max_length; length++)
{
CHAR *s1 = (CHAR *) buf1 + max_length - length;
CHAR *s2 = (CHAR *) buf2 + max_length - length;
const int exp_result = SIMPLE_MEMCMP (s1, s2, length);
FOR_EACH_IMPL (impl, 0)
check_result (impl, s1, s2, length, exp_result);
}
}
int
test_main (void)
{
size_t i;
test_init ();
check1 ();
check2 ();
printf ("%23s", "");
FOR_EACH_IMPL (impl, 0)
printf ("\t%s", impl->name);
putchar ('\n');
for (i = 1; i < 16; ++i)
{
do_test (i * CHARBYTES, i * CHARBYTES, i, 0);
do_test (i * CHARBYTES, i * CHARBYTES, i, 1);
do_test (i * CHARBYTES, i * CHARBYTES, i, -1);
}
for (i = 0; i < 16; ++i)
{
do_test (0, 0, i, 0);
do_test (0, 0, i, 1);
do_test (0, 0, i, -1);
}
for (i = 1; i < 10; ++i)
{
do_test (0, 0, 2 << i, 0);
do_test (0, 0, 2 << i, 1);
do_test (0, 0, 2 << i, -1);
do_test (0, 0, 16 << i, 0);
do_test ((8 - i) * CHARBYTES, (2 * i) * CHARBYTES, 16 << i, 0);
do_test (0, 0, 16 << i, 1);
do_test (0, 0, 16 << i, -1);
}
for (i = 1; i < 8; ++i)
{
do_test (i * CHARBYTES, 2 * (i * CHARBYTES), 8 << i, 0);
do_test (i * CHARBYTES, 2 * (i * CHARBYTES), 8 << i, 1);
do_test (i * CHARBYTES, 2 * (i * CHARBYTES), 8 << i, -1);
}
do_random_tests ();
return ret;
}
#include <support/test-driver.c>
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