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glibc/string/test-strchr.c
Noah Goldstein 7da0886247 x86: Fix bug in strchrnul-evex512 [BZ #32078] 
Issue was we were expecting not matches with CHAR before the start of
the string in the page cross case.

The check code in the page cross case:
```
    and    $0xffffffffffffffc0,%rax
    vmovdqa64 (%rax),%zmm17
    vpcmpneqb %zmm17,%zmm16,%k1
    vptestmb %zmm17,%zmm17,%k0{%k1}
    kmovq  %k0,%rax
    inc    %rax
    shr    %cl,%rax
    je     L(continue)
```

expects that all characters that neither match null nor CHAR will be
1s in `rax` prior to the `inc`. Then the `inc` will overflow all of
the 1s where no relevant match was found.

This is incorrect in the page-cross case, as the
`vmovdqa64 (%rax),%zmm17` loads from before the start of the input
string.

If there are matches with CHAR before the start of the string, `rax`
won't properly overflow.

The fix is quite simple. Just replace:

```
    inc    %rax
    shr    %cl,%rax
```
With:
```
    sar    %cl,%rax
    inc    %rax
```

The arithmetic shift will clear any matches prior to the start of the
string while maintaining the signbit so the 1s can properly overflow
to zero in the case of no matches.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
2024-08-15 08:11:33 -07:00

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/* Test STRCHR functions.
Copyright (C) 1999-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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
<https://www.gnu.org/licenses/>. */
#define TEST_MAIN
#ifndef WIDE
# ifdef USE_FOR_STRCHRNUL
# define TEST_NAME "strchrnul"
# else
# define TEST_NAME "strchr"
# endif /* !USE_FOR_STRCHRNUL */
#else
# ifdef USE_FOR_STRCHRNUL
# define TEST_NAME "wcschrnul"
# else
# define TEST_NAME "wcschr"
# endif /* !USE_FOR_STRCHRNUL */
#endif /* WIDE */
#include "test-string.h"
#ifndef WIDE
# ifdef USE_FOR_STRCHRNUL
# define STRCHR strchrnul
# else
# define STRCHR strchr
# endif /* !USE_FOR_STRCHRNUL */
# define STRLEN strlen
# define CHAR char
# define BIG_CHAR CHAR_MAX
# define MIDDLE_CHAR 127
# define SMALL_CHAR 23
# define UCHAR unsigned char
# define L(s) s
#else
# include <wchar.h>
# ifdef USE_FOR_STRCHRNUL
# define STRCHR wcschrnul
# else
# define STRCHR wcschr
# endif /* !USE_FOR_STRCHRNUL */
# define STRLEN wcslen
# define CHAR wchar_t
# define BIG_CHAR WCHAR_MAX
# define MIDDLE_CHAR 1121
# define SMALL_CHAR 851
# define UCHAR wchar_t
# define L(s) L ## s
#endif /* WIDE */
#ifdef USE_FOR_STRCHRNUL
# define NULLRET(endptr) endptr
#else
# define NULLRET(endptr) NULL
#endif /* !USE_FOR_STRCHRNUL */
typedef CHAR *(*proto_t) (const CHAR *, int);
IMPL (STRCHR, 1)
/* Also check the generic implementation. */
#undef STRCHR
#undef weak_alias
#define weak_alias(a, b)
#undef libc_hidden_builtin_def
#define libc_hidden_builtin_def(a)
#undef libc_hidden_def
#define libc_hidden_def(a)
#undef libc_hidden_weak
#define libc_hidden_weak(a)
#ifndef WIDE
# define STRCHRNUL __strchrnul_default
# include "string/strchrnul.c"
# ifndef USE_FOR_STRCHRNUL
# define STRCHR __strchr_default
# include "string/strchr.c"
# define STRCHR_DEFAULT STRCHR
# else
# define STRCHR_DEFAULT STRCHRNUL
# endif
#else
# ifndef USE_FOR_STRCHRNUL
# define WCSCHR __wcschr_default
# include "wcsmbs/wcschr.c"
# define STRCHR_DEFAULT WCSCHR
# else
# define WCSCHRNUL __wcschrnul_default
# include "wcsmbs/wcschrnul.c"
# define STRCHR_DEFAULT WCSCHRNUL
# endif
#endif
IMPL (STRCHR_DEFAULT, 1)
static int
check_result (impl_t *impl, const CHAR *s, int c, const CHAR *exp_res)
{
CHAR *res = CALL (impl, s, c);
if (res != exp_res)
{
error (0, 0, "Wrong result in function %s(%p) %#x %p %p", impl->name, s,
c, res, exp_res);
ret = 1;
return -1;
}
return 0;
}
static int
do_one_test (impl_t *impl, const CHAR *s, int c, const CHAR *exp_res)
{
return check_result (impl, s, c, exp_res);
}
static void
do_test (size_t align, size_t pos, size_t len, int seek_char, int max_char)
/* For wcschr: align here means align not in bytes,
but in wchar_ts, in bytes it will equal to align * (sizeof (wchar_t))
len for wcschr here isn't in bytes but it's number of wchar_t symbols. */
{
size_t i;
CHAR *result;
CHAR *buf = (CHAR *) buf1;
align &= 127;
if ((align + len) * sizeof (CHAR) >= page_size)
return;
for (i = 0; i < len; ++i)
{
buf[align + i] = 32 + 23 * i % max_char;
if (buf[align + i] == seek_char)
buf[align + i] = seek_char + 1;
else if (buf[align + i] == 0)
buf[align + i] = 1;
}
buf[align + len] = 0;
if (pos < len)
{
buf[align + pos] = seek_char;
result = buf + align + pos;
}
else if (seek_char == 0)
result = buf + align + len;
else
result = NULLRET (buf + align + len);
FOR_EACH_IMPL (impl, 0)
{
if (do_one_test (impl, buf + align, seek_char, result) != 0)
{
error (0, 0,
"\tAlign=%zu, Pos=%zu, Len=%zu, seek=%d, max_char=%d, "
"Buf=%p, Res=%p",
align, pos, len, seek_char, max_char, buf, result);
}
}
}
static void
do_random_tests (void)
{
size_t i, j, n, align, pos, len;
int seek_char;
CHAR *result;
UCHAR *p = (UCHAR *) (buf1 + page_size - 512 * sizeof (CHAR));
for (n = 0; n < ITERATIONS; n++)
{
/* For wcschr: align here means align not in bytes, but in wchar_ts,
in bytes it will equal to align * (sizeof (wchar_t)). */
align = random () & 15;
pos = random () & 511;
seek_char = random () & 255;
if (pos + align >= 511)
pos = 510 - align - (random () & 7);
/* len for wcschr here isn't in bytes but it's number of wchar_t
symbols. */
len = random () & 511;
if ((pos == len && seek_char)
|| (pos > len && (random () & 1)))
len = pos + 1 + (random () & 7);
if (len + align >= 512)
len = 511 - align - (random () & 7);
if (pos == len && seek_char)
len = pos + 1;
j = (pos > len ? pos : len) + align + 64;
if (j > 512)
j = 512;
for (i = 0; i < j; i++)
{
if (i == pos + align)
p[i] = seek_char;
else if (i == len + align)
p[i] = 0;
else
{
p[i] = random () & 255;
if (i < pos + align && p[i] == seek_char)
p[i] = seek_char + 13;
if (i < len + align && !p[i])
{
p[i] = seek_char - 13;
if (!p[i])
p[i] = 140;
}
}
}
if (pos <= len)
result = (CHAR *) (p + pos + align);
else if (seek_char == 0)
result = (CHAR *) (p + len + align);
else
result = NULLRET ((CHAR *) (p + len + align));
FOR_EACH_IMPL (impl, 1)
if (CALL (impl, (CHAR *) (p + align), seek_char) != result)
{
error (0, 0, "Iteration %zd - wrong result in function \
%s (align in bytes: %zd, seek_char: %d, len: %zd, pos: %zd) %p != %p, p %p",
n, impl->name, align * sizeof (CHAR), seek_char, len, pos,
CALL (impl, (CHAR *) (p + align), seek_char), result, p);
ret = 1;
}
}
}
static void
check1 (void)
{
CHAR s[] __attribute__((aligned(16))) = L ("\xff");
CHAR c = L ('\xfe');
#ifndef USE_FOR_STRCHRNUL
CHAR *exp_result = NULL;
#else
CHAR *exp_result = s + STRLEN (s);
#endif
FOR_EACH_IMPL (impl, 0)
check_result (impl, s, c, exp_result);
}
static void
check2 (void)
{
CHAR *s = (CHAR *) (buf1 + getpagesize () - 4 * sizeof (CHAR));
CHAR *s_begin = (CHAR *) (buf1 + getpagesize () - 64);
#ifndef USE_FOR_STRCHRNUL
CHAR *exp_result = NULL;
#else
CHAR *exp_result = s + 1;
#endif
CHAR val = 0x12;
for (; s_begin != s; ++s_begin)
*s_begin = val;
s[0] = val + 1;
s[1] = 0;
s[2] = val + 1;
s[3] = val + 1;
{
FOR_EACH_IMPL (impl, 0)
check_result (impl, s, val, exp_result);
}
s[3] = val;
{
FOR_EACH_IMPL (impl, 0)
check_result (impl, s, val, exp_result);
}
exp_result = s;
s[0] = val;
{
FOR_EACH_IMPL (impl, 0)
check_result (impl, s, val, exp_result);
}
s[3] = val + 1;
{
FOR_EACH_IMPL (impl, 0)
check_result (impl, s, val, exp_result);
}
s[0] = val + 1;
s[1] = val + 1;
s[2] = val + 1;
s[3] = val + 1;
s[4] = val;
exp_result = s + 4;
{
FOR_EACH_IMPL (impl, 0)
check_result (impl, s, val, exp_result);
}
s[4] = 0;
#ifndef USE_FOR_STRCHRNUL
exp_result = NULL;
#else
exp_result = s + 4;
#endif
{
FOR_EACH_IMPL (impl, 0)
check_result (impl, s, val, exp_result);
}
}
int
test_main (void)
{
size_t i;
test_init ();
check1 ();
check2 ();
printf ("%20s", "");
FOR_EACH_IMPL (impl, 0)
printf ("\t%s", impl->name);
putchar ('\n');
for (i = 1; i < 8; ++i)
{
do_test (0, 16 << i, 2048, SMALL_CHAR, MIDDLE_CHAR);
do_test (i, 16 << i, 2048, SMALL_CHAR, MIDDLE_CHAR);
}
for (i = 1; i < 8; ++i)
{
do_test (0, 16 << i, 4096, SMALL_CHAR, MIDDLE_CHAR);
do_test (i, 16 << i, 4096, SMALL_CHAR, MIDDLE_CHAR);
}
for (i = 1; i < 8; ++i)
{
do_test (i, 64, 256, SMALL_CHAR, MIDDLE_CHAR);
do_test (i, 64, 256, SMALL_CHAR, BIG_CHAR);
}
for (i = 0; i < 8; ++i)
{
do_test (16 * i, 256, 512, SMALL_CHAR, MIDDLE_CHAR);
do_test (16 * i, 256, 512, SMALL_CHAR, BIG_CHAR);
}
for (i = 0; i < 32; ++i)
{
do_test (0, i, i + 1, SMALL_CHAR, MIDDLE_CHAR);
do_test (0, i, i + 1, SMALL_CHAR, BIG_CHAR);
}
for (i = 1; i < 8; ++i)
{
do_test (0, 16 << i, 2048, 0, MIDDLE_CHAR);
do_test (i, 16 << i, 2048, 0, MIDDLE_CHAR);
}
for (i = 1; i < 8; ++i)
{
do_test (0, 16 << i, 4096, 0, MIDDLE_CHAR);
do_test (i, 16 << i, 4096, 0, MIDDLE_CHAR);
}
for (i = 1; i < 8; ++i)
{
do_test (i, 64, 256, 0, MIDDLE_CHAR);
do_test (i, 64, 256, 0, BIG_CHAR);
}
for (i = 0; i < 8; ++i)
{
do_test (16 * i, 256, 512, 0, MIDDLE_CHAR);
do_test (16 * i, 256, 512, 0, BIG_CHAR);
}
for (i = 0; i < 32; ++i)
{
do_test (0, i, i + 1, 0, MIDDLE_CHAR);
do_test (0, i, i + 1, 0, BIG_CHAR);
}
do_random_tests ();
return ret;
}
#include <support/test-driver.c>
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