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x86: Fallback {str|wcs}cmp RTM in the ncmp overflow case [BZ #28896]

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In the overflow fallback strncmp-avx2-rtm and wcsncmp-avx2-rtm would
call strcmp-avx2 and wcscmp-avx2 respectively. This would have
not checks around vzeroupper and would trigger spurious
aborts. This commit fixes that.

test-strcmp, test-strncmp, test-wcscmp, and test-wcsncmp all pass on
AVX2 machines with and without RTM.

Co-authored-by: H.J. Lu <hjl.tools@gmail.com>
This commit is contained in:
Noah Goldstein
2022-02-15 08:18:15 -06:00
parent aa5a720056
commit c627209832
7 changed files with 23 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
sysdeps/x86/Makefile
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@@ -109,7 +109,7 @@ CFLAGS-tst-memset-rtm.c += -mrtm
CFLAGS-tst-strchr-rtm.c += -mrtm CFLAGS-tst-strchr-rtm.c += -mrtm
CFLAGS-tst-strcpy-rtm.c += -mrtm CFLAGS-tst-strcpy-rtm.c += -mrtm
CFLAGS-tst-strlen-rtm.c += -mrtm CFLAGS-tst-strlen-rtm.c += -mrtm
CFLAGS-tst-strncmp-rtm.c += -mrtm CFLAGS-tst-strncmp-rtm.c += -mrtm -Wno-error
CFLAGS-tst-strrchr-rtm.c += -mrtm CFLAGS-tst-strrchr-rtm.c += -mrtm
endif endif

17
sysdeps/x86/tst-strncmp-rtm.c
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@@ -16,6 +16,7 @@
License along with the GNU C Library; if not, see License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */ <https://www.gnu.org/licenses/>. */
#include <stdint.h>
#include <tst-string-rtm.h> #include <tst-string-rtm.h>
#define LOOP 3000 #define LOOP 3000
@@ -45,8 +46,22 @@ function (void)
return 1; return 1;
} }
__attribute__ ((noinline, noclone))
static int
function_overflow (void)
{
if (strncmp (string1, string2, SIZE_MAX) == 0)
return 0;
else
return 1;
}
static int static int
do_test (void) do_test (void)
{ {
return do_test_1 ("strncmp", LOOP, prepare, function); int status = do_test_1 ("strncmp", LOOP, prepare, function);
if (status != EXIT_SUCCESS)
return status;
status = do_test_1 ("strncmp", LOOP, prepare, function_overflow);
return status;
} }

8
sysdeps/x86_64/multiarch/strcmp-avx2.S
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@@ -193,10 +193,10 @@ L(ret_zero):
.p2align 4,, 5 .p2align 4,, 5
L(one_or_less): L(one_or_less):
jb L(ret_zero) jb L(ret_zero)
# ifdef USE_AS_WCSCMP
/* 'nbe' covers the case where length is negative (large /* 'nbe' covers the case where length is negative (large
unsigned). */ unsigned). */
jnbe __wcscmp_avx2 jnbe OVERFLOW_STRCMP
# ifdef USE_AS_WCSCMP
movl (%rdi), %edx movl (%rdi), %edx
xorl %eax, %eax xorl %eax, %eax
cmpl (%rsi), %edx cmpl (%rsi), %edx
@@ -205,10 +205,6 @@ L(one_or_less):
negl %eax negl %eax
orl $1, %eax orl $1, %eax
# else # else
/* 'nbe' covers the case where length is negative (large
unsigned). */
jnbe __strcmp_avx2
movzbl (%rdi), %eax movzbl (%rdi), %eax
movzbl (%rsi), %ecx movzbl (%rsi), %ecx
subl %ecx, %eax subl %ecx, %eax

1
sysdeps/x86_64/multiarch/strncmp-avx2-rtm.S
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@@ -1,3 +1,4 @@
#define STRCMP __strncmp_avx2_rtm #define STRCMP __strncmp_avx2_rtm
#define USE_AS_STRNCMP 1 #define USE_AS_STRNCMP 1
#define OVERFLOW_STRCMP __strcmp_avx2_rtm
#include "strcmp-avx2-rtm.S" #include "strcmp-avx2-rtm.S"

1
sysdeps/x86_64/multiarch/strncmp-avx2.S
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@@ -1,3 +1,4 @@
#define STRCMP __strncmp_avx2 #define STRCMP __strncmp_avx2
#define USE_AS_STRNCMP 1 #define USE_AS_STRNCMP 1
#define OVERFLOW_STRCMP __strcmp_avx2
#include "strcmp-avx2.S" #include "strcmp-avx2.S"

2
sysdeps/x86_64/multiarch/wcsncmp-avx2-rtm.S
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@@ -1,5 +1,5 @@
#define STRCMP __wcsncmp_avx2_rtm #define STRCMP __wcsncmp_avx2_rtm
#define USE_AS_STRNCMP 1 #define USE_AS_STRNCMP 1
#define USE_AS_WCSCMP 1 #define USE_AS_WCSCMP 1
#define OVERFLOW_STRCMP __wcscmp_avx2_rtm
#include "strcmp-avx2-rtm.S" #include "strcmp-avx2-rtm.S"

2
sysdeps/x86_64/multiarch/wcsncmp-avx2.S
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@@ -1,5 +1,5 @@
#define STRCMP __wcsncmp_avx2 #define STRCMP __wcsncmp_avx2
#define USE_AS_STRNCMP 1 #define USE_AS_STRNCMP 1
#define USE_AS_WCSCMP 1 #define USE_AS_WCSCMP 1
#define OVERFLOW_STRCMP __wcscmp_avx2
#include "strcmp-avx2.S" #include "strcmp-avx2.S"