[PATCH v5] x86: Fallback {str|wcs}cmp RTM in the ncmp overflow case [BZ #28896]
H.J. Lu
hjl.tools@gmail.com
Wed May 25 19:56:39 GMT 2022
On Wed, May 25, 2022 at 12:52 PM Sunil Pandey <skpgkp2@gmail.com> wrote:
>
> On Thu, Feb 17, 2022 at 11:21 AM H.J. Lu via Libc-alpha
> <libc-alpha@sourceware.org> wrote:
> >
> > On Thu, Feb 17, 2022 at 11:15 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> > >
> > > In the overflow fallback strncmp-avx2-rtm and wcsncmp-avx2-rtm would
> > > call strcmp-avx2 and wcsncmp-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>
> > > ---
> > > sysdeps/x86/Makefile | 2 +-
> > > sysdeps/x86/tst-strncmp-rtm.c | 17 ++++++++++++++++-
> > > sysdeps/x86_64/multiarch/strcmp-avx2.S | 8 ++------
> > > sysdeps/x86_64/multiarch/strncmp-avx2-rtm.S | 1 +
> > > sysdeps/x86_64/multiarch/strncmp-avx2.S | 1 +
> > > sysdeps/x86_64/multiarch/wcsncmp-avx2-rtm.S | 2 +-
> > > sysdeps/x86_64/multiarch/wcsncmp-avx2.S | 2 +-
> > > 7 files changed, 23 insertions(+), 10 deletions(-)
> > >
> > > diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
> > > index 6cf708335c..d110f7b7f2 100644
> > > --- a/sysdeps/x86/Makefile
> > > +++ b/sysdeps/x86/Makefile
> > > @@ -109,7 +109,7 @@ CFLAGS-tst-memset-rtm.c += -mrtm
> > > CFLAGS-tst-strchr-rtm.c += -mrtm
> > > CFLAGS-tst-strcpy-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
> > > endif
> > >
> > > diff --git a/sysdeps/x86/tst-strncmp-rtm.c b/sysdeps/x86/tst-strncmp-rtm.c
> > > index 09ed6fa0d6..9e20abaacc 100644
> > > --- a/sysdeps/x86/tst-strncmp-rtm.c
> > > +++ b/sysdeps/x86/tst-strncmp-rtm.c
> > > @@ -16,6 +16,7 @@
> > > License along with the GNU C Library; if not, see
> > > <https://www.gnu.org/licenses/>. */
> > >
> > > +#include <stdint.h>
> > > #include <tst-string-rtm.h>
> > >
> > > #define LOOP 3000
> > > @@ -45,8 +46,22 @@ function (void)
> > > return 1;
> > > }
> > >
> > > +__attribute__ ((noinline, noclone))
> > > +static int
> > > +function_overflow (void)
> > > +{
> > > + if (strncmp (string1, string2, SIZE_MAX) == 0)
> > > + return 0;
> > > + else
> > > + return 1;
> > > +}
> > > +
> > > static int
> > > 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;
> > > }
> > > diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S
> > > index 07a5a2c889..52ff5ad724 100644
> > > --- a/sysdeps/x86_64/multiarch/strcmp-avx2.S
> > > +++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S
> > > @@ -193,10 +193,10 @@ L(ret_zero):
> > > .p2align 4,, 5
> > > L(one_or_less):
> > > jb L(ret_zero)
> > > -# ifdef USE_AS_WCSCMP
> > > /* 'nbe' covers the case where length is negative (large
> > > unsigned). */
> > > - jnbe __wcscmp_avx2
> > > + jnbe OVERFLOW_STRCMP
> > > +# ifdef USE_AS_WCSCMP
> > > movl (%rdi), %edx
> > > xorl %eax, %eax
> > > cmpl (%rsi), %edx
> > > @@ -205,10 +205,6 @@ L(one_or_less):
> > > negl %eax
> > > orl $1, %eax
> > > # else
> > > - /* 'nbe' covers the case where length is negative (large
> > > - unsigned). */
> > > -
> > > - jnbe __strcmp_avx2
> > > movzbl (%rdi), %eax
> > > movzbl (%rsi), %ecx
> > > subl %ecx, %eax
> > > diff --git a/sysdeps/x86_64/multiarch/strncmp-avx2-rtm.S b/sysdeps/x86_64/multiarch/strncmp-avx2-rtm.S
> > > index 37d1224bb9..68bad365ba 100644
> > > --- a/sysdeps/x86_64/multiarch/strncmp-avx2-rtm.S
> > > +++ b/sysdeps/x86_64/multiarch/strncmp-avx2-rtm.S
> > > @@ -1,3 +1,4 @@
> > > #define STRCMP __strncmp_avx2_rtm
> > > #define USE_AS_STRNCMP 1
> > > +#define OVERFLOW_STRCMP __strcmp_avx2_rtm
> > > #include "strcmp-avx2-rtm.S"
> > > diff --git a/sysdeps/x86_64/multiarch/strncmp-avx2.S b/sysdeps/x86_64/multiarch/strncmp-avx2.S
> > > index 1678bcc235..f138e9f1fd 100644
> > > --- a/sysdeps/x86_64/multiarch/strncmp-avx2.S
> > > +++ b/sysdeps/x86_64/multiarch/strncmp-avx2.S
> > > @@ -1,3 +1,4 @@
> > > #define STRCMP __strncmp_avx2
> > > #define USE_AS_STRNCMP 1
> > > +#define OVERFLOW_STRCMP __strcmp_avx2
> > > #include "strcmp-avx2.S"
> > > diff --git a/sysdeps/x86_64/multiarch/wcsncmp-avx2-rtm.S b/sysdeps/x86_64/multiarch/wcsncmp-avx2-rtm.S
> > > index 4e88c70cc6..f467582cbe 100644
> > > --- a/sysdeps/x86_64/multiarch/wcsncmp-avx2-rtm.S
> > > +++ b/sysdeps/x86_64/multiarch/wcsncmp-avx2-rtm.S
> > > @@ -1,5 +1,5 @@
> > > #define STRCMP __wcsncmp_avx2_rtm
> > > #define USE_AS_STRNCMP 1
> > > #define USE_AS_WCSCMP 1
> > > -
> > > +#define OVERFLOW_STRCMP __wcscmp_avx2_rtm
> > > #include "strcmp-avx2-rtm.S"
> > > diff --git a/sysdeps/x86_64/multiarch/wcsncmp-avx2.S b/sysdeps/x86_64/multiarch/wcsncmp-avx2.S
> > > index 4fa1de4d3f..e9ede522b8 100644
> > > --- a/sysdeps/x86_64/multiarch/wcsncmp-avx2.S
> > > +++ b/sysdeps/x86_64/multiarch/wcsncmp-avx2.S
> > > @@ -1,5 +1,5 @@
> > > #define STRCMP __wcsncmp_avx2
> > > #define USE_AS_STRNCMP 1
> > > #define USE_AS_WCSCMP 1
> > > -
> > > +#define OVERFLOW_STRCMP __wcscmp_avx2
> > > #include "strcmp-avx2.S"
> > > --
> > > 2.25.1
> > >
> >
> > LGTM.
> >
> > Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
> >
> > Thanks.
> >
> > --
> > H.J.
>
> I would like to backport this patch to release branches.
> Any comments or objections?
>
> Patch attached, it fixes BZ# 29127.
>
> --Sunil
LGTM.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Thanks.
--
H.J.
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