* Re: [PATCH v5] x86: Fallback {str|wcs}cmp RTM in the ncmp overflow case [BZ #28896]
[not found] ` <CAMe9rOo9mvpH+vPeZJTOvw8CmR1GuRY305GiB+1TqOV482mPdg@mail.gmail.com>
@ 2022-05-25 19:51 ` Sunil Pandey
2022-05-25 19:56 ` H.J. Lu
0 siblings, 1 reply; 2+ messages in thread
From: Sunil Pandey @ 2022-05-25 19:51 UTC (permalink / raw)
To: H.J. Lu, Libc-stable Mailing List; +Cc: Noah Goldstein, GNU C Library
[-- Attachment #1: Type: text/plain, Size: 5570 bytes --]
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
[-- Attachment #2: 0001-x86-Fallback-str-wcs-cmp-RTM-in-the-ncmp-overflow-ca.patch --]
[-- Type: application/octet-stream, Size: 1770 bytes --]
From 3ffb50c2fdbfabcc098289d863be13d250898acb Mon Sep 17 00:00:00 2001
From: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Tue, 15 Feb 2022 08:18:15 -0600
Subject: [PATCH] x86: Fallback {str|wcs}cmp RTM in the ncmp overflow case [BZ
#29127]
Re-cherry-pick commit c627209832 for strcmp-avx2.S change which was
omitted in intial cherry pick because at the time this bug was not
present on release branch.
Fixes BZ #29127.
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>
(cherry picked from commit c6272098323153db373f2986c67786ea8c85f1cf)
---
sysdeps/x86_64/multiarch/strcmp-avx2.S | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S
index 3366d0b083..8da09bd86d 100644
--- a/sysdeps/x86_64/multiarch/strcmp-avx2.S
+++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S
@@ -345,10 +345,10 @@ L(one_or_less):
movq %LOCALE_REG, %rdx
# endif
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
@@ -357,10 +357,6 @@ 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
TOLOWER_gpr (%rax, %eax)
--
2.35.3
^ permalink raw reply [flat|nested] 2+ messages in thread