From 8f2267e67ea924c949ca4a70a0d2c484d81a8fc9 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

 #28896]

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/Makefile                        |  2 +-

 sysdeps/x86/tst-strncmp-rtm.c               | 17 ++++++++++++++++-

 sysdeps/x86_64/multiarch/strcmp-avx2.S      |  2 +-

 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, 22 insertions(+), 5 deletions(-)

diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile

index 5be71ada..2d814915 100644

--- a/sysdeps/x86/Makefile

+++ b/sysdeps/x86/Makefile

@@ -38,7 +38,7 @@ 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 236ad951..4d0004b5 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 5d1c9d90..433ae047 100644

--- a/sysdeps/x86_64/multiarch/strcmp-avx2.S

+++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S

@@ -95,7 +95,7 @@ ENTRY (STRCMP)

 	   length to bound a valid memory region. In these cases just use

 	   'wcscmp'.  */

 	shrq	$56, %rcx

-	jnz	__wcscmp_avx2

+	jnz	OVERFLOW_STRCMP

 #  endif

 	/* Convert units: from wide to byte char.  */

 	shl	$2, %RDX_LP

diff --git a/sysdeps/x86_64/multiarch/strncmp-avx2-rtm.S b/sysdeps/x86_64/multiarch/strncmp-avx2-rtm.S

index 37d1224b..68bad365 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 1678bcc2..f138e9f1 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 4e88c70c..f467582c 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 4fa1de4d..e9ede522 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"

-- 

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