diff mbox series

x86-64: Use notl in EVEX strcmp [BZ #28646]

Message ID 20211204032420.3158-1-hjl.tools@gmail.com
State Committed
Commit 4df1fa6ddc8925a75f3da644d5da3bb16eb33f02
Headers show
Series x86-64: Use notl in EVEX strcmp [BZ #28646] | expand

Checks

Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent
dj/TryBot-32bit success Build for i686

Commit Message

H.J. Lu Dec. 4, 2021, 3:24 a.m. UTC
From: Noah Goldstein <goldstein.w.n@gmail.com>

Must use notl %edi here as lower bits are for CHAR comparisons
potentially out of range thus can be 0 without indicating mismatch.
This fixes BZ #28646.

Co-Authored-By: H.J. Lu <hjl.tools@gmail.com>
---
 string/test-strcmp.c                   | 28 ++++++++++++++++++++++++++
 sysdeps/x86_64/multiarch/strcmp-evex.S | 14 +++++++------
 2 files changed, 36 insertions(+), 6 deletions(-)

Comments

Noah Goldstein Dec. 4, 2021, 3:50 a.m. UTC | #1
On Fri, Dec 3, 2021 at 9:24 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> From: Noah Goldstein <goldstein.w.n@gmail.com>
>
> Must use notl %edi here as lower bits are for CHAR comparisons
> potentially out of range thus can be 0 without indicating mismatch.
> This fixes BZ #28646.
>
> Co-Authored-By: H.J. Lu <hjl.tools@gmail.com>
> ---
>  string/test-strcmp.c                   | 28 ++++++++++++++++++++++++++
>  sysdeps/x86_64/multiarch/strcmp-evex.S | 14 +++++++------
>  2 files changed, 36 insertions(+), 6 deletions(-)
>
> diff --git a/string/test-strcmp.c b/string/test-strcmp.c
> index 77ae73110f..42178a260b 100644
> --- a/string/test-strcmp.c
> +++ b/string/test-strcmp.c
> @@ -23,6 +23,7 @@
>  # define TEST_NAME "strcmp"
>  #endif
>  #include "test-string.h"
> +#include <support/test-driver.h>
>
>  #ifdef WIDE
>  # include <wchar.h>
> @@ -390,6 +391,32 @@ check2 (void)
>         }
>  }
>
> +static void
> +check3 (void)
> +{
> +  size_t size = 0xd000 + 0x4000;
> +  CHAR *s1, *s2;
> +  CHAR *buffer1 = mmap (NULL, size, PROT_READ | PROT_WRITE,
> +                       MAP_PRIVATE | MAP_ANON, -1, 0);
> +  CHAR *buffer2 = mmap (NULL, size, PROT_READ | PROT_WRITE,
> +                       MAP_PRIVATE | MAP_ANON, -1, 0);
> +  if (buffer1 == MAP_FAILED || buffer1 == MAP_FAILED)
> +    error (EXIT_UNSUPPORTED, errno, "mmap failed");
> +
> +  s1 = (CHAR *) (buffer1 + 0x8f8 / sizeof (CHAR));
> +  s2 = (CHAR *) (buffer2 + 0xcff3 / sizeof (CHAR));
> +
> +  STRCPY(s1, L("/export/redhat/rpms/BUILD/java-1.8.0-openjdk-1.8.0.312.b07-2.fc35.x86_64/openjdk/langtools/src/share/classes/com/sun/tools/doclets/internal/toolkit/util/PathDocFileFactory.java"));
> +  STRCPY(s2, L("/export/redhat/rpms/BUILD/java-1.8.0-openjdk-1.8.0.312.b07-2.fc35.x86_64/openjdk/langtools/src/share/classes/com/sun/tools/doclets/internal/toolkit/taglets/ThrowsTaglet.java"));
> +
> +  int exp_result = SIMPLE_STRCMP (s1, s2);
> +  FOR_EACH_IMPL (impl, 0)
> +    check_result (impl, s1, s2, exp_result);
> +
> +  munmap ((void *) buffer1, size);
> +  munmap ((void *) buffer2, size);
> +}
> +
>  int
>  test_main (void)
>  {
> @@ -398,6 +425,7 @@ test_main (void)
>    test_init ();
>    check();
>    check2 ();
> +  check3 ();
>
>    printf ("%23s", "");
>    FOR_EACH_IMPL (impl, 0)
> diff --git a/sysdeps/x86_64/multiarch/strcmp-evex.S b/sysdeps/x86_64/multiarch/strcmp-evex.S
> index 0bea318abd..b68e1f7a1e 100644
> --- a/sysdeps/x86_64/multiarch/strcmp-evex.S
> +++ b/sysdeps/x86_64/multiarch/strcmp-evex.S
> @@ -646,12 +646,13 @@ L(loop_cross_page):
>            in YMM3 and 32 bytes at VEC_SIZE(%rdx, %r10).  */
>         VPCMP   $0, VEC_SIZE(%rdx, %r10), %YMM3, %k3{%k4}
>         kmovd   %k3, %edi
> +    /* Must use notl %edi here as lower bits are for CHAR
> +          comparisons potentially out of range thus can be 0 without
> +          indicating mismatch.  */
> +       notl    %edi
>  # ifdef USE_AS_WCSCMP
>         /* Don't use subl since it is the upper 8 bits of EDI below.  */
> -       notl    %edi
>         andl    $0xff, %edi
> -# else
> -       incl    %edi
>  # endif
>
>  # ifdef USE_AS_WCSCMP
> @@ -733,12 +734,13 @@ L(loop_cross_page_2_vec):
>            in YMM1 and 32 bytes at (VEC_SIZE * 3)(%rdx, %r10).  */
>         VPCMP   $0, (VEC_SIZE * 3)(%rdx, %r10), %YMM1, %k3{%k4}
>         kmovd   %k3, %edi
> +       /* Must use notl %edi here as lower bits are for CHAR
> +          comparisons potentially out of range thus can be 0 without
> +          indicating mismatch.  */
> +       notl    %edi
>  # ifdef USE_AS_WCSCMP
>         /* Don't use subl since it is the upper 8 bits of EDI below.  */
> -       notl    %edi
>         andl    $0xff, %edi
> -# else
> -       incl    %edi
>  # endif
>
>  # ifdef USE_AS_WCSCMP
> --
> 2.33.1
>

LGTM
Andreas Schwab Dec. 4, 2021, 8:14 a.m. UTC | #2
On Dez 03 2021, H.J. Lu via Libc-alpha wrote:

> diff --git a/sysdeps/x86_64/multiarch/strcmp-evex.S b/sysdeps/x86_64/multiarch/strcmp-evex.S
> index 0bea318abd..b68e1f7a1e 100644
> --- a/sysdeps/x86_64/multiarch/strcmp-evex.S
> +++ b/sysdeps/x86_64/multiarch/strcmp-evex.S
> @@ -646,12 +646,13 @@ L(loop_cross_page):
>  	   in YMM3 and 32 bytes at VEC_SIZE(%rdx, %r10).  */
>  	VPCMP	$0, VEC_SIZE(%rdx, %r10), %YMM3, %k3{%k4}
>  	kmovd	%k3, %edi
> +    /* Must use notl %edi here as lower bits are for CHAR
> +	   comparisons potentially out of range thus can be 0 without
> +	   indicating mismatch.  */
> +	notl	%edi

Spacing off in the first line.

Andreas.
Sunil K Pandey April 23, 2022, 1:49 a.m. UTC | #3
On Fri, Dec 3, 2021 at 7:50 PM Noah Goldstein via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> On Fri, Dec 3, 2021 at 9:24 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > From: Noah Goldstein <goldstein.w.n@gmail.com>
> >
> > Must use notl %edi here as lower bits are for CHAR comparisons
> > potentially out of range thus can be 0 without indicating mismatch.
> > This fixes BZ #28646.
> >
> > Co-Authored-By: H.J. Lu <hjl.tools@gmail.com>
> > ---
> >  string/test-strcmp.c                   | 28 ++++++++++++++++++++++++++
> >  sysdeps/x86_64/multiarch/strcmp-evex.S | 14 +++++++------
> >  2 files changed, 36 insertions(+), 6 deletions(-)
> >
> > diff --git a/string/test-strcmp.c b/string/test-strcmp.c
> > index 77ae73110f..42178a260b 100644
> > --- a/string/test-strcmp.c
> > +++ b/string/test-strcmp.c
> > @@ -23,6 +23,7 @@
> >  # define TEST_NAME "strcmp"
> >  #endif
> >  #include "test-string.h"
> > +#include <support/test-driver.h>
> >
> >  #ifdef WIDE
> >  # include <wchar.h>
> > @@ -390,6 +391,32 @@ check2 (void)
> >         }
> >  }
> >
> > +static void
> > +check3 (void)
> > +{
> > +  size_t size = 0xd000 + 0x4000;
> > +  CHAR *s1, *s2;
> > +  CHAR *buffer1 = mmap (NULL, size, PROT_READ | PROT_WRITE,
> > +                       MAP_PRIVATE | MAP_ANON, -1, 0);
> > +  CHAR *buffer2 = mmap (NULL, size, PROT_READ | PROT_WRITE,
> > +                       MAP_PRIVATE | MAP_ANON, -1, 0);
> > +  if (buffer1 == MAP_FAILED || buffer1 == MAP_FAILED)
> > +    error (EXIT_UNSUPPORTED, errno, "mmap failed");
> > +
> > +  s1 = (CHAR *) (buffer1 + 0x8f8 / sizeof (CHAR));
> > +  s2 = (CHAR *) (buffer2 + 0xcff3 / sizeof (CHAR));
> > +
> > +  STRCPY(s1, L("/export/redhat/rpms/BUILD/java-1.8.0-openjdk-1.8.0.312.b07-2.fc35.x86_64/openjdk/langtools/src/share/classes/com/sun/tools/doclets/internal/toolkit/util/PathDocFileFactory.java"));
> > +  STRCPY(s2, L("/export/redhat/rpms/BUILD/java-1.8.0-openjdk-1.8.0.312.b07-2.fc35.x86_64/openjdk/langtools/src/share/classes/com/sun/tools/doclets/internal/toolkit/taglets/ThrowsTaglet.java"));
> > +
> > +  int exp_result = SIMPLE_STRCMP (s1, s2);
> > +  FOR_EACH_IMPL (impl, 0)
> > +    check_result (impl, s1, s2, exp_result);
> > +
> > +  munmap ((void *) buffer1, size);
> > +  munmap ((void *) buffer2, size);
> > +}
> > +
> >  int
> >  test_main (void)
> >  {
> > @@ -398,6 +425,7 @@ test_main (void)
> >    test_init ();
> >    check();
> >    check2 ();
> > +  check3 ();
> >
> >    printf ("%23s", "");
> >    FOR_EACH_IMPL (impl, 0)
> > diff --git a/sysdeps/x86_64/multiarch/strcmp-evex.S b/sysdeps/x86_64/multiarch/strcmp-evex.S
> > index 0bea318abd..b68e1f7a1e 100644
> > --- a/sysdeps/x86_64/multiarch/strcmp-evex.S
> > +++ b/sysdeps/x86_64/multiarch/strcmp-evex.S
> > @@ -646,12 +646,13 @@ L(loop_cross_page):
> >            in YMM3 and 32 bytes at VEC_SIZE(%rdx, %r10).  */
> >         VPCMP   $0, VEC_SIZE(%rdx, %r10), %YMM3, %k3{%k4}
> >         kmovd   %k3, %edi
> > +    /* Must use notl %edi here as lower bits are for CHAR
> > +          comparisons potentially out of range thus can be 0 without
> > +          indicating mismatch.  */
> > +       notl    %edi
> >  # ifdef USE_AS_WCSCMP
> >         /* Don't use subl since it is the upper 8 bits of EDI below.  */
> > -       notl    %edi
> >         andl    $0xff, %edi
> > -# else
> > -       incl    %edi
> >  # endif
> >
> >  # ifdef USE_AS_WCSCMP
> > @@ -733,12 +734,13 @@ L(loop_cross_page_2_vec):
> >            in YMM1 and 32 bytes at (VEC_SIZE * 3)(%rdx, %r10).  */
> >         VPCMP   $0, (VEC_SIZE * 3)(%rdx, %r10), %YMM1, %k3{%k4}
> >         kmovd   %k3, %edi
> > +       /* Must use notl %edi here as lower bits are for CHAR
> > +          comparisons potentially out of range thus can be 0 without
> > +          indicating mismatch.  */
> > +       notl    %edi
> >  # ifdef USE_AS_WCSCMP
> >         /* Don't use subl since it is the upper 8 bits of EDI below.  */
> > -       notl    %edi
> >         andl    $0xff, %edi
> > -# else
> > -       incl    %edi
> >  # endif
> >
> >  # ifdef USE_AS_WCSCMP
> > --
> > 2.33.1
> >
>
> LGTM

I would like to backport this patch to release branches.
Any comments or objections?

--Sunil
diff mbox series

Patch

diff --git a/string/test-strcmp.c b/string/test-strcmp.c
index 77ae73110f..42178a260b 100644
--- a/string/test-strcmp.c
+++ b/string/test-strcmp.c
@@ -23,6 +23,7 @@ 
 # define TEST_NAME "strcmp"
 #endif
 #include "test-string.h"
+#include <support/test-driver.h>
 
 #ifdef WIDE
 # include <wchar.h>
@@ -390,6 +391,32 @@  check2 (void)
 	}
 }
 
+static void
+check3 (void)
+{
+  size_t size = 0xd000 + 0x4000;
+  CHAR *s1, *s2;
+  CHAR *buffer1 = mmap (NULL, size, PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANON, -1, 0);
+  CHAR *buffer2 = mmap (NULL, size, PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANON, -1, 0);
+  if (buffer1 == MAP_FAILED || buffer1 == MAP_FAILED)
+    error (EXIT_UNSUPPORTED, errno, "mmap failed");
+
+  s1 = (CHAR *) (buffer1 + 0x8f8 / sizeof (CHAR));
+  s2 = (CHAR *) (buffer2 + 0xcff3 / sizeof (CHAR));
+
+  STRCPY(s1, L("/export/redhat/rpms/BUILD/java-1.8.0-openjdk-1.8.0.312.b07-2.fc35.x86_64/openjdk/langtools/src/share/classes/com/sun/tools/doclets/internal/toolkit/util/PathDocFileFactory.java"));
+  STRCPY(s2, L("/export/redhat/rpms/BUILD/java-1.8.0-openjdk-1.8.0.312.b07-2.fc35.x86_64/openjdk/langtools/src/share/classes/com/sun/tools/doclets/internal/toolkit/taglets/ThrowsTaglet.java"));
+
+  int exp_result = SIMPLE_STRCMP (s1, s2);
+  FOR_EACH_IMPL (impl, 0)
+    check_result (impl, s1, s2, exp_result);
+
+  munmap ((void *) buffer1, size);
+  munmap ((void *) buffer2, size);
+}
+
 int
 test_main (void)
 {
@@ -398,6 +425,7 @@  test_main (void)
   test_init ();
   check();
   check2 ();
+  check3 ();
 
   printf ("%23s", "");
   FOR_EACH_IMPL (impl, 0)
diff --git a/sysdeps/x86_64/multiarch/strcmp-evex.S b/sysdeps/x86_64/multiarch/strcmp-evex.S
index 0bea318abd..b68e1f7a1e 100644
--- a/sysdeps/x86_64/multiarch/strcmp-evex.S
+++ b/sysdeps/x86_64/multiarch/strcmp-evex.S
@@ -646,12 +646,13 @@  L(loop_cross_page):
 	   in YMM3 and 32 bytes at VEC_SIZE(%rdx, %r10).  */
 	VPCMP	$0, VEC_SIZE(%rdx, %r10), %YMM3, %k3{%k4}
 	kmovd	%k3, %edi
+    /* Must use notl %edi here as lower bits are for CHAR
+	   comparisons potentially out of range thus can be 0 without
+	   indicating mismatch.  */
+	notl	%edi
 # ifdef USE_AS_WCSCMP
 	/* Don't use subl since it is the upper 8 bits of EDI below.  */
-	notl	%edi
 	andl	$0xff, %edi
-# else
-	incl	%edi
 # endif
 
 # ifdef USE_AS_WCSCMP
@@ -733,12 +734,13 @@  L(loop_cross_page_2_vec):
 	   in YMM1 and 32 bytes at (VEC_SIZE * 3)(%rdx, %r10).  */
 	VPCMP	$0, (VEC_SIZE * 3)(%rdx, %r10), %YMM1, %k3{%k4}
 	kmovd	%k3, %edi
+	/* Must use notl %edi here as lower bits are for CHAR
+	   comparisons potentially out of range thus can be 0 without
+	   indicating mismatch.  */
+	notl	%edi
 # ifdef USE_AS_WCSCMP
 	/* Don't use subl since it is the upper 8 bits of EDI below.  */
-	notl	%edi
 	andl	$0xff, %edi
-# else
-	incl	%edi
 # endif
 
 # ifdef USE_AS_WCSCMP