diff mbox series

[v1,12/23] x86: Fix fallback for wcsncmp_avx2 in strcmp-avx2.S [BZ #28896]

Message ID 20220323215734.3927131-12-goldstein.w.n@gmail.com
State Superseded, archived
Headers
Series [v1,01/23] benchtests: Use json-lib in bench-strchr.c |

Checks

Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent

Commit Message

Noah Goldstein March 23, 2022, 9:57 p.m. UTC 
  Overflow case for __wcsncmp_avx2_rtm should be __wcscmp_avx2_rtm not
__wcscmp_avx2.

All string/memory tests pass.
---
 sysdeps/x86_64/multiarch/strcmp-avx2.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

H.J. Lu March 24, 2022, 6:59 p.m. UTC | #1 
On Wed, Mar 23, 2022 at 3:01 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> Overflow case for __wcsncmp_avx2_rtm should be __wcscmp_avx2_rtm not
> __wcscmp_avx2.
>
> All string/memory tests pass.
> ---
>  sysdeps/x86_64/multiarch/strcmp-avx2.S | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S
> index 52ff5ad724..86a86b68e3 100644
> --- a/sysdeps/x86_64/multiarch/strcmp-avx2.S
> +++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S
> @@ -122,7 +122,7 @@ ENTRY(STRCMP)
>            are cases where length is large enough that it can never be a
>            bound on valid memory so just use wcscmp.  */
>         shrq    $56, %rcx
> -       jnz     __wcscmp_avx2
> +       jnz     OVERFLOW_STRCMP
>
>         leaq    (, %rdx, 4), %rdx
>  #  endif
> --
> 2.25.1
>

Isn't it a bug?  Is there a glibc bug? Should this also be fixed on release
branches?
Noah Goldstein March 24, 2022, 7:18 p.m. UTC | #2 
On Thu, Mar 24, 2022 at 2:00 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Wed, Mar 23, 2022 at 3:01 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> >
> > Overflow case for __wcsncmp_avx2_rtm should be __wcscmp_avx2_rtm not
> > __wcscmp_avx2.
> >
> > All string/memory tests pass.
> > ---
> >  sysdeps/x86_64/multiarch/strcmp-avx2.S | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S
> > index 52ff5ad724..86a86b68e3 100644
> > --- a/sysdeps/x86_64/multiarch/strcmp-avx2.S
> > +++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S
> > @@ -122,7 +122,7 @@ ENTRY(STRCMP)
> >            are cases where length is large enough that it can never be a
> >            bound on valid memory so just use wcscmp.  */
> >         shrq    $56, %rcx
> > -       jnz     __wcscmp_avx2
> > +       jnz     OVERFLOW_STRCMP
> >
> >         leaq    (, %rdx, 4), %rdx
> >  #  endif
> > --
> > 2.25.1
> >
>
> Isn't it a bug?  Is there a glibc bug? Should this also be fixed on release
> branches?

It is bug but no need for backport.
>
> --
> H.J.
H.J. Lu March 24, 2022, 7:34 p.m. UTC | #3 
On Thu, Mar 24, 2022 at 12:18 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> On Thu, Mar 24, 2022 at 2:00 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > On Wed, Mar 23, 2022 at 3:01 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> > >
> > > Overflow case for __wcsncmp_avx2_rtm should be __wcscmp_avx2_rtm not
> > > __wcscmp_avx2.
> > >
> > > All string/memory tests pass.
> > > ---
> > >  sysdeps/x86_64/multiarch/strcmp-avx2.S | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S
> > > index 52ff5ad724..86a86b68e3 100644
> > > --- a/sysdeps/x86_64/multiarch/strcmp-avx2.S
> > > +++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S
> > > @@ -122,7 +122,7 @@ ENTRY(STRCMP)
> > >            are cases where length is large enough that it can never be a
> > >            bound on valid memory so just use wcscmp.  */
> > >         shrq    $56, %rcx
> > > -       jnz     __wcscmp_avx2
> > > +       jnz     OVERFLOW_STRCMP
> > >
> > >         leaq    (, %rdx, 4), %rdx
> > >  #  endif
> > > --
> > > 2.25.1
> > >
> >
> > Isn't it a bug?  Is there a glibc bug? Should this also be fixed on release
> > branches?
>
> It is bug but no need for backport.

Why no need for backport? Is there a testcase?
Noah Goldstein March 24, 2022, 7:39 p.m. UTC | #4 
On Thu, Mar 24, 2022 at 2:34 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Thu, Mar 24, 2022 at 12:18 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> >
> > On Thu, Mar 24, 2022 at 2:00 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> > >
> > > On Wed, Mar 23, 2022 at 3:01 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> > > >
> > > > Overflow case for __wcsncmp_avx2_rtm should be __wcscmp_avx2_rtm not
> > > > __wcscmp_avx2.
> > > >
> > > > All string/memory tests pass.
> > > > ---
> > > >  sysdeps/x86_64/multiarch/strcmp-avx2.S | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S
> > > > index 52ff5ad724..86a86b68e3 100644
> > > > --- a/sysdeps/x86_64/multiarch/strcmp-avx2.S
> > > > +++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S
> > > > @@ -122,7 +122,7 @@ ENTRY(STRCMP)
> > > >            are cases where length is large enough that it can never be a
> > > >            bound on valid memory so just use wcscmp.  */
> > > >         shrq    $56, %rcx
> > > > -       jnz     __wcscmp_avx2
> > > > +       jnz     OVERFLOW_STRCMP
> > > >
> > > >         leaq    (, %rdx, 4), %rdx
> > > >  #  endif
> > > > --
> > > > 2.25.1
> > > >
> > >
> > > Isn't it a bug?  Is there a glibc bug? Should this also be fixed on release
> > > branches?
> >
> > It is bug but no need for backport.
>
> Why no need for backport? Is there a testcase?

Oh no, you're right. It needs to be backported. Had thought it was a different
commit that introduced.

Sorry, I'll update the commit message with more info, ping on the bugzilla,
and add a test case.

Going to push the rest of the patchset, will add v2 for this shortly.
>
> --
> H.J.
diff mbox series

Patch

diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S
index 52ff5ad724..86a86b68e3 100644
--- a/sysdeps/x86_64/multiarch/strcmp-avx2.S
+++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S
@@ -122,7 +122,7 @@  ENTRY(STRCMP)
 	   are cases where length is large enough that it can never be a
 	   bound on valid memory so just use wcscmp.  */
 	shrq	$56, %rcx
-	jnz	__wcscmp_avx2
+	jnz	OVERFLOW_STRCMP
 
 	leaq	(, %rdx, 4), %rdx
 #  endif