[PATCH] x86: Fix bug about glibc.cpu.hwcaps.

[Noah Goldstein]

On Tue, Mar 7, 2023 at 7:18 AM caiyinyu <caiyinyu@loongson.cn> wrote:
>
>
> 在 2023/3/7 下午9:02, Xi Ruoyao 写道:
> > On Tue, 2023-03-07 at 20:45 +0800, caiyinyu wrote:
> >> 在 2023/3/2 下午12:22, H.J. Lu 写道:
> >>> On Wed, Mar 1, 2023 at 6:36 PM caiyinyu <caiyinyu@loongson.cn>
> >>> wrote:
> >>>> Recorded in [BZ #30183]:
> >>>>
> >>>> 1. export GLIBC_TUNABLES=glibc.cpu.hwcaps=-AVX512
> >>>> 2. Add  _dl_printf("p -- %s\n", p); just before switch(nl) in
> >>>>      sysdeps/x86/cpu-tunables.c
> >>>> 3. compiled and run ./testrun.sh /usr/bin/ls
> >>>> you will get:
> >>>>
> >>>> p -- -AVX512
> >>>> p -- LC_ADDRESS=en_US.UTF-8
> >>>> p -- LC_NUMERIC=C
> >>>> ...
> >>>>
> >>>> The function, TUNABLE_CALLBACK (set_hwcaps)
> >>>> (tunable_val_t *valp), checks far more than it should and it
> >>>> should stop at end of "-AVX512".
> >>>> ---
> >>>>    sysdeps/x86/cpu-tunables.c | 6 +++---
> >>>>    1 file changed, 3 insertions(+), 3 deletions(-)
> >>>>
> >>>> diff --git a/sysdeps/x86/cpu-tunables.c b/sysdeps/x86/cpu-
> >>>> tunables.c
> >>>> index d3e1367bda..772fb0c4c2 100644
> >>>> --- a/sysdeps/x86/cpu-tunables.c
> >>>> +++ b/sysdeps/x86/cpu-tunables.c
> >>>> @@ -107,13 +107,13 @@ TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t
> >>>> *valp)
> >>>>         NOTE: the IFUNC selection may change over time.  Please
> >>>> check all
> >>>>         multiarch implementations when experimenting.  */
> >>>>
> >>>> -  const char *p = valp->strval;
> >>>> +  const char *p = valp->strval, *c;
> >>>>      struct cpu_features *cpu_features =
> >>>> &GLRO(dl_x86_cpu_features);
> >>>>      size_t len;
> >>>>
> >>>>      do
> >>>>        {
> >>>> -      const char *c, *n;
> >>>> +      const char *n;
> >>>>          bool disable;
> >>>>          size_t nl;
> >>>>
> >>>> @@ -283,7 +283,7 @@ TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t
> >>>> *valp)
> >>>>           }
> >>>>          p += len + 1;
> >>>>        }
> >>>> -  while (*p != '\0');
> >>>> +  while (*c != '\0');
> >>>>    }
> >>>>
> >>>>    # if CET_ENABLED
> >>>> --
> >>>> 2.31.1
> >>>>
> >>> OK.
> >>>
> >>> Thanks.
> >> Could you help to push this patch?
> > I guess you can push it yourself.  A port maintainer has write access to
> > the entire Git repository, just use it carefully (i. e. always get a
> > permission before changing other subsystems).
> >
> OK, thanks.

did you add the tests HJ asked for?
>