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

[H.J. Lu]

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.

-- 
H.J.