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

["H.J. Lu" <hjl.tools@gmail.com>]

On Wed, Mar 1, 2023 at 8:43 AM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> On Wed, Mar 1, 2023 at 3:11 AM caiyinyu <caiyinyu@loongson.cn> wrote:
> >
> >
> > 在 2023/3/1 下午12:19, Noah Goldstein 写道:
> > > On Tue, Feb 28, 2023 at 9:22 PM caiyinyu <caiyinyu@loongson.cn> wrote:
> > >> 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
> > >>
> > > Can you make a bugzilla for this?
> > bugzilla:
> >
> > https://sourceware.org/bugzilla/show_bug.cgi?id=30183
> >
> >
> Can you append '[BZ #30183]' to the commit message.
> Otherwise looks good.

Is it possible to add a testcase?

-- 
H.J.