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

[caiyinyu <caiyinyu@loongson.cn>]

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