[FFmpeg-devel] [PATCH] avutil: [LA] use getauxval to do runtime check.

[Steven Liu]

Shiyou Yin <yinshiyou-hf at loongson.cn> 于2023年2月27日周一 09:03写道：
>
>
>
> > 2023年2月23日 15:48，Steven Liu <lingjiujianke at gmail.com> 写道：
> >
> > Shiyou Yin <yinshiyou-hf at loongson.cn> 于2023年2月14日周二 20:26写道：
> >>
> >> Replace cpucfg with getauxval to avoid crash in case of
> >> some processor capabilities are not supportted by kernel used.
> >> ---
> >> libavutil/loongarch/cpu.c | 24 ++++++++----------------
> >> 1 file changed, 8 insertions(+), 16 deletions(-)
> >>
> >> diff --git a/libavutil/loongarch/cpu.c b/libavutil/loongarch/cpu.c
> >> index e4b240bc44..cad8504fde 100644
> >> --- a/libavutil/loongarch/cpu.c
> >> +++ b/libavutil/loongarch/cpu.c
> >> @@ -21,26 +21,18 @@
> >>
> >> #include <stdint.h>
> >> #include "cpu.h"
> >> +#include <sys/auxv.h>
> >>
> >> -#define LOONGARCH_CFG2 0x2
> >> -#define LOONGARCH_CFG2_LSX    (1 << 6)
> >> -#define LOONGARCH_CFG2_LASX   (1 << 7)
> >> -
> >> -static int cpu_flags_cpucfg(void)
> >> +#define LA_HWCAP_LSX    (1<<4)
> >> +#define LA_HWCAP_LASX   (1<<5)
> >> +static int cpu_flags_getauxval(void)
> >> {
> >>     int flags = 0;
> >> -    uint32_t cfg2 = 0;
> >> -
> >> -    __asm__ volatile(
> >> -        "cpucfg %0, %1 \n\t"
> >> -        : "+&r"(cfg2)
> >> -        : "r"(LOONGARCH_CFG2)
> >> -    );
> >> +    int flag  = (int)getauxval(AT_HWCAP);
> >>
> >> -    if (cfg2 & LOONGARCH_CFG2_LSX)
> >> +    if (flag & LA_HWCAP_LSX)
> >>         flags |= AV_CPU_FLAG_LSX;
> >> -
> >> -    if (cfg2 & LOONGARCH_CFG2_LASX)
> >> +    if (flag & LA_HWCAP_LASX)
> >>         flags |= AV_CPU_FLAG_LASX;
> >>
> >>     return flags;
> >> @@ -49,7 +41,7 @@ static int cpu_flags_cpucfg(void)
> >> int ff_get_cpu_flags_loongarch(void)
> >> {
> >> #if defined __linux__
> >> -    return cpu_flags_cpucfg();
> >> +    return cpu_flags_getauxval();
> >> #else
> >>     /* Assume no SIMD ASE supported */
> >>     return 0;
> >> --
> >> 2.20.1
> >>
> >> _______________________________________________
> >> ffmpeg-devel mailing list
> >> ffmpeg-devel at ffmpeg.org
> >> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> >>
> >> To unsubscribe, visit link above, or email
> >> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
> >
> >
> > LGTM
> >
> > Thanks
> > Steven
> > _______________________________________________
>
> Could you please help to merge this patch.


I have no permission now, maybe there have some problem?

(base) adeMacBook-Pro:project liuqi$ git clone git at source.ffmpeg.org:ffmpeg
正克隆到 'ffmpeg'...
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ED25519 key sent by the remote host is
SHA256:dUNFtMwS3Z25nnzFF8UPYWsE0WiUR4majWLbWrsHBXU.
Please contact your system administrator.


Thanks
Steven
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