Re: [PATCH v2 5/6] x86: Add x86-64-vN check to early startup

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

On Fri, Jan 14, 2022 at 8:53 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> This ISA level covers the glibc build itself.  <dl-hwcap-check.h>
> cannot be used because this check (by design) happens before
> DL_PLATFORM_INIT and the x86 CPU flags initialization.
> ---
> v2: Reflect renamed Makefile variable.
>  sysdeps/x86/Makefile              |  1 +
>  sysdeps/x86/dl-get-cpu-features.c | 31 ++++++++++++++++++++++++++++++-
>  2 files changed, 31 insertions(+), 1 deletion(-)
>
> diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
> index 402986ff68..6cf708335c 100644
> --- a/sysdeps/x86/Makefile
> +++ b/sysdeps/x86/Makefile
> @@ -7,6 +7,7 @@ sysdep_routines += get-cpuid-feature-leaf
>  sysdep-dl-routines += dl-get-cpu-features
>  sysdep_headers += sys/platform/x86.h bits/platform/x86.h
>
> +CFLAGS-dl-get-cpu-features.os += $(rtld-early-cflags)
>  CFLAGS-get-cpuid-feature-leaf.o += $(no-stack-protector)
>
>  tests += tst-get-cpu-features tst-get-cpu-features-static \
> diff --git a/sysdeps/x86/dl-get-cpu-features.c b/sysdeps/x86/dl-get-cpu-features.c
> index 6339c9df4e..4ec0e5d2af 100644
> --- a/sysdeps/x86/dl-get-cpu-features.c
> +++ b/sysdeps/x86/dl-get-cpu-features.c
> @@ -20,6 +20,7 @@
>
>  #ifdef SHARED
>  # include <cpu-features.c>
> +# include <gcc-macros.h>
>
>  /* NB: Normally, DL_PLATFORM_INIT calls init_cpu_features to initialize
>     CPU features in dynamic executable.  But when loading ld.so inside of
> @@ -36,7 +37,35 @@ _dl_x86_init_cpu_features (void)
>  {
>    struct cpu_features *cpu_features = __get_cpu_features ();
>    if (cpu_features->basic.kind == arch_kind_unknown)
> -    init_cpu_features (cpu_features);
> +    {
> +      init_cpu_features (cpu_features);
> +
> +# if IS_IN (rtld)
> +      /* See isa-level.c.  */
> +#  if defined GCCMACRO__GCC_HAVE_SYNC_COMPARE_AND_SWAP_16              \
> +  && defined HAVE_X86_LAHF_SAHF && defined GCCMACRO__POPCNT__          \
> +  && defined GCCMACRO__SSE3__ && defined GCCMACRO__SSSE3__             \
> +  && defined GCCMACRO__SSE4_1__ && defined GCCMACRO__SSE4_2__
> +      if (!(cpu_features->isa_1 & GNU_PROPERTY_X86_ISA_1_V2))
> +       _dl_fatal_printf ("\
> +Fatal glibc error: CPU does not support x86-64-v%d\n", 2);
> +#   if defined GCCMACRO__AVX__ && defined GCCMACRO__AVX2__ \
> +  && defined GCCMACRO__F16C__ && defined GCCMACRO__FMA__   \
> +  && defined GCCMACRO__LZCNT__ && defined HAVE_X86_MOVBE
> +      if (!(cpu_features->isa_1 & GNU_PROPERTY_X86_ISA_1_V3))
> +       _dl_fatal_printf ("\
> +Fatal glibc error: CPU does not support x86-64-v%d\n", 3);
> +#    if defined GCCMACRO__AVX512F__ && defined GCCMACRO__AVX512BW__ \
> +     && defined GCCMACRO__AVX512CD__ && defined GCCMACRO__AVX512DQ__ \
> +     && defined GCCMACRO__AVX512VL__
> +      if (!(cpu_features->isa_1 & GNU_PROPERTY_X86_ISA_1_V4))
> +       _dl_fatal_printf ("\
> +Fatal glibc error: CPU does not support x86-64-v%d\n", 4);
> +#    endif /* ISA level 4 */
> +#   endif /* ISA level 3 */
> +#  endif /* ISA level 2 */
> +# endif /* IS_IN (rtld) */
> +    }
>  }
>
>  __ifunc (__x86_cpu_features, __x86_cpu_features, NULL, void,
> --
> 2.34.1
>
>

LGTM.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>

Thanks.

-- 
H.J.