Re: [PATCH v2] x86: Define MINIMUM_X86_ISA_LEVEL in config.h [BZ #31676]

[Sunil Pandey <skpgkp2@gmail.com>]

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On Tue, Apr 23, 2024 at 1:59 PM H.J. Lu <hjl.tools@gmail.com> wrote:

> Define MINIMUM_X86_ISA_LEVEL at configure time to avoid
>
> /usr/bin/ld: …/build/elf/librtld.os: in function `init_cpu_features':
> …/git/elf/../sysdeps/x86/cpu-features.c:1202: undefined reference to
> `_dl_runtime_resolve_fxsave'
> /usr/bin/ld: …/build/elf/librtld.os: relocation R_X86_64_PC32 against
> undefined hidden symbol `_dl_runtime_resolve_fxsave' can not be used when
> making a shared object
> /usr/bin/ld: final link failed: bad value
> collect2: error: ld returned 1 exit status
>
> when glibc is built with -march=x86-64-v3 and configured with
> --with-rtld-early-cflags=-march=x86-64, which is used to allow ld.so to
> print an error message on unsupported CPUs:
>
> Fatal glibc error: CPU does not support x86-64-v3
>
> This fixes BZ #31676.
> ---
>  config.h.in              | 3 +++
>  sysdeps/x86/configure    | 7 +++++++
>  sysdeps/x86/configure.ac | 5 +++++
>  sysdeps/x86/isa-level.h  | 4 +++-
>  4 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/config.h.in b/config.h.in
> index 69ac450356..c4cc7d3b9a 100644
> --- a/config.h.in
> +++ b/config.h.in
> @@ -285,6 +285,9 @@
>  /* Define if x86 ISA level should be included in shared libraries.  */
>  #undef INCLUDE_X86_ISA_LEVEL
>
> +/* The x86 ISA level.  1 for baseline.  Undefined on non-x86.  */
> +#undef MINIMUM_X86_ISA_LEVEL
> +
>  /* Define if -msahf is enabled by default on x86.  */
>  #undef HAVE_X86_LAHF_SAHF
>
> diff --git a/sysdeps/x86/configure b/sysdeps/x86/configure
> index 2a5421bb31..d28d9bcb29 100644
> --- a/sysdeps/x86/configure
> +++ b/sysdeps/x86/configure
> @@ -151,6 +151,13 @@ printf "%s\n" "$libc_cv_have_x86_isa_level" >&6; }
>  else
>    libc_cv_have_x86_isa_level=baseline
>  fi
> +if test $libc_cv_have_x86_isa_level = baseline; then
> +  printf "%s\n" "#define MINIMUM_X86_ISA_LEVEL 1" >>confdefs.h
> +
> +else
> +  printf "%s\n" "#define MINIMUM_X86_ISA_LEVEL
> $libc_cv_have_x86_isa_level" >>confdefs.h
> +
> +fi
>  config_vars="$config_vars
>  have-x86-isa-level = $libc_cv_have_x86_isa_level"
>  config_vars="$config_vars
> diff --git a/sysdeps/x86/configure.ac b/sysdeps/x86/configure.ac
> index 78ff7c8f41..5b0acd03d2 100644
> --- a/sysdeps/x86/configure.ac
> +++ b/sysdeps/x86/configure.ac
> @@ -105,6 +105,11 @@ EOF
>  else
>    libc_cv_have_x86_isa_level=baseline
>  fi
> +if test $libc_cv_have_x86_isa_level = baseline; then
> +  AC_DEFINE_UNQUOTED(MINIMUM_X86_ISA_LEVEL, 1)
> +else
> +  AC_DEFINE_UNQUOTED(MINIMUM_X86_ISA_LEVEL, $libc_cv_have_x86_isa_level)
> +fi
>  LIBC_CONFIG_VAR([have-x86-isa-level], [$libc_cv_have_x86_isa_level])
>  LIBC_CONFIG_VAR([x86-isa-level-3-or-above], [3 4])
>  LIBC_CONFIG_VAR([enable-x86-isa-level], [$libc_cv_include_x86_isa_level])
> diff --git a/sysdeps/x86/isa-level.h b/sysdeps/x86/isa-level.h
> index 11fe1ca90c..2c7f74212b 100644
> --- a/sysdeps/x86/isa-level.h
> +++ b/sysdeps/x86/isa-level.h
> @@ -61,8 +61,10 @@
>  # define __X86_ISA_V4 0
>  #endif
>
> -#define MINIMUM_X86_ISA_LEVEL
>      \
> +#ifndef MINIMUM_X86_ISA_LEVEL
> +# define MINIMUM_X86_ISA_LEVEL
>      \
>    (__X86_ISA_V1 + __X86_ISA_V2 + __X86_ISA_V3 + __X86_ISA_V4)
> +#endif
>
>  /* Depending on the minimum ISA level, a feature check result can be a
>     compile-time constant.. */
> --
> 2.44.0
>
> LGTM
Reviewed-by: Sunil K Pandey <skpgkp2@gmail.com>

Thanks,
Sunil

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