[v3,2/2] x86_64: Add glibc-hwcaps support

The subdirectories match those in the x86-64 psABI:

https://gitlab.com/x86-psABIs/x86-64-ABI/-/commit/77566eb03bc6a326811cb7e9a6b9396884b67c7c
---
 elf/Makefile                       |  2 +-
 sysdeps/x86_64/Makefile            | 36 +++++++++++++-
 sysdeps/x86_64/dl-hwcaps-subdirs.c | 66 ++++++++++++++++++++++++++
 sysdeps/x86_64/tst-glibc-hwcaps.c  | 76 ++++++++++++++++++++++++++++++
 4 files changed, 178 insertions(+), 2 deletions(-)
 create mode 100644 sysdeps/x86_64/dl-hwcaps-subdirs.c
 create mode 100644 sysdeps/x86_64/tst-glibc-hwcaps.c

On Thu, Oct 29, 2020 at 11:17 AM Florian Weimer via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> The subdirectories match those in the x86-64 psABI:
>
> https://gitlab.com/x86-psABIs/x86-64-ABI/-/commit/77566eb03bc6a326811cb7e9a6b9396884b67c7c
> ---
>  elf/Makefile                       |  2 +-
>  sysdeps/x86_64/Makefile            | 36 +++++++++++++-
>  sysdeps/x86_64/dl-hwcaps-subdirs.c | 66 ++++++++++++++++++++++++++
>  sysdeps/x86_64/tst-glibc-hwcaps.c  | 76 ++++++++++++++++++++++++++++++
>  4 files changed, 178 insertions(+), 2 deletions(-)
>  create mode 100644 sysdeps/x86_64/dl-hwcaps-subdirs.c
>  create mode 100644 sysdeps/x86_64/tst-glibc-hwcaps.c
>
> diff --git a/elf/Makefile b/elf/Makefile
> index 01c1b2dae1..b02e72dffd 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -1819,7 +1819,7 @@ $(objpfx)argv0test.out: tst-rtld-argv0.sh $(objpfx)ld.so \
>
>  # Most likely search subdirectories, for each supported architecture.
>  # Used to obtain test coverage wide test coverage.
> -glibc-hwcaps-first-subdirs-for-tests =
> +glibc-hwcaps-first-subdirs-for-tests = x86-64-v2
>
>  # The test modules are parameterized by preprocessor macros.
>  LDFLAGS-markermod1-1.so += -Wl,-soname,markermod1.so
> diff --git a/sysdeps/x86_64/Makefile b/sysdeps/x86_64/Makefile
> index 42b97c5cc7..16030715e7 100644
> --- a/sysdeps/x86_64/Makefile
> +++ b/sysdeps/x86_64/Makefile
> @@ -144,7 +144,41 @@ CFLAGS-tst-auditmod10b.c += $(AVX512-CFLAGS)
>  CFLAGS-tst-avx512-aux.c += $(AVX512-CFLAGS)
>  CFLAGS-tst-avx512mod.c += $(AVX512-CFLAGS)
>  endif
> -endif
> +
> +$(objpfx)tst-glibc-hwcaps: \
> +  $(objpfx)markermod2-1.so $(objpfx)markermod3-1.so $(objpfx)markermod4-1.so
> +$(objpfx)tst-glibc-hwcaps.out: \
> +  $(objpfx)markermod2.so \
> +    $(objpfx)glibc-hwcaps/x86-64-v2/markermod2.so \
> +  $(objpfx)markermod3.so \
> +    $(objpfx)glibc-hwcaps/x86-64-v2/markermod3.so \
> +    $(objpfx)glibc-hwcaps/x86-64-v3/markermod3.so \
> +  $(objpfx)markermod4.so \
> +    $(objpfx)glibc-hwcaps/x86-64-v2/markermod4.so \
> +    $(objpfx)glibc-hwcaps/x86-64-v3/markermod4.so \
> +    $(objpfx)glibc-hwcaps/x86-64-v4/markermod4.so \
> +
> +$(objpfx)glibc-hwcaps/x86-64-v2/markermod2.so: $(objpfx)markermod2-2.so
> +       $(make-target-directory)
> +       cp $< $@
> +$(objpfx)glibc-hwcaps/x86-64-v2/markermod3.so: $(objpfx)markermod3-2.so
> +       $(make-target-directory)
> +       cp $< $@
> +$(objpfx)glibc-hwcaps/x86-64-v3/markermod3.so: $(objpfx)markermod3-3.so
> +       $(make-target-directory)
> +       cp $< $@
> +$(objpfx)glibc-hwcaps/x86-64-v2/markermod4.so: $(objpfx)markermod4-2.so
> +       $(make-target-directory)
> +       cp $< $@
> +$(objpfx)glibc-hwcaps/x86-64-v3/markermod4.so: $(objpfx)markermod4-3.so
> +       $(make-target-directory)
> +       cp $< $@
> +$(objpfx)glibc-hwcaps/x86-64-v4/markermod4.so: $(objpfx)markermod4-4.so
> +       $(make-target-directory)
> +       cp $< $@
> +
> +
> +endif # $(subdir) == elf
>
>  ifeq ($(subdir),csu)
>  gen-as-const-headers += tlsdesc.sym rtld-offsets.sym
> diff --git a/sysdeps/x86_64/dl-hwcaps-subdirs.c b/sysdeps/x86_64/dl-hwcaps-subdirs.c
> new file mode 100644
> index 0000000000..8810a822ef
> --- /dev/null
> +++ b/sysdeps/x86_64/dl-hwcaps-subdirs.c
> @@ -0,0 +1,66 @@
> +/* Architecture-specific glibc-hwcaps subdirectories.  x86 version.
> +   Copyright (C) 2020 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <dl-hwcaps.h>
> +#include <cpu-features.h>
> +
> +const char _dl_hwcaps_subdirs[] = "x86-64-v4:x86-64-v3:x86-64-v2";
> +enum { subdirs_count = 3 }; /* Number of components in _dl_hwcaps_subdirs.  */
> +
> +uint32_t
> +_dl_hwcaps_subdirs_active (void)
> +{
> +  int active = 0;
> +
> +  /* Test in reverse preference order.  */
> +
> +  /* x86-64-v2.  */
> +  if (!(CPU_FEATURE_USABLE (CMPXCHG16B)
> +        && CPU_FEATURE_USABLE (LAHF64_SAHF64)
> +        && CPU_FEATURE_USABLE (POPCNT)
> +        && CPU_FEATURE_USABLE (SSE3)
> +        && CPU_FEATURE_USABLE (SSE4_1)
> +        && CPU_FEATURE_USABLE (SSE4_2)
> +        && CPU_FEATURE_USABLE (SSSE3)))
> +    return _dl_hwcaps_subdirs_build_bitmask (subdirs_count, active);
> +  ++active;
> +
> +  /* x86-64-v3.  */
> +  if (!(CPU_FEATURE_USABLE (AVX)
> +        && CPU_FEATURE_USABLE (AVX2)
> +        && CPU_FEATURE_USABLE (BMI1)
> +        && CPU_FEATURE_USABLE (BMI2)
> +        && CPU_FEATURE_USABLE (F16C)
> +        && CPU_FEATURE_USABLE (FMA)
> +        && CPU_FEATURE_USABLE (LZCNT)
> +        && CPU_FEATURE_USABLE (MOVBE)
> +        && CPU_FEATURE_USABLE (OSXSAVE)))
> +    return _dl_hwcaps_subdirs_build_bitmask (subdirs_count, active);
> +  ++active;
> +
> + /* x86-64-v4.  */
> +  if (!(CPU_FEATURE_USABLE (AVX512F)
> +        && CPU_FEATURE_USABLE (AVX512BW)
> +        && CPU_FEATURE_USABLE (AVX512CD)
> +        && CPU_FEATURE_USABLE (AVX512DQ)
> +        && CPU_FEATURE_USABLE (AVX512VL)))
> +    return _dl_hwcaps_subdirs_build_bitmask (subdirs_count, active);
> +  ++active;
> +
> +  return _dl_hwcaps_subdirs_build_bitmask (subdirs_count, active);
> +}
> diff --git a/sysdeps/x86_64/tst-glibc-hwcaps.c b/sysdeps/x86_64/tst-glibc-hwcaps.c
> new file mode 100644
> index 0000000000..3075a8286d
> --- /dev/null
> +++ b/sysdeps/x86_64/tst-glibc-hwcaps.c
> @@ -0,0 +1,76 @@
> +/* glibc-hwcaps subdirectory test.  x86_64 version.
> +   Copyright (C) 2020 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <stdio.h>
> +#include <support/check.h>
> +#include <sys/param.h>
> +#include <sys/platform/x86.h>
> +
> +extern int marker2 (void);
> +extern int marker3 (void);
> +extern int marker4 (void);
> +
> +/* Return the x86-64-vN level, 1 for the baseline.  */
> +static int
> +compute_level (void)
> +{
> +  const struct cpu_features *cpu_features
> +    = __x86_get_cpu_features (COMMON_CPUID_INDEX_MAX);
> +
> + if (!(CPU_FEATURE_USABLE_P (cpu_features, CMPXCHG16B)
> +       && CPU_FEATURE_USABLE_P (cpu_features, LAHF64_SAHF64)
> +       && CPU_FEATURE_USABLE_P (cpu_features, POPCNT)
> +       && CPU_FEATURE_USABLE_P (cpu_features, MMX)
> +       && CPU_FEATURE_USABLE_P (cpu_features, SSE)
> +       && CPU_FEATURE_USABLE_P (cpu_features, SSE2)
> +       && CPU_FEATURE_USABLE_P (cpu_features, SSE3)
> +       && CPU_FEATURE_USABLE_P (cpu_features, SSSE3)
> +       && CPU_FEATURE_USABLE_P (cpu_features, SSE4_1)
> +       && CPU_FEATURE_USABLE_P (cpu_features, SSE4_2)))
> +   return 1;
> + if (!(CPU_FEATURE_USABLE_P (cpu_features, AVX)
> +       && CPU_FEATURE_USABLE_P (cpu_features, AVX2)
> +       && CPU_FEATURE_USABLE_P (cpu_features, BMI1)
> +       && CPU_FEATURE_USABLE_P (cpu_features, BMI2)
> +       && CPU_FEATURE_USABLE_P (cpu_features, F16C)
> +       && CPU_FEATURE_USABLE_P (cpu_features, FMA)
> +       && CPU_FEATURE_USABLE_P (cpu_features, LZCNT)
> +       && CPU_FEATURE_USABLE_P (cpu_features, MOVBE)
> +       && CPU_FEATURE_USABLE_P (cpu_features, OSXSAVE)))
> +   return 2;
> + if (!(CPU_FEATURE_USABLE_P (cpu_features, AVX512F)
> +       && CPU_FEATURE_USABLE_P (cpu_features, AVX512BW)
> +       && CPU_FEATURE_USABLE_P (cpu_features, AVX512CD)
> +       && CPU_FEATURE_USABLE_P (cpu_features, AVX512DQ)
> +       && CPU_FEATURE_USABLE_P (cpu_features, AVX512VL)))
> +   return 3;
> + return 4;
> +}
> +
> +static int
> +do_test (void)
> +{
> +  int level = compute_level ();
> +  printf ("info: detected x86-64 micro-architecture level: %d\n", level);
> +  TEST_COMPARE (marker2 (), MIN (level, 2));
> +  TEST_COMPARE (marker3 (), MIN (level, 3));
> +  TEST_COMPARE (marker4 (), MIN (level, 4));
> +  return 0;
> +}
> +

My GNU_PROPERTY_X86_ISA_1_V[234] marker patch:

https://sourceware.org/pipermail/libc-alpha/2020-October/119252.html

has similar codes to check for ISA levels.  We need to factor them out
to share one copy of such codes.