V6: [PATCH] x86: Install <sys/platform/x86.h> [BZ #26124]

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

On Thu, Jun 25, 2020 at 05:30:59AM -0700, H.J. Lu wrote:
> On Thu, Jun 25, 2020 at 09:33:26AM +0200, Florian Weimer wrote:
> > * H. J. Lu via Libc-alpha:
> > 
> > >> is not expected to be extendable. The macro API is not my favorite way of
> > >
> > > We can expand the cpuid array.  We just need to add an alias to
> > > __x86_get_cpu_features
> > > with a new symbol version.
> > 
> > Agreed, from a GNU gABI perspective.
> > 
> > However, for some distributions, this requirement will put hardware
> > enablement for new CPUs on hold until we have reworked our package
> > dependency generation, so that we can express symbol-specific version
> > information.  Debian & downstreams can already do this, with some manual
> > work, but Fedora & downstreams can only express versions on sonames.
> > (Without these changes, we would have to backport the entire GLIBC_2.33
> > symbol set to get __x86_get_cpu_features@GLIBC_2.33, for example.  This
> > is not something we will be able to do in all cases, depending on the
> > other changes that are going in.)
> > 
> > Even then, we can only backport such changes if a glibc release has
> > happened (so that we can be sure that the meaning of the symbol version
> > will not change again).
> > 
> > My proposal, where the index is passed to the function and the function
> > returns the flag word, does not have these issues: old glibcs will
> > simply return 0 flags, and the feature appears unusable/unavailable.
> > This is what already happens with your approach, too, if we use more
> > bits inside the existing array elements.
> > 
> > I'm not entirely opposed to enhancing the RPM dependency generation, but
> > I already tried once and couldn't get it done, and if I fail again, it
> > might seriously impact CPU hardware enablement in Red Hat Enterprise
> > Linux 9.  I hope this explains my reservations about this interface
> > design.
> > 
> 
> Thanks for your detailed explanation.  Here is the revised patch.
> COMMON_CPUID_INDEX_MAX and USABLE_FEATURE_INDEX_MAX are passed to
> __x86_get_cpu_features so that when USABLE_FEATURE_INDEX_MAX or
> COMMON_CPUID_INDEX_MAX are increased to support new processor features,
> __x86_get_cpu_features in the older glibc binaries returns NULL and
> HAS_CPU_FEATURE/CPU_FEATURE_USABLE return falses on the new processor
> feature.  No new symbol version is neeeded.
> 
> Any comments?
> 

Small update:

const struct cpu_features *
__x86_get_cpu_features (unsigned int max, int cpuid)
{
  if (cpuid)
    {
      if (max > COMMON_CPUID_INDEX_MAX)
	return NULL;
    }
  else if (max > USABLE_FEATURE_INDEX_MAX)
    return NULL;
  return &GLRO(dl_x86_cpu_features);
}

Don't return NULL when checking the cpuid array when COMMON_CPUID_INDEX_MAX
is unchanged, but USABLE_FEATURE_INDEX_MAX is changed.

H.J.
---
Install <sys/platform/x86.h> so that programmers can do

 #if __has_include(<sys/platform/x86.h>)
 #include <sys/platform/x86.h>
 #endif
 ...

   if (HAS_CPU_FEATURE (SSE2))
 ...
   if (CPU_FEATURE_USABLE (AVX2))
 ...

<sys/platform/x86.h> exports only:

enum
{
  /* The integer bit array index for the first set of usable feature
     bits.  */
  USABLE_FEATURE_INDEX_1 = 0,
  /* The current maximum size of the feature integer bit array.  */
  USABLE_FEATURE_INDEX_MAX
};

enum
{
  COMMON_CPUID_INDEX_1 = 0,
  COMMON_CPUID_INDEX_7,
  COMMON_CPUID_INDEX_80000001,
  COMMON_CPUID_INDEX_D_ECX_1,
  COMMON_CPUID_INDEX_80000007,
  COMMON_CPUID_INDEX_80000008,
  COMMON_CPUID_INDEX_7_ECX_1,
  /* Keep the following line at the end.  */
  COMMON_CPUID_INDEX_MAX
};

struct cpu_features
{
  struct cpu_features_basic basic;
  unsigned int *usable_p;
  struct cpuid_registers cpuid[COMMON_CPUID_INDEX_MAX];
};

/* Get a pointer to the CPU features structure.  */
extern const struct cpu_features *__x86_get_cpu_features
  (unsigned int max, int cpuid) __attribute__ ((const));

Since all feature checks are done through macros, programs compiled with
a newer <sys/platform/x86.h> are compatible with the older glibc binaries
as long as the layout of struct cpu_features is identical.  The cpuid
array can be expanded with backward binary compatibility for both .o and
.so files.  When USABLE_FEATURE_INDEX_MAX or COMMON_CPUID_INDEX_MAX are
increased to support new processor features, __x86_get_cpu_features in the
older glibc binaries returns NULL and HAS_CPU_FEATURE/CPU_FEATURE_USABLE
return falses on the new processor feature.  No new symbol version is
neeeded.

Note: Although GCC has __builtin_cpu_supports, it only supports a subset
of <sys/platform/x86.h> and it is equivalent to CPU_FEATURE_USABLE.  It
doesn't support HAS_CPU_FEATURE.
---
 NEWS                                          |   2 +
 manual/platform.texi                          |  27 +++
 sysdeps/unix/sysv/linux/i386/ld.abilist       |   1 +
 sysdeps/unix/sysv/linux/x86_64/64/ld.abilist  |   1 +
 sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist |   1 +
 sysdeps/x86/Makefile                          |   1 +
 sysdeps/x86/Versions                          |   4 +-
 sysdeps/x86/dl-get-cpu-features.c             |  11 +-
 sysdeps/x86/include/cpu-features.h            | 209 ++++++++++++++++++
 .../{cpu-features.h => sys/platform/x86.h}    | 183 ++-------------
 sysdeps/x86/tst-get-cpu-features.c            |   6 +-
 sysdeps/x86_64/fpu/math-tests-arch.h          |   8 +-
 sysdeps/x86_64/multiarch/test-multiarch.c     |  10 +-
 13 files changed, 286 insertions(+), 178 deletions(-)
 create mode 100644 sysdeps/x86/include/cpu-features.h
 rename sysdeps/x86/{cpu-features.h => sys/platform/x86.h} (77%)

diff --git a/NEWS b/NEWS
index a660fc59a8..ae7d1ece35 100644
--- a/NEWS
+++ b/NEWS
@@ -9,6 +9,8 @@ Version 2.32
 
 Major new features:
 
+* Add <sys/platform/x86.h> to provide query macros for x86 CPU features.
+
 * Unicode 12.1.0 Support: Character encoding, character type info, and
   transliteration tables are all updated to Unicode 12.1.0, using
   generator scripts contributed by Mike FABIAN (Red Hat).
diff --git a/manual/platform.texi b/manual/platform.texi
index 504addc956..6c7cad9792 100644
--- a/manual/platform.texi
+++ b/manual/platform.texi
@@ -7,6 +7,7 @@
 @menu
 * PowerPC::           Facilities Specific to the PowerPC Architecture
 * RISC-V::            Facilities Specific to the RISC-V Architecture
+* X86::               Facilities Specific to the X86 Architecture
 @end menu
 
 @node PowerPC
@@ -134,3 +135,29 @@ all threads in the current process.  Setting the
 ordering on only the current thread is necessary.  All other flag bits are
 reserved.
 @end deftypefun
+
+@node X86
+@appendixsec X86-specific Facilities
+
+Facilities specific to X86 that are not specific to a particular
+operating system are declared in @file{sys/platform/x86.h}.
+
+@deftypefun {const struct cpu_features *} __x86_get_cpu_features
+(unsigned int @var{max}, int @var{cpuid})
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+Return a pointer to x86 CPU feature structure used by query macros for x86
+CPU features.  If @var{cpuid} is non-zero and @var{max} exceeds
+@code{COMMON_CPUID_INDEX_MAX}, the function returns @code{NULL}.  If
+@var{cpuid} is zero and @var{max} exceeds
+@code{USABLE_FEATURE_INDEX_MAX}, the function returns @code{NULL}.
+@end deftypefun
+
+@deftypefn Macro int HAS_CPU_FEATURE (@var{name})
+This macro returns a nonzero value (true) if the processor has the feature
+@var{name}.
+@end deftypefn
+
+@deftypefn Macro int CPU_FEATURE_USABLE (@var{name})
+This macro returns a nonzero value (true) if the processor has the feature
+@var{name} and the feature is supported by the operating system.
+@end deftypefn
diff --git a/sysdeps/unix/sysv/linux/i386/ld.abilist b/sysdeps/unix/sysv/linux/i386/ld.abilist
index 0478e22071..1226876689 100644
--- a/sysdeps/unix/sysv/linux/i386/ld.abilist
+++ b/sysdeps/unix/sysv/linux/i386/ld.abilist
@@ -3,3 +3,4 @@ GLIBC_2.1 __libc_stack_end D 0x4
 GLIBC_2.1 _dl_mcount F
 GLIBC_2.3 ___tls_get_addr F
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.32 __x86_get_cpu_features F
diff --git a/sysdeps/unix/sysv/linux/x86_64/64/ld.abilist b/sysdeps/unix/sysv/linux/x86_64/64/ld.abilist
index d3cdf7611e..886e57abd5 100644
--- a/sysdeps/unix/sysv/linux/x86_64/64/ld.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/64/ld.abilist
@@ -2,3 +2,4 @@ GLIBC_2.2.5 __libc_stack_end D 0x8
 GLIBC_2.2.5 _dl_mcount F
 GLIBC_2.2.5 _r_debug D 0x28
 GLIBC_2.3 __tls_get_addr F
+GLIBC_2.32 __x86_get_cpu_features F
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist
index c70bccf782..0d2f8a2cc5 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/ld.abilist
@@ -2,3 +2,4 @@ GLIBC_2.16 __libc_stack_end D 0x4
 GLIBC_2.16 __tls_get_addr F
 GLIBC_2.16 _dl_mcount F
 GLIBC_2.16 _r_debug D 0x14
+GLIBC_2.32 __x86_get_cpu_features F
diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
index beab426f67..0e4d132803 100644
--- a/sysdeps/x86/Makefile
+++ b/sysdeps/x86/Makefile
@@ -4,6 +4,7 @@ endif
 
 ifeq ($(subdir),elf)
 sysdep-dl-routines += dl-get-cpu-features
+sysdep_headers += sys/platform/x86.h
 
 tests += tst-get-cpu-features tst-get-cpu-features-static
 tests-static += tst-get-cpu-features-static
diff --git a/sysdeps/x86/Versions b/sysdeps/x86/Versions
index e02923708e..7e3139dbb1 100644
--- a/sysdeps/x86/Versions
+++ b/sysdeps/x86/Versions
@@ -1,5 +1,5 @@
 ld {
-  GLIBC_PRIVATE {
-    __get_cpu_features;
+  GLIBC_2.32 {
+    __x86_get_cpu_features;
   }
 }
diff --git a/sysdeps/x86/dl-get-cpu-features.c b/sysdeps/x86/dl-get-cpu-features.c
index 9d61cd56be..ba4df1d9e1 100644
--- a/sysdeps/x86/dl-get-cpu-features.c
+++ b/sysdeps/x86/dl-get-cpu-features.c
@@ -18,10 +18,17 @@
 
 #include <ldsodefs.h>
 
-#undef __get_cpu_features
+#undef __x86_get_cpu_features
 
 const struct cpu_features *
-__get_cpu_features (void)
+__x86_get_cpu_features (unsigned int max, int cpuid)
 {
+  if (cpuid)
+    {
+      if (max > COMMON_CPUID_INDEX_MAX)
+	return NULL;
+    }
+  else if (max > USABLE_FEATURE_INDEX_MAX)
+    return NULL;
   return &GLRO(dl_x86_cpu_features);
 }
diff --git a/sysdeps/x86/include/cpu-features.h b/sysdeps/x86/include/cpu-features.h
new file mode 100644
index 0000000000..9424b4a924
--- /dev/null
+++ b/sysdeps/x86/include/cpu-features.h
@@ -0,0 +1,209 @@
+/* Data structure for x86 CPU features.
+   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/>.  */
+
+#ifndef	_PRIVATE_CPU_FEATURES_H
+#define	_PRIVATE_CPU_FEATURES_H	1
+
+#ifdef _CPU_FEATURES_H
+# error this should be impossible
+#endif
+
+#ifndef _ISOMAC
+/* Get most of the contents from the public header, but we define a
+   different `struct cpu_features' type for private use.  */
+# define cpu_features		cpu_features_public
+# define __x86_get_cpu_features	__x86_get_cpu_features_public
+#endif
+
+#include <sysdeps/x86/sys/platform/x86.h>
+
+#ifndef _ISOMAC
+
+# undef	cpu_features
+# undef __x86_get_cpu_features
+# define __get_cpu_features()	__x86_get_cpu_features (0, 0)
+
+enum
+{
+  /* The integer bit array index for the first set of preferred feature
+     bits.  */
+  PREFERRED_FEATURE_INDEX_1 = 0,
+  /* The current maximum size of the feature integer bit array.  */
+  PREFERRED_FEATURE_INDEX_MAX
+};
+
+# undef CPU_FEATURES_ARCH_P
+# define CPU_FEATURES_ARCH_P(ptr, name) \
+  ((ptr->feature_##name[index_arch_##name] & (bit_arch_##name)) != 0)
+
+/* HAS_CPU_FEATURE evaluates to true if CPU supports the feature.  */
+# undef HAS_CPU_FEATURE
+# define HAS_CPU_FEATURE(name) \
+  CPU_FEATURES_CPU_P (__x86_get_cpu_features (0, 0), name)
+/* HAS_ARCH_FEATURE evaluates to true if we may use the feature at
+   runtime.  */
+# define HAS_ARCH_FEATURE(name)	\
+  CPU_FEATURES_ARCH_P (__x86_get_cpu_features (0, 0), name)
+/* CPU_FEATURE_USABLE evaluates to true if the feature is usable.  */
+# undef CPU_FEATURE_USABLE
+# define CPU_FEATURE_USABLE(name) \
+  CPU_FEATURES_ARCH_P (__x86_get_cpu_features (0, 0), name##_Usable)
+
+/* USABLE_FEATURE_INDEX_1.  */
+# define feature_AVX_Usable			usable
+# define feature_AVX2_Usable			usable
+# define feature_AVX512F_Usable			usable
+# define feature_AVX512CD_Usable		usable
+# define feature_AVX512ER_Usable		usable
+# define feature_AVX512PF_Usable		usable
+# define feature_AVX512VL_Usable		usable
+# define feature_AVX512BW_Usable		usable
+# define feature_AVX512DQ_Usable		usable
+# define feature_AVX512_4FMAPS_Usable		usable
+# define feature_AVX512_4VNNIW_Usable		usable
+# define feature_AVX512_BITALG_Usable		usable
+# define feature_AVX512_IFMA_Usable		usable
+# define feature_AVX512_VBMI_Usable		usable
+# define feature_AVX512_VBMI2_Usable		usable
+# define feature_AVX512_VNNI_Usable		usable
+# define feature_AVX512_VPOPCNTDQ_Usable	usable
+# define feature_FMA_Usable			usable
+# define feature_FMA4_Usable			usable
+# define feature_VAES_Usable			usable
+# define feature_VPCLMULQDQ_Usable		usable
+# define feature_XOP_Usable			usable
+# define feature_XSAVEC_Usable			usable
+# define feature_F16C_Usable			usable
+# define feature_AVX512_VP2INTERSECT_Usable	usable
+# define feature_AVX512_BF16_Usable		usable
+# define feature_PKU_Usable			usable
+
+/* PREFERRED_FEATURE_INDEX_1.  */
+# define bit_arch_I586				(1u << 0)
+# define bit_arch_I686				(1u << 1)
+# define bit_arch_Fast_Rep_String		(1u << 2)
+# define bit_arch_Fast_Copy_Backward		(1u << 3)
+# define bit_arch_Fast_Unaligned_Load		(1u << 4)
+# define bit_arch_Fast_Unaligned_Copy		(1u << 5)
+# define bit_arch_Slow_BSF			(1u << 6)
+# define bit_arch_Slow_SSE4_2			(1u << 7)
+# define bit_arch_AVX_Fast_Unaligned_Load	(1u << 8)
+# define bit_arch_Prefer_MAP_32BIT_EXEC		(1u << 9)
+# define bit_arch_Prefer_PMINUB_for_stringop	(1u << 10)
+# define bit_arch_Prefer_No_VZEROUPPER		(1u << 11)
+# define bit_arch_Prefer_ERMS			(1u << 12)
+# define bit_arch_Prefer_FSRM			(1u << 13)
+# define bit_arch_Prefer_No_AVX512		(1u << 14)
+# define bit_arch_MathVec_Prefer_No_AVX512	(1u << 15)
+
+# define index_arch_Fast_Rep_String		PREFERRED_FEATURE_INDEX_1
+# define index_arch_Fast_Copy_Backward		PREFERRED_FEATURE_INDEX_1
+# define index_arch_Slow_BSF			PREFERRED_FEATURE_INDEX_1
+# define index_arch_Fast_Unaligned_Load		PREFERRED_FEATURE_INDEX_1
+# define index_arch_Prefer_PMINUB_for_stringop 	PREFERRED_FEATURE_INDEX_1
+# define index_arch_Fast_Unaligned_Copy		PREFERRED_FEATURE_INDEX_1
+# define index_arch_I586			PREFERRED_FEATURE_INDEX_1
+# define index_arch_I686			PREFERRED_FEATURE_INDEX_1
+# define index_arch_Slow_SSE4_2			PREFERRED_FEATURE_INDEX_1
+# define index_arch_AVX_Fast_Unaligned_Load	PREFERRED_FEATURE_INDEX_1
+# define index_arch_Prefer_MAP_32BIT_EXEC	PREFERRED_FEATURE_INDEX_1
+# define index_arch_Prefer_No_VZEROUPPER	PREFERRED_FEATURE_INDEX_1
+# define index_arch_Prefer_ERMS			PREFERRED_FEATURE_INDEX_1
+# define index_arch_Prefer_No_AVX512		PREFERRED_FEATURE_INDEX_1
+# define index_arch_MathVec_Prefer_No_AVX512	PREFERRED_FEATURE_INDEX_1
+# define index_arch_Prefer_FSRM			PREFERRED_FEATURE_INDEX_1
+
+# define feature_Fast_Rep_String		preferred
+# define feature_Fast_Copy_Backward		preferred
+# define feature_Slow_BSF			preferred
+# define feature_Fast_Unaligned_Load		preferred
+# define feature_Prefer_PMINUB_for_stringop 	preferred
+# define feature_Fast_Unaligned_Copy		preferred
+# define feature_I586				preferred
+# define feature_I686				preferred
+# define feature_Slow_SSE4_2			preferred
+# define feature_AVX_Fast_Unaligned_Load	preferred
+# define feature_Prefer_MAP_32BIT_EXEC		preferred
+# define feature_Prefer_No_VZEROUPPER		preferred
+# define feature_Prefer_ERMS			preferred
+# define feature_Prefer_No_AVX512		preferred
+# define feature_MathVec_Prefer_No_AVX512	preferred
+# define feature_Prefer_FSRM			preferred
+
+/* XCR0 Feature flags.  */
+# define bit_XMM_state		(1u << 1)
+# define bit_YMM_state		(1u << 2)
+# define bit_Opmask_state	(1u << 5)
+# define bit_ZMM0_15_state	(1u << 6)
+# define bit_ZMM16_31_state	(1u << 7)
+
+struct cpu_features
+{
+  struct cpu_features_basic basic;
+  unsigned int *usable_p;
+  struct cpuid_registers cpuid[COMMON_CPUID_INDEX_MAX];
+  unsigned int usable[USABLE_FEATURE_INDEX_MAX];
+  unsigned int preferred[PREFERRED_FEATURE_INDEX_MAX];
+  /* The state size for XSAVEC or XSAVE.  The type must be unsigned long
+     int so that we use
+
+	sub xsave_state_size_offset(%rip) %RSP_LP
+
+     in _dl_runtime_resolve.  */
+  unsigned long int xsave_state_size;
+  /* The full state size for XSAVE when XSAVEC is disabled by
+
+     GLIBC_TUNABLES=glibc.cpu.hwcaps=-XSAVEC_Usable
+   */
+  unsigned int xsave_state_full_size;
+  /* Data cache size for use in memory and string routines, typically
+     L1 size.  */
+  unsigned long int data_cache_size;
+  /* Shared cache size for use in memory and string routines, typically
+     L2 or L3 size.  */
+  unsigned long int shared_cache_size;
+  /* Threshold to use non temporal store.  */
+  unsigned long int non_temporal_threshold;
+};
+
+# if defined (_LIBC) && !IS_IN (nonlib)
+/* Unused for x86.  */
+#  define INIT_ARCH()
+#  define __x86_get_cpu_features(max, cpuid) (&GLRO(dl_x86_cpu_features))
+# endif
+
+# ifdef __x86_64__
+#  define HAS_CPUID 1
+# elif (defined __i586__ || defined __pentium__	\
+	|| defined __geode__ || defined __k6__)
+#  define HAS_CPUID 1
+#  define HAS_I586 1
+#  define HAS_I686 HAS_ARCH_FEATURE (I686)
+# elif defined __i486__
+#  define HAS_CPUID 0
+#  define HAS_I586 HAS_ARCH_FEATURE (I586)
+#  define HAS_I686 HAS_ARCH_FEATURE (I686)
+# else
+#  define HAS_CPUID 1
+#  define HAS_I586 1
+#  define HAS_I686 1
+# endif
+
+#endif /* !_ISOMAC */
+
+#endif /* include/cpu-features.h */
diff --git a/sysdeps/x86/cpu-features.h b/sysdeps/x86/sys/platform/x86.h
similarity index 77%
rename from sysdeps/x86/cpu-features.h
rename to sysdeps/x86/sys/platform/x86.h
index 574f055e0c..62718c3a8d 100644
--- a/sysdeps/x86/cpu-features.h
+++ b/sysdeps/x86/sys/platform/x86.h
@@ -1,4 +1,5 @@
-/* This file is part of the GNU C Library.
+/* Data structure for x86 CPU features.
+   This file is part of the GNU C Library.
    Copyright (C) 2008-2020 Free Software Foundation, Inc.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -15,8 +16,8 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#ifndef cpu_features_h
-#define cpu_features_h
+#ifndef _SYS_PLATFORM_X86_H
+#define _SYS_PLATFORM_X86_H
 
 enum
 {
@@ -27,15 +28,6 @@ enum
   USABLE_FEATURE_INDEX_MAX
 };
 
-enum
-{
-  /* The integer bit array index for the first set of preferred feature
-     bits.  */
-  PREFERRED_FEATURE_INDEX_1 = 0,
-  /* The current maximum size of the feature integer bit array.  */
-  PREFERRED_FEATURE_INDEX_MAX
-};
-
 enum
 {
   COMMON_CPUID_INDEX_1 = 0,
@@ -80,51 +72,30 @@ struct cpu_features
   struct cpu_features_basic basic;
   unsigned int *usable_p;
   struct cpuid_registers cpuid[COMMON_CPUID_INDEX_MAX];
-  unsigned int usable[USABLE_FEATURE_INDEX_MAX];
-  unsigned int preferred[PREFERRED_FEATURE_INDEX_MAX];
-  /* The state size for XSAVEC or XSAVE.  The type must be unsigned long
-     int so that we use
-
-	sub xsave_state_size_offset(%rip) %RSP_LP
-
-     in _dl_runtime_resolve.  */
-  unsigned long int xsave_state_size;
-  /* The full state size for XSAVE when XSAVEC is disabled by
-
-     GLIBC_TUNABLES=glibc.cpu.hwcaps=-XSAVEC_Usable
-   */
-  unsigned int xsave_state_full_size;
-  /* Data cache size for use in memory and string routines, typically
-     L1 size.  */
-  unsigned long int data_cache_size;
-  /* Shared cache size for use in memory and string routines, typically
-     L2 or L3 size.  */
-  unsigned long int shared_cache_size;
-  /* Threshold to use non temporal store.  */
-  unsigned long int non_temporal_threshold;
 };
 
-/* Used from outside of glibc to get access to the CPU features
-   structure.  */
-extern const struct cpu_features *__get_cpu_features (void)
+/* Get a pointer to the CPU features structure.  */
+extern const struct cpu_features *__x86_get_cpu_features (unsigned int,
+							  int)
      __attribute__ ((const));
 
-/* Only used directly in cpu-features.c.  */
-# define CPU_FEATURES_CPU_P(ptr, name) \
+#define CPU_FEATURES_CPU_P(ptr, name) \
   ((ptr->cpuid[index_cpu_##name].reg_##name & (bit_cpu_##name)) != 0)
-# define CPU_FEATURES_ARCH_P(ptr, name) \
-  ((ptr->feature_##name[index_arch_##name] & (bit_arch_##name)) != 0)
+#define CPU_FEATURES_ARCH_P(ptr, name) \
+  ((ptr->usable_p[index_arch_##name] & (bit_arch_##name)) != 0)
 
 /* HAS_CPU_FEATURE evaluates to true if CPU supports the feature.  */
-#define HAS_CPU_FEATURE(name) \
-  CPU_FEATURES_CPU_P (__get_cpu_features (), name)
-/* HAS_ARCH_FEATURE evaluates to true if we may use the feature at
-   runtime.  */
-# define HAS_ARCH_FEATURE(name) \
-  CPU_FEATURES_ARCH_P (__get_cpu_features (), name)
+#define HAS_CPU_FEATURE(name)					\
+  (__extension__						\
+   ({ const struct cpu_features *__ptr =			\
+	__x86_get_cpu_features (COMMON_CPUID_INDEX_MAX, 1);	\
+      __ptr && CPU_FEATURES_CPU_P (__ptr, name); }))
 /* CPU_FEATURE_USABLE evaluates to true if the feature is usable.  */
-#define CPU_FEATURE_USABLE(name) \
-  HAS_ARCH_FEATURE (name##_Usable)
+#define CPU_FEATURE_USABLE(name)				\
+  (__extension__						\
+   ({ const struct cpu_features *__ptr =			\
+	__x86_get_cpu_features (USABLE_FEATURE_INDEX_MAX, 0);	\
+      __ptr && CPU_FEATURES_ARCH_P (__ptr, name##_Usable); }))
 
 /* Architecture features.  */
 
@@ -185,34 +156,6 @@ extern const struct cpu_features *__get_cpu_features (void)
 #define index_arch_AVX512_BF16_Usable		USABLE_FEATURE_INDEX_1
 #define index_arch_PKU_Usable			USABLE_FEATURE_INDEX_1
 
-#define feature_AVX_Usable			usable
-#define feature_AVX2_Usable			usable
-#define feature_AVX512F_Usable			usable
-#define feature_AVX512CD_Usable			usable
-#define feature_AVX512ER_Usable			usable
-#define feature_AVX512PF_Usable			usable
-#define feature_AVX512VL_Usable			usable
-#define feature_AVX512BW_Usable			usable
-#define feature_AVX512DQ_Usable			usable
-#define feature_AVX512_4FMAPS_Usable		usable
-#define feature_AVX512_4VNNIW_Usable		usable
-#define feature_AVX512_BITALG_Usable		usable
-#define feature_AVX512_IFMA_Usable		usable
-#define feature_AVX512_VBMI_Usable		usable
-#define feature_AVX512_VBMI2_Usable		usable
-#define feature_AVX512_VNNI_Usable		usable
-#define feature_AVX512_VPOPCNTDQ_Usable		usable
-#define feature_FMA_Usable			usable
-#define feature_FMA4_Usable			usable
-#define feature_VAES_Usable			usable
-#define feature_VPCLMULQDQ_Usable		usable
-#define feature_XOP_Usable			usable
-#define feature_XSAVEC_Usable			usable
-#define feature_F16C_Usable			usable
-#define feature_AVX512_VP2INTERSECT_Usable	usable
-#define feature_AVX512_BF16_Usable		usable
-#define feature_PKU_Usable			usable
-
 /* CPU features.  */
 
 /* COMMON_CPUID_INDEX_1.  */
@@ -761,88 +704,4 @@ extern const struct cpu_features *__get_cpu_features (void)
 /* EAX.  */
 #define reg_AVX512_BF16		eax
 
-/* FEATURE_INDEX_2.  */
-#define bit_arch_I586				(1u << 0)
-#define bit_arch_I686				(1u << 1)
-#define bit_arch_Fast_Rep_String		(1u << 2)
-#define bit_arch_Fast_Copy_Backward		(1u << 3)
-#define bit_arch_Fast_Unaligned_Load		(1u << 4)
-#define bit_arch_Fast_Unaligned_Copy		(1u << 5)
-#define bit_arch_Slow_BSF			(1u << 6)
-#define bit_arch_Slow_SSE4_2			(1u << 7)
-#define bit_arch_AVX_Fast_Unaligned_Load	(1u << 8)
-#define bit_arch_Prefer_MAP_32BIT_EXEC		(1u << 9)
-#define bit_arch_Prefer_PMINUB_for_stringop	(1u << 10)
-#define bit_arch_Prefer_No_VZEROUPPER		(1u << 11)
-#define bit_arch_Prefer_ERMS			(1u << 12)
-#define bit_arch_Prefer_FSRM			(1u << 13)
-#define bit_arch_Prefer_No_AVX512		(1u << 14)
-#define bit_arch_MathVec_Prefer_No_AVX512	(1u << 15)
-
-#define index_arch_Fast_Rep_String		PREFERRED_FEATURE_INDEX_1
-#define index_arch_Fast_Copy_Backward		PREFERRED_FEATURE_INDEX_1
-#define index_arch_Slow_BSF			PREFERRED_FEATURE_INDEX_1
-#define index_arch_Fast_Unaligned_Load		PREFERRED_FEATURE_INDEX_1
-#define index_arch_Prefer_PMINUB_for_stringop 	PREFERRED_FEATURE_INDEX_1
-#define index_arch_Fast_Unaligned_Copy		PREFERRED_FEATURE_INDEX_1
-#define index_arch_I586				PREFERRED_FEATURE_INDEX_1
-#define index_arch_I686				PREFERRED_FEATURE_INDEX_1
-#define index_arch_Slow_SSE4_2			PREFERRED_FEATURE_INDEX_1
-#define index_arch_AVX_Fast_Unaligned_Load	PREFERRED_FEATURE_INDEX_1
-#define index_arch_Prefer_MAP_32BIT_EXEC	PREFERRED_FEATURE_INDEX_1
-#define index_arch_Prefer_No_VZEROUPPER		PREFERRED_FEATURE_INDEX_1
-#define index_arch_Prefer_ERMS			PREFERRED_FEATURE_INDEX_1
-#define index_arch_Prefer_No_AVX512		PREFERRED_FEATURE_INDEX_1
-#define index_arch_MathVec_Prefer_No_AVX512	PREFERRED_FEATURE_INDEX_1
-#define index_arch_Prefer_FSRM			PREFERRED_FEATURE_INDEX_1
-
-#define feature_Fast_Rep_String			preferred
-#define feature_Fast_Copy_Backward		preferred
-#define feature_Slow_BSF			preferred
-#define feature_Fast_Unaligned_Load		preferred
-#define feature_Prefer_PMINUB_for_stringop 	preferred
-#define feature_Fast_Unaligned_Copy		preferred
-#define feature_I586				preferred
-#define feature_I686				preferred
-#define feature_Slow_SSE4_2			preferred
-#define feature_AVX_Fast_Unaligned_Load		preferred
-#define feature_Prefer_MAP_32BIT_EXEC		preferred
-#define feature_Prefer_No_VZEROUPPER		preferred
-#define feature_Prefer_ERMS			preferred
-#define feature_Prefer_No_AVX512		preferred
-#define feature_MathVec_Prefer_No_AVX512	preferred
-#define feature_Prefer_FSRM			preferred
-
-/* XCR0 Feature flags.  */
-#define bit_XMM_state		(1u << 1)
-#define bit_YMM_state		(1u << 2)
-#define bit_Opmask_state	(1u << 5)
-#define bit_ZMM0_15_state	(1u << 6)
-#define bit_ZMM16_31_state	(1u << 7)
-
-# if defined (_LIBC) && !IS_IN (nonlib)
-/* Unused for x86.  */
-#  define INIT_ARCH()
-#  define __get_cpu_features()	(&GLRO(dl_x86_cpu_features))
-#  define x86_get_cpuid_registers(i) \
-       (&(GLRO(dl_x86_cpu_features).cpuid[i]))
-# endif
-
-#ifdef __x86_64__
-# define HAS_CPUID 1
-#elif (defined __i586__ || defined __pentium__	\
-       || defined __geode__ || defined __k6__)
-# define HAS_CPUID 1
-# define HAS_I586 1
-# define HAS_I686 HAS_ARCH_FEATURE (I686)
-#elif defined __i486__
-# define HAS_CPUID 0
-# define HAS_I586 HAS_ARCH_FEATURE (I586)
-# define HAS_I686 HAS_ARCH_FEATURE (I686)
-#else
-# define HAS_CPUID 1
-# define HAS_I586 1
-# define HAS_I686 1
-#endif
-
-#endif  /* cpu_features_h */
+#endif  /* _SYS_PLATFORM_X86_H */
diff --git a/sysdeps/x86/tst-get-cpu-features.c b/sysdeps/x86/tst-get-cpu-features.c
index c60918cf00..60a18fed33 100644
--- a/sysdeps/x86/tst-get-cpu-features.c
+++ b/sysdeps/x86/tst-get-cpu-features.c
@@ -1,4 +1,4 @@
-/* Test case for x86 __get_cpu_features interface
+/* Test case for __x86_get_cpu_features interface
    Copyright (C) 2015-2020 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -18,7 +18,7 @@
 
 #include <stdlib.h>
 #include <stdio.h>
-#include <cpu-features.h>
+#include <sys/platform/x86.h>
 #include <support/check.h>
 
 #define CHECK_CPU_FEATURE(name)		\
@@ -45,7 +45,7 @@ static const char * const cpu_kinds[] =
 static int
 do_test (void)
 {
-  const struct cpu_features *cpu_features = __get_cpu_features ();
+  const struct cpu_features *cpu_features = __x86_get_cpu_features (0, 0);
 
   switch (cpu_features->basic.kind)
     {
diff --git a/sysdeps/x86_64/fpu/math-tests-arch.h b/sysdeps/x86_64/fpu/math-tests-arch.h
index 435ddad991..cc3c2b0c11 100644
--- a/sysdeps/x86_64/fpu/math-tests-arch.h
+++ b/sysdeps/x86_64/fpu/math-tests-arch.h
@@ -16,7 +16,7 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <cpu-features.h>
+#include <sys/platform/x86.h>
 
 #if defined REQUIRE_AVX
 
@@ -24,7 +24,7 @@
 # define CHECK_ARCH_EXT                                        \
   do                                                           \
     {                                                          \
-      if (!HAS_ARCH_FEATURE (AVX_Usable)) return;              \
+      if (!CPU_FEATURE_USABLE (AVX)) return;                   \
     }                                                          \
   while (0)
 
@@ -34,7 +34,7 @@
 # define CHECK_ARCH_EXT                                        \
   do                                                           \
     {                                                          \
-      if (!HAS_ARCH_FEATURE (AVX2_Usable)) return;             \
+      if (!CPU_FEATURE_USABLE (AVX2)) return;                  \
     }                                                          \
   while (0)
 
@@ -44,7 +44,7 @@
 # define CHECK_ARCH_EXT                                        \
   do                                                           \
     {                                                          \
-      if (!HAS_ARCH_FEATURE (AVX512F_Usable)) return;          \
+      if (!CPU_FEATURE_USABLE (AVX512F)) return;               \
     }                                                          \
   while (0)
 
diff --git a/sysdeps/x86_64/multiarch/test-multiarch.c b/sysdeps/x86_64/multiarch/test-multiarch.c
index 317373ceda..9feaf057e5 100644
--- a/sysdeps/x86_64/multiarch/test-multiarch.c
+++ b/sysdeps/x86_64/multiarch/test-multiarch.c
@@ -16,7 +16,7 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <cpu-features.h>
+#include <sys/platform/x86.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -75,10 +75,10 @@ do_test (int argc, char **argv)
   int fails;
 
   get_cpuinfo ();
-  fails = check_proc ("avx", HAS_ARCH_FEATURE (AVX_Usable),
-		      "HAS_ARCH_FEATURE (AVX_Usable)");
-  fails += check_proc ("fma4", HAS_ARCH_FEATURE (FMA4_Usable),
-		       "HAS_ARCH_FEATURE (FMA4_Usable)");
+  fails = check_proc ("avx", CPU_FEATURE_USABLE (AVX),
+		      "CPU_FEATURE_USABLE (AVX)");
+  fails += check_proc ("fma4", CPU_FEATURE_USABLE (FMA4),
+		       "CPU_FEATURE_USABLE (FMA4)");
   fails += check_proc ("sse4_2", HAS_CPU_FEATURE (SSE4_2),
 		       "HAS_CPU_FEATURE (SSE4_2)");
   fails += check_proc ("sse4_1", HAS_CPU_FEATURE (SSE4_1)
-- 
2.26.2