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

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

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

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

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

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 cpuid_features
{
  struct cpuid_registers cpuid;
  struct cpuid_registers usable;
};

struct cpu_features
{
  struct cpu_features_basic basic;
  struct cpuid_features features[COMMON_CPUID_INDEX_MAX];
};

/* Get a pointer to the CPU features structure.  */
extern const struct cpu_features *__x86_get_cpu_features
  (unsigned int max) __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 features
array can be expanded with backward binary compatibility for both .o and
.so files.  When COMMON_CPUID_INDEX_MAX is 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 false on the
new processor feature.  No new symbol version is neeeded.

Both CPU_FEATURE_USABLE and HAS_CPU_FEATURE are provided.  HAS_CPU_FEATURE
can be used to identify processor features.

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.

8 files changed, 654 insertions, 141 deletions

diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
index a6736aef25..c369faf00d 100644
--- a/sysdeps/x86/Makefile
+++ b/sysdeps/x86/Makefile
@@ -4,8 +4,10 @@ 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 += tst-get-cpu-features tst-get-cpu-features-static \
+	 tst-cpu-features-cpuinfo tst-cpu-features-supports
 tests-static += tst-get-cpu-features-static
 endif
 
diff --git a/sysdeps/x86/Versions b/sysdeps/x86/Versions
index e02923708e..59db578a9d 100644
--- a/sysdeps/x86/Versions
+++ b/sysdeps/x86/Versions
@@ -1,5 +1,5 @@
 ld {
-  GLIBC_PRIVATE {
-    __get_cpu_features;
+  GLIBC_2.33 {
+    __x86_get_cpu_features;
   }
 }
diff --git a/sysdeps/x86/dl-get-cpu-features.c b/sysdeps/x86/dl-get-cpu-features.c
index 9d61cd56be..5f9e46b0c6 100644
--- a/sysdeps/x86/dl-get-cpu-features.c
+++ b/sysdeps/x86/dl-get-cpu-features.c
@@ -18,10 +18,12 @@
 
 #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)
 {
+  if (max > COMMON_CPUID_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..dcf29b6fe8
--- /dev/null
+++ b/sysdeps/x86/include/cpu-features.h
@@ -0,0 +1,183 @@
+/* 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)
+
+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
+};
+
+/* Only used directly in cpu-features.c.  */
+# define CPU_FEATURE_SET(ptr, name) \
+  ptr->features[index_cpu_##name].usable.reg_##name |= bit_cpu_##name;
+# define CPU_FEATURE_UNSET(ptr, name) \
+  ptr->features[index_cpu_##name].usable.reg_##name &= ~bit_cpu_##name;
+# define CPU_FEATURE_SET_USABLE(ptr, name) \
+  ptr->features[index_cpu_##name].usable.reg_##name \
+     |= ptr->features[index_cpu_##name].cpuid.reg_##name & bit_cpu_##name;
+# define CPU_FEATURE_PREFERRED_P(ptr, name) \
+  ((ptr->preferred[index_arch_##name] & bit_arch_##name) != 0)
+# define CPU_FEATURE_CPU_P(ptr, name) \
+  CPU_FEATURE_CHECK_P (ptr, name, cpuid)
+
+/* HAS_CPU_FEATURE evaluates to true if CPU supports the feature.  */
+# undef HAS_CPU_FEATURE
+# define HAS_CPU_FEATURE(name) \
+  CPU_FEATURE_CPU_P (__x86_get_cpu_features (0), name)
+/* CPU_FEATURE_USABLE evaluates to true if the feature is usable.  */
+# undef CPU_FEATURE_USABLE
+# define CPU_FEATURE_USABLE(name) \
+  CPU_FEATURE_USABLE_P (__x86_get_cpu_features (0), name)
+/* CPU_FEATURE_PREFER evaluates to true if we prefer the feature at
+   runtime.  */
+# define CPU_FEATURE_PREFERRED(name) \
+  CPU_FEATURE_PREFERRED_P(__get_cpu_features (), name)
+
+# define CPU_FEATURES_CPU_P(ptr, name) \
+  CPU_FEATURE_CPU_P (ptr, name)
+# define CPU_FEATURES_ARCH_P(ptr, name) \
+  CPU_FEATURE_PREFERRED_P (ptr, name)
+# define HAS_ARCH_FEATURE(name) \
+  CPU_FEATURE_PREFERRED (name)
+
+/* 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
+
+/* 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)
+# define bit_XTILECFG_state	(1u << 17)
+# define bit_XTILEDATA_state	(1u << 18)
+
+struct cpu_features
+{
+  struct cpu_features_basic basic;
+  struct cpuid_features features[COMMON_CPUID_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
+   */
+  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;
+  /* Threshold to use "rep movsb".  */
+  unsigned long int rep_movsb_threshold;
+  /* Threshold to use "rep stosb".  */
+  unsigned long int rep_stosb_threshold;
+};
+
+# if defined (_LIBC) && !IS_IN (nonlib)
+/* Unused for x86.  */
+#  define INIT_ARCH()
+#  define __x86_get_cpu_features(max) (&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
index 78fcec251e..bf3727ebc0 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
@@ -15,17 +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
-
-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
-};
+#ifndef _SYS_PLATFORM_X86_H
+#define _SYS_PLATFORM_X86_H
 
 enum
 {
@@ -76,73 +68,32 @@ struct cpu_features
 {
   struct cpu_features_basic basic;
   struct cpuid_features features[COMMON_CPUID_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
-   */
-  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;
-  /* Threshold to use "rep movsb".  */
-  unsigned long int rep_movsb_threshold;
-  /* Threshold to use "rep stosb".  */
-  unsigned long int rep_stosb_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)
      __attribute__ ((const));
 
-/* Only used directly in cpu-features.c.  */
 #define CPU_FEATURE_CHECK_P(ptr, name, check) \
   ((ptr->features[index_cpu_##name].check.reg_##name \
     & bit_cpu_##name) != 0)
-#define CPU_FEATURE_SET(ptr, name) \
-  ptr->features[index_cpu_##name].usable.reg_##name |= bit_cpu_##name;
-#define CPU_FEATURE_UNSET(ptr, name) \
-  ptr->features[index_cpu_##name].usable.reg_##name &= ~bit_cpu_##name;
-#define CPU_FEATURE_SET_USABLE(ptr, name) \
-  ptr->features[index_cpu_##name].usable.reg_##name \
-     |= ptr->features[index_cpu_##name].cpuid.reg_##name & bit_cpu_##name;
-#define CPU_FEATURE_PREFERRED_P(ptr, name) \
-  ((ptr->preferred[index_arch_##name] & bit_arch_##name) != 0)
 #define CPU_FEATURE_CPU_P(ptr, name) \
   CPU_FEATURE_CHECK_P (ptr, name, cpuid)
 #define CPU_FEATURE_USABLE_P(ptr, name) \
   CPU_FEATURE_CHECK_P (ptr, name, usable)
 
 /* HAS_CPU_FEATURE evaluates to true if CPU supports the feature.  */
-#define HAS_CPU_FEATURE(name) \
-  CPU_FEATURE_CPU_P (__get_cpu_features (), name)
+#define HAS_CPU_FEATURE(name)					\
+  (__extension__						\
+   ({ const struct cpu_features *__ptr =			\
+	__x86_get_cpu_features (COMMON_CPUID_INDEX_MAX);	\
+      __ptr && CPU_FEATURE_CPU_P (__ptr, name); }))
 /* CPU_FEATURE_USABLE evaluates to true if the feature is usable.  */
-#define CPU_FEATURE_USABLE(name) \
-  CPU_FEATURE_USABLE_P (__get_cpu_features (), name)
-/* CPU_FEATURE_PREFER evaluates to true if we prefer the feature at
-   runtime.  */
-#define CPU_FEATURE_PREFERRED(name) \
-  CPU_FEATURE_PREFERRED_P(__get_cpu_features (), name)
-
-#define CPU_FEATURES_CPU_P(ptr, name) \
-  CPU_FEATURE_CPU_P (ptr, name)
-#define CPU_FEATURES_ARCH_P(ptr, name) \
-  CPU_FEATURE_PREFERRED_P (ptr, name)
-#define HAS_ARCH_FEATURE(name) \
-  CPU_FEATURE_PREFERRED (name)
+#define CPU_FEATURE_USABLE(name)				\
+  (__extension__						\
+   ({ const struct cpu_features *__ptr =			\
+	__x86_get_cpu_features (COMMON_CPUID_INDEX_MAX);	\
+      __ptr && CPU_FEATURE_USABLE_P (__ptr, name); }))
 
 /* CPU features.  */
 
@@ -787,71 +738,4 @@ 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
-
-/* 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)
-#define bit_XTILECFG_state	(1u << 17)
-#define bit_XTILEDATA_state	(1u << 18)
-
-# if defined (_LIBC) && !IS_IN (nonlib)
-/* Unused for x86.  */
-#  define INIT_ARCH()
-#  define __get_cpu_features()	(&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  /* cpu_features_h */
+#endif  /* _SYS_PLATFORM_X86_H */
diff --git a/sysdeps/x86/tst-cpu-features-cpuinfo.c b/sysdeps/x86/tst-cpu-features-cpuinfo.c
new file mode 100644
index 0000000000..96277284d1
--- /dev/null
+++ b/sysdeps/x86/tst-cpu-features-cpuinfo.c
@@ -0,0 +1,250 @@
+/* Test CPU feature data against /proc/cpuinfo.
+   This file is part of the GNU C Library.
+   Copyright (C) 2012-2020 Free Software Foundation, Inc.
+
+   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 <sys/platform/x86.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static char *cpu_flags;
+
+/* Search for flags in /proc/cpuinfo and store line
+   in cpu_flags.  */
+void
+get_cpuinfo (void)
+{
+  FILE *f;
+  char *line = NULL;
+  size_t len = 0;
+  ssize_t read;
+
+  f = fopen ("/proc/cpuinfo", "r");
+  if (f == NULL)
+    {
+      printf ("cannot open /proc/cpuinfo\n");
+      exit (1);
+    }
+
+  while ((read = getline (&line, &len, f)) != -1)
+    {
+      if (strncmp (line, "flags", 5) == 0)
+       {
+         cpu_flags = strdup (line);
+         break;
+       }
+    }
+  fclose (f);
+  free (line);
+}
+
+int
+check_proc (const char *proc_name, int flag, int usable, const char *name)
+{
+  int found = 0;
+
+  printf ("Checking %s:\n", name);
+  if (!usable)
+    {
+      printf ("  %s: insufficient usable info, skipped\n", name);
+      return 0;
+    }
+  printf ("  %s: %d\n", name, flag);
+  if (strstr (cpu_flags, proc_name) != NULL)
+    found = 1;
+  printf ("  cpuinfo (%s): %d\n", proc_name, found);
+
+  if (found != flag)
+    printf (" *** failure ***\n");
+
+  return (found != flag);
+}
+
+#define CHECK_PROC(str, name) \
+  check_proc (#str, HAS_CPU_FEATURE (name), CPU_FEATURE_USABLE (name), \
+	      "HAS_CPU_FEATURE (" #name ")");
+
+static int
+do_test (int argc, char **argv)
+{
+  int fails = 0;
+
+  get_cpuinfo ();
+  fails += CHECK_PROC (acpi, ACPI);
+  fails += CHECK_PROC (adx, ADX);
+  fails += CHECK_PROC (apic, APIC);
+  fails += CHECK_PROC (aes, AES);
+  fails += CHECK_PROC (amx_bf16, AMX_BF16);
+  fails += CHECK_PROC (amx_int8, AMX_INT8);
+  fails += CHECK_PROC (amx_tile, AMX_TILE);
+  fails += CHECK_PROC (arch_capabilities, ARCH_CAPABILITIES);
+  fails += CHECK_PROC (avx, AVX);
+  fails += CHECK_PROC (avx2, AVX2);
+  fails += CHECK_PROC (avx512_4fmaps, AVX512_4FMAPS);
+  fails += CHECK_PROC (avx512_4vnniw, AVX512_4VNNIW);
+  fails += CHECK_PROC (avx512_bf16, AVX512_BF16);
+  fails += CHECK_PROC (avx512_bitalg, AVX512_BITALG);
+  fails += CHECK_PROC (avx512ifma, AVX512_IFMA);
+  fails += CHECK_PROC (avx512_vbmi, AVX512_VBMI);
+  fails += CHECK_PROC (avx512_vbmi2, AVX512_VBMI2);
+  fails += CHECK_PROC (avx512_vnni, AVX512_VNNI);
+  fails += CHECK_PROC (avx512_vp2intersect, AVX512_VP2INTERSECT);
+  fails += CHECK_PROC (avx512_vpopcntdq, AVX512_VPOPCNTDQ);
+  fails += CHECK_PROC (avx512bw, AVX512BW);
+  fails += CHECK_PROC (avx512cd, AVX512CD);
+  fails += CHECK_PROC (avx512er, AVX512ER);
+  fails += CHECK_PROC (avx512dq, AVX512DQ);
+  fails += CHECK_PROC (avx512f, AVX512F);
+  fails += CHECK_PROC (avx512pf, AVX512PF);
+  fails += CHECK_PROC (avx512vl, AVX512VL);
+  fails += CHECK_PROC (bmi1, BMI1);
+  fails += CHECK_PROC (bmi2, BMI2);
+  fails += CHECK_PROC (cldemote, CLDEMOTE);
+  fails += CHECK_PROC (clflushopt, CLFLUSHOPT);
+  fails += CHECK_PROC (clflush, CLFSH);
+  fails += CHECK_PROC (clwb, CLWB);
+  fails += CHECK_PROC (cmov, CMOV);
+  fails += CHECK_PROC (cx16, CMPXCHG16B);
+  fails += CHECK_PROC (cnxt_id, CNXT_ID);
+  fails += CHECK_PROC (core_capabilities, CORE_CAPABILITIES);
+  fails += CHECK_PROC (cx8, CX8);
+  fails += CHECK_PROC (dca, DCA);
+  fails += CHECK_PROC (de, DE);
+  fails += CHECK_PROC (zero_fcs_fds, DEPR_FPU_CS_DS);
+  fails += CHECK_PROC (ds, DS);
+  fails += CHECK_PROC (ds_cpl, DS_CPL);
+  fails += CHECK_PROC (dtes64, DTES64);
+  fails += CHECK_PROC (est, EIST);
+  fails += CHECK_PROC (enqcmd, ENQCMD);
+  fails += CHECK_PROC (erms, ERMS);
+  fails += CHECK_PROC (f16c, F16C);
+  fails += CHECK_PROC (fma, FMA);
+  fails += CHECK_PROC (fma4, FMA4);
+  fails += CHECK_PROC (fpu, FPU);
+  fails += CHECK_PROC (fsgsbase, FSGSBASE);
+  fails += CHECK_PROC (fsrm, FSRM);
+  fails += CHECK_PROC (fxsr, FXSR);
+  fails += CHECK_PROC (gfni, GFNI);
+  fails += CHECK_PROC (hle, HLE);
+  fails += CHECK_PROC (ht, HTT);
+  fails += CHECK_PROC (hybrid, HYBRID);
+  fails += CHECK_PROC (ibrs, IBRS_IBPB);
+  fails += CHECK_PROC (ibt, IBT);
+  fails += CHECK_PROC (invariant_tsc, INVARIANT_TSC);
+  fails += CHECK_PROC (invpcid, INVPCID);
+  fails += CHECK_PROC (flush_l1d, L1D_FLUSH);
+  fails += CHECK_PROC (lahf_lm, LAHF64_SAHF64);
+  fails += CHECK_PROC (lm, LM);
+  fails += CHECK_PROC (lwp, LWP);
+  fails += CHECK_PROC (abm, LZCNT);
+  fails += CHECK_PROC (mca, MCA);
+  fails += CHECK_PROC (mce, MCE);
+  fails += CHECK_PROC (md_clear, MD_CLEAR);
+  fails += CHECK_PROC (mmx, MMX);
+  fails += CHECK_PROC (monitor, MONITOR);
+  fails += CHECK_PROC (movbe, MOVBE);
+  fails += CHECK_PROC (movdiri, MOVDIRI);
+  fails += CHECK_PROC (movdir64b, MOVDIR64B);
+  fails += CHECK_PROC (mpx, MPX);
+  fails += CHECK_PROC (msr, MSR);
+  fails += CHECK_PROC (mtrr, MTRR);
+  fails += CHECK_PROC (nx, NX);
+  fails += CHECK_PROC (ospke, OSPKE);
+#if 0
+  /* NB: /proc/cpuinfo doesn't report this feature.  */
+  fails += CHECK_PROC (osxsave, OSXSAVE);
+#endif
+  fails += CHECK_PROC (pae, PAE);
+  fails += CHECK_PROC (pdpe1gb, PAGE1GB);
+  fails += CHECK_PROC (pat, PAT);
+  fails += CHECK_PROC (pbe, PBE);
+  fails += CHECK_PROC (pcid, PCID);
+  fails += CHECK_PROC (pclmulqdq, PCLMULQDQ);
+  fails += CHECK_PROC (pconfig, PCONFIG);
+  fails += CHECK_PROC (pdcm, PDCM);
+  fails += CHECK_PROC (pge, PGE);
+  fails += CHECK_PROC (pks, PKS);
+  fails += CHECK_PROC (pku, PKU);
+  fails += CHECK_PROC (popcnt, POPCNT);
+  fails += CHECK_PROC (3dnowprefetch, PREFETCHW);
+  fails += CHECK_PROC (prefetchwt1, PREFETCHWT1);
+  fails += CHECK_PROC (pse, PSE);
+  fails += CHECK_PROC (pse36, PSE_36);
+  fails += CHECK_PROC (psn, PSN);
+  fails += CHECK_PROC (rdpid, RDPID);
+  fails += CHECK_PROC (rdrand, RDRAND);
+  fails += CHECK_PROC (rdseed, RDSEED);
+  fails += CHECK_PROC (rdt_a, RDT_A);
+  fails += CHECK_PROC (cqm, RDT_M);
+  fails += CHECK_PROC (rdtscp, RDTSCP);
+  fails += CHECK_PROC (rtm, RTM);
+  fails += CHECK_PROC (sdbg, SDBG);
+  fails += CHECK_PROC (sep, SEP);
+  fails += CHECK_PROC (serialize, SERIALIZE);
+  fails += CHECK_PROC (sgx, SGX);
+  fails += CHECK_PROC (sgx_lc, SGX_LC);
+  fails += CHECK_PROC (sha_ni, SHA);
+  fails += CHECK_PROC (shstk, SHSTK);
+  fails += CHECK_PROC (smap, SMAP);
+  fails += CHECK_PROC (smep, SMEP);
+  fails += CHECK_PROC (smx, SMX);
+  fails += CHECK_PROC (ss, SS);
+  fails += CHECK_PROC (ssbd, SSBD);
+  fails += CHECK_PROC (sse, SSE);
+  fails += CHECK_PROC (sse2, SSE2);
+  fails += CHECK_PROC (sse3, SSE3);
+  fails += CHECK_PROC (sse4_1, SSE4_1);
+  fails += CHECK_PROC (sse4_2, SSE4_2);
+  fails += CHECK_PROC (sse4a, SSE4A);
+  fails += CHECK_PROC (ssse3, SSSE3);
+  fails += CHECK_PROC (stibp, STIBP);
+  fails += CHECK_PROC (svm, SVM);
+#ifdef __x86_64__
+  /* NB: SYSCALL_SYSRET is 64-bit only.  */
+  fails += CHECK_PROC (syscall, SYSCALL_SYSRET);
+#endif
+  fails += CHECK_PROC (tbm, TBM);
+  fails += CHECK_PROC (tm, TM);
+  fails += CHECK_PROC (tm2, TM2);
+  fails += CHECK_PROC (intel_pt, TRACE);
+  fails += CHECK_PROC (tsc, TSC);
+  fails += CHECK_PROC (tsc_adjust, TSC_ADJUST);
+  fails += CHECK_PROC (tsc_deadline, TSC_DEADLINE);
+  fails += CHECK_PROC (tsxldtrk, TSXLDTRK);
+  fails += CHECK_PROC (umip, UMIP);
+  fails += CHECK_PROC (vaes, VAES);
+  fails += CHECK_PROC (vme, VME);
+  fails += CHECK_PROC (vmx, VMX);
+  fails += CHECK_PROC (vpclmulqdq, VPCLMULQDQ);
+  fails += CHECK_PROC (waitpkg, WAITPKG);
+  fails += CHECK_PROC (wbnoinvd, WBNOINVD);
+  fails += CHECK_PROC (x2apic, X2APIC);
+  fails += CHECK_PROC (xfd, XFD);
+  fails += CHECK_PROC (xgetbv1, XGETBV_ECX_1);
+  fails += CHECK_PROC (xop, XOP);
+  fails += CHECK_PROC (xsave, XSAVE);
+  fails += CHECK_PROC (xsavec, XSAVEC);
+  fails += CHECK_PROC (xsaveopt, XSAVEOPT);
+  fails += CHECK_PROC (xsaves, XSAVES);
+  fails += CHECK_PROC (xtpr, XTPRUPDCTRL);
+
+  printf ("%d differences between /proc/cpuinfo and glibc code.\n", fails);
+
+  return (fails != 0);
+}
+
+#include "../../../test-skeleton.c"
diff --git a/sysdeps/x86/tst-cpu-features-supports.c b/sysdeps/x86/tst-cpu-features-supports.c
new file mode 100644
index 0000000000..bf881b531f
--- /dev/null
+++ b/sysdeps/x86/tst-cpu-features-supports.c
@@ -0,0 +1,192 @@
+/* Test CPU feature data against __builtin_cpu_supports.
+   This file is part of the GNU C Library.
+   Copyright (C) 2020 Free Software Foundation, Inc.
+
+   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 <sys/platform/x86.h>
+#include <stdio.h>
+
+int
+check_supports (int supports, int usable, const char *supports_name,
+		const char *name)
+{
+  printf ("Checking %s:\n", name);
+  printf ("  %s: %d\n", name, usable);
+  printf ("  __builtin_cpu_supports (%s): %d\n",
+	  supports_name, supports);
+
+  if ((supports != 0) != (usable != 0))
+    {
+      printf (" *** failure ***\n");
+      return 1;
+    }
+
+  return 0;
+}
+
+#define CHECK_SUPPORTS(str, name) \
+  check_supports (__builtin_cpu_supports (#str), \
+		  CPU_FEATURE_USABLE (name), \
+		  #str, "HAS_CPU_FEATURE (" #name ")");
+
+static int
+do_test (int argc, char **argv)
+{
+  int fails = 0;
+
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (adx, ADX);
+#endif
+#if __GNUC_PREREQ (6, 0)
+  fails += CHECK_SUPPORTS (aes, AES);
+#endif
+#if __GNUC_PREREQ (11, 1)
+  fails += CHECK_SUPPORTS (amx_bf16, AMX_BF16);
+  fails += CHECK_SUPPORTS (amx_int8, AMX_INT8);
+  fails += CHECK_SUPPORTS (amx_tile, AMX_TILE);
+#endif
+  fails += CHECK_SUPPORTS (avx, AVX);
+  fails += CHECK_SUPPORTS (avx2, AVX2);
+#if __GNUC_PREREQ (7, 0)
+  fails += CHECK_SUPPORTS (avx5124fmaps, AVX512_4FMAPS);
+  fails += CHECK_SUPPORTS (avx5124vnniw, AVX512_4VNNIW);
+#endif
+#if __GNUC_PREREQ (10, 0)
+  fails += CHECK_SUPPORTS (avx512bf16, AVX512_BF16);
+#endif
+#if __GNUC_PREREQ (8, 0)
+  fails += CHECK_SUPPORTS (avx512bitalg, AVX512_BITALG);
+#endif
+#if __GNUC_PREREQ (6, 0)
+  fails += CHECK_SUPPORTS (avx512ifma, AVX512_IFMA);
+  fails += CHECK_SUPPORTS (avx512vbmi, AVX512_VBMI);
+#endif
+#if __GNUC_PREREQ (8, 0)
+  fails += CHECK_SUPPORTS (avx512vbmi2, AVX512_VBMI2);
+  fails += CHECK_SUPPORTS (avx512vnni, AVX512_VNNI);
+#endif
+#if __GNUC_PREREQ (10, 0)
+  fails += CHECK_SUPPORTS (avx512vp2intersect, AVX512_VP2INTERSECT);
+#endif
+#if __GNUC_PREREQ (7, 0)
+  fails += CHECK_SUPPORTS (avx512vpopcntdq, AVX512_VPOPCNTDQ);
+#endif
+#if __GNUC_PREREQ (6, 0)
+  fails += CHECK_SUPPORTS (avx512bw, AVX512BW);
+  fails += CHECK_SUPPORTS (avx512cd, AVX512CD);
+  fails += CHECK_SUPPORTS (avx512er, AVX512ER);
+  fails += CHECK_SUPPORTS (avx512dq, AVX512DQ);
+#endif
+#if __GNUC_PREREQ (5, 0)
+  fails += CHECK_SUPPORTS (avx512f, AVX512F);
+#endif
+#if __GNUC_PREREQ (6, 0)
+  fails += CHECK_SUPPORTS (avx512pf, AVX512PF);
+  fails += CHECK_SUPPORTS (avx512vl, AVX512VL);
+#endif
+#if __GNUC_PREREQ (5, 0)
+  fails += CHECK_SUPPORTS (bmi, BMI1);
+  fails += CHECK_SUPPORTS (bmi2, BMI2);
+#endif
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (cldemote, CLDEMOTE);
+  fails += CHECK_SUPPORTS (clflushopt, CLFLUSHOPT);
+  fails += CHECK_SUPPORTS (clwb, CLWB);
+#endif
+  fails += CHECK_SUPPORTS (cmov, CMOV);
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (cmpxchg16b, CMPXCHG16B);
+  fails += CHECK_SUPPORTS (cmpxchg8b, CX8);
+  fails += CHECK_SUPPORTS (enqcmd, ENQCMD);
+  fails += CHECK_SUPPORTS (f16c, F16C);
+#endif
+#if __GNUC_PREREQ (4, 9)
+  fails += CHECK_SUPPORTS (fma, FMA);
+  fails += CHECK_SUPPORTS (fma4, FMA4);
+#endif
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (fsgsbase, FSGSBASE);
+  fails += CHECK_SUPPORTS (fxsave, FXSR);
+#endif
+#if __GNUC_PREREQ (8, 0)
+  fails += CHECK_SUPPORTS (gfni, GFNI);
+#endif
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (hle, HLE);
+  fails += CHECK_SUPPORTS (ibt, IBT);
+  fails += CHECK_SUPPORTS (lahf_lm, LAHF64_SAHF64);
+  fails += CHECK_SUPPORTS (lm, LM);
+  fails += CHECK_SUPPORTS (lwp, LWP);
+  fails += CHECK_SUPPORTS (lzcnt, LZCNT);
+#endif
+  fails += CHECK_SUPPORTS (mmx, MMX);
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (movbe, MOVBE);
+  fails += CHECK_SUPPORTS (movdiri, MOVDIRI);
+  fails += CHECK_SUPPORTS (movdir64b, MOVDIR64B);
+  fails += CHECK_SUPPORTS (osxsave, OSXSAVE);
+  fails += CHECK_SUPPORTS (pconfig, PCONFIG);
+  fails += CHECK_SUPPORTS (pku, PKU);
+#endif
+  fails += CHECK_SUPPORTS (popcnt, POPCNT);
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (prefetchwt1, PREFETCHWT1);
+  fails += CHECK_SUPPORTS (rdpid, RDPID);
+  fails += CHECK_SUPPORTS (rdrnd, RDRAND);
+  fails += CHECK_SUPPORTS (rdseed, RDSEED);
+  fails += CHECK_SUPPORTS (rtm, RTM);
+  fails += CHECK_SUPPORTS (serialize, SERIALIZE);
+  fails += CHECK_SUPPORTS (sha, SHA);
+  fails += CHECK_SUPPORTS (shstk, SHSTK);
+#endif
+  fails += CHECK_SUPPORTS (sse, SSE);
+  fails += CHECK_SUPPORTS (sse2, SSE2);
+  fails += CHECK_SUPPORTS (sse3, SSE3);
+  fails += CHECK_SUPPORTS (sse4.1, SSE4_1);
+  fails += CHECK_SUPPORTS (sse4.2, SSE4_2);
+#if __GNUC_PREREQ (4, 9)
+  fails += CHECK_SUPPORTS (sse4a, SSE4A);
+#endif
+  fails += CHECK_SUPPORTS (ssse3, SSSE3);
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (tbm, TBM);
+  fails += CHECK_SUPPORTS (tsxldtrk, TSXLDTRK);
+  fails += CHECK_SUPPORTS (vaes, VAES);
+#endif
+#if __GNUC_PREREQ (8, 0)
+  fails += CHECK_SUPPORTS (vpclmulqdq, VPCLMULQDQ);
+#endif
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (waitpkg, WAITPKG);
+  fails += CHECK_SUPPORTS (wbnoinvd, WBNOINVD);
+#endif
+#if __GNUC_PREREQ (4, 9)
+  fails += CHECK_SUPPORTS (xop, XOP);
+#endif
+#if __GNUC_PREREQ (11, 0)
+  fails += CHECK_SUPPORTS (xsave, XSAVE);
+  fails += CHECK_SUPPORTS (xsavec, XSAVEC);
+  fails += CHECK_SUPPORTS (xsaveopt, XSAVEOPT);
+  fails += CHECK_SUPPORTS (xsaves, XSAVES);
+#endif
+
+  printf ("%d differences between __builtin_cpu_supports and glibc code.\n",
+	  fails);
+
+  return (fails != 0);
+}
+
+#include "../../../test-skeleton.c"
diff --git a/sysdeps/x86/tst-get-cpu-features.c b/sysdeps/x86/tst-get-cpu-features.c
index 6bfdef0829..3447d17e23 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);
 
   switch (cpu_features->basic.kind)
     {