glibc/sysdeps/x86/cacheinfo.c

/* x86_64 cache info.
   Copyright (C) 2003-2020 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/>.  */

#if IS_IN (libc)

#include <assert.h>
#include <stdbool.h>
#include <stdlib.h>
#include <unistd.h>
#include <cpuid.h>
#include <init-arch.h>

static const struct intel_02_cache_info
{
  unsigned char idx;
  unsigned char assoc;
  unsigned char linesize;
  unsigned char rel_name;
  unsigned int size;
} intel_02_known [] =
  {
#define M(sc) ((sc) - _SC_LEVEL1_ICACHE_SIZE)
    { 0x06,  4, 32, M(_SC_LEVEL1_ICACHE_SIZE),    8192 },
    { 0x08,  4, 32, M(_SC_LEVEL1_ICACHE_SIZE),   16384 },
    { 0x09,  4, 32, M(_SC_LEVEL1_ICACHE_SIZE),   32768 },
    { 0x0a,  2, 32, M(_SC_LEVEL1_DCACHE_SIZE),    8192 },
    { 0x0c,  4, 32, M(_SC_LEVEL1_DCACHE_SIZE),   16384 },
    { 0x0d,  4, 64, M(_SC_LEVEL1_DCACHE_SIZE),   16384 },
    { 0x0e,  6, 64, M(_SC_LEVEL1_DCACHE_SIZE),   24576 },
    { 0x21,  8, 64, M(_SC_LEVEL2_CACHE_SIZE),   262144 },
    { 0x22,  4, 64, M(_SC_LEVEL3_CACHE_SIZE),   524288 },
    { 0x23,  8, 64, M(_SC_LEVEL3_CACHE_SIZE),  1048576 },
    { 0x25,  8, 64, M(_SC_LEVEL3_CACHE_SIZE),  2097152 },
    { 0x29,  8, 64, M(_SC_LEVEL3_CACHE_SIZE),  4194304 },
    { 0x2c,  8, 64, M(_SC_LEVEL1_DCACHE_SIZE),   32768 },
    { 0x30,  8, 64, M(_SC_LEVEL1_ICACHE_SIZE),   32768 },
    { 0x39,  4, 64, M(_SC_LEVEL2_CACHE_SIZE),   131072 },
    { 0x3a,  6, 64, M(_SC_LEVEL2_CACHE_SIZE),   196608 },
    { 0x3b,  2, 64, M(_SC_LEVEL2_CACHE_SIZE),   131072 },
    { 0x3c,  4, 64, M(_SC_LEVEL2_CACHE_SIZE),   262144 },
    { 0x3d,  6, 64, M(_SC_LEVEL2_CACHE_SIZE),   393216 },
    { 0x3e,  4, 64, M(_SC_LEVEL2_CACHE_SIZE),   524288 },
    { 0x3f,  2, 64, M(_SC_LEVEL2_CACHE_SIZE),   262144 },
    { 0x41,  4, 32, M(_SC_LEVEL2_CACHE_SIZE),   131072 },
    { 0x42,  4, 32, M(_SC_LEVEL2_CACHE_SIZE),   262144 },
    { 0x43,  4, 32, M(_SC_LEVEL2_CACHE_SIZE),   524288 },
    { 0x44,  4, 32, M(_SC_LEVEL2_CACHE_SIZE),  1048576 },
    { 0x45,  4, 32, M(_SC_LEVEL2_CACHE_SIZE),  2097152 },
    { 0x46,  4, 64, M(_SC_LEVEL3_CACHE_SIZE),  4194304 },
    { 0x47,  8, 64, M(_SC_LEVEL3_CACHE_SIZE),  8388608 },
    { 0x48, 12, 64, M(_SC_LEVEL2_CACHE_SIZE),  3145728 },
    { 0x49, 16, 64, M(_SC_LEVEL2_CACHE_SIZE),  4194304 },
    { 0x4a, 12, 64, M(_SC_LEVEL3_CACHE_SIZE),  6291456 },
    { 0x4b, 16, 64, M(_SC_LEVEL3_CACHE_SIZE),  8388608 },
    { 0x4c, 12, 64, M(_SC_LEVEL3_CACHE_SIZE), 12582912 },
    { 0x4d, 16, 64, M(_SC_LEVEL3_CACHE_SIZE), 16777216 },
    { 0x4e, 24, 64, M(_SC_LEVEL2_CACHE_SIZE),  6291456 },
    { 0x60,  8, 64, M(_SC_LEVEL1_DCACHE_SIZE),   16384 },
    { 0x66,  4, 64, M(_SC_LEVEL1_DCACHE_SIZE),    8192 },
    { 0x67,  4, 64, M(_SC_LEVEL1_DCACHE_SIZE),   16384 },
    { 0x68,  4, 64, M(_SC_LEVEL1_DCACHE_SIZE),   32768 },
    { 0x78,  8, 64, M(_SC_LEVEL2_CACHE_SIZE),  1048576 },
    { 0x79,  8, 64, M(_SC_LEVEL2_CACHE_SIZE),   131072 },
    { 0x7a,  8, 64, M(_SC_LEVEL2_CACHE_SIZE),   262144 },
    { 0x7b,  8, 64, M(_SC_LEVEL2_CACHE_SIZE),   524288 },
    { 0x7c,  8, 64, M(_SC_LEVEL2_CACHE_SIZE),  1048576 },
    { 0x7d,  8, 64, M(_SC_LEVEL2_CACHE_SIZE),  2097152 },
    { 0x7f,  2, 64, M(_SC_LEVEL2_CACHE_SIZE),   524288 },
    { 0x80,  8, 64, M(_SC_LEVEL2_CACHE_SIZE),   524288 },
    { 0x82,  8, 32, M(_SC_LEVEL2_CACHE_SIZE),   262144 },
    { 0x83,  8, 32, M(_SC_LEVEL2_CACHE_SIZE),   524288 },
    { 0x84,  8, 32, M(_SC_LEVEL2_CACHE_SIZE),  1048576 },
    { 0x85,  8, 32, M(_SC_LEVEL2_CACHE_SIZE),  2097152 },
    { 0x86,  4, 64, M(_SC_LEVEL2_CACHE_SIZE),   524288 },
    { 0x87,  8, 64, M(_SC_LEVEL2_CACHE_SIZE),  1048576 },
    { 0xd0,  4, 64, M(_SC_LEVEL3_CACHE_SIZE),   524288 },
    { 0xd1,  4, 64, M(_SC_LEVEL3_CACHE_SIZE),  1048576 },
    { 0xd2,  4, 64, M(_SC_LEVEL3_CACHE_SIZE),  2097152 },
    { 0xd6,  8, 64, M(_SC_LEVEL3_CACHE_SIZE),  1048576 },
    { 0xd7,  8, 64, M(_SC_LEVEL3_CACHE_SIZE),  2097152 },
    { 0xd8,  8, 64, M(_SC_LEVEL3_CACHE_SIZE),  4194304 },
    { 0xdc, 12, 64, M(_SC_LEVEL3_CACHE_SIZE),  2097152 },
    { 0xdd, 12, 64, M(_SC_LEVEL3_CACHE_SIZE),  4194304 },
    { 0xde, 12, 64, M(_SC_LEVEL3_CACHE_SIZE),  8388608 },
    { 0xe2, 16, 64, M(_SC_LEVEL3_CACHE_SIZE),  2097152 },
    { 0xe3, 16, 64, M(_SC_LEVEL3_CACHE_SIZE),  4194304 },
    { 0xe4, 16, 64, M(_SC_LEVEL3_CACHE_SIZE),  8388608 },
    { 0xea, 24, 64, M(_SC_LEVEL3_CACHE_SIZE), 12582912 },
    { 0xeb, 24, 64, M(_SC_LEVEL3_CACHE_SIZE), 18874368 },
    { 0xec, 24, 64, M(_SC_LEVEL3_CACHE_SIZE), 25165824 },
  };

#define nintel_02_known (sizeof (intel_02_known) / sizeof (intel_02_known [0]))

static int
intel_02_known_compare (const void *p1, const void *p2)
{
  const struct intel_02_cache_info *i1;
  const struct intel_02_cache_info *i2;

  i1 = (const struct intel_02_cache_info *) p1;
  i2 = (const struct intel_02_cache_info *) p2;

  if (i1->idx == i2->idx)
    return 0;

  return i1->idx < i2->idx ? -1 : 1;
}


static long int
__attribute__ ((noinline))
intel_check_word (int name, unsigned int value, bool *has_level_2,
		  bool *no_level_2_or_3,
		  const struct cpu_features *cpu_features)
{
  if ((value & 0x80000000) != 0)
    /* The register value is reserved.  */
    return 0;

  /* Fold the name.  The _SC_ constants are always in the order SIZE,
     ASSOC, LINESIZE.  */
  int folded_rel_name = (M(name) / 3) * 3;

  while (value != 0)
    {
      unsigned int byte = value & 0xff;

      if (byte == 0x40)
	{
	  *no_level_2_or_3 = true;

	  if (folded_rel_name == M(_SC_LEVEL3_CACHE_SIZE))
	    /* No need to look further.  */
	    break;
	}
      else if (byte == 0xff)
	{
	  /* CPUID leaf 0x4 contains all the information.  We need to
	     iterate over it.  */
	  unsigned int eax;
	  unsigned int ebx;
	  unsigned int ecx;
	  unsigned int edx;

	  unsigned int round = 0;
	  while (1)
	    {
	      __cpuid_count (4, round, eax, ebx, ecx, edx);

	      enum { null = 0, data = 1, inst = 2, uni = 3 } type = eax & 0x1f;
	      if (type == null)
		/* That was the end.  */
		break;

	      unsigned int level = (eax >> 5) & 0x7;

	      if ((level == 1 && type == data
		   && folded_rel_name == M(_SC_LEVEL1_DCACHE_SIZE))
		  || (level == 1 && type == inst
		      && folded_rel_name == M(_SC_LEVEL1_ICACHE_SIZE))
		  || (level == 2 && folded_rel_name == M(_SC_LEVEL2_CACHE_SIZE))
		  || (level == 3 && folded_rel_name == M(_SC_LEVEL3_CACHE_SIZE))
		  || (level == 4 && folded_rel_name == M(_SC_LEVEL4_CACHE_SIZE)))
		{
		  unsigned int offset = M(name) - folded_rel_name;

		  if (offset == 0)
		    /* Cache size.  */
		    return (((ebx >> 22) + 1)
			    * (((ebx >> 12) & 0x3ff) + 1)
			    * ((ebx & 0xfff) + 1)
			    * (ecx + 1));
		  if (offset == 1)
		    return (ebx >> 22) + 1;

		  assert (offset == 2);
		  return (ebx & 0xfff) + 1;
		}

	      ++round;
	    }
	  /* There is no other cache information anywhere else.  */
	  break;
	}
      else
	{
	  if (byte == 0x49 && folded_rel_name == M(_SC_LEVEL3_CACHE_SIZE))
	    {
	      /* Intel reused this value.  For family 15, model 6 it
		 specifies the 3rd level cache.  Otherwise the 2nd
		 level cache.  */
	      unsigned int family = cpu_features->basic.family;
	      unsigned int model = cpu_features->basic.model;

	      if (family == 15 && model == 6)
		{
		  /* The level 3 cache is encoded for this model like
		     the level 2 cache is for other models.  Pretend
		     the caller asked for the level 2 cache.  */
		  name = (_SC_LEVEL2_CACHE_SIZE
			  + (name - _SC_LEVEL3_CACHE_SIZE));
		  folded_rel_name = M(_SC_LEVEL2_CACHE_SIZE);
		}
	    }

	  struct intel_02_cache_info *found;
	  struct intel_02_cache_info search;

	  search.idx = byte;
	  found = bsearch (&search, intel_02_known, nintel_02_known,
			   sizeof (intel_02_known[0]), intel_02_known_compare);
	  if (found != NULL)
	    {
	      if (found->rel_name == folded_rel_name)
		{
		  unsigned int offset = M(name) - folded_rel_name;

		  if (offset == 0)
		    /* Cache size.  */
		    return found->size;
		  if (offset == 1)
		    return found->assoc;

		  assert (offset == 2);
		  return found->linesize;
		}

	      if (found->rel_name == M(_SC_LEVEL2_CACHE_SIZE))
		*has_level_2 = true;
	    }
	}

      /* Next byte for the next round.  */
      value >>= 8;
    }

  /* Nothing found.  */
  return 0;
}


static long int __attribute__ ((noinline))
handle_intel (int name, const struct cpu_features *cpu_features)
{
  unsigned int maxidx = cpu_features->basic.max_cpuid;

  /* Return -1 for older CPUs.  */
  if (maxidx < 2)
    return -1;

  /* OK, we can use the CPUID instruction to get all info about the
     caches.  */
  unsigned int cnt = 0;
  unsigned int max = 1;
  long int result = 0;
  bool no_level_2_or_3 = false;
  bool has_level_2 = false;

  while (cnt++ < max)
    {
      unsigned int eax;
      unsigned int ebx;
      unsigned int ecx;
      unsigned int edx;
      __cpuid (2, eax, ebx, ecx, edx);

      /* The low byte of EAX in the first round contain the number of
	 rounds we have to make.  At least one, the one we are already
	 doing.  */
      if (cnt == 1)
	{
	  max = eax & 0xff;
	  eax &= 0xffffff00;
	}

      /* Process the individual registers' value.  */
      result = intel_check_word (name, eax, &has_level_2,
				 &no_level_2_or_3, cpu_features);
      if (result != 0)
	return result;

      result = intel_check_word (name, ebx, &has_level_2,
				 &no_level_2_or_3, cpu_features);
      if (result != 0)
	return result;

      result = intel_check_word (name, ecx, &has_level_2,
				 &no_level_2_or_3, cpu_features);
      if (result != 0)
	return result;

      result = intel_check_word (name, edx, &has_level_2,
				 &no_level_2_or_3, cpu_features);
      if (result != 0)
	return result;
    }

  if (name >= _SC_LEVEL2_CACHE_SIZE && name <= _SC_LEVEL3_CACHE_LINESIZE
      && no_level_2_or_3)
    return -1;

  return 0;
}


static long int __attribute__ ((noinline))
handle_amd (int name)
{
  unsigned int eax;
  unsigned int ebx;
  unsigned int ecx;
  unsigned int edx;
  __cpuid (0x80000000, eax, ebx, ecx, edx);

  /* No level 4 cache (yet).  */
  if (name > _SC_LEVEL3_CACHE_LINESIZE)
    return 0;

  unsigned int fn = 0x80000005 + (name >= _SC_LEVEL2_CACHE_SIZE);
  if (eax < fn)
    return 0;

  __cpuid (fn, eax, ebx, ecx, edx);

  if (name < _SC_LEVEL1_DCACHE_SIZE)
    {
      name += _SC_LEVEL1_DCACHE_SIZE - _SC_LEVEL1_ICACHE_SIZE;
      ecx = edx;
    }

  switch (name)
    {
    case _SC_LEVEL1_DCACHE_SIZE:
      return (ecx >> 14) & 0x3fc00;

    case _SC_LEVEL1_DCACHE_ASSOC:
      ecx >>= 16;
      if ((ecx & 0xff) == 0xff)
	/* Fully associative.  */
	return (ecx << 2) & 0x3fc00;
      return ecx & 0xff;

    case _SC_LEVEL1_DCACHE_LINESIZE:
      return ecx & 0xff;

    case _SC_LEVEL2_CACHE_SIZE:
      return (ecx & 0xf000) == 0 ? 0 : (ecx >> 6) & 0x3fffc00;

    case _SC_LEVEL2_CACHE_ASSOC:
      switch ((ecx >> 12) & 0xf)
	{
	case 0:
	case 1:
	case 2:
	case 4:
	  return (ecx >> 12) & 0xf;
	case 6:
	  return 8;
	case 8:
	  return 16;
	case 10:
	  return 32;
	case 11:
	  return 48;
	case 12:
	  return 64;
	case 13:
	  return 96;
	case 14:
	  return 128;
	case 15:
	  return ((ecx >> 6) & 0x3fffc00) / (ecx & 0xff);
	default:
	  return 0;
	}
      /* NOTREACHED */

    case _SC_LEVEL2_CACHE_LINESIZE:
      return (ecx & 0xf000) == 0 ? 0 : ecx & 0xff;

    case _SC_LEVEL3_CACHE_SIZE:
      return (edx & 0xf000) == 0 ? 0 : (edx & 0x3ffc0000) << 1;

    case _SC_LEVEL3_CACHE_ASSOC:
      switch ((edx >> 12) & 0xf)
	{
	case 0:
	case 1:
	case 2:
	case 4:
	  return (edx >> 12) & 0xf;
	case 6:
	  return 8;
	case 8:
	  return 16;
	case 10:
	  return 32;
	case 11:
	  return 48;
	case 12:
	  return 64;
	case 13:
	  return 96;
	case 14:
	  return 128;
	case 15:
	  return ((edx & 0x3ffc0000) << 1) / (edx & 0xff);
	default:
	  return 0;
	}
      /* NOTREACHED */

    case _SC_LEVEL3_CACHE_LINESIZE:
      return (edx & 0xf000) == 0 ? 0 : edx & 0xff;

    default:
      assert (! "cannot happen");
    }
  return -1;
}


/* Get the value of the system variable NAME.  */
long int
attribute_hidden
__cache_sysconf (int name)
{
  const struct cpu_features *cpu_features = __get_cpu_features ();

  if (cpu_features->basic.kind == arch_kind_intel)
    return handle_intel (name, cpu_features);

  if (cpu_features->basic.kind == arch_kind_amd)
    return handle_amd (name);

  // XXX Fill in more vendors.

  /* CPU not known, we have no information.  */
  return 0;
}


/* Data cache size for use in memory and string routines, typically
   L1 size, rounded to multiple of 256 bytes.  */
long int __x86_data_cache_size_half attribute_hidden = 32 * 1024 / 2;
long int __x86_data_cache_size attribute_hidden = 32 * 1024;
/* Similar to __x86_data_cache_size_half, but not rounded.  */
long int __x86_raw_data_cache_size_half attribute_hidden = 32 * 1024 / 2;
/* Similar to __x86_data_cache_size, but not rounded.  */
long int __x86_raw_data_cache_size attribute_hidden = 32 * 1024;
/* Shared cache size for use in memory and string routines, typically
   L2 or L3 size, rounded to multiple of 256 bytes.  */
long int __x86_shared_cache_size_half attribute_hidden = 1024 * 1024 / 2;
long int __x86_shared_cache_size attribute_hidden = 1024 * 1024;
/* Similar to __x86_shared_cache_size_half, but not rounded.  */
long int __x86_raw_shared_cache_size_half attribute_hidden = 1024 * 1024 / 2;
/* Similar to __x86_shared_cache_size, but not rounded.  */
long int __x86_raw_shared_cache_size attribute_hidden = 1024 * 1024;

/* Threshold to use non temporal store.  */
long int __x86_shared_non_temporal_threshold attribute_hidden;

#ifndef DISABLE_PREFETCHW
/* PREFETCHW support flag for use in memory and string routines.  */
int __x86_prefetchw attribute_hidden;
#endif


static void
__attribute__((constructor))
init_cacheinfo (void)
{
  /* Find out what brand of processor.  */
  unsigned int eax;
  unsigned int ebx;
  unsigned int ecx;
  unsigned int edx;
  int max_cpuid_ex;
  long int data = -1;
  long int shared = -1;
  unsigned int level;
  unsigned int threads = 0;
  const struct cpu_features *cpu_features = __get_cpu_features ();
  int max_cpuid = cpu_features->basic.max_cpuid;

  if (cpu_features->basic.kind == arch_kind_intel)
    {
      data = handle_intel (_SC_LEVEL1_DCACHE_SIZE, cpu_features);

      long int core = handle_intel (_SC_LEVEL2_CACHE_SIZE, cpu_features);
      bool inclusive_cache = true;

      /* Try L3 first.  */
      level  = 3;
      shared = handle_intel (_SC_LEVEL3_CACHE_SIZE, cpu_features);

      /* Number of logical processors sharing L2 cache.  */
      int threads_l2;

      /* Number of logical processors sharing L3 cache.  */
      int threads_l3;

      if (shared <= 0)
	{
	  /* Try L2 otherwise.  */
	  level  = 2;
	  shared = core;
	  threads_l2 = 0;
	  threads_l3 = -1;
	}
      else
	{
	  threads_l2 = 0;
	  threads_l3 = 0;
	}

      /* A value of 0 for the HTT bit indicates there is only a single
	 logical processor.  */
      if (HAS_CPU_FEATURE (HTT))
	{
	  /* Figure out the number of logical threads that share the
	     highest cache level.  */
	  if (max_cpuid >= 4)
	    {
	      unsigned int family = cpu_features->basic.family;
	      unsigned int model = cpu_features->basic.model;

	      int i = 0;

	      /* Query until cache level 2 and 3 are enumerated.  */
	      int check = 0x1 | (threads_l3 == 0) << 1;
	      do
		{
		  __cpuid_count (4, i++, eax, ebx, ecx, edx);

		  /* There seems to be a bug in at least some Pentium Ds
		     which sometimes fail to iterate all cache parameters.
		     Do not loop indefinitely here, stop in this case and
		     assume there is no such information.  */
		  if ((eax & 0x1f) == 0)
		    goto intel_bug_no_cache_info;

		  switch ((eax >> 5) & 0x7)
		    {
		    default:
		      break;
		    case 2:
		      if ((check & 0x1))
			{
			  /* Get maximum number of logical processors
			     sharing L2 cache.  */
			  threads_l2 = (eax >> 14) & 0x3ff;
			  check &= ~0x1;
			}
		      break;
		    case 3:
		      if ((check & (0x1 << 1)))
			{
			  /* Get maximum number of logical processors
			     sharing L3 cache.  */
			  threads_l3 = (eax >> 14) & 0x3ff;

			  /* Check if L2 and L3 caches are inclusive.  */
			  inclusive_cache = (edx & 0x2) != 0;
			  check &= ~(0x1 << 1);
			}
		      break;
		    }
		}
	      while (check);

	      /* If max_cpuid >= 11, THREADS_L2/THREADS_L3 are the maximum
		 numbers of addressable IDs for logical processors sharing
		 the cache, instead of the maximum number of threads
		 sharing the cache.  */
	      if (max_cpuid >= 11)
		{
		  /* Find the number of logical processors shipped in
		     one core and apply count mask.  */
		  i = 0;

		  /* Count SMT only if there is L3 cache.  Always count
		     core if there is no L3 cache.  */
		  int count = ((threads_l2 > 0 && level == 3)
			       | ((threads_l3 > 0
				   || (threads_l2 > 0 && level == 2)) << 1));

		  while (count)
		    {
		      __cpuid_count (11, i++, eax, ebx, ecx, edx);

		      int shipped = ebx & 0xff;
		      int type = ecx & 0xff00;
		      if (shipped == 0 || type == 0)
			break;
		      else if (type == 0x100)
			{
			  /* Count SMT.  */
			  if ((count & 0x1))
			    {
			      int count_mask;

			      /* Compute count mask.  */
			      asm ("bsr %1, %0"
				   : "=r" (count_mask) : "g" (threads_l2));
			      count_mask = ~(-1 << (count_mask + 1));
			      threads_l2 = (shipped - 1) & count_mask;
			      count &= ~0x1;
			    }
			}
		      else if (type == 0x200)
			{
			  /* Count core.  */
			  if ((count & (0x1 << 1)))
			    {
			      int count_mask;
			      int threads_core
				= (level == 2 ? threads_l2 : threads_l3);

			      /* Compute count mask.  */
			      asm ("bsr %1, %0"
				   : "=r" (count_mask) : "g" (threads_core));
			      count_mask = ~(-1 << (count_mask + 1));
			      threads_core = (shipped - 1) & count_mask;
			      if (level == 2)
				threads_l2 = threads_core;
			      else
				threads_l3 = threads_core;
			      count &= ~(0x1 << 1);
			    }
			}
		    }
		}
	      if (threads_l2 > 0)
		threads_l2 += 1;
	      if (threads_l3 > 0)
		threads_l3 += 1;
	      if (level == 2)
		{
		  if (threads_l2)
		    {
		      threads = threads_l2;
		      if (threads > 2 && family == 6)
			switch (model)
			  {
			  case 0x37:
			  case 0x4a:
			  case 0x4d:
			  case 0x5a:
			  case 0x5d:
			    /* Silvermont has L2 cache shared by 2 cores.  */
			    threads = 2;
			    break;
			  default:
			    break;
			  }
		    }
		}
	      else if (threads_l3)
		threads = threads_l3;
	    }
	  else
	    {
intel_bug_no_cache_info:
	      /* Assume that all logical threads share the highest cache
		 level.  */

	      threads
		= ((cpu_features->cpuid[COMMON_CPUID_INDEX_1].ebx
		    >> 16) & 0xff);
	    }

	  /* Cap usage of highest cache level to the number of supported
	     threads.  */
	  if (shared > 0 && threads > 0)
	    shared /= threads;
	}

      /* Account for non-inclusive L2 and L3 caches.  */
      if (!inclusive_cache)
	{
	  if (threads_l2 > 0)
	    core /= threads_l2;
	  shared += core;
	}
    }
  else if (cpu_features->basic.kind == arch_kind_amd)
    {
      data   = handle_amd (_SC_LEVEL1_DCACHE_SIZE);
      long int core = handle_amd (_SC_LEVEL2_CACHE_SIZE);
      shared = handle_amd (_SC_LEVEL3_CACHE_SIZE);

      /* Get maximum extended function. */
      __cpuid (0x80000000, max_cpuid_ex, ebx, ecx, edx);

      if (shared <= 0)
	/* No shared L3 cache.  All we have is the L2 cache.  */
	shared = core;
      else
	{
	  /* Figure out the number of logical threads that share L3.  */
	  if (max_cpuid_ex >= 0x80000008)
	    {
	      /* Get width of APIC ID.  */
	      __cpuid (0x80000008, max_cpuid_ex, ebx, ecx, edx);
	      threads = 1 << ((ecx >> 12) & 0x0f);
	    }

	  if (threads == 0)
	    {
	      /* If APIC ID width is not available, use logical
		 processor count.  */
	      __cpuid (0x00000001, max_cpuid_ex, ebx, ecx, edx);

	      if ((edx & (1 << 28)) != 0)
		threads = (ebx >> 16) & 0xff;
	    }

	  /* Cap usage of highest cache level to the number of
	     supported threads.  */
	  if (threads > 0)
	    shared /= threads;

	  /* Account for exclusive L2 and L3 caches.  */
	  shared += core;
	}

#ifndef DISABLE_PREFETCHW
      if (max_cpuid_ex >= 0x80000001)
	{
	  __cpuid (0x80000001, eax, ebx, ecx, edx);
	  /*  PREFETCHW     || 3DNow!  */
	  if ((ecx & 0x100) || (edx & 0x80000000))
	    __x86_prefetchw = -1;
	}
#endif
    }

  if (cpu_features->data_cache_size != 0)
    data = cpu_features->data_cache_size;

  if (data > 0)
    {
      __x86_raw_data_cache_size_half = data / 2;
      __x86_raw_data_cache_size = data;
      /* Round data cache size to multiple of 256 bytes.  */
      data = data & ~255L;
      __x86_data_cache_size_half = data / 2;
      __x86_data_cache_size = data;
    }

  if (cpu_features->shared_cache_size != 0)
    shared = cpu_features->shared_cache_size;

  if (shared > 0)
    {
      __x86_raw_shared_cache_size_half = shared / 2;
      __x86_raw_shared_cache_size = shared;
      /* Round shared cache size to multiple of 256 bytes.  */
      shared = shared & ~255L;
      __x86_shared_cache_size_half = shared / 2;
      __x86_shared_cache_size = shared;
    }

  /* The large memcpy micro benchmark in glibc shows that 6 times of
     shared cache size is the approximate value above which non-temporal
     store becomes faster on a 8-core processor.  This is the 3/4 of the
     total shared cache size.  */
  __x86_shared_non_temporal_threshold
    = (cpu_features->non_temporal_threshold != 0
       ? cpu_features->non_temporal_threshold
       : __x86_shared_cache_size * threads * 3 / 4);
}

#endif