path: root/sysdeps/x86_64/cacheinfo.c

/* x86_64 cache info.
   Copyright (C) 2003, 2004, 2006, 2007 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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.
*/

#include <assert.h>
#include <stdbool.h>
#include <stdlib.h>
#include <unistd.h>

static const struct intel_02_cache_info
{
  unsigned int idx;
  int name;
  long int size;
  long int assoc;
  long int linesize;
} intel_02_known [] =
  {
    { 0x06, _SC_LEVEL1_ICACHE_SIZE,    8192,  4, 32 },
    { 0x08, _SC_LEVEL1_ICACHE_SIZE,   16384,  4, 32 },
    { 0x0a, _SC_LEVEL1_DCACHE_SIZE,    8192,  2, 32 },
    { 0x0c, _SC_LEVEL1_DCACHE_SIZE,   16384,  4, 32 },
    { 0x22, _SC_LEVEL3_CACHE_SIZE,   524288,  4, 64 },
    { 0x23, _SC_LEVEL3_CACHE_SIZE,  1048576,  8, 64 },
    { 0x25, _SC_LEVEL3_CACHE_SIZE,  2097152,  8, 64 },
    { 0x29, _SC_LEVEL3_CACHE_SIZE,  4194304,  8, 64 },
    { 0x2c, _SC_LEVEL1_DCACHE_SIZE,   32768,  8, 64 },
    { 0x30, _SC_LEVEL1_ICACHE_SIZE,   32768,  8, 64 },
    { 0x39, _SC_LEVEL2_CACHE_SIZE,   131072,  4, 64 },
    { 0x3a, _SC_LEVEL2_CACHE_SIZE,   196608,  6, 64 },
    { 0x3b, _SC_LEVEL2_CACHE_SIZE,   131072,  2, 64 },
    { 0x3c, _SC_LEVEL2_CACHE_SIZE,   262144,  4, 64 },
    { 0x3d, _SC_LEVEL2_CACHE_SIZE,   393216,  6, 64 },
    { 0x3e, _SC_LEVEL2_CACHE_SIZE,   524288,  4, 64 },
    { 0x41, _SC_LEVEL2_CACHE_SIZE,   131072,  4, 32 },
    { 0x42, _SC_LEVEL2_CACHE_SIZE,   262144,  4, 32 },
    { 0x43, _SC_LEVEL2_CACHE_SIZE,   524288,  4, 32 },
    { 0x44, _SC_LEVEL2_CACHE_SIZE,  1048576,  4, 32 },
    { 0x45, _SC_LEVEL2_CACHE_SIZE,  2097152,  4, 32 },
    { 0x46, _SC_LEVEL3_CACHE_SIZE,  4194304,  4, 64 },
    { 0x47, _SC_LEVEL3_CACHE_SIZE,  8388608,  8, 64 },
    { 0x49, _SC_LEVEL2_CACHE_SIZE,  4194304, 16, 64 },
    { 0x4a, _SC_LEVEL3_CACHE_SIZE,  6291456, 12, 64 },
    { 0x4b, _SC_LEVEL3_CACHE_SIZE,  8388608, 16, 64 },
    { 0x4c, _SC_LEVEL3_CACHE_SIZE, 12582912, 12, 64 },
    { 0x4d, _SC_LEVEL3_CACHE_SIZE, 16777216, 16, 64 },
    { 0x60, _SC_LEVEL1_DCACHE_SIZE,   16384,  8, 64 },
    { 0x66, _SC_LEVEL1_DCACHE_SIZE,    8192,  4, 64 },
    { 0x67, _SC_LEVEL1_DCACHE_SIZE,   16384,  4, 64 },
    { 0x68, _SC_LEVEL1_DCACHE_SIZE,   32768,  4, 64 },
    { 0x78, _SC_LEVEL2_CACHE_SIZE,  1048576,  8, 64 },
    { 0x79, _SC_LEVEL2_CACHE_SIZE,   131072,  8, 64 },
    { 0x7a, _SC_LEVEL2_CACHE_SIZE,   262144,  8, 64 },
    { 0x7b, _SC_LEVEL2_CACHE_SIZE,   524288,  8, 64 },
    { 0x7c, _SC_LEVEL2_CACHE_SIZE,  1048576,  8, 64 },
    { 0x7d, _SC_LEVEL2_CACHE_SIZE,  2097152,  8, 64 },
    { 0x7f, _SC_LEVEL2_CACHE_SIZE,   524288,  2, 64 },
    { 0x82, _SC_LEVEL2_CACHE_SIZE,   262144,  8, 32 },
    { 0x83, _SC_LEVEL2_CACHE_SIZE,   524288,  8, 32 },
    { 0x84, _SC_LEVEL2_CACHE_SIZE,  1048576,  8, 32 },
    { 0x85, _SC_LEVEL2_CACHE_SIZE,  2097152,  8, 32 },
    { 0x86, _SC_LEVEL2_CACHE_SIZE,   524288,  4, 64 },
    { 0x87, _SC_LEVEL2_CACHE_SIZE,  1048576,  8, 64 },
  };

#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)
{
  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_name = (_SC_LEVEL1_ICACHE_SIZE
		     + ((name - _SC_LEVEL1_ICACHE_SIZE) / 3) * 3);

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

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

	  if (folded_name == _SC_LEVEL3_CACHE_SIZE)
	    /* No need to look further.  */
	    break;
	}
      else
	{
	  if (byte == 0x49 && folded_name == _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 eax;
	      unsigned int ebx;
	      unsigned int ecx;
	      unsigned int edx;
	      asm volatile ("cpuid"
			    : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
			    : "0" (1));

	      unsigned int family = ((eax >> 20) & 0xff) + ((eax >> 8) & 0xf);
	      unsigned int model = ((((eax >>16) & 0xf) << 4)
				    + ((eax >> 4) & 0xf));
	      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_name = _SC_LEVEL3_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->name == folded_name)
		{
		  unsigned int offset = name - folded_name;

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

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

	      if (found->name == _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, unsigned int maxidx)
{
  assert (maxidx >= 2);

  /* 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;
      asm volatile ("cpuid"
		    : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
		    : "0" (2));

      /* 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);
      if (result != 0)
	return result;

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

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

      result = intel_check_word (name, edx, &has_level_2, &no_level_2_or_3);
      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;
  asm volatile ("cpuid"
		: "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
		: "0" (0x80000000));

  if (name >= _SC_LEVEL3_CACHE_SIZE)
    return 0;

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

  asm volatile ("cpuid"
		: "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
		: "0" (fn));

  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:
      ecx >>= 12;
      switch (ecx & 0xf)
        {
        case 0:
        case 1:
        case 2:
        case 4:
	  return ecx & 0xf;
	case 6:
	  return 8;
	case 8:
	  return 16;
	case 0xf:
	  return (ecx << 6) & 0x3fffc00;
	default:
	  return 0;
        }
    case _SC_LEVEL2_CACHE_LINESIZE:
      return (ecx & 0xf000) == 0 ? 0 : ecx & 0xff;
    default:
      assert (! "cannot happen");
    }
  return -1;
}


/* Get the value of the system variable NAME.  */
long int
attribute_hidden
__cache_sysconf (int name)
{
  /* Find out what brand of processor.  */
  unsigned int eax;
  unsigned int ebx;
  unsigned int ecx;
  unsigned int edx;
  asm volatile ("cpuid"
		: "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
		: "0" (0));

  /* This spells out "GenuineIntel".  */
  if (ebx == 0x756e6547 && ecx == 0x6c65746e && edx == 0x49656e69)
    return handle_intel (name, eax);

  /* This spells out "AuthenticAMD".  */
  if (ebx == 0x68747541 && ecx == 0x444d4163 && edx == 0x69746e65)
    return handle_amd (name);

  // XXX Fill in more vendors.

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


/* Half the core cache size for use in memory and string routines, typically
   L1 size. */
long int __x86_64_core_cache_size_half attribute_hidden = 32 * 1024 / 2;
/* Shared cache size for use in memory and string routines, typically
   L2 or L3 size. */
long int __x86_64_shared_cache_size_half attribute_hidden = 1024 * 1024 / 2;
/* PREFETCHW support flag for use in memory and string routines. */
int __x86_64_prefetchw attribute_hidden;


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;
  int max_cpuid_ex;
  long int core = -1;
  long int shared = -1;
  unsigned int level;
  unsigned int threads = 0;

  asm volatile ("cpuid"
		: "=a" (max_cpuid), "=b" (ebx), "=c" (ecx), "=d" (edx)
		: "0" (0));

  /* This spells out "GenuineIntel".  */
  if (ebx == 0x756e6547 && ecx == 0x6c65746e && edx == 0x49656e69)
    {
      core = handle_intel (_SC_LEVEL1_DCACHE_SIZE, max_cpuid);

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

      if (shared <= 0)
        {
	  /* Try L2 otherwise. */
          level  = 2;
          shared = handle_intel (_SC_LEVEL2_CACHE_SIZE, max_cpuid);
	}

      /* Figure out the number of logical threads that share the
	 highest cache level. */
      if (max_cpuid >= 4)
        {
	  int i = 0;

	  /* Query until desired cache level is enumerated. */
	  do
	    {
              asm volatile ("cpuid"
		            : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
		            : "0" (4), "2" (i++));
	    }
          while (((eax >> 5) & 0x7) != level);

	  threads = ((eax >> 14) & 0x3ff) + 1;
	}
      else
        {
	  /* Assume that all logical threads share the highest cache level. */
          asm volatile ("cpuid"
		        : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
		        : "0" (1));

	  threads = (ebx >> 16) & 0xff;
	}

      /* Cap usage of highest cache level to the number of supported
	 threads. */
      if (shared > 0 && threads > 0)
        shared /= threads;
    }
  /* This spells out "AuthenticAMD".  */
  else if (ebx == 0x68747541 && ecx == 0x444d4163 && edx == 0x69746e65)
    {
      core   = handle_amd (_SC_LEVEL1_DCACHE_SIZE);
      shared = handle_amd (_SC_LEVEL2_CACHE_SIZE);

      asm volatile ("cpuid"
		    : "=a" (max_cpuid_ex), "=b" (ebx), "=c" (ecx), "=d" (edx)
		    : "0" (0x80000000));

      if (max_cpuid_ex >= 0x80000001)
	{
	  asm volatile ("cpuid"
			: "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
			: "0" (0x80000001));
	  /*  PREFETCHW     || 3DNow! */
	  if ((ecx & 0x100) || (edx & 0x80000000))
	    __x86_64_prefetchw = -1;
	}
    }

  if (core > 0)
    __x86_64_core_cache_size_half = core / 2;

  if (shared > 0)
    __x86_64_shared_cache_size_half = shared / 2;
}