sysdeps/x86_64/multiarch/init-arch.c

   1 /* Initialize CPU feature data.
   2    This file is part of the GNU C Library.
   3    Copyright (C) 2008, 2009 Free Software Foundation, Inc.
   4    Contributed by Ulrich Drepper <drepper@redhat.com>.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <cpuid.h>
  22 #include "init-arch.h"
  23
  24
  25 struct cpu_features __cpu_features attribute_hidden;
  26
  27
  28 static void
  29 get_common_indeces (void)
  30 {
  31   __cpuid (1, __cpu_features.cpuid[COMMON_CPUID_INDEX_1].eax,
  32            __cpu_features.cpuid[COMMON_CPUID_INDEX_1].ebx,
  33            __cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx,
  34            __cpu_features.cpuid[COMMON_CPUID_INDEX_1].edx);
  35
  36   unsigned int eax = __cpu_features.cpuid[COMMON_CPUID_INDEX_1].eax;
  37   __cpu_features.family = (eax >> 8) & 0x0f;
  38   __cpu_features.model = (eax >> 4) & 0x0f;
  39 }
  40
  41
  42 void
  43 __init_cpu_features (void)
  44 {
  45   unsigned int ebx;
  46   unsigned int ecx;
  47   unsigned int edx;
  48
  49   __cpuid (0, __cpu_features.max_cpuid, ebx, ecx, edx);
  50
  51   /* This spells out "GenuineIntel".  */
  52   if (ebx == 0x756e6547 && ecx == 0x6c65746e && edx == 0x49656e69)
  53     {
  54       __cpu_features.kind = arch_kind_intel;
  55
  56       get_common_indeces ();
  57
  58       unsigned int eax = __cpu_features.cpuid[COMMON_CPUID_INDEX_1].eax;
  59       unsigned int extended_family = (eax >> 20) & 0xff;
  60       unsigned int extended_model = (eax >> 12) & 0xf0;
  61       if (__cpu_features.family == 0x0f)
  62         {
  63           __cpu_features.family += extended_family;
  64           __cpu_features.model += extended_model;
  65         }
  66       else if (__cpu_features.family == 0x06)
  67         {
  68           __cpu_features.model += extended_model;
  69
  70 #ifndef ENABLE_SSSE3_ON_ATOM
  71           if (__cpu_features.model == 0x1c)
  72             /* Avoid SSSE3 on Atom since it is slow.  */
  73             __cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx &= ~(1 << 9);
  74 #endif
  75         }
  76     }
  77   /* This spells out "AuthenticAMD".  */
  78   else if (ebx == 0x68747541 && ecx == 0x444d4163 && edx == 0x69746e65)
  79     {
  80       __cpu_features.kind = arch_kind_amd;
  81
  82       get_common_indeces ();
  83     }
  84   else
  85     __cpu_features.kind = arch_kind_other;
  86 }
  87
  88
  89 const struct cpu_features *
  90 __get_cpu_features (void)
  91 {
  92   if (__cpu_features.kind == arch_kind_unknown)
  93     __init_cpu_features ();
  94
  95   return &__cpu_features;
  96 }