arch/x86/boot/cpucheck.c

   1 /* -*- linux-c -*- ------------------------------------------------------- *
   2  *
   3  *   Copyright (C) 1991, 1992 Linus Torvalds
   4  *   Copyright 2007 rPath, Inc. - All Rights Reserved
   5  *
   6  *   This file is part of the Linux kernel, and is made available under
   7  *   the terms of the GNU General Public License version 2.
   8  *
   9  * ----------------------------------------------------------------------- */
  10
  11 /*
  12  * Check for obligatory CPU features and abort if the features are not
  13  * present.  This code should be compilable as 16-, 32- or 64-bit
  14  * code, so be very careful with types and inline assembly.
  15  *
  16  * This code should not contain any messages; that requires an
  17  * additional wrapper.
  18  *
  19  * As written, this code is not safe for inclusion into the kernel
  20  * proper (after FPU initialization, in particular).
  21  */
  22
  23 #ifdef _SETUP
  24 # include "boot.h"
  25 #endif
  26 #include <linux/types.h>
  27 #include <asm/processor-flags.h>
  28 #include <asm/required-features.h>
  29 #include <asm/msr-index.h>
  30
  31 struct cpu_features cpu;
  32 static u32 cpu_vendor[3];
  33 static u32 err_flags[NCAPINTS];
  34
  35 static const int req_level = CONFIG_X86_MINIMUM_CPU_FAMILY;
  36
  37 static const u32 req_flags[NCAPINTS] =
  38 {
  39         REQUIRED_MASK0,
  40         REQUIRED_MASK1,
  41         0, /* REQUIRED_MASK2 not implemented in this file */
  42         0, /* REQUIRED_MASK3 not implemented in this file */
  43         REQUIRED_MASK4,
  44         0, /* REQUIRED_MASK5 not implemented in this file */
  45         REQUIRED_MASK6,
  46         0, /* REQUIRED_MASK7 not implemented in this file */
  47 };
  48
  49 #define A32(a, b, c, d) (((d) << 24)+((c) << 16)+((b) << 8)+(a))
  50
  51 static int is_amd(void)
  52 {
  53         return cpu_vendor[0] == A32('A', 'u', 't', 'h') &&
  54                cpu_vendor[1] == A32('e', 'n', 't', 'i') &&
  55                cpu_vendor[2] == A32('c', 'A', 'M', 'D');
  56 }
  57
  58 static int is_centaur(void)
  59 {
  60         return cpu_vendor[0] == A32('C', 'e', 'n', 't') &&
  61                cpu_vendor[1] == A32('a', 'u', 'r', 'H') &&
  62                cpu_vendor[2] == A32('a', 'u', 'l', 's');
  63 }
  64
  65 static int is_transmeta(void)
  66 {
  67         return cpu_vendor[0] == A32('G', 'e', 'n', 'u') &&
  68                cpu_vendor[1] == A32('i', 'n', 'e', 'T') &&
  69                cpu_vendor[2] == A32('M', 'x', '8', '6');
  70 }
  71
  72 static int has_fpu(void)
  73 {
  74         u16 fcw = -1, fsw = -1;
  75         u32 cr0;
  76
  77         asm("movl %%cr0,%0" : "=r" (cr0));
  78         if (cr0 & (X86_CR0_EM|X86_CR0_TS)) {
  79                 cr0 &= ~(X86_CR0_EM|X86_CR0_TS);
  80                 asm volatile("movl %0,%%cr0" : : "r" (cr0));
  81         }
  82
  83         asm volatile("fninit ; fnstsw %0 ; fnstcw %1"
  84                      : "+m" (fsw), "+m" (fcw));
  85
  86         return fsw == 0 && (fcw & 0x103f) == 0x003f;
  87 }
  88
  89 static int has_eflag(u32 mask)
  90 {
  91         u32 f0, f1;
  92
  93         asm("pushfl ; "
  94             "pushfl ; "
  95             "popl %0 ; "
  96             "movl %0,%1 ; "
  97             "xorl %2,%1 ; "
  98             "pushl %1 ; "
  99             "popfl ; "
 100             "pushfl ; "
 101             "popl %1 ; "
 102             "popfl"
 103             : "=&r" (f0), "=&r" (f1)
 104             : "ri" (mask));
 105
 106         return !!((f0^f1) & mask);
 107 }
 108
 109 static void get_flags(void)
 110 {
 111         u32 max_intel_level, max_amd_level;
 112         u32 tfms;
 113
 114         if (has_fpu())
 115                 set_bit(X86_FEATURE_FPU, cpu.flags);
 116
 117         if (has_eflag(X86_EFLAGS_ID)) {
 118                 asm("cpuid"
 119                     : "=a" (max_intel_level),
 120                       "=b" (cpu_vendor[0]),
 121                       "=d" (cpu_vendor[1]),
 122                       "=c" (cpu_vendor[2])
 123                     : "a" (0));
 124
 125                 if (max_intel_level >= 0x00000001 &&
 126                     max_intel_level <= 0x0000ffff) {
 127                         asm("cpuid"
 128                             : "=a" (tfms),
 129                               "=c" (cpu.flags[4]),
 130                               "=d" (cpu.flags[0])
 131                             : "a" (0x00000001)
 132                             : "ebx");
 133                         cpu.level = (tfms >> 8) & 15;
 134                         cpu.model = (tfms >> 4) & 15;
 135                         if (cpu.level >= 6)
 136                                 cpu.model += ((tfms >> 16) & 0xf) << 4;
 137                 }
 138
 139                 asm("cpuid"
 140                     : "=a" (max_amd_level)
 141                     : "a" (0x80000000)
 142                     : "ebx", "ecx", "edx");
 143
 144                 if (max_amd_level >= 0x80000001 &&
 145                     max_amd_level <= 0x8000ffff) {
 146                         u32 eax = 0x80000001;
 147                         asm("cpuid"
 148                             : "+a" (eax),
 149                               "=c" (cpu.flags[6]),
 150                               "=d" (cpu.flags[1])
 151                             : : "ebx");
 152                 }
 153         }
 154 }
 155
 156 /* Returns a bitmask of which words we have error bits in */
 157 static int check_flags(void)
 158 {
 159         u32 err;
 160         int i;
 161
 162         err = 0;
 163         for (i = 0; i < NCAPINTS; i++) {
 164                 err_flags[i] = req_flags[i] & ~cpu.flags[i];
 165                 if (err_flags[i])
 166                         err |= 1 << i;
 167         }
 168
 169         return err;
 170 }
 171
 172 /*
 173  * Returns -1 on error.
 174  *
 175  * *cpu_level is set to the current CPU level; *req_level to the required
 176  * level.  x86-64 is considered level 64 for this purpose.
 177  *
 178  * *err_flags_ptr is set to the flags error array if there are flags missing.
 179  */
 180 int check_cpu(int *cpu_level_ptr, int *req_level_ptr, u32 **err_flags_ptr)
 181 {
 182         int err;
 183
 184         memset(&cpu.flags, 0, sizeof cpu.flags);
 185         cpu.level = 3;
 186
 187         if (has_eflag(X86_EFLAGS_AC))
 188                 cpu.level = 4;
 189
 190         get_flags();
 191         err = check_flags();
 192
 193         if (test_bit(X86_FEATURE_LM, cpu.flags))
 194                 cpu.level = 64;
 195
 196         if (err == 0x01 &&
 197             !(err_flags[0] &
 198               ~((1 << X86_FEATURE_XMM)|(1 << X86_FEATURE_XMM2))) &&
 199             is_amd()) {
 200                 /* If this is an AMD and we're only missing SSE+SSE2, try to
 201                    turn them on */
 202
 203                 u32 ecx = MSR_K7_HWCR;
 204                 u32 eax, edx;
 205
 206                 asm("rdmsr" : "=a" (eax), "=d" (edx) : "c" (ecx));
 207                 eax &= ~(1 << 15);
 208                 asm("wrmsr" : : "a" (eax), "d" (edx), "c" (ecx));
 209
 210                 get_flags();    /* Make sure it really did something */
 211                 err = check_flags();
 212         } else if (err == 0x01 &&
 213                    !(err_flags[0] & ~(1 << X86_FEATURE_CX8)) &&
 214                    is_centaur() && cpu.model >= 6) {
 215                 /* If this is a VIA C3, we might have to enable CX8
 216                    explicitly */
 217
 218                 u32 ecx = MSR_VIA_FCR;
 219                 u32 eax, edx;
 220
 221                 asm("rdmsr" : "=a" (eax), "=d" (edx) : "c" (ecx));
 222                 eax |= (1<<1)|(1<<7);
 223                 asm("wrmsr" : : "a" (eax), "d" (edx), "c" (ecx));
 224
 225                 set_bit(X86_FEATURE_CX8, cpu.flags);
 226                 err = check_flags();
 227         } else if (err == 0x01 && is_transmeta()) {
 228                 /* Transmeta might have masked feature bits in word 0 */
 229
 230                 u32 ecx = 0x80860004;
 231                 u32 eax, edx;
 232                 u32 level = 1;
 233
 234                 asm("rdmsr" : "=a" (eax), "=d" (edx) : "c" (ecx));
 235                 asm("wrmsr" : : "a" (~0), "d" (edx), "c" (ecx));
 236                 asm("cpuid"
 237                     : "+a" (level), "=d" (cpu.flags[0])
 238                     : : "ecx", "ebx");
 239                 asm("wrmsr" : : "a" (eax), "d" (edx), "c" (ecx));
 240
 241                 err = check_flags();
 242         }
 243
 244         if (err_flags_ptr)
 245                 *err_flags_ptr = err ? err_flags : NULL;
 246         if (cpu_level_ptr)
 247                 *cpu_level_ptr = cpu.level;
 248         if (req_level_ptr)
 249                 *req_level_ptr = req_level;
 250
 251         return (cpu.level < req_level || err) ? -1 : 0;
 252 }