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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 | /* -*- linux-c -*- ------------------------------------------------------- *
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright 2007 rPath, Inc. - All Rights Reserved
*
* This file is part of the Linux kernel, and is made available under
* the terms of the GNU General Public License version 2.
*
* ----------------------------------------------------------------------- */
/*
* Check for obligatory CPU features and abort if the features are not
* present. This code should be compilable as 16-, 32- or 64-bit
* code, so be very careful with types and inline assembly.
*
* This code should not contain any messages; that requires an
* additional wrapper.
*
* As written, this code is not safe for inclusion into the kernel
* proper (after FPU initialization, in particular).
*/
#ifdef _SETUP
# include "boot.h"
#endif
#include <linux/types.h>
#include <asm/processor-flags.h>
#include <asm/required-features.h>
#include <asm/msr-index.h>
#include "string.h"
static u32 err_flags[NCAPINTS];
static const int req_level = CONFIG_X86_MINIMUM_CPU_FAMILY;
static const u32 req_flags[NCAPINTS] =
{
REQUIRED_MASK0,
REQUIRED_MASK1,
0, /* REQUIRED_MASK2 not implemented in this file */
0, /* REQUIRED_MASK3 not implemented in this file */
REQUIRED_MASK4,
0, /* REQUIRED_MASK5 not implemented in this file */
REQUIRED_MASK6,
0, /* REQUIRED_MASK7 not implemented in this file */
};
#define A32(a, b, c, d) (((d) << 24)+((c) << 16)+((b) << 8)+(a))
static int is_amd(void)
{
return cpu_vendor[0] == A32('A', 'u', 't', 'h') &&
cpu_vendor[1] == A32('e', 'n', 't', 'i') &&
cpu_vendor[2] == A32('c', 'A', 'M', 'D');
}
static int is_centaur(void)
{
return cpu_vendor[0] == A32('C', 'e', 'n', 't') &&
cpu_vendor[1] == A32('a', 'u', 'r', 'H') &&
cpu_vendor[2] == A32('a', 'u', 'l', 's');
}
static int is_transmeta(void)
{
return cpu_vendor[0] == A32('G', 'e', 'n', 'u') &&
cpu_vendor[1] == A32('i', 'n', 'e', 'T') &&
cpu_vendor[2] == A32('M', 'x', '8', '6');
}
static int is_intel(void)
{
return cpu_vendor[0] == A32('G', 'e', 'n', 'u') &&
cpu_vendor[1] == A32('i', 'n', 'e', 'I') &&
cpu_vendor[2] == A32('n', 't', 'e', 'l');
}
/* Returns a bitmask of which words we have error bits in */
static int check_cpuflags(void)
{
u32 err;
int i;
err = 0;
for (i = 0; i < NCAPINTS; i++) {
err_flags[i] = req_flags[i] & ~cpu.flags[i];
if (err_flags[i])
err |= 1 << i;
}
return err;
}
/*
* Returns -1 on error.
*
* *cpu_level is set to the current CPU level; *req_level to the required
* level. x86-64 is considered level 64 for this purpose.
*
* *err_flags_ptr is set to the flags error array if there are flags missing.
*/
int check_cpu(int *cpu_level_ptr, int *req_level_ptr, u32 **err_flags_ptr)
{
int err;
memset(&cpu.flags, 0, sizeof cpu.flags);
cpu.level = 3;
if (has_eflag(X86_EFLAGS_AC))
cpu.level = 4;
get_cpuflags();
err = check_cpuflags();
if (test_bit(X86_FEATURE_LM, cpu.flags))
cpu.level = 64;
if (err == 0x01 &&
!(err_flags[0] &
~((1 << X86_FEATURE_XMM)|(1 << X86_FEATURE_XMM2))) &&
is_amd()) {
/* If this is an AMD and we're only missing SSE+SSE2, try to
turn them on */
u32 ecx = MSR_K7_HWCR;
u32 eax, edx;
asm("rdmsr" : "=a" (eax), "=d" (edx) : "c" (ecx));
eax &= ~(1 << 15);
asm("wrmsr" : : "a" (eax), "d" (edx), "c" (ecx));
get_cpuflags(); /* Make sure it really did something */
err = check_cpuflags();
} else if (err == 0x01 &&
!(err_flags[0] & ~(1 << X86_FEATURE_CX8)) &&
is_centaur() && cpu.model >= 6) {
/* If this is a VIA C3, we might have to enable CX8
explicitly */
u32 ecx = MSR_VIA_FCR;
u32 eax, edx;
asm("rdmsr" : "=a" (eax), "=d" (edx) : "c" (ecx));
eax |= (1<<1)|(1<<7);
asm("wrmsr" : : "a" (eax), "d" (edx), "c" (ecx));
set_bit(X86_FEATURE_CX8, cpu.flags);
err = check_cpuflags();
} else if (err == 0x01 && is_transmeta()) {
/* Transmeta might have masked feature bits in word 0 */
u32 ecx = 0x80860004;
u32 eax, edx;
u32 level = 1;
asm("rdmsr" : "=a" (eax), "=d" (edx) : "c" (ecx));
asm("wrmsr" : : "a" (~0), "d" (edx), "c" (ecx));
asm("cpuid"
: "+a" (level), "=d" (cpu.flags[0])
: : "ecx", "ebx");
asm("wrmsr" : : "a" (eax), "d" (edx), "c" (ecx));
err = check_cpuflags();
} else if (err == 0x01 &&
!(err_flags[0] & ~(1 << X86_FEATURE_PAE)) &&
is_intel() && cpu.level == 6 &&
(cpu.model == 9 || cpu.model == 13)) {
/* PAE is disabled on this Pentium M but can be forced */
if (cmdline_find_option_bool("forcepae")) {
puts("WARNING: Forcing PAE in CPU flags\n");
set_bit(X86_FEATURE_PAE, cpu.flags);
err = check_cpuflags();
}
else {
puts("WARNING: PAE disabled. Use parameter 'forcepae' to enable at your own risk!\n");
}
}
if (err_flags_ptr)
*err_flags_ptr = err ? err_flags : NULL;
if (cpu_level_ptr)
*cpu_level_ptr = cpu.level;
if (req_level_ptr)
*req_level_ptr = req_level;
return (cpu.level < req_level || err) ? -1 : 0;
}
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