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31b54f40 PA |
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 | /* | |
31b54f40 PA |
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" | |
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25 | #endif |
26 | #include <linux/types.h> | |
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27 | #include <asm/processor-flags.h> |
28 | #include <asm/required-features.h> | |
29 | #include <asm/msr-index.h> | |
30 | ||
31b54f40 PA |
31 | static u32 err_flags[NCAPINTS]; |
32 | ||
31b54f40 | 33 | static const int req_level = CONFIG_X86_MINIMUM_CPU_FAMILY; |
31b54f40 PA |
34 | |
35 | static const u32 req_flags[NCAPINTS] = | |
36 | { | |
37 | REQUIRED_MASK0, | |
38 | REQUIRED_MASK1, | |
b74b06c5 PA |
39 | 0, /* REQUIRED_MASK2 not implemented in this file */ |
40 | 0, /* REQUIRED_MASK3 not implemented in this file */ | |
31b54f40 | 41 | REQUIRED_MASK4, |
b74b06c5 | 42 | 0, /* REQUIRED_MASK5 not implemented in this file */ |
31b54f40 | 43 | REQUIRED_MASK6, |
b74b06c5 | 44 | 0, /* REQUIRED_MASK7 not implemented in this file */ |
31b54f40 PA |
45 | }; |
46 | ||
7030760a | 47 | #define A32(a, b, c, d) (((d) << 24)+((c) << 16)+((b) << 8)+(a)) |
31b54f40 PA |
48 | |
49 | static int is_amd(void) | |
50 | { | |
7030760a PC |
51 | return cpu_vendor[0] == A32('A', 'u', 't', 'h') && |
52 | cpu_vendor[1] == A32('e', 'n', 't', 'i') && | |
53 | cpu_vendor[2] == A32('c', 'A', 'M', 'D'); | |
31b54f40 PA |
54 | } |
55 | ||
56 | static int is_centaur(void) | |
57 | { | |
7030760a PC |
58 | return cpu_vendor[0] == A32('C', 'e', 'n', 't') && |
59 | cpu_vendor[1] == A32('a', 'u', 'r', 'H') && | |
60 | cpu_vendor[2] == A32('a', 'u', 'l', 's'); | |
31b54f40 PA |
61 | } |
62 | ||
63 | static int is_transmeta(void) | |
64 | { | |
7030760a PC |
65 | return cpu_vendor[0] == A32('G', 'e', 'n', 'u') && |
66 | cpu_vendor[1] == A32('i', 'n', 'e', 'T') && | |
67 | cpu_vendor[2] == A32('M', 'x', '8', '6'); | |
31b54f40 PA |
68 | } |
69 | ||
69f2366c CB |
70 | static int is_intel(void) |
71 | { | |
72 | return cpu_vendor[0] == A32('G', 'e', 'n', 'u') && | |
73 | cpu_vendor[1] == A32('i', 'n', 'e', 'I') && | |
74 | cpu_vendor[2] == A32('n', 't', 'e', 'l'); | |
75 | } | |
76 | ||
31b54f40 | 77 | /* Returns a bitmask of which words we have error bits in */ |
6e6a4932 | 78 | static int check_cpuflags(void) |
31b54f40 PA |
79 | { |
80 | u32 err; | |
81 | int i; | |
82 | ||
83 | err = 0; | |
84 | for (i = 0; i < NCAPINTS; i++) { | |
85 | err_flags[i] = req_flags[i] & ~cpu.flags[i]; | |
86 | if (err_flags[i]) | |
87 | err |= 1 << i; | |
88 | } | |
89 | ||
90 | return err; | |
91 | } | |
92 | ||
93 | /* | |
94 | * Returns -1 on error. | |
95 | * | |
96 | * *cpu_level is set to the current CPU level; *req_level to the required | |
97 | * level. x86-64 is considered level 64 for this purpose. | |
98 | * | |
99 | * *err_flags_ptr is set to the flags error array if there are flags missing. | |
100 | */ | |
101 | int check_cpu(int *cpu_level_ptr, int *req_level_ptr, u32 **err_flags_ptr) | |
102 | { | |
103 | int err; | |
104 | ||
105 | memset(&cpu.flags, 0, sizeof cpu.flags); | |
106 | cpu.level = 3; | |
107 | ||
108 | if (has_eflag(X86_EFLAGS_AC)) | |
109 | cpu.level = 4; | |
110 | ||
6e6a4932 PA |
111 | get_cpuflags(); |
112 | err = check_cpuflags(); | |
31b54f40 PA |
113 | |
114 | if (test_bit(X86_FEATURE_LM, cpu.flags)) | |
115 | cpu.level = 64; | |
116 | ||
117 | if (err == 0x01 && | |
118 | !(err_flags[0] & | |
119 | ~((1 << X86_FEATURE_XMM)|(1 << X86_FEATURE_XMM2))) && | |
120 | is_amd()) { | |
121 | /* If this is an AMD and we're only missing SSE+SSE2, try to | |
122 | turn them on */ | |
123 | ||
124 | u32 ecx = MSR_K7_HWCR; | |
125 | u32 eax, edx; | |
126 | ||
127 | asm("rdmsr" : "=a" (eax), "=d" (edx) : "c" (ecx)); | |
128 | eax &= ~(1 << 15); | |
129 | asm("wrmsr" : : "a" (eax), "d" (edx), "c" (ecx)); | |
130 | ||
6e6a4932 PA |
131 | get_cpuflags(); /* Make sure it really did something */ |
132 | err = check_cpuflags(); | |
31b54f40 PA |
133 | } else if (err == 0x01 && |
134 | !(err_flags[0] & ~(1 << X86_FEATURE_CX8)) && | |
135 | is_centaur() && cpu.model >= 6) { | |
136 | /* If this is a VIA C3, we might have to enable CX8 | |
137 | explicitly */ | |
138 | ||
139 | u32 ecx = MSR_VIA_FCR; | |
140 | u32 eax, edx; | |
141 | ||
142 | asm("rdmsr" : "=a" (eax), "=d" (edx) : "c" (ecx)); | |
143 | eax |= (1<<1)|(1<<7); | |
144 | asm("wrmsr" : : "a" (eax), "d" (edx), "c" (ecx)); | |
145 | ||
146 | set_bit(X86_FEATURE_CX8, cpu.flags); | |
6e6a4932 | 147 | err = check_cpuflags(); |
31b54f40 PA |
148 | } else if (err == 0x01 && is_transmeta()) { |
149 | /* Transmeta might have masked feature bits in word 0 */ | |
150 | ||
151 | u32 ecx = 0x80860004; | |
152 | u32 eax, edx; | |
153 | u32 level = 1; | |
154 | ||
155 | asm("rdmsr" : "=a" (eax), "=d" (edx) : "c" (ecx)); | |
156 | asm("wrmsr" : : "a" (~0), "d" (edx), "c" (ecx)); | |
157 | asm("cpuid" | |
158 | : "+a" (level), "=d" (cpu.flags[0]) | |
159 | : : "ecx", "ebx"); | |
160 | asm("wrmsr" : : "a" (eax), "d" (edx), "c" (ecx)); | |
161 | ||
6e6a4932 | 162 | err = check_cpuflags(); |
69f2366c CB |
163 | } else if (err == 0x01 && |
164 | !(err_flags[0] & ~(1 << X86_FEATURE_PAE)) && | |
165 | is_intel() && cpu.level == 6 && | |
166 | (cpu.model == 9 || cpu.model == 13)) { | |
167 | /* PAE is disabled on this Pentium M but can be forced */ | |
168 | if (cmdline_find_option_bool("forcepae")) { | |
169 | puts("WARNING: Forcing PAE in CPU flags\n"); | |
170 | set_bit(X86_FEATURE_PAE, cpu.flags); | |
171 | err = check_cpuflags(); | |
172 | } | |
173 | else { | |
174 | puts("WARNING: PAE disabled. Use parameter 'forcepae' to enable at your own risk!\n"); | |
175 | } | |
31b54f40 PA |
176 | } |
177 | ||
178 | if (err_flags_ptr) | |
179 | *err_flags_ptr = err ? err_flags : NULL; | |
180 | if (cpu_level_ptr) | |
181 | *cpu_level_ptr = cpu.level; | |
182 | if (req_level_ptr) | |
183 | *req_level_ptr = req_level; | |
184 | ||
185 | return (cpu.level < req_level || err) ? -1 : 0; | |
186 | } |