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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 | * arch/i386/boot/cpucheck.c | |
13 | * | |
14 | * Check for obligatory CPU features and abort if the features are not | |
15 | * present. This code should be compilable as 16-, 32- or 64-bit | |
16 | * code, so be very careful with types and inline assembly. | |
17 | * | |
18 | * This code should not contain any messages; that requires an | |
19 | * additional wrapper. | |
20 | * | |
21 | * As written, this code is not safe for inclusion into the kernel | |
22 | * proper (after FPU initialization, in particular). | |
23 | */ | |
24 | ||
25 | #ifdef _SETUP | |
26 | # include "boot.h" | |
27 | # include "bitops.h" | |
28 | #endif | |
29 | #include <linux/types.h> | |
30 | #include <asm/cpufeature.h> | |
31 | #include <asm/processor-flags.h> | |
32 | #include <asm/required-features.h> | |
33 | #include <asm/msr-index.h> | |
34 | ||
35 | struct cpu_features { | |
36 | int level; /* Family, or 64 for x86-64 */ | |
37 | int model; | |
38 | u32 flags[NCAPINTS]; | |
39 | }; | |
40 | ||
41 | static struct cpu_features cpu; | |
42 | static u32 cpu_vendor[3]; | |
43 | static u32 err_flags[NCAPINTS]; | |
44 | ||
45 | #ifdef CONFIG_X86_64 | |
46 | static const int req_level = 64; | |
47 | #elif defined(CONFIG_X86_MINIMUM_CPU_FAMILY) | |
48 | static const int req_level = CONFIG_X86_MINIMUM_CPU_FAMILY; | |
49 | #else | |
50 | static const int req_level = 3; | |
51 | #endif | |
52 | ||
53 | static const u32 req_flags[NCAPINTS] = | |
54 | { | |
55 | REQUIRED_MASK0, | |
56 | REQUIRED_MASK1, | |
57 | REQUIRED_MASK2, | |
58 | REQUIRED_MASK3, | |
59 | REQUIRED_MASK4, | |
60 | REQUIRED_MASK5, | |
61 | REQUIRED_MASK6, | |
62 | REQUIRED_MASK7, | |
63 | }; | |
64 | ||
65 | #define A32(a,b,c,d) (((d) << 24)+((c) << 16)+((b) << 8)+(a)) | |
66 | ||
67 | static int is_amd(void) | |
68 | { | |
69 | return cpu_vendor[0] == A32('A','u','t','h') && | |
70 | cpu_vendor[1] == A32('e','n','t','i') && | |
71 | cpu_vendor[2] == A32('c','A','M','D'); | |
72 | } | |
73 | ||
74 | static int is_centaur(void) | |
75 | { | |
76 | return cpu_vendor[0] == A32('C','e','n','t') && | |
77 | cpu_vendor[1] == A32('a','u','r','H') && | |
78 | cpu_vendor[2] == A32('a','u','l','s'); | |
79 | } | |
80 | ||
81 | static int is_transmeta(void) | |
82 | { | |
83 | return cpu_vendor[0] == A32('G','e','n','u') && | |
84 | cpu_vendor[1] == A32('i','n','e','T') && | |
85 | cpu_vendor[2] == A32('M','x','8','6'); | |
86 | } | |
87 | ||
88 | static int has_fpu(void) | |
89 | { | |
90 | u16 fcw = -1, fsw = -1; | |
91 | u32 cr0; | |
92 | ||
93 | asm("movl %%cr0,%0" : "=r" (cr0)); | |
94 | if (cr0 & (X86_CR0_EM|X86_CR0_TS)) { | |
95 | cr0 &= ~(X86_CR0_EM|X86_CR0_TS); | |
96 | asm volatile("movl %0,%%cr0" : : "r" (cr0)); | |
97 | } | |
98 | ||
99 | asm("fninit ; fnstsw %0 ; fnstcw %1" : "+m" (fsw), "+m" (fcw)); | |
100 | ||
101 | return fsw == 0 && (fcw & 0x103f) == 0x003f; | |
102 | } | |
103 | ||
104 | static int has_eflag(u32 mask) | |
105 | { | |
106 | u32 f0, f1; | |
107 | ||
108 | asm("pushfl ; " | |
109 | "pushfl ; " | |
110 | "popl %0 ; " | |
111 | "movl %0,%1 ; " | |
112 | "xorl %2,%1 ; " | |
113 | "pushl %1 ; " | |
114 | "popfl ; " | |
115 | "pushfl ; " | |
116 | "popl %1 ; " | |
117 | "popfl" | |
118 | : "=r" (f0), "=r" (f1) | |
119 | : "g" (mask)); | |
120 | ||
121 | return !!((f0^f1) & mask); | |
122 | } | |
123 | ||
124 | static void get_flags(void) | |
125 | { | |
126 | u32 max_intel_level, max_amd_level; | |
127 | u32 tfms; | |
128 | ||
129 | if (has_fpu()) | |
130 | set_bit(X86_FEATURE_FPU, cpu.flags); | |
131 | ||
132 | if (has_eflag(X86_EFLAGS_ID)) { | |
133 | asm("cpuid" | |
134 | : "=a" (max_intel_level), | |
135 | "=b" (cpu_vendor[0]), | |
136 | "=d" (cpu_vendor[1]), | |
137 | "=c" (cpu_vendor[2]) | |
138 | : "a" (0)); | |
139 | ||
140 | if (max_intel_level >= 0x00000001 && | |
141 | max_intel_level <= 0x0000ffff) { | |
142 | asm("cpuid" | |
143 | : "=a" (tfms), | |
144 | "=c" (cpu.flags[4]), | |
145 | "=d" (cpu.flags[0]) | |
146 | : "a" (0x00000001) | |
147 | : "ebx"); | |
148 | cpu.level = (tfms >> 8) & 15; | |
149 | cpu.model = (tfms >> 4) & 15; | |
150 | if (cpu.level >= 6) | |
151 | cpu.model += ((tfms >> 16) & 0xf) << 4; | |
152 | } | |
153 | ||
154 | asm("cpuid" | |
155 | : "=a" (max_amd_level) | |
156 | : "a" (0x80000000) | |
157 | : "ebx", "ecx", "edx"); | |
158 | ||
159 | if (max_amd_level >= 0x80000001 && | |
160 | max_amd_level <= 0x8000ffff) { | |
161 | u32 eax = 0x80000001; | |
162 | asm("cpuid" | |
163 | : "+a" (eax), | |
164 | "=c" (cpu.flags[6]), | |
165 | "=d" (cpu.flags[1]) | |
166 | : : "ebx"); | |
167 | } | |
168 | } | |
169 | } | |
170 | ||
171 | /* Returns a bitmask of which words we have error bits in */ | |
172 | static int check_flags(void) | |
173 | { | |
174 | u32 err; | |
175 | int i; | |
176 | ||
177 | err = 0; | |
178 | for (i = 0; i < NCAPINTS; i++) { | |
179 | err_flags[i] = req_flags[i] & ~cpu.flags[i]; | |
180 | if (err_flags[i]) | |
181 | err |= 1 << i; | |
182 | } | |
183 | ||
184 | return err; | |
185 | } | |
186 | ||
187 | /* | |
188 | * Returns -1 on error. | |
189 | * | |
190 | * *cpu_level is set to the current CPU level; *req_level to the required | |
191 | * level. x86-64 is considered level 64 for this purpose. | |
192 | * | |
193 | * *err_flags_ptr is set to the flags error array if there are flags missing. | |
194 | */ | |
195 | int check_cpu(int *cpu_level_ptr, int *req_level_ptr, u32 **err_flags_ptr) | |
196 | { | |
197 | int err; | |
198 | ||
199 | memset(&cpu.flags, 0, sizeof cpu.flags); | |
200 | cpu.level = 3; | |
201 | ||
202 | if (has_eflag(X86_EFLAGS_AC)) | |
203 | cpu.level = 4; | |
204 | ||
205 | get_flags(); | |
206 | err = check_flags(); | |
207 | ||
208 | if (test_bit(X86_FEATURE_LM, cpu.flags)) | |
209 | cpu.level = 64; | |
210 | ||
211 | if (err == 0x01 && | |
212 | !(err_flags[0] & | |
213 | ~((1 << X86_FEATURE_XMM)|(1 << X86_FEATURE_XMM2))) && | |
214 | is_amd()) { | |
215 | /* If this is an AMD and we're only missing SSE+SSE2, try to | |
216 | turn them on */ | |
217 | ||
218 | u32 ecx = MSR_K7_HWCR; | |
219 | u32 eax, edx; | |
220 | ||
221 | asm("rdmsr" : "=a" (eax), "=d" (edx) : "c" (ecx)); | |
222 | eax &= ~(1 << 15); | |
223 | asm("wrmsr" : : "a" (eax), "d" (edx), "c" (ecx)); | |
224 | ||
225 | get_flags(); /* Make sure it really did something */ | |
226 | err = check_flags(); | |
227 | } else if (err == 0x01 && | |
228 | !(err_flags[0] & ~(1 << X86_FEATURE_CX8)) && | |
229 | is_centaur() && cpu.model >= 6) { | |
230 | /* If this is a VIA C3, we might have to enable CX8 | |
231 | explicitly */ | |
232 | ||
233 | u32 ecx = MSR_VIA_FCR; | |
234 | u32 eax, edx; | |
235 | ||
236 | asm("rdmsr" : "=a" (eax), "=d" (edx) : "c" (ecx)); | |
237 | eax |= (1<<1)|(1<<7); | |
238 | asm("wrmsr" : : "a" (eax), "d" (edx), "c" (ecx)); | |
239 | ||
240 | set_bit(X86_FEATURE_CX8, cpu.flags); | |
241 | err = check_flags(); | |
242 | } else if (err == 0x01 && is_transmeta()) { | |
243 | /* Transmeta might have masked feature bits in word 0 */ | |
244 | ||
245 | u32 ecx = 0x80860004; | |
246 | u32 eax, edx; | |
247 | u32 level = 1; | |
248 | ||
249 | asm("rdmsr" : "=a" (eax), "=d" (edx) : "c" (ecx)); | |
250 | asm("wrmsr" : : "a" (~0), "d" (edx), "c" (ecx)); | |
251 | asm("cpuid" | |
252 | : "+a" (level), "=d" (cpu.flags[0]) | |
253 | : : "ecx", "ebx"); | |
254 | asm("wrmsr" : : "a" (eax), "d" (edx), "c" (ecx)); | |
255 | ||
256 | err = check_flags(); | |
257 | } | |
258 | ||
259 | if (err_flags_ptr) | |
260 | *err_flags_ptr = err ? err_flags : NULL; | |
261 | if (cpu_level_ptr) | |
262 | *cpu_level_ptr = cpu.level; | |
263 | if (req_level_ptr) | |
264 | *req_level_ptr = req_level; | |
265 | ||
266 | return (cpu.level < req_level || err) ? -1 : 0; | |
267 | } |