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Commit | Line | Data |
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1353ebb4 | 1 | /* |
1353ebb4 JF |
2 | * Copyright (C) 1994 Linus Torvalds |
3 | * | |
4 | * Cyrix stuff, June 1998 by: | |
5 | * - Rafael R. Reilova (moved everything from head.S), | |
6 | * <rreilova@ececs.uc.edu> | |
7 | * - Channing Corn (tests & fixes), | |
8 | * - Andrew D. Balsa (code cleanup). | |
9 | */ | |
10 | #include <linux/init.h> | |
11 | #include <linux/utsname.h> | |
91eb1b79 | 12 | #include <asm/bugs.h> |
1353ebb4 | 13 | #include <asm/processor.h> |
7ebad705 | 14 | #include <asm/processor-flags.h> |
1353ebb4 JF |
15 | #include <asm/i387.h> |
16 | #include <asm/msr.h> | |
17 | #include <asm/paravirt.h> | |
18 | #include <asm/alternative.h> | |
19 | ||
20 | static int __init no_halt(char *s) | |
21 | { | |
cdaab4a0 | 22 | WARN_ONCE(1, "\"no-hlt\" is deprecated, please use \"idle=poll\"\n"); |
1353ebb4 JF |
23 | boot_cpu_data.hlt_works_ok = 0; |
24 | return 1; | |
25 | } | |
26 | ||
27 | __setup("no-hlt", no_halt); | |
28 | ||
1353ebb4 JF |
29 | static int __init no_387(char *s) |
30 | { | |
31 | boot_cpu_data.hard_math = 0; | |
7ebad705 | 32 | write_cr0(X86_CR0_TS | X86_CR0_EM | X86_CR0_MP | read_cr0()); |
1353ebb4 JF |
33 | return 1; |
34 | } | |
35 | ||
36 | __setup("no387", no_387); | |
37 | ||
38 | static double __initdata x = 4195835.0; | |
39 | static double __initdata y = 3145727.0; | |
40 | ||
41 | /* | |
42 | * This used to check for exceptions.. | |
43 | * However, it turns out that to support that, | |
44 | * the XMM trap handlers basically had to | |
45 | * be buggy. So let's have a correct XMM trap | |
46 | * handler, and forget about printing out | |
47 | * some status at boot. | |
48 | * | |
49 | * We should really only care about bugs here | |
50 | * anyway. Not features. | |
51 | */ | |
52 | static void __init check_fpu(void) | |
53 | { | |
e0d22d03 KH |
54 | s32 fdiv_bug; |
55 | ||
1353ebb4 JF |
56 | if (!boot_cpu_data.hard_math) { |
57 | #ifndef CONFIG_MATH_EMULATION | |
58 | printk(KERN_EMERG "No coprocessor found and no math emulation present.\n"); | |
59 | printk(KERN_EMERG "Giving up.\n"); | |
60 | for (;;) ; | |
61 | #endif | |
62 | return; | |
63 | } | |
64 | ||
3e7cf5b0 SS |
65 | kernel_fpu_begin(); |
66 | ||
bfe4bb15 MV |
67 | /* |
68 | * trap_init() enabled FXSR and company _before_ testing for FP | |
69 | * problems here. | |
70 | * | |
71 | * Test for the divl bug.. | |
72 | */ | |
1353ebb4 JF |
73 | __asm__("fninit\n\t" |
74 | "fldl %1\n\t" | |
75 | "fdivl %2\n\t" | |
76 | "fmull %2\n\t" | |
77 | "fldl %1\n\t" | |
78 | "fsubp %%st,%%st(1)\n\t" | |
79 | "fistpl %0\n\t" | |
80 | "fwait\n\t" | |
81 | "fninit" | |
e0d22d03 | 82 | : "=m" (*&fdiv_bug) |
1353ebb4 | 83 | : "m" (*&x), "m" (*&y)); |
e0d22d03 | 84 | |
3e7cf5b0 SS |
85 | kernel_fpu_end(); |
86 | ||
e0d22d03 | 87 | boot_cpu_data.fdiv_bug = fdiv_bug; |
1353ebb4 | 88 | if (boot_cpu_data.fdiv_bug) |
8bdbd962 | 89 | printk(KERN_WARNING "Hmm, FPU with FDIV bug.\n"); |
1353ebb4 JF |
90 | } |
91 | ||
92 | static void __init check_hlt(void) | |
93 | { | |
2b107d93 | 94 | if (boot_cpu_data.x86 >= 5 || paravirt_enabled()) |
1353ebb4 JF |
95 | return; |
96 | ||
97 | printk(KERN_INFO "Checking 'hlt' instruction... "); | |
98 | if (!boot_cpu_data.hlt_works_ok) { | |
99 | printk("disabled\n"); | |
100 | return; | |
101 | } | |
102 | halt(); | |
103 | halt(); | |
104 | halt(); | |
105 | halt(); | |
8bdbd962 | 106 | printk(KERN_CONT "OK.\n"); |
1353ebb4 JF |
107 | } |
108 | ||
109 | /* | |
110 | * Most 386 processors have a bug where a POPAD can lock the | |
111 | * machine even from user space. | |
112 | */ | |
113 | ||
114 | static void __init check_popad(void) | |
115 | { | |
116 | #ifndef CONFIG_X86_POPAD_OK | |
117 | int res, inp = (int) &res; | |
118 | ||
119 | printk(KERN_INFO "Checking for popad bug... "); | |
120 | __asm__ __volatile__( | |
121 | "movl $12345678,%%eax; movl $0,%%edi; pusha; popa; movl (%%edx,%%edi),%%ecx " | |
122 | : "=&a" (res) | |
123 | : "d" (inp) | |
bfe4bb15 MV |
124 | : "ecx", "edi"); |
125 | /* | |
126 | * If this fails, it means that any user program may lock the | |
127 | * CPU hard. Too bad. | |
128 | */ | |
129 | if (res != 12345678) | |
8bdbd962 | 130 | printk(KERN_CONT "Buggy.\n"); |
bfe4bb15 | 131 | else |
8bdbd962 | 132 | printk(KERN_CONT "OK.\n"); |
1353ebb4 JF |
133 | #endif |
134 | } | |
135 | ||
136 | /* | |
137 | * Check whether we are able to run this kernel safely on SMP. | |
138 | * | |
139 | * - In order to run on a i386, we need to be compiled for i386 | |
140 | * (for due to lack of "invlpg" and working WP on a i386) | |
141 | * - In order to run on anything without a TSC, we need to be | |
142 | * compiled for a i486. | |
593f4a78 | 143 | */ |
1353ebb4 JF |
144 | |
145 | static void __init check_config(void) | |
146 | { | |
147 | /* | |
148 | * We'd better not be a i386 if we're configured to use some | |
149 | * i486+ only features! (WP works in supervisor mode and the | |
150 | * new "invlpg" and "bswap" instructions) | |
151 | */ | |
bfe4bb15 MV |
152 | #if defined(CONFIG_X86_WP_WORKS_OK) || defined(CONFIG_X86_INVLPG) || \ |
153 | defined(CONFIG_X86_BSWAP) | |
1353ebb4 JF |
154 | if (boot_cpu_data.x86 == 3) |
155 | panic("Kernel requires i486+ for 'invlpg' and other features"); | |
156 | #endif | |
1353ebb4 JF |
157 | } |
158 | ||
159 | ||
160 | void __init check_bugs(void) | |
161 | { | |
162 | identify_boot_cpu(); | |
163 | #ifndef CONFIG_SMP | |
8bdbd962 | 164 | printk(KERN_INFO "CPU: "); |
1353ebb4 JF |
165 | print_cpu_info(&boot_cpu_data); |
166 | #endif | |
167 | check_config(); | |
168 | check_fpu(); | |
169 | check_hlt(); | |
170 | check_popad(); | |
bfe4bb15 MV |
171 | init_utsname()->machine[1] = |
172 | '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86); | |
1353ebb4 JF |
173 | alternative_instructions(); |
174 | } |