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