Commit | Line | Data |
---|---|---|
1353ebb4 JF |
1 | /* |
2 | * arch/i386/cpu/bugs.c | |
3 | * | |
4 | * Copyright (C) 1994 Linus Torvalds | |
5 | * | |
6 | * Cyrix stuff, June 1998 by: | |
7 | * - Rafael R. Reilova (moved everything from head.S), | |
8 | * <rreilova@ececs.uc.edu> | |
9 | * - Channing Corn (tests & fixes), | |
10 | * - Andrew D. Balsa (code cleanup). | |
11 | */ | |
12 | #include <linux/init.h> | |
13 | #include <linux/utsname.h> | |
14 | #include <asm/processor.h> | |
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 | ||
28 | static int __init mca_pentium(char *s) | |
29 | { | |
30 | mca_pentium_flag = 1; | |
31 | return 1; | |
32 | } | |
33 | ||
34 | __setup("mca-pentium", mca_pentium); | |
35 | ||
36 | static int __init no_387(char *s) | |
37 | { | |
38 | boot_cpu_data.hard_math = 0; | |
39 | write_cr0(0xE | read_cr0()); | |
40 | return 1; | |
41 | } | |
42 | ||
43 | __setup("no387", no_387); | |
44 | ||
45 | static double __initdata x = 4195835.0; | |
46 | static double __initdata y = 3145727.0; | |
47 | ||
48 | /* | |
49 | * This used to check for exceptions.. | |
50 | * However, it turns out that to support that, | |
51 | * the XMM trap handlers basically had to | |
52 | * be buggy. So let's have a correct XMM trap | |
53 | * handler, and forget about printing out | |
54 | * some status at boot. | |
55 | * | |
56 | * We should really only care about bugs here | |
57 | * anyway. Not features. | |
58 | */ | |
59 | static void __init check_fpu(void) | |
60 | { | |
61 | if (!boot_cpu_data.hard_math) { | |
62 | #ifndef CONFIG_MATH_EMULATION | |
63 | printk(KERN_EMERG "No coprocessor found and no math emulation present.\n"); | |
64 | printk(KERN_EMERG "Giving up.\n"); | |
65 | for (;;) ; | |
66 | #endif | |
67 | return; | |
68 | } | |
69 | ||
70 | /* trap_init() enabled FXSR and company _before_ testing for FP problems here. */ | |
71 | /* Test for the divl bug.. */ | |
72 | __asm__("fninit\n\t" | |
73 | "fldl %1\n\t" | |
74 | "fdivl %2\n\t" | |
75 | "fmull %2\n\t" | |
76 | "fldl %1\n\t" | |
77 | "fsubp %%st,%%st(1)\n\t" | |
78 | "fistpl %0\n\t" | |
79 | "fwait\n\t" | |
80 | "fninit" | |
81 | : "=m" (*&boot_cpu_data.fdiv_bug) | |
82 | : "m" (*&x), "m" (*&y)); | |
83 | if (boot_cpu_data.fdiv_bug) | |
84 | printk("Hmm, FPU with FDIV bug.\n"); | |
85 | } | |
86 | ||
87 | static void __init check_hlt(void) | |
88 | { | |
89 | if (paravirt_enabled()) | |
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(); | |
101 | printk("OK.\n"); | |
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) | |
119 | : "ecx", "edi" ); | |
120 | /* If this fails, it means that any user program may lock the CPU hard. Too bad. */ | |
121 | if (res != 12345678) printk( "Buggy.\n" ); | |
122 | else printk( "OK.\n" ); | |
123 | #endif | |
124 | } | |
125 | ||
126 | /* | |
127 | * Check whether we are able to run this kernel safely on SMP. | |
128 | * | |
129 | * - In order to run on a i386, we need to be compiled for i386 | |
130 | * (for due to lack of "invlpg" and working WP on a i386) | |
131 | * - In order to run on anything without a TSC, we need to be | |
132 | * compiled for a i486. | |
133 | * - In order to support the local APIC on a buggy Pentium machine, | |
134 | * we need to be compiled with CONFIG_X86_GOOD_APIC disabled, | |
135 | * which happens implicitly if compiled for a Pentium or lower | |
136 | * (unless an advanced selection of CPU features is used) as an | |
137 | * otherwise config implies a properly working local APIC without | |
138 | * the need to do extra reads from the APIC. | |
139 | */ | |
140 | ||
141 | static void __init check_config(void) | |
142 | { | |
143 | /* | |
144 | * We'd better not be a i386 if we're configured to use some | |
145 | * i486+ only features! (WP works in supervisor mode and the | |
146 | * new "invlpg" and "bswap" instructions) | |
147 | */ | |
148 | #if defined(CONFIG_X86_WP_WORKS_OK) || defined(CONFIG_X86_INVLPG) || defined(CONFIG_X86_BSWAP) | |
149 | if (boot_cpu_data.x86 == 3) | |
150 | panic("Kernel requires i486+ for 'invlpg' and other features"); | |
151 | #endif | |
152 | ||
153 | /* | |
154 | * If we configured ourselves for a TSC, we'd better have one! | |
155 | */ | |
156 | #ifdef CONFIG_X86_TSC | |
157 | if (!cpu_has_tsc && !tsc_disable) | |
158 | panic("Kernel compiled for Pentium+, requires TSC feature!"); | |
159 | #endif | |
160 | ||
161 | /* | |
162 | * If we were told we had a good local APIC, check for buggy Pentia, | |
163 | * i.e. all B steppings and the C2 stepping of P54C when using their | |
164 | * integrated APIC (see 11AP erratum in "Pentium Processor | |
165 | * Specification Update"). | |
166 | */ | |
167 | #if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86_GOOD_APIC) | |
168 | if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL | |
169 | && cpu_has_apic | |
170 | && boot_cpu_data.x86 == 5 | |
171 | && boot_cpu_data.x86_model == 2 | |
172 | && (boot_cpu_data.x86_mask < 6 || boot_cpu_data.x86_mask == 11)) | |
173 | panic("Kernel compiled for PMMX+, assumes a local APIC without the read-before-write bug!"); | |
174 | #endif | |
175 | } | |
176 | ||
177 | ||
178 | void __init check_bugs(void) | |
179 | { | |
180 | identify_boot_cpu(); | |
181 | #ifndef CONFIG_SMP | |
182 | printk("CPU: "); | |
183 | print_cpu_info(&boot_cpu_data); | |
184 | #endif | |
185 | check_config(); | |
186 | check_fpu(); | |
187 | check_hlt(); | |
188 | check_popad(); | |
189 | init_utsname()->machine[1] = '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86); | |
190 | alternative_instructions(); | |
191 | } |