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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * include/asm-i386/bugs.h
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).
Linus Torvalds1da177e2005-04-16 15:20:36 -070011 */
12
13/*
14 * This is included by init/main.c to check for architecture-dependent bugs.
15 *
16 * Needs:
17 * void check_bugs(void);
18 */
19
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/init.h>
21#include <asm/processor.h>
22#include <asm/i387.h>
23#include <asm/msr.h>
24
25static int __init no_halt(char *s)
26{
27 boot_cpu_data.hlt_works_ok = 0;
28 return 1;
29}
30
31__setup("no-hlt", no_halt);
32
33static int __init mca_pentium(char *s)
34{
35 mca_pentium_flag = 1;
36 return 1;
37}
38
39__setup("mca-pentium", mca_pentium);
40
41static int __init no_387(char *s)
42{
43 boot_cpu_data.hard_math = 0;
44 write_cr0(0xE | read_cr0());
45 return 1;
46}
47
48__setup("no387", no_387);
49
50static double __initdata x = 4195835.0;
51static double __initdata y = 3145727.0;
52
53/*
54 * This used to check for exceptions..
55 * However, it turns out that to support that,
56 * the XMM trap handlers basically had to
57 * be buggy. So let's have a correct XMM trap
58 * handler, and forget about printing out
59 * some status at boot.
60 *
61 * We should really only care about bugs here
62 * anyway. Not features.
63 */
64static void __init check_fpu(void)
65{
66 if (!boot_cpu_data.hard_math) {
67#ifndef CONFIG_MATH_EMULATION
68 printk(KERN_EMERG "No coprocessor found and no math emulation present.\n");
69 printk(KERN_EMERG "Giving up.\n");
70 for (;;) ;
71#endif
72 return;
73 }
74
Jan Beulichd43c6e82006-01-06 00:11:49 -080075/* trap_init() enabled FXSR and company _before_ testing for FP problems here. */
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 /* Test for the divl bug.. */
77 __asm__("fninit\n\t"
78 "fldl %1\n\t"
79 "fdivl %2\n\t"
80 "fmull %2\n\t"
81 "fldl %1\n\t"
82 "fsubp %%st,%%st(1)\n\t"
83 "fistpl %0\n\t"
84 "fwait\n\t"
85 "fninit"
86 : "=m" (*&boot_cpu_data.fdiv_bug)
87 : "m" (*&x), "m" (*&y));
88 if (boot_cpu_data.fdiv_bug)
89 printk("Hmm, FPU with FDIV bug.\n");
90}
91
92static void __init check_hlt(void)
93{
94 printk(KERN_INFO "Checking 'hlt' instruction... ");
95 if (!boot_cpu_data.hlt_works_ok) {
96 printk("disabled\n");
97 return;
98 }
Zachary Amsden4bb0d3e2005-09-03 15:56:36 -070099 halt();
100 halt();
101 halt();
102 halt();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 printk("OK.\n");
104}
105
106/*
107 * Most 386 processors have a bug where a POPAD can lock the
108 * machine even from user space.
109 */
110
111static void __init check_popad(void)
112{
113#ifndef CONFIG_X86_POPAD_OK
114 int res, inp = (int) &res;
115
116 printk(KERN_INFO "Checking for popad bug... ");
117 __asm__ __volatile__(
118 "movl $12345678,%%eax; movl $0,%%edi; pusha; popa; movl (%%edx,%%edi),%%ecx "
119 : "=&a" (res)
120 : "d" (inp)
121 : "ecx", "edi" );
122 /* If this fails, it means that any user program may lock the CPU hard. Too bad. */
123 if (res != 12345678) printk( "Buggy.\n" );
124 else printk( "OK.\n" );
125#endif
126}
127
128/*
129 * Check whether we are able to run this kernel safely on SMP.
130 *
131 * - In order to run on a i386, we need to be compiled for i386
132 * (for due to lack of "invlpg" and working WP on a i386)
133 * - In order to run on anything without a TSC, we need to be
134 * compiled for a i486.
135 * - In order to support the local APIC on a buggy Pentium machine,
136 * we need to be compiled with CONFIG_X86_GOOD_APIC disabled,
137 * which happens implicitly if compiled for a Pentium or lower
138 * (unless an advanced selection of CPU features is used) as an
139 * otherwise config implies a properly working local APIC without
140 * the need to do extra reads from the APIC.
141*/
142
143static void __init check_config(void)
144{
145/*
146 * We'd better not be a i386 if we're configured to use some
147 * i486+ only features! (WP works in supervisor mode and the
148 * new "invlpg" and "bswap" instructions)
149 */
150#if defined(CONFIG_X86_WP_WORKS_OK) || defined(CONFIG_X86_INVLPG) || defined(CONFIG_X86_BSWAP)
151 if (boot_cpu_data.x86 == 3)
152 panic("Kernel requires i486+ for 'invlpg' and other features");
153#endif
154
155/*
156 * If we configured ourselves for a TSC, we'd better have one!
157 */
158#ifdef CONFIG_X86_TSC
159 if (!cpu_has_tsc)
160 panic("Kernel compiled for Pentium+, requires TSC feature!");
161#endif
162
163/*
164 * If we were told we had a good local APIC, check for buggy Pentia,
165 * i.e. all B steppings and the C2 stepping of P54C when using their
166 * integrated APIC (see 11AP erratum in "Pentium Processor
167 * Specification Update").
168 */
169#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86_GOOD_APIC)
170 if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL
171 && cpu_has_apic
172 && boot_cpu_data.x86 == 5
173 && boot_cpu_data.x86_model == 2
174 && (boot_cpu_data.x86_mask < 6 || boot_cpu_data.x86_mask == 11))
175 panic("Kernel compiled for PMMX+, assumes a local APIC without the read-before-write bug!");
176#endif
177}
178
179extern void alternative_instructions(void);
180
181static void __init check_bugs(void)
182{
183 identify_cpu(&boot_cpu_data);
184#ifndef CONFIG_SMP
185 printk("CPU: ");
186 print_cpu_info(&boot_cpu_data);
187#endif
188 check_config();
189 check_fpu();
190 check_hlt();
191 check_popad();
Serge E. Hallyn96b644b2006-10-02 02:18:13 -0700192 init_utsname()->machine[1] = '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 alternative_instructions();
194}