Loading...
1/*
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>
12#include <asm/bugs.h>
13#include <asm/processor.h>
14#include <asm/processor-flags.h>
15#include <asm/i387.h>
16#include <asm/msr.h>
17#include <asm/paravirt.h>
18#include <asm/alternative.h>
19
20static int __init no_halt(char *s)
21{
22 WARN_ONCE(1, "\"no-hlt\" is deprecated, please use \"idle=poll\"\n");
23 boot_cpu_data.hlt_works_ok = 0;
24 return 1;
25}
26
27__setup("no-hlt", no_halt);
28
29static int __init no_387(char *s)
30{
31 boot_cpu_data.hard_math = 0;
32 write_cr0(X86_CR0_TS | X86_CR0_EM | X86_CR0_MP | read_cr0());
33 return 1;
34}
35
36__setup("no387", no_387);
37
38static double __initdata x = 4195835.0;
39static 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 */
52static void __init check_fpu(void)
53{
54 s32 fdiv_bug;
55
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
65 kernel_fpu_begin();
66
67 /*
68 * trap_init() enabled FXSR and company _before_ testing for FP
69 * problems here.
70 *
71 * Test for the divl bug..
72 */
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"
82 : "=m" (*&fdiv_bug)
83 : "m" (*&x), "m" (*&y));
84
85 kernel_fpu_end();
86
87 boot_cpu_data.fdiv_bug = fdiv_bug;
88 if (boot_cpu_data.fdiv_bug)
89 printk(KERN_WARNING "Hmm, FPU with FDIV bug.\n");
90}
91
92static void __init check_hlt(void)
93{
94 if (boot_cpu_data.x86 >= 5 || paravirt_enabled())
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();
106 printk(KERN_CONT "OK.\n");
107}
108
109/*
110 * Most 386 processors have a bug where a POPAD can lock the
111 * machine even from user space.
112 */
113
114static 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)
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)
130 printk(KERN_CONT "Buggy.\n");
131 else
132 printk(KERN_CONT "OK.\n");
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.
143 */
144
145static 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 */
152#if defined(CONFIG_X86_WP_WORKS_OK) || defined(CONFIG_X86_INVLPG) || \
153 defined(CONFIG_X86_BSWAP)
154 if (boot_cpu_data.x86 == 3)
155 panic("Kernel requires i486+ for 'invlpg' and other features");
156#endif
157}
158
159
160void __init check_bugs(void)
161{
162 identify_boot_cpu();
163#ifndef CONFIG_SMP
164 printk(KERN_INFO "CPU: ");
165 print_cpu_info(&boot_cpu_data);
166#endif
167 check_config();
168 check_fpu();
169 check_hlt();
170 check_popad();
171 init_utsname()->machine[1] =
172 '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
173 alternative_instructions();
174}
1/*
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>
12#include <asm/bugs.h>
13#include <asm/processor.h>
14#include <asm/processor-flags.h>
15#include <asm/i387.h>
16#include <asm/msr.h>
17#include <asm/paravirt.h>
18#include <asm/alternative.h>
19
20static int __init no_halt(char *s)
21{
22 WARN_ONCE(1, "\"no-hlt\" is deprecated, please use \"idle=poll\"\n");
23 boot_cpu_data.hlt_works_ok = 0;
24 return 1;
25}
26
27__setup("no-hlt", no_halt);
28
29static int __init no_387(char *s)
30{
31 boot_cpu_data.hard_math = 0;
32 write_cr0(X86_CR0_TS | X86_CR0_EM | X86_CR0_MP | read_cr0());
33 return 1;
34}
35
36__setup("no387", no_387);
37
38static double __initdata x = 4195835.0;
39static 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 */
52static void __init check_fpu(void)
53{
54 s32 fdiv_bug;
55
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
65 kernel_fpu_begin();
66
67 /*
68 * trap_init() enabled FXSR and company _before_ testing for FP
69 * problems here.
70 *
71 * Test for the divl bug..
72 */
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"
82 : "=m" (*&fdiv_bug)
83 : "m" (*&x), "m" (*&y));
84
85 kernel_fpu_end();
86
87 boot_cpu_data.fdiv_bug = fdiv_bug;
88 if (boot_cpu_data.fdiv_bug)
89 printk(KERN_WARNING "Hmm, FPU with FDIV bug.\n");
90}
91
92static void __init check_hlt(void)
93{
94 if (boot_cpu_data.x86 >= 5 || paravirt_enabled())
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();
106 printk(KERN_CONT "OK.\n");
107}
108
109/*
110 * Most 386 processors have a bug where a POPAD can lock the
111 * machine even from user space.
112 */
113
114static 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)
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)
130 printk(KERN_CONT "Buggy.\n");
131 else
132 printk(KERN_CONT "OK.\n");
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.
143 */
144
145static 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 */
152#if defined(CONFIG_X86_WP_WORKS_OK) || defined(CONFIG_X86_INVLPG) || \
153 defined(CONFIG_X86_BSWAP)
154 if (boot_cpu_data.x86 == 3)
155 panic("Kernel requires i486+ for 'invlpg' and other features");
156#endif
157}
158
159
160void __init check_bugs(void)
161{
162 identify_boot_cpu();
163#ifndef CONFIG_SMP
164 printk(KERN_INFO "CPU: ");
165 print_cpu_info(&boot_cpu_data);
166#endif
167 check_config();
168 check_fpu();
169 check_hlt();
170 check_popad();
171 init_utsname()->machine[1] =
172 '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
173 alternative_instructions();
174}