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