-
Notifications
You must be signed in to change notification settings - Fork 53.2k
/
verify_cpu.S
141 lines (126 loc) · 3.7 KB
/
verify_cpu.S
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
/*
*
* verify_cpu.S - Code for cpu long mode and SSE verification. This
* code has been borrowed from boot/setup.S and was introduced by
* Andi Kleen.
*
* Copyright (c) 2007 Andi Kleen (ak@suse.de)
* Copyright (c) 2007 Eric Biederman (ebiederm@xmission.com)
* Copyright (c) 2007 Vivek Goyal (vgoyal@in.ibm.com)
* Copyright (c) 2010 Kees Cook (kees.cook@canonical.com)
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*
* This is a common code for verification whether CPU supports
* long mode and SSE or not. It is not called directly instead this
* file is included at various places and compiled in that context.
* This file is expected to run in 32bit code. Currently:
*
* arch/x86/boot/compressed/head_64.S: Boot cpu verification
* arch/x86/kernel/trampoline_64.S: secondary processor verification
* arch/x86/kernel/head_32.S: processor startup
*
* verify_cpu, returns the status of longmode and SSE in register %eax.
* 0: Success 1: Failure
*
* On Intel, the XD_DISABLE flag will be cleared as a side-effect.
*
* The caller needs to check for the error code and take the action
* appropriately. Either display a message or halt.
*/
#include <asm/cpufeatures.h>
#include <asm/msr-index.h>
verify_cpu:
pushf # Save caller passed flags
push $0 # Kill any dangerous flags
popf
#ifndef __x86_64__
pushfl # standard way to check for cpuid
popl %eax
movl %eax,%ebx
xorl $0x200000,%eax
pushl %eax
popfl
pushfl
popl %eax
cmpl %eax,%ebx
jz .Lverify_cpu_no_longmode # cpu has no cpuid
#endif
movl $0x0,%eax # See if cpuid 1 is implemented
cpuid
cmpl $0x1,%eax
jb .Lverify_cpu_no_longmode # no cpuid 1
xor %di,%di
cmpl $0x68747541,%ebx # AuthenticAMD
jnz .Lverify_cpu_noamd
cmpl $0x69746e65,%edx
jnz .Lverify_cpu_noamd
cmpl $0x444d4163,%ecx
jnz .Lverify_cpu_noamd
mov $1,%di # cpu is from AMD
jmp .Lverify_cpu_check
.Lverify_cpu_noamd:
cmpl $0x756e6547,%ebx # GenuineIntel?
jnz .Lverify_cpu_check
cmpl $0x49656e69,%edx
jnz .Lverify_cpu_check
cmpl $0x6c65746e,%ecx
jnz .Lverify_cpu_check
# only call IA32_MISC_ENABLE when:
# family > 6 || (family == 6 && model >= 0xd)
movl $0x1, %eax # check CPU family and model
cpuid
movl %eax, %ecx
andl $0x0ff00f00, %eax # mask family and extended family
shrl $8, %eax
cmpl $6, %eax
ja .Lverify_cpu_clear_xd # family > 6, ok
jb .Lverify_cpu_check # family < 6, skip
andl $0x000f00f0, %ecx # mask model and extended model
shrl $4, %ecx
cmpl $0xd, %ecx
jb .Lverify_cpu_check # family == 6, model < 0xd, skip
.Lverify_cpu_clear_xd:
movl $MSR_IA32_MISC_ENABLE, %ecx
rdmsr
btrl $2, %edx # clear MSR_IA32_MISC_ENABLE_XD_DISABLE
jnc .Lverify_cpu_check # only write MSR if bit was changed
wrmsr
.Lverify_cpu_check:
movl $0x1,%eax # Does the cpu have what it takes
cpuid
andl $REQUIRED_MASK0,%edx
xorl $REQUIRED_MASK0,%edx
jnz .Lverify_cpu_no_longmode
movl $0x80000000,%eax # See if extended cpuid is implemented
cpuid
cmpl $0x80000001,%eax
jb .Lverify_cpu_no_longmode # no extended cpuid
movl $0x80000001,%eax # Does the cpu have what it takes
cpuid
andl $REQUIRED_MASK1,%edx
xorl $REQUIRED_MASK1,%edx
jnz .Lverify_cpu_no_longmode
.Lverify_cpu_sse_test:
movl $1,%eax
cpuid
andl $SSE_MASK,%edx
cmpl $SSE_MASK,%edx
je .Lverify_cpu_sse_ok
test %di,%di
jz .Lverify_cpu_no_longmode # only try to force SSE on AMD
movl $MSR_K7_HWCR,%ecx
rdmsr
btr $15,%eax # enable SSE
wrmsr
xor %di,%di # don't loop
jmp .Lverify_cpu_sse_test # try again
.Lverify_cpu_no_longmode:
popf # Restore caller passed flags
movl $1,%eax
ret
.Lverify_cpu_sse_ok:
popf # Restore caller passed flags
xorl %eax, %eax
ret