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a4831e08 VG |
1 | /* |
2 | * | |
3 | * verify_cpu.S - Code for cpu long mode and SSE verification. This | |
4 | * code has been borrowed from boot/setup.S and was introduced by | |
5 | * Andi Kleen. | |
6 | * | |
7 | * Copyright (c) 2007 Andi Kleen (ak@suse.de) | |
8 | * Copyright (c) 2007 Eric Biederman (ebiederm@xmission.com) | |
9 | * Copyright (c) 2007 Vivek Goyal (vgoyal@in.ibm.com) | |
ae84739c | 10 | * Copyright (c) 2010 Kees Cook (kees.cook@canonical.com) |
a4831e08 VG |
11 | * |
12 | * This source code is licensed under the GNU General Public License, | |
13 | * Version 2. See the file COPYING for more details. | |
14 | * | |
15 | * This is a common code for verification whether CPU supports | |
16 | * long mode and SSE or not. It is not called directly instead this | |
17 | * file is included at various places and compiled in that context. | |
ae84739c | 18 | * This file is expected to run in 32bit code. Currently: |
a4831e08 | 19 | * |
79250af2 | 20 | * arch/x86/boot/compressed/head_64.S: Boot cpu verification |
0d2eb44f | 21 | * arch/x86/kernel/trampoline_64.S: secondary processor verification |
79250af2 | 22 | * arch/x86/kernel/head_32.S: processor startup |
a4831e08 | 23 | * |
ae84739c | 24 | * verify_cpu, returns the status of longmode and SSE in register %eax. |
a4831e08 VG |
25 | * 0: Success 1: Failure |
26 | * | |
ae84739c KC |
27 | * On Intel, the XD_DISABLE flag will be cleared as a side-effect. |
28 | * | |
a4831e08 VG |
29 | * The caller needs to check for the error code and take the action |
30 | * appropriately. Either display a message or halt. | |
31 | */ | |
32 | ||
72b1b1d0 | 33 | #include <asm/cpufeature.h> |
cfaa71ee | 34 | #include <asm/msr-index.h> |
a4831e08 | 35 | |
72b1b1d0 | 36 | verify_cpu: |
a4831e08 VG |
37 | pushfl # Save caller passed flags |
38 | pushl $0 # Kill any dangerous flags | |
39 | popfl | |
40 | ||
a4831e08 VG |
41 | pushfl # standard way to check for cpuid |
42 | popl %eax | |
43 | movl %eax,%ebx | |
44 | xorl $0x200000,%eax | |
45 | pushl %eax | |
46 | popfl | |
47 | pushfl | |
48 | popl %eax | |
49 | cmpl %eax,%ebx | |
50 | jz verify_cpu_no_longmode # cpu has no cpuid | |
51 | ||
52 | movl $0x0,%eax # See if cpuid 1 is implemented | |
53 | cpuid | |
54 | cmpl $0x1,%eax | |
55 | jb verify_cpu_no_longmode # no cpuid 1 | |
56 | ||
57 | xor %di,%di | |
58 | cmpl $0x68747541,%ebx # AuthenticAMD | |
59 | jnz verify_cpu_noamd | |
60 | cmpl $0x69746e65,%edx | |
61 | jnz verify_cpu_noamd | |
62 | cmpl $0x444d4163,%ecx | |
63 | jnz verify_cpu_noamd | |
64 | mov $1,%di # cpu is from AMD | |
ae84739c | 65 | jmp verify_cpu_check |
a4831e08 VG |
66 | |
67 | verify_cpu_noamd: | |
ae84739c KC |
68 | cmpl $0x756e6547,%ebx # GenuineIntel? |
69 | jnz verify_cpu_check | |
70 | cmpl $0x49656e69,%edx | |
71 | jnz verify_cpu_check | |
72 | cmpl $0x6c65746e,%ecx | |
73 | jnz verify_cpu_check | |
74 | ||
75 | # only call IA32_MISC_ENABLE when: | |
76 | # family > 6 || (family == 6 && model >= 0xd) | |
77 | movl $0x1, %eax # check CPU family and model | |
78 | cpuid | |
79 | movl %eax, %ecx | |
80 | ||
81 | andl $0x0ff00f00, %eax # mask family and extended family | |
82 | shrl $8, %eax | |
83 | cmpl $6, %eax | |
84 | ja verify_cpu_clear_xd # family > 6, ok | |
85 | jb verify_cpu_check # family < 6, skip | |
86 | ||
87 | andl $0x000f00f0, %ecx # mask model and extended model | |
88 | shrl $4, %ecx | |
89 | cmpl $0xd, %ecx | |
90 | jb verify_cpu_check # family == 6, model < 0xd, skip | |
91 | ||
92 | verify_cpu_clear_xd: | |
93 | movl $MSR_IA32_MISC_ENABLE, %ecx | |
94 | rdmsr | |
95 | btrl $2, %edx # clear MSR_IA32_MISC_ENABLE_XD_DISABLE | |
96 | jnc verify_cpu_check # only write MSR if bit was changed | |
97 | wrmsr | |
98 | ||
99 | verify_cpu_check: | |
a4831e08 VG |
100 | movl $0x1,%eax # Does the cpu have what it takes |
101 | cpuid | |
ec481536 PA |
102 | andl $REQUIRED_MASK0,%edx |
103 | xorl $REQUIRED_MASK0,%edx | |
a4831e08 VG |
104 | jnz verify_cpu_no_longmode |
105 | ||
106 | movl $0x80000000,%eax # See if extended cpuid is implemented | |
107 | cpuid | |
108 | cmpl $0x80000001,%eax | |
109 | jb verify_cpu_no_longmode # no extended cpuid | |
110 | ||
111 | movl $0x80000001,%eax # Does the cpu have what it takes | |
112 | cpuid | |
ec481536 PA |
113 | andl $REQUIRED_MASK1,%edx |
114 | xorl $REQUIRED_MASK1,%edx | |
a4831e08 VG |
115 | jnz verify_cpu_no_longmode |
116 | ||
117 | verify_cpu_sse_test: | |
118 | movl $1,%eax | |
119 | cpuid | |
120 | andl $SSE_MASK,%edx | |
121 | cmpl $SSE_MASK,%edx | |
122 | je verify_cpu_sse_ok | |
123 | test %di,%di | |
124 | jz verify_cpu_no_longmode # only try to force SSE on AMD | |
cfaa71ee | 125 | movl $MSR_K7_HWCR,%ecx |
a4831e08 VG |
126 | rdmsr |
127 | btr $15,%eax # enable SSE | |
128 | wrmsr | |
129 | xor %di,%di # don't loop | |
130 | jmp verify_cpu_sse_test # try again | |
131 | ||
132 | verify_cpu_no_longmode: | |
133 | popfl # Restore caller passed flags | |
134 | movl $1,%eax | |
135 | ret | |
136 | verify_cpu_sse_ok: | |
137 | popfl # Restore caller passed flags | |
138 | xorl %eax, %eax | |
139 | ret |