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
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
|
/* Initialize CPU feature data.
This file is part of the GNU C Library.
Copyright (C) 2008-2015 Free Software Foundation, Inc.
Contributed by Ulrich Drepper <drepper@redhat.com>.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <atomic.h>
#include <cpuid.h>
#include "init-arch.h"
struct cpu_features __cpu_features attribute_hidden;
static void
get_common_indeces (unsigned int *family, unsigned int *model)
{
__cpuid (1, __cpu_features.cpuid[COMMON_CPUID_INDEX_1].eax,
__cpu_features.cpuid[COMMON_CPUID_INDEX_1].ebx,
__cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx,
__cpu_features.cpuid[COMMON_CPUID_INDEX_1].edx);
unsigned int eax = __cpu_features.cpuid[COMMON_CPUID_INDEX_1].eax;
*family = (eax >> 8) & 0x0f;
*model = (eax >> 4) & 0x0f;
}
void
__init_cpu_features (void)
{
unsigned int ebx;
unsigned int ecx;
unsigned int edx;
unsigned int family = 0;
unsigned int model = 0;
enum cpu_features_kind kind;
__cpuid (0, __cpu_features.max_cpuid, ebx, ecx, edx);
/* This spells out "GenuineIntel". */
if (ebx == 0x756e6547 && ecx == 0x6c65746e && edx == 0x49656e69)
{
kind = arch_kind_intel;
get_common_indeces (&family, &model);
unsigned int eax = __cpu_features.cpuid[COMMON_CPUID_INDEX_1].eax;
unsigned int extended_family = (eax >> 20) & 0xff;
unsigned int extended_model = (eax >> 12) & 0xf0;
if (family == 0x0f)
{
family += extended_family;
model += extended_model;
}
else if (family == 0x06)
{
ecx = __cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx;
model += extended_model;
switch (model)
{
case 0x1c:
case 0x26:
/* BSF is slow on Atom. */
__cpu_features.feature[index_Slow_BSF] |= bit_Slow_BSF;
break;
case 0x37:
case 0x4a:
case 0x4d:
/* Unaligned load versions are faster than SSSE3
on Silvermont. */
#if index_Fast_Unaligned_Load != index_Prefer_PMINUB_for_stringop
# error index_Fast_Unaligned_Load != index_Prefer_PMINUB_for_stringop
#endif
#if index_Fast_Unaligned_Load != index_Slow_SSE4_2
# error index_Fast_Unaligned_Load != index_Slow_SSE4_2
#endif
__cpu_features.feature[index_Fast_Unaligned_Load]
|= (bit_Fast_Unaligned_Load
| bit_Prefer_PMINUB_for_stringop
| bit_Slow_SSE4_2);
break;
default:
/* Unknown family 0x06 processors. Assuming this is one
of Core i3/i5/i7 processors if AVX is available. */
if ((ecx & bit_AVX) == 0)
break;
case 0x1a:
case 0x1e:
case 0x1f:
case 0x25:
case 0x2c:
case 0x2e:
case 0x2f:
/* Rep string instructions, copy backward, unaligned loads
and pminub are fast on Intel Core i3, i5 and i7. */
#if index_Fast_Rep_String != index_Fast_Copy_Backward
# error index_Fast_Rep_String != index_Fast_Copy_Backward
#endif
#if index_Fast_Rep_String != index_Fast_Unaligned_Load
# error index_Fast_Rep_String != index_Fast_Unaligned_Load
#endif
#if index_Fast_Rep_String != index_Prefer_PMINUB_for_stringop
# error index_Fast_Rep_String != index_Prefer_PMINUB_for_stringop
#endif
__cpu_features.feature[index_Fast_Rep_String]
|= (bit_Fast_Rep_String
| bit_Fast_Copy_Backward
| bit_Fast_Unaligned_Load
| bit_Prefer_PMINUB_for_stringop);
break;
}
}
}
/* This spells out "AuthenticAMD". */
else if (ebx == 0x68747541 && ecx == 0x444d4163 && edx == 0x69746e65)
{
kind = arch_kind_amd;
get_common_indeces (&family, &model);
ecx = __cpu_features.cpuid[COMMON_CPUID_INDEX_1].ecx;
unsigned int eax;
__cpuid (0x80000000, eax, ebx, ecx, edx);
if (eax >= 0x80000001)
__cpuid (0x80000001,
__cpu_features.cpuid[COMMON_CPUID_INDEX_80000001].eax,
__cpu_features.cpuid[COMMON_CPUID_INDEX_80000001].ebx,
__cpu_features.cpuid[COMMON_CPUID_INDEX_80000001].ecx,
__cpu_features.cpuid[COMMON_CPUID_INDEX_80000001].edx);
}
else
kind = arch_kind_other;
if (__cpu_features.max_cpuid >= 7)
__cpuid_count (7, 0,
__cpu_features.cpuid[COMMON_CPUID_INDEX_7].eax,
__cpu_features.cpuid[COMMON_CPUID_INDEX_7].ebx,
__cpu_features.cpuid[COMMON_CPUID_INDEX_7].ecx,
__cpu_features.cpuid[COMMON_CPUID_INDEX_7].edx);
/* Can we call xgetbv? */
if (CPUID_OSXSAVE)
{
unsigned int xcrlow;
unsigned int xcrhigh;
asm ("xgetbv" : "=a" (xcrlow), "=d" (xcrhigh) : "c" (0));
/* Is YMM and XMM state usable? */
if ((xcrlow & (bit_YMM_state | bit_XMM_state)) ==
(bit_YMM_state | bit_XMM_state))
{
/* Determine if AVX is usable. */
if (CPUID_AVX)
__cpu_features.feature[index_AVX_Usable] |= bit_AVX_Usable;
/* Determine if AVX2 is usable. */
if (CPUID_AVX2)
__cpu_features.feature[index_AVX2_Usable] |= bit_AVX2_Usable;
/* Determine if FMA is usable. */
if (CPUID_FMA)
__cpu_features.feature[index_FMA_Usable] |= bit_FMA_Usable;
/* Determine if FMA4 is usable. */
if (CPUID_FMA4)
__cpu_features.feature[index_FMA4_Usable] |= bit_FMA4_Usable;
}
}
__cpu_features.family = family;
__cpu_features.model = model;
atomic_write_barrier ();
__cpu_features.kind = kind;
}
#undef __get_cpu_features
const struct cpu_features *
__get_cpu_features (void)
{
if (__cpu_features.kind == arch_kind_unknown)
__init_cpu_features ();
return &__cpu_features;
}
|
