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Linux kernel mirror (for testing)
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linux
1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _ASM_UM_CPUFEATURE_H
3#define _ASM_UM_CPUFEATURE_H
4
5#include <asm/processor.h>
6
7#if defined(__KERNEL__) && !defined(__ASSEMBLER__)
8
9#include <asm/asm.h>
10#include <linux/bitops.h>
11
12extern const char * const x86_cap_flags[NCAPINTS*32];
13extern const char * const x86_power_flags[32];
14#define X86_CAP_FMT "%s"
15#define x86_cap_flag(flag) x86_cap_flags[flag]
16
17/*
18 * In order to save room, we index into this array by doing
19 * X86_BUG_<name> - NCAPINTS*32.
20 */
21extern const char * const x86_bug_flags[NBUGINTS*32];
22
23#define test_cpu_cap(c, bit) \
24 test_bit(bit, (unsigned long *)((c)->x86_capability))
25
26/*
27 * There are 32 bits/features in each mask word. The high bits
28 * (selected with (bit>>5) give us the word number and the low 5
29 * bits give us the bit/feature number inside the word.
30 * (1UL<<((bit)&31) gives us a mask for the feature_bit so we can
31 * see if it is set in the mask word.
32 */
33#define CHECK_BIT_IN_MASK_WORD(maskname, word, bit) \
34 (((bit)>>5)==(word) && (1UL<<((bit)&31) & maskname##word ))
35
36#define cpu_has(c, bit) \
37 test_cpu_cap(c, bit)
38
39#define this_cpu_has(bit) \
40 (__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 : \
41 x86_this_cpu_test_bit(bit, cpu_info.x86_capability))
42
43/*
44 * This macro is for detection of features which need kernel
45 * infrastructure to be used. It may *not* directly test the CPU
46 * itself. Use the cpu_has() family if you want true runtime
47 * testing of CPU features, like in hypervisor code where you are
48 * supporting a possible guest feature where host support for it
49 * is not relevant.
50 */
51#define cpu_feature_enabled(bit) \
52 (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : static_cpu_has(bit))
53
54#define boot_cpu_has(bit) cpu_has(&boot_cpu_data, bit)
55
56#define set_cpu_cap(c, bit) set_bit(bit, (unsigned long *)((c)->x86_capability))
57
58extern void setup_clear_cpu_cap(unsigned int bit);
59
60#define setup_force_cpu_cap(bit) do { \
61 set_cpu_cap(&boot_cpu_data, bit); \
62 set_bit(bit, (unsigned long *)cpu_caps_set); \
63} while (0)
64
65#define setup_force_cpu_bug(bit) setup_force_cpu_cap(bit)
66
67/*
68 * Static testing of CPU features. Used the same as boot_cpu_has(). It
69 * statically patches the target code for additional performance. Use
70 * static_cpu_has() only in fast paths, where every cycle counts. Which
71 * means that the boot_cpu_has() variant is already fast enough for the
72 * majority of cases and you should stick to using it as it is generally
73 * only two instructions: a RIP-relative MOV and a TEST.
74 */
75static __always_inline bool _static_cpu_has(u16 bit)
76{
77 asm goto("1: jmp 6f\n"
78 "2:\n"
79 ".skip -(((5f-4f) - (2b-1b)) > 0) * "
80 "((5f-4f) - (2b-1b)),0x90\n"
81 "3:\n"
82 ".section .altinstructions,\"a\"\n"
83 " .long 1b - .\n" /* src offset */
84 " .long 4f - .\n" /* repl offset */
85 " .word %P[always]\n" /* always replace */
86 " .byte 3b - 1b\n" /* src len */
87 " .byte 5f - 4f\n" /* repl len */
88 " .byte 3b - 2b\n" /* pad len */
89 ".previous\n"
90 ".section .altinstr_replacement,\"ax\"\n"
91 "4: jmp %l[t_no]\n"
92 "5:\n"
93 ".previous\n"
94 ".section .altinstructions,\"a\"\n"
95 " .long 1b - .\n" /* src offset */
96 " .long 0\n" /* no replacement */
97 " .word %P[feature]\n" /* feature bit */
98 " .byte 3b - 1b\n" /* src len */
99 " .byte 0\n" /* repl len */
100 " .byte 0\n" /* pad len */
101 ".previous\n"
102 ".section .altinstr_aux,\"ax\"\n"
103 "6:\n"
104 " testb %[bitnum],%[cap_byte]\n"
105 " jnz %l[t_yes]\n"
106 " jmp %l[t_no]\n"
107 ".previous\n"
108 : : [feature] "i" (bit),
109 [always] "i" (X86_FEATURE_ALWAYS),
110 [bitnum] "i" (1 << (bit & 7)),
111 [cap_byte] "m" (((const char *)boot_cpu_data.x86_capability)[bit >> 3])
112 : : t_yes, t_no);
113t_yes:
114 return true;
115t_no:
116 return false;
117}
118
119#define static_cpu_has(bit) \
120( \
121 __builtin_constant_p(boot_cpu_has(bit)) ? \
122 boot_cpu_has(bit) : \
123 _static_cpu_has(bit) \
124)
125
126#define cpu_has_bug(c, bit) cpu_has(c, (bit))
127#define set_cpu_bug(c, bit) set_cpu_cap(c, (bit))
128
129#define static_cpu_has_bug(bit) static_cpu_has((bit))
130#define boot_cpu_has_bug(bit) cpu_has_bug(&boot_cpu_data, (bit))
131#define boot_cpu_set_bug(bit) set_cpu_cap(&boot_cpu_data, (bit))
132
133#define MAX_CPU_FEATURES (NCAPINTS * 32)
134#define cpu_have_feature boot_cpu_has
135
136#define CPU_FEATURE_TYPEFMT "x86,ven%04Xfam%04Xmod%04X"
137#define CPU_FEATURE_TYPEVAL boot_cpu_data.x86_vendor, boot_cpu_data.x86, \
138 boot_cpu_data.x86_model
139
140#endif /* defined(__KERNEL__) && !defined(__ASSEMBLER__) */
141#endif /* _ASM_UM_CPUFEATURE_H */