summaryrefslogtreecommitdiff
path: root/arch/um/include/asm/cpufeature.h
blob: 4b6d1b526bc1217e2e89d4670f9c4385e68dacc7 (plain)
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
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_UM_CPUFEATURE_H
#define _ASM_UM_CPUFEATURE_H

#include <asm/processor.h>

#if defined(__KERNEL__) && !defined(__ASSEMBLY__)

#include <asm/asm.h>
#include <linux/bitops.h>

extern const char * const x86_cap_flags[NCAPINTS*32];
extern const char * const x86_power_flags[32];
#define X86_CAP_FMT "%s"
#define x86_cap_flag(flag) x86_cap_flags[flag]

/*
 * In order to save room, we index into this array by doing
 * X86_BUG_<name> - NCAPINTS*32.
 */
extern const char * const x86_bug_flags[NBUGINTS*32];

#define test_cpu_cap(c, bit)						\
	 test_bit(bit, (unsigned long *)((c)->x86_capability))

/*
 * There are 32 bits/features in each mask word.  The high bits
 * (selected with (bit>>5) give us the word number and the low 5
 * bits give us the bit/feature number inside the word.
 * (1UL<<((bit)&31) gives us a mask for the feature_bit so we can
 * see if it is set in the mask word.
 */
#define CHECK_BIT_IN_MASK_WORD(maskname, word, bit)	\
	(((bit)>>5)==(word) && (1UL<<((bit)&31) & maskname##word ))

#define cpu_has(c, bit)							\
	 test_cpu_cap(c, bit)

#define this_cpu_has(bit)						\
	(__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 :	\
	 x86_this_cpu_test_bit(bit,					\
		(unsigned long __percpu *)&cpu_info.x86_capability))

/*
 * This macro is for detection of features which need kernel
 * infrastructure to be used.  It may *not* directly test the CPU
 * itself.  Use the cpu_has() family if you want true runtime
 * testing of CPU features, like in hypervisor code where you are
 * supporting a possible guest feature where host support for it
 * is not relevant.
 */
#define cpu_feature_enabled(bit)	\
	(__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : static_cpu_has(bit))

#define boot_cpu_has(bit)	cpu_has(&boot_cpu_data, bit)

#define set_cpu_cap(c, bit)	set_bit(bit, (unsigned long *)((c)->x86_capability))

extern void setup_clear_cpu_cap(unsigned int bit);

#define setup_force_cpu_cap(bit) do { \
	set_cpu_cap(&boot_cpu_data, bit);	\
	set_bit(bit, (unsigned long *)cpu_caps_set);	\
} while (0)

#define setup_force_cpu_bug(bit) setup_force_cpu_cap(bit)

/*
 * Static testing of CPU features. Used the same as boot_cpu_has(). It
 * statically patches the target code for additional performance. Use
 * static_cpu_has() only in fast paths, where every cycle counts. Which
 * means that the boot_cpu_has() variant is already fast enough for the
 * majority of cases and you should stick to using it as it is generally
 * only two instructions: a RIP-relative MOV and a TEST.
 */
static __always_inline bool _static_cpu_has(u16 bit)
{
	asm_volatile_goto("1: jmp 6f\n"
		 "2:\n"
		 ".skip -(((5f-4f) - (2b-1b)) > 0) * "
			 "((5f-4f) - (2b-1b)),0x90\n"
		 "3:\n"
		 ".section .altinstructions,\"a\"\n"
		 " .long 1b - .\n"		/* src offset */
		 " .long 4f - .\n"		/* repl offset */
		 " .word %P[always]\n"		/* always replace */
		 " .byte 3b - 1b\n"		/* src len */
		 " .byte 5f - 4f\n"		/* repl len */
		 " .byte 3b - 2b\n"		/* pad len */
		 ".previous\n"
		 ".section .altinstr_replacement,\"ax\"\n"
		 "4: jmp %l[t_no]\n"
		 "5:\n"
		 ".previous\n"
		 ".section .altinstructions,\"a\"\n"
		 " .long 1b - .\n"		/* src offset */
		 " .long 0\n"			/* no replacement */
		 " .word %P[feature]\n"		/* feature bit */
		 " .byte 3b - 1b\n"		/* src len */
		 " .byte 0\n"			/* repl len */
		 " .byte 0\n"			/* pad len */
		 ".previous\n"
		 ".section .altinstr_aux,\"ax\"\n"
		 "6:\n"
		 " testb %[bitnum],%[cap_byte]\n"
		 " jnz %l[t_yes]\n"
		 " jmp %l[t_no]\n"
		 ".previous\n"
		 : : [feature]  "i" (bit),
		     [always]   "i" (X86_FEATURE_ALWAYS),
		     [bitnum]   "i" (1 << (bit & 7)),
		     [cap_byte] "m" (((const char *)boot_cpu_data.x86_capability)[bit >> 3])
		 : : t_yes, t_no);
t_yes:
	return true;
t_no:
	return false;
}

#define static_cpu_has(bit)					\
(								\
	__builtin_constant_p(boot_cpu_has(bit)) ?		\
		boot_cpu_has(bit) :				\
		_static_cpu_has(bit)				\
)

#define cpu_has_bug(c, bit)		cpu_has(c, (bit))
#define set_cpu_bug(c, bit)		set_cpu_cap(c, (bit))

#define static_cpu_has_bug(bit)		static_cpu_has((bit))
#define boot_cpu_has_bug(bit)		cpu_has_bug(&boot_cpu_data, (bit))
#define boot_cpu_set_bug(bit)		set_cpu_cap(&boot_cpu_data, (bit))

#define MAX_CPU_FEATURES		(NCAPINTS * 32)
#define cpu_have_feature		boot_cpu_has

#define CPU_FEATURE_TYPEFMT		"x86,ven%04Xfam%04Xmod%04X"
#define CPU_FEATURE_TYPEVAL		boot_cpu_data.x86_vendor, boot_cpu_data.x86, \
					boot_cpu_data.x86_model

#endif /* defined(__KERNEL__) && !defined(__ASSEMBLY__) */
#endif /* _ASM_UM_CPUFEATURE_H */