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(__ASSEMBLY__)
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,					\
42		(unsigned long __percpu *)&cpu_info.x86_capability))
43
44/*
45 * This macro is for detection of features which need kernel
46 * infrastructure to be used.  It may *not* directly test the CPU
47 * itself.  Use the cpu_has() family if you want true runtime
48 * testing of CPU features, like in hypervisor code where you are
49 * supporting a possible guest feature where host support for it
50 * is not relevant.
51 */
52#define cpu_feature_enabled(bit)	\
53	(__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : static_cpu_has(bit))
54
55#define boot_cpu_has(bit)	cpu_has(&boot_cpu_data, bit)
56
57#define set_cpu_cap(c, bit)	set_bit(bit, (unsigned long *)((c)->x86_capability))
58
59extern void setup_clear_cpu_cap(unsigned int bit);
60
61#define setup_force_cpu_cap(bit) do { \
62	set_cpu_cap(&boot_cpu_data, bit);	\
63	set_bit(bit, (unsigned long *)cpu_caps_set);	\
64} while (0)
65
66#define setup_force_cpu_bug(bit) setup_force_cpu_cap(bit)
67
68/*
69 * Static testing of CPU features. Used the same as boot_cpu_has(). It
70 * statically patches the target code for additional performance. Use
71 * static_cpu_has() only in fast paths, where every cycle counts. Which
72 * means that the boot_cpu_has() variant is already fast enough for the
73 * majority of cases and you should stick to using it as it is generally
74 * only two instructions: a RIP-relative MOV and a TEST.
75 */
76static __always_inline bool _static_cpu_has(u16 bit)
77{
78	asm goto("1: jmp 6f\n"
79		 "2:\n"
80		 ".skip -(((5f-4f) - (2b-1b)) > 0) * "
81			 "((5f-4f) - (2b-1b)),0x90\n"
82		 "3:\n"
83		 ".section .altinstructions,\"a\"\n"
84		 " .long 1b - .\n"		/* src offset */
85		 " .long 4f - .\n"		/* repl offset */
86		 " .word %P[always]\n"		/* always replace */
87		 " .byte 3b - 1b\n"		/* src len */
88		 " .byte 5f - 4f\n"		/* repl len */
89		 " .byte 3b - 2b\n"		/* pad len */
90		 ".previous\n"
91		 ".section .altinstr_replacement,\"ax\"\n"
92		 "4: jmp %l[t_no]\n"
93		 "5:\n"
94		 ".previous\n"
95		 ".section .altinstructions,\"a\"\n"
96		 " .long 1b - .\n"		/* src offset */
97		 " .long 0\n"			/* no replacement */
98		 " .word %P[feature]\n"		/* feature bit */
99		 " .byte 3b - 1b\n"		/* src len */
100		 " .byte 0\n"			/* repl len */
101		 " .byte 0\n"			/* pad len */
102		 ".previous\n"
103		 ".section .altinstr_aux,\"ax\"\n"
104		 "6:\n"
105		 " testb %[bitnum],%[cap_byte]\n"
106		 " jnz %l[t_yes]\n"
107		 " jmp %l[t_no]\n"
108		 ".previous\n"
109		 : : [feature]  "i" (bit),
110		     [always]   "i" (X86_FEATURE_ALWAYS),
111		     [bitnum]   "i" (1 << (bit & 7)),
112		     [cap_byte] "m" (((const char *)boot_cpu_data.x86_capability)[bit >> 3])
113		 : : t_yes, t_no);
114t_yes:
115	return true;
116t_no:
117	return false;
118}
119
120#define static_cpu_has(bit)					\
121(								\
122	__builtin_constant_p(boot_cpu_has(bit)) ?		\
123		boot_cpu_has(bit) :				\
124		_static_cpu_has(bit)				\
125)
126
127#define cpu_has_bug(c, bit)		cpu_has(c, (bit))
128#define set_cpu_bug(c, bit)		set_cpu_cap(c, (bit))
129
130#define static_cpu_has_bug(bit)		static_cpu_has((bit))
131#define boot_cpu_has_bug(bit)		cpu_has_bug(&boot_cpu_data, (bit))
132#define boot_cpu_set_bug(bit)		set_cpu_cap(&boot_cpu_data, (bit))
133
134#define MAX_CPU_FEATURES		(NCAPINTS * 32)
135#define cpu_have_feature		boot_cpu_has
136
137#define CPU_FEATURE_TYPEFMT		"x86,ven%04Xfam%04Xmod%04X"
138#define CPU_FEATURE_TYPEVAL		boot_cpu_data.x86_vendor, boot_cpu_data.x86, \
139					boot_cpu_data.x86_model
140
141#endif /* defined(__KERNEL__) && !defined(__ASSEMBLY__) */
142#endif /* _ASM_UM_CPUFEATURE_H */
143