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
12 extern const char * const x86_cap_flags[NCAPINTS*32];
13 extern 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 */
21 extern 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
59 extern 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 #if defined(__clang__) && !defined(CONFIG_CC_HAS_ASM_GOTO)
69
70 /*
71 * Workaround for the sake of BPF compilation which utilizes kernel
72 * headers, but clang does not support ASM GOTO and fails the build.
73 */
74 #ifndef __BPF_TRACING__
75 #warning "Compiler lacks ASM_GOTO support. Add -D __BPF_TRACING__ to your compiler arguments"
76 #endif
77
78 #define static_cpu_has(bit) boot_cpu_has(bit)
79
80 #else
81
82 /*
83 * Static testing of CPU features. Used the same as boot_cpu_has(). It
84 * statically patches the target code for additional performance. Use
85 * static_cpu_has() only in fast paths, where every cycle counts. Which
86 * means that the boot_cpu_has() variant is already fast enough for the
87 * majority of cases and you should stick to using it as it is generally
88 * only two instructions: a RIP-relative MOV and a TEST.
89 */
_static_cpu_has(u16 bit)90 static __always_inline bool _static_cpu_has(u16 bit)
91 {
92 asm_volatile_goto("1: jmp 6f\n"
93 "2:\n"
94 ".skip -(((5f-4f) - (2b-1b)) > 0) * "
95 "((5f-4f) - (2b-1b)),0x90\n"
96 "3:\n"
97 ".section .altinstructions,\"a\"\n"
98 " .long 1b - .\n" /* src offset */
99 " .long 4f - .\n" /* repl offset */
100 " .word %P[always]\n" /* always replace */
101 " .byte 3b - 1b\n" /* src len */
102 " .byte 5f - 4f\n" /* repl len */
103 " .byte 3b - 2b\n" /* pad len */
104 ".previous\n"
105 ".section .altinstr_replacement,\"ax\"\n"
106 "4: jmp %l[t_no]\n"
107 "5:\n"
108 ".previous\n"
109 ".section .altinstructions,\"a\"\n"
110 " .long 1b - .\n" /* src offset */
111 " .long 0\n" /* no replacement */
112 " .word %P[feature]\n" /* feature bit */
113 " .byte 3b - 1b\n" /* src len */
114 " .byte 0\n" /* repl len */
115 " .byte 0\n" /* pad len */
116 ".previous\n"
117 ".section .altinstr_aux,\"ax\"\n"
118 "6:\n"
119 " testb %[bitnum],%[cap_byte]\n"
120 " jnz %l[t_yes]\n"
121 " jmp %l[t_no]\n"
122 ".previous\n"
123 : : [feature] "i" (bit),
124 [always] "i" (X86_FEATURE_ALWAYS),
125 [bitnum] "i" (1 << (bit & 7)),
126 [cap_byte] "m" (((const char *)boot_cpu_data.x86_capability)[bit >> 3])
127 : : t_yes, t_no);
128 t_yes:
129 return true;
130 t_no:
131 return false;
132 }
133
134 #define static_cpu_has(bit) \
135 ( \
136 __builtin_constant_p(boot_cpu_has(bit)) ? \
137 boot_cpu_has(bit) : \
138 _static_cpu_has(bit) \
139 )
140 #endif
141
142 #define cpu_has_bug(c, bit) cpu_has(c, (bit))
143 #define set_cpu_bug(c, bit) set_cpu_cap(c, (bit))
144
145 #define static_cpu_has_bug(bit) static_cpu_has((bit))
146 #define boot_cpu_has_bug(bit) cpu_has_bug(&boot_cpu_data, (bit))
147 #define boot_cpu_set_bug(bit) set_cpu_cap(&boot_cpu_data, (bit))
148
149 #define MAX_CPU_FEATURES (NCAPINTS * 32)
150 #define cpu_have_feature boot_cpu_has
151
152 #define CPU_FEATURE_TYPEFMT "x86,ven%04Xfam%04Xmod%04X"
153 #define CPU_FEATURE_TYPEVAL boot_cpu_data.x86_vendor, boot_cpu_data.x86, \
154 boot_cpu_data.x86_model
155
156 #endif /* defined(__KERNEL__) && !defined(__ASSEMBLY__) */
157 #endif /* _ASM_UM_CPUFEATURE_H */
158