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 */ 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