LXR linux/arch/um/include/asm/cpufeature.h

   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#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 */
  90static __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);
 128t_yes:
 129        return true;
 130t_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