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
  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 /*
  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  */
  76 static __always_inline bool _static_cpu_has(u16 bit)
  77 {
  78         asm_volatile_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);
 114 t_yes:
 115         return true;
 116 t_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 */