s390/kernel/cpufeature.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright IBM Corp. 2022
   4  */
   5
   6 #include <linux/cpufeature.h>
   7 #include <linux/bug.h>
   8 #include <asm/elf.h>
   9
  10 enum {
  11         TYPE_HWCAP,
  12         TYPE_FACILITY,
  13 };
  14
  15 struct s390_cpu_feature {
  16         unsigned int type       : 4;
  17         unsigned int num        : 28;
  18 };
  19
  20 static struct s390_cpu_feature s390_cpu_features[MAX_CPU_FEATURES] = {
  21         [S390_CPU_FEATURE_MSA]  = {.type = TYPE_HWCAP, .num = HWCAP_NR_MSA},
  22         [S390_CPU_FEATURE_VXRS] = {.type = TYPE_HWCAP, .num = HWCAP_NR_VXRS},
  23         [S390_CPU_FEATURE_UV]   = {.type = TYPE_FACILITY, .num = 158},
  24 };
  25
  26 /*
  27  * cpu_have_feature - Test CPU features on module initialization
  28  */
  29 int cpu_have_feature(unsigned int num)
  30 {
  31         struct s390_cpu_feature *feature;
  32
  33         if (WARN_ON_ONCE(num >= MAX_CPU_FEATURES))
  34                 return 0;
  35         feature = &s390_cpu_features[num];
  36         switch (feature->type) {
  37         case TYPE_HWCAP:
  38                 return !!(elf_hwcap & BIT(feature->num));
  39         case TYPE_FACILITY:
  40                 return test_facility(feature->num);
  41         default:
  42                 WARN_ON_ONCE(1);
  43                 return 0;
  44         }
  45 }
  46 EXPORT_SYMBOL(cpu_have_feature);