Quelle  cpufeature.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright IBM Corp. 2022
 */

#include <linux/cpufeature.h>
#include <linux/export.h>
#include <linux/bug.h>
#include <asm/machine.h>
#include <asm/elf.h>

enum {
 TYPE_HWCAP,
 TYPE_FACILITY,
 TYPE_MACHINE,
};

struct s390_cpu_feature {
 unsigned int type : 4;
 unsigned int num : 28;
};

static struct s390_cpu_feature s390_cpu_features[MAX_CPU_FEATURES] = {
 [S390_CPU_FEATURE_MSA] = {.type = TYPE_HWCAP, .num = HWCAP_NR_MSA},
 [S390_CPU_FEATURE_VXRS] = {.type = TYPE_HWCAP, .num = HWCAP_NR_VXRS},
 [S390_CPU_FEATURE_UV] = {.type = TYPE_FACILITY, .num = 158},
 [S390_CPU_FEATURE_D288] = {.type = TYPE_MACHINE, .num = MFEATURE_DIAG288},
};

/*
 * cpu_have_feature - Test CPU features on module initialization
 */
int cpu_have_feature(unsigned int num)
{
 struct s390_cpu_feature *feature;

 if (WARN_ON_ONCE(num >= MAX_CPU_FEATURES))
  return 0;
 feature = &s390_cpu_features[num];
 switch (feature->type) {
 case TYPE_HWCAP:
  return !!(elf_hwcap & BIT(feature->num));
 case TYPE_FACILITY:
  return test_facility(feature->num);
 case TYPE_MACHINE:
  return test_machine_feature(feature->num);
 default:
  WARN_ON_ONCE(1);
  return 0;
 }
}
EXPORT_SYMBOL(cpu_have_feature);