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/export.h>
 8#include <linux/bug.h>
 9#include <asm/machine.h>
10#include <asm/elf.h>
11
12enum {
13	TYPE_HWCAP,
14	TYPE_FACILITY,
15	TYPE_MACHINE,
16};
17
18struct s390_cpu_feature {
19	unsigned int type	: 4;
20	unsigned int num	: 28;
21};
22
23static struct s390_cpu_feature s390_cpu_features[MAX_CPU_FEATURES] = {
24	[S390_CPU_FEATURE_MSA]	= {.type = TYPE_HWCAP, .num = HWCAP_NR_MSA},
25	[S390_CPU_FEATURE_VXRS]	= {.type = TYPE_HWCAP, .num = HWCAP_NR_VXRS},
26	[S390_CPU_FEATURE_UV]	= {.type = TYPE_FACILITY, .num = 158},
27	[S390_CPU_FEATURE_D288]	= {.type = TYPE_MACHINE, .num = MFEATURE_DIAG288},
28};
29
30/*
31 * cpu_have_feature - Test CPU features on module initialization
32 */
33int cpu_have_feature(unsigned int num)
34{
35	struct s390_cpu_feature *feature;
36
37	if (WARN_ON_ONCE(num >= MAX_CPU_FEATURES))
38		return 0;
39	feature = &s390_cpu_features[num];
40	switch (feature->type) {
41	case TYPE_HWCAP:
42		return !!(elf_hwcap & BIT(feature->num));
43	case TYPE_FACILITY:
44		return test_facility(feature->num);
45	case TYPE_MACHINE:
46		return test_machine_feature(feature->num);
47	default:
48		WARN_ON_ONCE(1);
49		return 0;
50	}
51}
52EXPORT_SYMBOL(cpu_have_feature);