Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1#include <linux/kernel.h>
2#include <linux/bits.h>
3#include <linux/bitfield.h>
4#include <stdio.h>
5#include <stdlib.h>
6#include <perf/cpumap.h>
7#include <api/fs/fs.h>
8#include <errno.h>
9#include "debug.h"
10#include "header.h"
11
12#define MIDR "/regs/identification/midr_el1"
13#define MIDR_SIZE 19
14#define MIDR_REVISION_MASK GENMASK(3, 0)
15#define MIDR_VARIANT_MASK GENMASK(23, 20)
16
17static int _get_cpuid(char *buf, size_t sz, struct perf_cpu cpu)
18{
19 char path[PATH_MAX];
20 FILE *file;
21 const char *sysfs = sysfs__mountpoint();
22
23 assert(cpu.cpu != -1);
24 if (!sysfs || sz < MIDR_SIZE)
25 return EINVAL;
26
27 scnprintf(path, PATH_MAX, "%s/devices/system/cpu/cpu%d" MIDR, sysfs, cpu.cpu);
28
29 file = fopen(path, "r");
30 if (!file) {
31 pr_debug("fopen failed for file %s\n", path);
32 return EINVAL;
33 }
34
35 if (!fgets(buf, MIDR_SIZE, file)) {
36 pr_debug("Failed to read file %s\n", path);
37 fclose(file);
38 return EINVAL;
39 }
40 fclose(file);
41 return 0;
42}
43
44int get_cpuid(char *buf, size_t sz, struct perf_cpu cpu)
45{
46 struct perf_cpu_map *cpus;
47 int idx;
48
49 if (cpu.cpu != -1)
50 return _get_cpuid(buf, sz, cpu);
51
52 cpus = perf_cpu_map__new_online_cpus();
53 if (!cpus)
54 return EINVAL;
55
56 perf_cpu_map__for_each_cpu(cpu, idx, cpus) {
57 int ret = _get_cpuid(buf, sz, cpu);
58
59 if (ret == 0)
60 return 0;
61 }
62 return EINVAL;
63}
64
65char *get_cpuid_str(struct perf_cpu cpu)
66{
67 char *buf = malloc(MIDR_SIZE);
68 int res;
69
70 if (!buf)
71 return NULL;
72
73 /* read midr from list of cpus mapped to this pmu */
74 res = get_cpuid(buf, MIDR_SIZE, cpu);
75 if (res) {
76 pr_err("failed to get cpuid string for CPU %d\n", cpu.cpu);
77 free(buf);
78 buf = NULL;
79 }
80
81 return buf;
82}
83
84/*
85 * Return 0 if idstr is a higher or equal to version of the same part as
86 * mapcpuid. Therefore, if mapcpuid has 0 for revision and variant then any
87 * version of idstr will match as long as it's the same CPU type.
88 *
89 * Return 1 if the CPU type is different or the version of idstr is lower.
90 */
91int strcmp_cpuid_str(const char *mapcpuid, const char *idstr)
92{
93 u64 map_id = strtoull(mapcpuid, NULL, 16);
94 char map_id_variant = FIELD_GET(MIDR_VARIANT_MASK, map_id);
95 char map_id_revision = FIELD_GET(MIDR_REVISION_MASK, map_id);
96 u64 id = strtoull(idstr, NULL, 16);
97 char id_variant = FIELD_GET(MIDR_VARIANT_MASK, id);
98 char id_revision = FIELD_GET(MIDR_REVISION_MASK, id);
99 u64 id_fields = ~(MIDR_VARIANT_MASK | MIDR_REVISION_MASK);
100
101 /* Compare without version first */
102 if ((map_id & id_fields) != (id & id_fields))
103 return 1;
104
105 /*
106 * ID matches, now compare version.
107 *
108 * Arm revisions (like r0p0) are compared here like two digit semver
109 * values eg. 1.3 < 2.0 < 2.1 < 2.2.
110 *
111 * r = high value = 'Variant' field in MIDR
112 * p = low value = 'Revision' field in MIDR
113 *
114 */
115 if (id_variant > map_id_variant)
116 return 0;
117
118 if (id_variant == map_id_variant && id_revision >= map_id_revision)
119 return 0;
120
121 /*
122 * variant is less than mapfile variant or variants are the same but
123 * the revision doesn't match. Return no match.
124 */
125 return 1;
126}