1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * (C) 2004-2009 Dominik Brodowski <linux@dominikbrodowski.de>
4 */
5
6 #include <sys/types.h>
7 #include <sys/stat.h>
8 #include <fcntl.h>
9 #include <unistd.h>
10 #include <stdio.h>
11 #include <errno.h>
12 #include <stdlib.h>
13
14 #include "cpupower.h"
15 #include "cpupower_intern.h"
16
cpupower_read_sysfs(const char * path,char * buf,size_t buflen)17 unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen)
18 {
19 int fd;
20 ssize_t numread;
21
22 fd = open(path, O_RDONLY);
23 if (fd == -1)
24 return 0;
25
26 numread = read(fd, buf, buflen - 1);
27 if (numread < 1) {
28 close(fd);
29 return 0;
30 }
31
32 buf[numread] = '\0';
33 close(fd);
34
35 return (unsigned int) numread;
36 }
37
38 /*
39 * Detect whether a CPU is online
40 *
41 * Returns:
42 * 1 -> if CPU is online
43 * 0 -> if CPU is offline
44 * negative errno values in error case
45 */
cpupower_is_cpu_online(unsigned int cpu)46 int cpupower_is_cpu_online(unsigned int cpu)
47 {
48 char path[SYSFS_PATH_MAX];
49 int fd;
50 ssize_t numread;
51 unsigned long long value;
52 char linebuf[MAX_LINE_LEN];
53 char *endp;
54 struct stat statbuf;
55
56 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u", cpu);
57
58 if (stat(path, &statbuf) != 0)
59 return 0;
60
61 /*
62 * kernel without CONFIG_HOTPLUG_CPU
63 * -> cpuX directory exists, but not cpuX/online file
64 */
65 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/online", cpu);
66 if (stat(path, &statbuf) != 0)
67 return 1;
68
69 fd = open(path, O_RDONLY);
70 if (fd == -1)
71 return -errno;
72
73 numread = read(fd, linebuf, MAX_LINE_LEN - 1);
74 if (numread < 1) {
75 close(fd);
76 return -EIO;
77 }
78 linebuf[numread] = '\0';
79 close(fd);
80
81 value = strtoull(linebuf, &endp, 0);
82 if (value > 1)
83 return -EINVAL;
84
85 return value;
86 }
87
88 /* returns -1 on failure, 0 on success */
sysfs_topology_read_file(unsigned int cpu,const char * fname,int * result)89 static int sysfs_topology_read_file(unsigned int cpu, const char *fname, int *result)
90 {
91 char linebuf[MAX_LINE_LEN];
92 char *endp;
93 char path[SYSFS_PATH_MAX];
94
95 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/topology/%s",
96 cpu, fname);
97 if (cpupower_read_sysfs(path, linebuf, MAX_LINE_LEN) == 0)
98 return -1;
99 *result = strtol(linebuf, &endp, 0);
100 if (endp == linebuf || errno == ERANGE)
101 return -1;
102 return 0;
103 }
104
__compare(const void * t1,const void * t2)105 static int __compare(const void *t1, const void *t2)
106 {
107 struct cpuid_core_info *top1 = (struct cpuid_core_info *)t1;
108 struct cpuid_core_info *top2 = (struct cpuid_core_info *)t2;
109 if (top1->pkg < top2->pkg)
110 return -1;
111 else if (top1->pkg > top2->pkg)
112 return 1;
113 else if (top1->core < top2->core)
114 return -1;
115 else if (top1->core > top2->core)
116 return 1;
117 else if (top1->cpu < top2->cpu)
118 return -1;
119 else if (top1->cpu > top2->cpu)
120 return 1;
121 else
122 return 0;
123 }
124
125 /*
126 * Returns amount of cpus, negative on error, cpu_top must be
127 * passed to cpu_topology_release to free resources
128 *
129 * Array is sorted after ->pkg, ->core, then ->cpu
130 */
get_cpu_topology(struct cpupower_topology * cpu_top)131 int get_cpu_topology(struct cpupower_topology *cpu_top)
132 {
133 int cpu, last_pkg, cpus = sysconf(_SC_NPROCESSORS_CONF);
134
135 cpu_top->core_info = malloc(sizeof(struct cpuid_core_info) * cpus);
136 if (cpu_top->core_info == NULL)
137 return -ENOMEM;
138 cpu_top->pkgs = cpu_top->cores = 0;
139 for (cpu = 0; cpu < cpus; cpu++) {
140 cpu_top->core_info[cpu].cpu = cpu;
141 cpu_top->core_info[cpu].is_online = cpupower_is_cpu_online(cpu);
142 if(sysfs_topology_read_file(
143 cpu,
144 "physical_package_id",
145 &(cpu_top->core_info[cpu].pkg)) < 0) {
146 cpu_top->core_info[cpu].pkg = -1;
147 cpu_top->core_info[cpu].core = -1;
148 continue;
149 }
150 if(sysfs_topology_read_file(
151 cpu,
152 "core_id",
153 &(cpu_top->core_info[cpu].core)) < 0) {
154 cpu_top->core_info[cpu].pkg = -1;
155 cpu_top->core_info[cpu].core = -1;
156 continue;
157 }
158 }
159
160 qsort(cpu_top->core_info, cpus, sizeof(struct cpuid_core_info),
161 __compare);
162
163 /* Count the number of distinct pkgs values. This works
164 because the primary sort of the core_info struct was just
165 done by pkg value. */
166 last_pkg = cpu_top->core_info[0].pkg;
167 for(cpu = 1; cpu < cpus; cpu++) {
168 if (cpu_top->core_info[cpu].pkg != last_pkg &&
169 cpu_top->core_info[cpu].pkg != -1) {
170
171 last_pkg = cpu_top->core_info[cpu].pkg;
172 cpu_top->pkgs++;
173 }
174 }
175 if (!(cpu_top->core_info[0].pkg == -1))
176 cpu_top->pkgs++;
177
178 /* Intel's cores count is not consecutively numbered, there may
179 * be a core_id of 3, but none of 2. Assume there always is 0
180 * Get amount of cores by counting duplicates in a package
181 for (cpu = 0; cpu_top->core_info[cpu].pkg = 0 && cpu < cpus; cpu++) {
182 if (cpu_top->core_info[cpu].core == 0)
183 cpu_top->cores++;
184 */
185 return cpus;
186 }
187
cpu_topology_release(struct cpupower_topology cpu_top)188 void cpu_topology_release(struct cpupower_topology cpu_top)
189 {
190 free(cpu_top.core_info);
191 }
192