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
17int is_valid_path(const char *path)
18{
19	if (access(path, F_OK) == -1)
20		return 0;
21	return 1;
22}
23
24unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen)
25{
26	ssize_t numread;
27	int fd;
28
29	fd = open(path, O_RDONLY);
30	if (fd == -1)
31		return 0;
32
33	numread = read(fd, buf, buflen - 1);
34	if (numread < 1) {
35		close(fd);
36		return 0;
37	}
38
39	buf[numread] = '\0';
40	close(fd);
41
42	return (unsigned int) numread;
43}
44
45unsigned int cpupower_write_sysfs(const char *path, char *buf, size_t buflen)
46{
47	ssize_t numwritten;
48	int fd;
49
50	fd = open(path, O_WRONLY);
51	if (fd == -1)
52		return 0;
53
54	numwritten = write(fd, buf, buflen - 1);
55	if (numwritten < 1) {
56		perror(path);
57		close(fd);
58		return -1;
59	}
60
61	close(fd);
62
63	return (unsigned int) numwritten;
64}
65
66/*
67 * Detect whether a CPU is online
68 *
69 * Returns:
70 *     1 -> if CPU is online
71 *     0 -> if CPU is offline
72 *     negative errno values in error case
73 */
74int cpupower_is_cpu_online(unsigned int cpu)
75{
76	char path[SYSFS_PATH_MAX];
77	int fd;
78	ssize_t numread;
79	unsigned long long value;
80	char linebuf[MAX_LINE_LEN];
81	char *endp;
82	struct stat statbuf;
83
84	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u", cpu);
85
86	if (stat(path, &statbuf) != 0)
87		return 0;
88
89	/*
90	 * kernel without CONFIG_HOTPLUG_CPU
91	 * -> cpuX directory exists, but not cpuX/online file
92	 */
93	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/online", cpu);
94	if (stat(path, &statbuf) != 0)
95		return 1;
96
97	fd = open(path, O_RDONLY);
98	if (fd == -1)
99		return -errno;
100
101	numread = read(fd, linebuf, MAX_LINE_LEN - 1);
102	if (numread < 1) {
103		close(fd);
104		return -EIO;
105	}
106	linebuf[numread] = '\0';
107	close(fd);
108
109	value = strtoull(linebuf, &endp, 0);
110	if (value > 1)
111		return -EINVAL;
112
113	return value;
114}
115
116/* returns -1 on failure, 0 on success */
117static int sysfs_topology_read_file(unsigned int cpu, const char *fname, int *result)
118{
119	char linebuf[MAX_LINE_LEN];
120	char *endp;
121	char path[SYSFS_PATH_MAX];
122
123	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/topology/%s",
124			 cpu, fname);
125	if (cpupower_read_sysfs(path, linebuf, MAX_LINE_LEN) == 0)
126		return -1;
127	*result = strtol(linebuf, &endp, 0);
128	if (endp == linebuf || errno == ERANGE)
129		return -1;
130	return 0;
131}
132
133static int __compare(const void *t1, const void *t2)
134{
135	struct cpuid_core_info *top1 = (struct cpuid_core_info *)t1;
136	struct cpuid_core_info *top2 = (struct cpuid_core_info *)t2;
137	if (top1->pkg < top2->pkg)
138		return -1;
139	else if (top1->pkg > top2->pkg)
140		return 1;
141	else if (top1->core < top2->core)
142		return -1;
143	else if (top1->core > top2->core)
144		return 1;
145	else if (top1->cpu < top2->cpu)
146		return -1;
147	else if (top1->cpu > top2->cpu)
148		return 1;
149	else
150		return 0;
151}
152
153/*
154 * Returns amount of cpus, negative on error, cpu_top must be
155 * passed to cpu_topology_release to free resources
156 *
157 * Array is sorted after ->pkg, ->core, then ->cpu
158 */
159int get_cpu_topology(struct cpupower_topology *cpu_top)
160{
161	int cpu, last_pkg, cpus = sysconf(_SC_NPROCESSORS_CONF);
162
163	cpu_top->core_info = malloc(sizeof(struct cpuid_core_info) * cpus);
164	if (cpu_top->core_info == NULL)
165		return -ENOMEM;
166	cpu_top->pkgs = cpu_top->cores = 0;
167	for (cpu = 0; cpu < cpus; cpu++) {
168		cpu_top->core_info[cpu].cpu = cpu;
169		cpu_top->core_info[cpu].is_online = cpupower_is_cpu_online(cpu);
170		if(sysfs_topology_read_file(
171			cpu,
172			"physical_package_id",
173			&(cpu_top->core_info[cpu].pkg)) < 0) {
174			cpu_top->core_info[cpu].pkg = -1;
175			cpu_top->core_info[cpu].core = -1;
176			continue;
177		}
178		if(sysfs_topology_read_file(
179			cpu,
180			"core_id",
181			&(cpu_top->core_info[cpu].core)) < 0) {
182			cpu_top->core_info[cpu].pkg = -1;
183			cpu_top->core_info[cpu].core = -1;
184			continue;
185		}
186	}
187
188	qsort(cpu_top->core_info, cpus, sizeof(struct cpuid_core_info),
189	      __compare);
190
191	/* Count the number of distinct pkgs values. This works
192	   because the primary sort of the core_info struct was just
193	   done by pkg value. */
194	last_pkg = cpu_top->core_info[0].pkg;
195	for(cpu = 1; cpu < cpus; cpu++) {
196		if (cpu_top->core_info[cpu].pkg != last_pkg &&
197				cpu_top->core_info[cpu].pkg != -1) {
198
199			last_pkg = cpu_top->core_info[cpu].pkg;
200			cpu_top->pkgs++;
201		}
202	}
203	if (!(cpu_top->core_info[0].pkg == -1))
204		cpu_top->pkgs++;
205
206	/* Intel's cores count is not consecutively numbered, there may
207	 * be a core_id of 3, but none of 2. Assume there always is 0
208	 * Get amount of cores by counting duplicates in a package
209	for (cpu = 0; cpu_top->core_info[cpu].pkg = 0 && cpu < cpus; cpu++) {
210		if (cpu_top->core_info[cpu].core == 0)
211	cpu_top->cores++;
212	*/
213	return cpus;
214}
215
216void cpu_topology_release(struct cpupower_topology cpu_top)
217{
218	free(cpu_top.core_info);
219}
220