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
17unsigned 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 */
46int 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 */
89static 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
105static 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 */
131int 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
188void cpu_topology_release(struct cpupower_topology cpu_top)
189{
190	free(cpu_top.core_info);
191}
192