1 /* SPDX-License-Identifier: GPL-2.0-only */
2
3 #include <sys/types.h>
4 #include <sys/stat.h>
5 #include <fcntl.h>
6 #include <unistd.h>
7 #include <string.h>
8 #include <errno.h>
9
10 #include "msrtool.h"
11
12 static int msr_fd[MAX_CORES] = {-1, -1, -1, -1, -1, -1, -1, -1};
13
linux_probe(const struct sysdef * system)14 int linux_probe(const struct sysdef *system) {
15 struct stat st;
16 return 0 == stat("/dev/cpu/0/msr", &st);
17 }
18
linux_open(uint8_t cpu,enum SysModes mode)19 int linux_open(uint8_t cpu, enum SysModes mode) {
20 int fmode;
21 char fn[32];
22 switch (mode) {
23 case SYS_RDWR:
24 fmode = O_RDWR;
25 break;
26 case SYS_WRONLY:
27 fmode = O_WRONLY;
28 break;
29 case SYS_RDONLY:
30 default:
31 fmode = O_RDONLY;
32 break;
33 }
34 if (cpu >= MAX_CORES) {
35 fprintf(stderr, "%s: only cores 0-%d are supported. requested=%d\n", __func__, MAX_CORES, cpu);
36 return 0;
37 }
38 if (snprintf(fn, sizeof(fn), "/dev/cpu/%d/msr", cpu) == -1) {
39 fprintf(stderr, "%s: snprintf: %s\n", __func__, strerror(errno));
40 return 0;
41 }
42 msr_fd[cpu] = open(fn, fmode);
43 if (-1 == msr_fd[cpu]) {
44 fprintf(stderr, "open(%s): %s\n", fn, strerror(errno));
45 return 0;
46 }
47 return 1;
48 }
49
linux_close(uint8_t cpu)50 int linux_close(uint8_t cpu) {
51 int ret;
52 if (cpu >= MAX_CORES) {
53 fprintf(stderr, "%s: only cores 0-%d are supported. requested=%d\n", __func__, MAX_CORES, cpu);
54 return 0;
55 }
56 ret = close(msr_fd[cpu]);
57 msr_fd[cpu] = 0;
58 return 0 == ret;
59 }
60
linux_rdmsr(uint8_t cpu,uint32_t addr,struct msr * val)61 int linux_rdmsr(uint8_t cpu, uint32_t addr, struct msr *val) {
62 struct msr tmp;
63 if (lseek(msr_fd[cpu], addr, SEEK_SET) == -1) {
64 SYSERROR(lseek, addr);
65 return 0;
66 }
67 if (read(msr_fd[cpu], &tmp, 8) != 8) {
68 SYSERROR(read, addr);
69 return 0;
70 }
71 val->hi = tmp.lo;
72 val->lo = tmp.hi;
73 return 1;
74 }
75