/* SPDX-License-Identifier: GPL-2.0-only */ #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> #include <string.h> #include <errno.h> #include "msrtool.h" static int msr_fd[MAX_CORES] = {-1, -1, -1, -1, -1, -1, -1, -1}; int linux_probe(const struct sysdef *system) { struct stat st; return 0 == stat("/dev/cpu/0/msr", &st); } int linux_open(uint8_t cpu, enum SysModes mode) { int fmode; char fn[32]; switch (mode) { case SYS_RDWR: fmode = O_RDWR; break; case SYS_WRONLY: fmode = O_WRONLY; break; case SYS_RDONLY: default: fmode = O_RDONLY; break; } if (cpu >= MAX_CORES) { fprintf(stderr, "%s: only cores 0-%d are supported. requested=%d\n", __func__, MAX_CORES, cpu); return 0; } if (snprintf(fn, sizeof(fn), "/dev/cpu/%d/msr", cpu) == -1) { fprintf(stderr, "%s: snprintf: %s\n", __func__, strerror(errno)); return 0; } msr_fd[cpu] = open(fn, fmode); if (-1 == msr_fd[cpu]) { fprintf(stderr, "open(%s): %s\n", fn, strerror(errno)); return 0; } return 1; } int linux_close(uint8_t cpu) { int ret; if (cpu >= MAX_CORES) { fprintf(stderr, "%s: only cores 0-%d are supported. requested=%d\n", __func__, MAX_CORES, cpu); return 0; } ret = close(msr_fd[cpu]); msr_fd[cpu] = 0; return 0 == ret; } int linux_rdmsr(uint8_t cpu, uint32_t addr, struct msr *val) { struct msr tmp; if (lseek(msr_fd[cpu], addr, SEEK_SET) == -1) { SYSERROR(lseek, addr); return 0; } if (read(msr_fd[cpu], &tmp, 8) != 8) { SYSERROR(read, addr); return 0; } val->hi = tmp.lo; val->lo = tmp.hi; return 1; }