1 #include <errno.h> 2 #include <stdio.h> 3 #include <stdlib.h> 4 #include <string.h> 5 #include <stdbool.h> 6 #include <sys/vfs.h> 7 #include <sys/mount.h> 8 #include <linux/kernel.h> 9 10 #include "debugfs.h" 11 12 char debugfs_mountpoint[PATH_MAX + 1] = "/sys/kernel/debug"; 13 14 static const char * const debugfs_known_mountpoints[] = { 15 "/sys/kernel/debug/", 16 "/debug/", 17 0, 18 }; 19 20 static bool debugfs_found; 21 22 /* find the path to the mounted debugfs */ 23 const char *debugfs_find_mountpoint(void) 24 { 25 const char * const *ptr; 26 char type[100]; 27 FILE *fp; 28 29 if (debugfs_found) 30 return (const char *)debugfs_mountpoint; 31 32 ptr = debugfs_known_mountpoints; 33 while (*ptr) { 34 if (debugfs_valid_mountpoint(*ptr) == 0) { 35 debugfs_found = true; 36 strcpy(debugfs_mountpoint, *ptr); 37 return debugfs_mountpoint; 38 } 39 ptr++; 40 } 41 42 /* give up and parse /proc/mounts */ 43 fp = fopen("/proc/mounts", "r"); 44 if (fp == NULL) 45 return NULL; 46 47 while (fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n", 48 debugfs_mountpoint, type) == 2) { 49 if (strcmp(type, "debugfs") == 0) 50 break; 51 } 52 fclose(fp); 53 54 if (strcmp(type, "debugfs") != 0) 55 return NULL; 56 57 debugfs_found = true; 58 59 return debugfs_mountpoint; 60 } 61 62 /* verify that a mountpoint is actually a debugfs instance */ 63 64 int debugfs_valid_mountpoint(const char *debugfs) 65 { 66 struct statfs st_fs; 67 68 if (statfs(debugfs, &st_fs) < 0) 69 return -ENOENT; 70 else if (st_fs.f_type != (long) DEBUGFS_MAGIC) 71 return -ENOENT; 72 73 return 0; 74 } 75 76 /* mount the debugfs somewhere if it's not mounted */ 77 char *debugfs_mount(const char *mountpoint) 78 { 79 #ifdef __APPLE__ 80 goto out; 81 #else 82 /* see if it's already mounted */ 83 if (debugfs_find_mountpoint()) 84 goto out; 85 86 /* if not mounted and no argument */ 87 if (mountpoint == NULL) { 88 /* see if environment variable set */ 89 mountpoint = getenv(PERF_DEBUGFS_ENVIRONMENT); 90 /* if no environment variable, use default */ 91 if (mountpoint == NULL) 92 mountpoint = "/sys/kernel/debug"; 93 } 94 95 if (mount(NULL, mountpoint, "debugfs", 0, NULL) < 0) 96 return NULL; 97 98 /* save the mountpoint */ 99 debugfs_found = true; 100 strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint)); 101 #endif 102 out: 103 return debugfs_mountpoint; 104 } 105
