diff options
Diffstat (limited to 'tools/lib/lk/debugfs.c')
-rw-r--r-- | tools/lib/lk/debugfs.c | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/tools/lib/lk/debugfs.c b/tools/lib/lk/debugfs.c new file mode 100644 index 00000000000..9cda7a6f591 --- /dev/null +++ b/tools/lib/lk/debugfs.c @@ -0,0 +1,116 @@ +#include <errno.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <stdbool.h> +#include <sys/vfs.h> +#include <sys/mount.h> +#include <linux/magic.h> +#include <linux/kernel.h> + +#include "debugfs.h" + +char debugfs_mountpoint[PATH_MAX + 1] = "/sys/kernel/debug"; +char tracing_events_path[PATH_MAX + 1] = "/sys/kernel/debug/tracing/events"; + +static const char * const debugfs_known_mountpoints[] = { + "/sys/kernel/debug/", + "/debug/", + 0, +}; + +static bool debugfs_found; + +/* find the path to the mounted debugfs */ +const char *debugfs_find_mountpoint(void) +{ + const char * const *ptr; + char type[100]; + FILE *fp; + + if (debugfs_found) + return (const char *)debugfs_mountpoint; + + ptr = debugfs_known_mountpoints; + while (*ptr) { + if (debugfs_valid_mountpoint(*ptr) == 0) { + debugfs_found = true; + strcpy(debugfs_mountpoint, *ptr); + return debugfs_mountpoint; + } + ptr++; + } + + /* give up and parse /proc/mounts */ + fp = fopen("/proc/mounts", "r"); + if (fp == NULL) + return NULL; + + while (fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n", + debugfs_mountpoint, type) == 2) { + if (strcmp(type, "debugfs") == 0) + break; + } + fclose(fp); + + if (strcmp(type, "debugfs") != 0) + return NULL; + + debugfs_found = true; + + return debugfs_mountpoint; +} + +/* verify that a mountpoint is actually a debugfs instance */ + +int debugfs_valid_mountpoint(const char *debugfs) +{ + struct statfs st_fs; + + if (statfs(debugfs, &st_fs) < 0) + return -ENOENT; + else if (st_fs.f_type != (long) DEBUGFS_MAGIC) + return -ENOENT; + + return 0; +} + +static void debugfs_set_tracing_events_path(const char *mountpoint) +{ + snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s", + mountpoint, "tracing/events"); +} + +/* mount the debugfs somewhere if it's not mounted */ + +char *debugfs_mount(const char *mountpoint) +{ + /* see if it's already mounted */ + if (debugfs_find_mountpoint()) + goto out; + + /* if not mounted and no argument */ + if (mountpoint == NULL) { + /* see if environment variable set */ + mountpoint = getenv(PERF_DEBUGFS_ENVIRONMENT); + /* if no environment variable, use default */ + if (mountpoint == NULL) + mountpoint = "/sys/kernel/debug"; + } + + if (mount(NULL, mountpoint, "debugfs", 0, NULL) < 0) + return NULL; + + /* save the mountpoint */ + debugfs_found = true; + strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint)); +out: + debugfs_set_tracing_events_path(debugfs_mountpoint); + return debugfs_mountpoint; +} + +void debugfs_set_path(const char *mountpoint) +{ + snprintf(debugfs_mountpoint, sizeof(debugfs_mountpoint), "%s", mountpoint); + debugfs_set_tracing_events_path(mountpoint); +} |