5693c92660
It's rather strange to be checking the debugfs MAGIC number for the tracing directory. A system admin may want to have a custom set of events to trace and it should be allowed to let the admin make a temp file (even for tracing virtual boxes, this is useful). Also with the coming tracefs, the files may not even be under debugfs, so checking the debugfs MAGIC number is pointless. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Jiri Olsa <jolsa@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Link: http://lkml.kernel.org/r/20150202193552.546175764@goodmis.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
144 lines
3.2 KiB
C
144 lines
3.2 KiB
C
#define _GNU_SOURCE
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdbool.h>
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#include <sys/vfs.h>
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#include <sys/mount.h>
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#include <linux/kernel.h>
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#include "debugfs.h"
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char debugfs_mountpoint[PATH_MAX + 1] = "/sys/kernel/debug";
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static const char * const debugfs_known_mountpoints[] = {
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"/sys/kernel/debug",
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"/debug",
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0,
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};
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static bool debugfs_found;
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/* verify that a mountpoint is actually a debugfs instance */
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static int debugfs_valid_mountpoint(const char *debugfs)
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{
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struct statfs st_fs;
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if (statfs(debugfs, &st_fs) < 0)
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return -ENOENT;
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else if ((long)st_fs.f_type != (long)DEBUGFS_MAGIC)
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return -ENOENT;
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return 0;
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}
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/* find the path to the mounted debugfs */
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const char *debugfs_find_mountpoint(void)
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{
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const char * const *ptr;
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char type[100];
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FILE *fp;
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if (debugfs_found)
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return (const char *)debugfs_mountpoint;
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ptr = debugfs_known_mountpoints;
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while (*ptr) {
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if (debugfs_valid_mountpoint(*ptr) == 0) {
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debugfs_found = true;
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strcpy(debugfs_mountpoint, *ptr);
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return debugfs_mountpoint;
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}
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ptr++;
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}
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/* give up and parse /proc/mounts */
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fp = fopen("/proc/mounts", "r");
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if (fp == NULL)
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return NULL;
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while (fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
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debugfs_mountpoint, type) == 2) {
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if (strcmp(type, "debugfs") == 0)
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break;
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}
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fclose(fp);
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if (strcmp(type, "debugfs") != 0)
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return NULL;
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debugfs_found = true;
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return debugfs_mountpoint;
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}
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/* mount the debugfs somewhere if it's not mounted */
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char *debugfs_mount(const char *mountpoint)
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{
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/* see if it's already mounted */
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if (debugfs_find_mountpoint())
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goto out;
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/* if not mounted and no argument */
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if (mountpoint == NULL) {
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/* see if environment variable set */
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mountpoint = getenv(PERF_DEBUGFS_ENVIRONMENT);
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/* if no environment variable, use default */
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if (mountpoint == NULL)
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mountpoint = "/sys/kernel/debug";
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}
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if (mount(NULL, mountpoint, "debugfs", 0, NULL) < 0)
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return NULL;
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/* save the mountpoint */
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debugfs_found = true;
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strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint));
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out:
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return debugfs_mountpoint;
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}
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int debugfs__strerror_open(int err, char *buf, size_t size, const char *filename)
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{
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char sbuf[128];
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switch (err) {
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case ENOENT:
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if (debugfs_found) {
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snprintf(buf, size,
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"Error:\tFile %s/%s not found.\n"
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"Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n",
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debugfs_mountpoint, filename);
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break;
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}
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snprintf(buf, size, "%s",
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"Error:\tUnable to find debugfs\n"
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"Hint:\tWas your kernel compiled with debugfs support?\n"
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"Hint:\tIs the debugfs filesystem mounted?\n"
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"Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
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break;
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case EACCES:
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snprintf(buf, size,
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"Error:\tNo permissions to read %s/%s\n"
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"Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
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debugfs_mountpoint, filename, debugfs_mountpoint);
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break;
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default:
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snprintf(buf, size, "%s", strerror_r(err, sbuf, sizeof(sbuf)));
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break;
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}
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return 0;
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}
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int debugfs__strerror_open_tp(int err, char *buf, size_t size, const char *sys, const char *name)
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{
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char path[PATH_MAX];
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snprintf(path, PATH_MAX, "tracing/events/%s/%s", sys, name ?: "*");
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return debugfs__strerror_open(err, buf, size, path);
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}
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