tools/lib/api/fs/tracing_path.c

   1 #ifndef _GNU_SOURCE
   2 # define _GNU_SOURCE
   3 #endif
   4
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <linux/string.h>
   9 #include <errno.h>
  10 #include <unistd.h>
  11 #include "fs.h"
  12
  13 #include "tracing_path.h"
  14
  15
  16 char tracing_mnt[PATH_MAX]         = "/sys/kernel/debug";
  17 char tracing_path[PATH_MAX]        = "/sys/kernel/debug/tracing";
  18 char tracing_events_path[PATH_MAX] = "/sys/kernel/debug/tracing/events";
  19
  20
  21 static void __tracing_path_set(const char *tracing, const char *mountpoint)
  22 {
  23         snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint);
  24         snprintf(tracing_path, sizeof(tracing_path), "%s/%s",
  25                  mountpoint, tracing);
  26         snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
  27                  mountpoint, tracing, "events");
  28 }
  29
  30 static const char *tracing_path_tracefs_mount(void)
  31 {
  32         const char *mnt;
  33
  34         mnt = tracefs__mount();
  35         if (!mnt)
  36                 return NULL;
  37
  38         __tracing_path_set("", mnt);
  39
  40         return mnt;
  41 }
  42
  43 static const char *tracing_path_debugfs_mount(void)
  44 {
  45         const char *mnt;
  46
  47         mnt = debugfs__mount();
  48         if (!mnt)
  49                 return NULL;
  50
  51         __tracing_path_set("tracing/", mnt);
  52
  53         return mnt;
  54 }
  55
  56 const char *tracing_path_mount(void)
  57 {
  58         const char *mnt;
  59
  60         mnt = tracing_path_tracefs_mount();
  61         if (mnt)
  62                 return mnt;
  63
  64         mnt = tracing_path_debugfs_mount();
  65
  66         return mnt;
  67 }
  68
  69 void tracing_path_set(const char *mntpt)
  70 {
  71         __tracing_path_set("tracing/", mntpt);
  72 }
  73
  74 char *get_tracing_file(const char *name)
  75 {
  76         char *file;
  77
  78         if (asprintf(&file, "%s/%s", tracing_path, name) < 0)
  79                 return NULL;
  80
  81         return file;
  82 }
  83
  84 void put_tracing_file(char *file)
  85 {
  86         free(file);
  87 }
  88
  89 int tracing_path__strerror_open_tp(int err, char *buf, size_t size,
  90                                    const char *sys, const char *name)
  91 {
  92         char sbuf[128];
  93         char filename[PATH_MAX];
  94
  95         snprintf(filename, PATH_MAX, "%s/%s", sys, name ?: "*");
  96
  97         switch (err) {
  98         case ENOENT:
  99                 /*
 100                  * We will get here if we can't find the tracepoint, but one of
 101                  * debugfs or tracefs is configured, which means you probably
 102                  * want some tracepoint which wasn't compiled in your kernel.
 103                  * - jirka
 104                  */
 105                 if (debugfs__configured() || tracefs__configured()) {
 106                         /* sdt markers */
 107                         if (!strncmp(filename, "sdt_", 4)) {
 108                                 snprintf(buf, size,
 109                                         "Error:\tFile %s/%s not found.\n"
 110                                         "Hint:\tSDT event cannot be directly recorded on.\n"
 111                                         "\tPlease first use 'perf probe %s:%s' before recording it.\n",
 112                                         tracing_events_path, filename, sys, name);
 113                         } else {
 114                                 snprintf(buf, size,
 115                                          "Error:\tFile %s/%s not found.\n"
 116                                          "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n",
 117                                          tracing_events_path, filename);
 118                         }
 119                         break;
 120                 }
 121                 snprintf(buf, size, "%s",
 122                          "Error:\tUnable to find debugfs/tracefs\n"
 123                          "Hint:\tWas your kernel compiled with debugfs/tracefs support?\n"
 124                          "Hint:\tIs the debugfs/tracefs filesystem mounted?\n"
 125                          "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
 126                 break;
 127         case EACCES: {
 128                 snprintf(buf, size,
 129                          "Error:\tNo permissions to read %s/%s\n"
 130                          "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
 131                          tracing_events_path, filename, tracing_mnt);
 132         }
 133                 break;
 134         default:
 135                 snprintf(buf, size, "%s", str_error_r(err, sbuf, sizeof(sbuf)));
 136                 break;
 137         }
 138
 139         return 0;
 140 }