1 files changed, 44 insertions, 1 deletions

diff --git a/tools/lib/api/fs/debugfs.c b/tools/lib/api/fs/debugfs.c
index a74fba6d7743..d2b18e887071 100644
--- a/tools/lib/api/fs/debugfs.c
+++ b/tools/lib/api/fs/debugfs.c
@@ -1,3 +1,4 @@
+#define _GNU_SOURCE
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -67,7 +68,7 @@ int debugfs_valid_mountpoint(const char *debugfs)
 
         if (statfs(debugfs, &st_fs) < 0)
                 return -ENOENT;
-        else if (st_fs.f_type != (long) DEBUGFS_MAGIC)
+        else if ((long)st_fs.f_type != (long)DEBUGFS_MAGIC)
                 return -ENOENT;
 
         return 0;
@@ -98,3 +99,45 @@ char *debugfs_mount(const char *mountpoint)
 out:
         return debugfs_mountpoint;
 }
+
+int debugfs__strerror_open(int err, char *buf, size_t size, const char *filename)
+{
+        char sbuf[128];
+
+        switch (err) {
+        case ENOENT:
+                if (debugfs_found) {
+                        snprintf(buf, size,
+                                 "Error:\tFile %s/%s not found.\n"
+                                 "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n",
+                                 debugfs_mountpoint, filename);
+                        break;
+                }
+                snprintf(buf, size, "%s",
+                         "Error:\tUnable to find debugfs\n"
+                         "Hint:\tWas your kernel compiled with debugfs support?\n"
+                         "Hint:\tIs the debugfs filesystem mounted?\n"
+                         "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
+                break;
+        case EACCES:
+                snprintf(buf, size,
+                         "Error:\tNo permissions to read %s/%s\n"
+                         "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
+                         debugfs_mountpoint, filename, debugfs_mountpoint);
+                break;
+        default:
+                snprintf(buf, size, "%s", strerror_r(err, sbuf, sizeof(sbuf)));
+                break;
+        }
+
+        return 0;
+}
+
+int debugfs__strerror_open_tp(int err, char *buf, size_t size, const char *sys, const char *name)
+{
+        char path[PATH_MAX];
+
+        snprintf(path, PATH_MAX, "tracing/events/%s/%s", sys, name ?: "*");
+
+        return debugfs__strerror_open(err, buf, size, path);
+}