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-rw-r--r--kernel/tools/lib/api/fs/debugfs.c118
1 files changed, 118 insertions, 0 deletions
diff --git a/kernel/tools/lib/api/fs/debugfs.c b/kernel/tools/lib/api/fs/debugfs.c
new file mode 100644
index 000000000..8305b3e9d
--- /dev/null
+++ b/kernel/tools/lib/api/fs/debugfs.c
@@ -0,0 +1,118 @@
+#define _GNU_SOURCE
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <sys/vfs.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mount.h>
+#include <linux/kernel.h>
+
+#include "debugfs.h"
+
+#ifndef DEBUGFS_DEFAULT_PATH
+#define DEBUGFS_DEFAULT_PATH "/sys/kernel/debug"
+#endif
+
+char debugfs_mountpoint[PATH_MAX + 1] = DEBUGFS_DEFAULT_PATH;
+
+static const char * const debugfs_known_mountpoints[] = {
+ DEBUGFS_DEFAULT_PATH,
+ "/debug",
+ 0,
+};
+
+static bool debugfs_found;
+
+bool debugfs_configured(void)
+{
+ return debugfs_find_mountpoint() != NULL;
+}
+
+/* find the path to the mounted debugfs */
+const char *debugfs_find_mountpoint(void)
+{
+ const char *ret;
+
+ if (debugfs_found)
+ return (const char *)debugfs_mountpoint;
+
+ ret = find_mountpoint("debugfs", (long) DEBUGFS_MAGIC,
+ debugfs_mountpoint, PATH_MAX + 1,
+ debugfs_known_mountpoints);
+ if (ret)
+ debugfs_found = true;
+
+ return ret;
+}
+
+/* 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 = DEBUGFS_DEFAULT_PATH;
+ }
+
+ if (mount(NULL, mountpoint, "debugfs", 0, NULL) < 0)
+ return NULL;
+
+ /* save the mountpoint */
+ debugfs_found = true;
+ strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_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);
+}