1 files changed, 217 insertions, 0 deletions

diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
new file mode 100644
index 000000000000..dd1f43588d70
--- /dev/null
+++ b/kernel/trace/trace_dynevent.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic dynamic event control interface
+ *
+ * Copyright (C) 2018 Masami Hiramatsu <mhiramat@kernel.org>
+ */
+
+#include <linux/debugfs.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/mm.h>
+#include <linux/mutex.h>
+#include <linux/tracefs.h>
+
+#include "trace.h"
+#include "trace_dynevent.h"
+
+static DEFINE_MUTEX(dyn_event_ops_mutex);
+static LIST_HEAD(dyn_event_ops_list);
+
+int dyn_event_register(struct dyn_event_operations *ops)
+{
+        if (!ops || !ops->create || !ops->show || !ops->is_busy ||
+            !ops->free || !ops->match)
+                return -EINVAL;
+
+        INIT_LIST_HEAD(&ops->list);
+        mutex_lock(&dyn_event_ops_mutex);
+        list_add_tail(&ops->list, &dyn_event_ops_list);
+        mutex_unlock(&dyn_event_ops_mutex);
+        return 0;
+}
+
+int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type)
+{
+        struct dyn_event *pos, *n;
+        char *system = NULL, *event, *p;
+        int ret = -ENOENT;
+
+        if (argv[0][0] == '-') {
+                if (argv[0][1] != ':')
+                        return -EINVAL;
+                event = &argv[0][2];
+        } else {
+                event = strchr(argv[0], ':');
+                if (!event)
+                        return -EINVAL;
+                event++;
+        }
+
+        p = strchr(event, '/');
+        if (p) {
+                system = event;
+                event = p + 1;
+                *p = '\0';
+        }
+        if (event[0] == '\0')
+                return -EINVAL;
+
+        mutex_lock(&event_mutex);
+        for_each_dyn_event_safe(pos, n) {
+                if (type && type != pos->ops)
+                        continue;
+                if (pos->ops->match(system, event, pos)) {
+                        ret = pos->ops->free(pos);
+                        break;
+                }
+        }
+        mutex_unlock(&event_mutex);
+
+        return ret;
+}
+
+static int create_dyn_event(int argc, char **argv)
+{
+        struct dyn_event_operations *ops;
+        int ret;
+
+        if (argv[0][0] == '-' || argv[0][0] == '!')
+                return dyn_event_release(argc, argv, NULL);
+
+        mutex_lock(&dyn_event_ops_mutex);
+        list_for_each_entry(ops, &dyn_event_ops_list, list) {
+                ret = ops->create(argc, (const char **)argv);
+                if (!ret || ret != -ECANCELED)
+                        break;
+        }
+        mutex_unlock(&dyn_event_ops_mutex);
+        if (ret == -ECANCELED)
+                ret = -EINVAL;
+
+        return ret;
+}
+
+/* Protected by event_mutex */
+LIST_HEAD(dyn_event_list);
+
+void *dyn_event_seq_start(struct seq_file *m, loff_t *pos)
+{
+        mutex_lock(&event_mutex);
+        return seq_list_start(&dyn_event_list, *pos);
+}
+
+void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+        return seq_list_next(v, &dyn_event_list, pos);
+}
+
+void dyn_event_seq_stop(struct seq_file *m, void *v)
+{
+        mutex_unlock(&event_mutex);
+}
+
+static int dyn_event_seq_show(struct seq_file *m, void *v)
+{
+        struct dyn_event *ev = v;
+
+        if (ev && ev->ops)
+                return ev->ops->show(m, ev);
+
+        return 0;
+}
+
+static const struct seq_operations dyn_event_seq_op = {
+        .start  = dyn_event_seq_start,
+        .next   = dyn_event_seq_next,
+        .stop   = dyn_event_seq_stop,
+        .show   = dyn_event_seq_show
+};
+
+/*
+ * dyn_events_release_all - Release all specific events
+ * @type:       the dyn_event_operations * which filters releasing events
+ *
+ * This releases all events which ->ops matches @type. If @type is NULL,
+ * all events are released.
+ * Return -EBUSY if any of them are in use, and return other errors when
+ * it failed to free the given event. Except for -EBUSY, event releasing
+ * process will be aborted at that point and there may be some other
+ * releasable events on the list.
+ */
+int dyn_events_release_all(struct dyn_event_operations *type)
+{
+        struct dyn_event *ev, *tmp;
+        int ret = 0;
+
+        mutex_lock(&event_mutex);
+        for_each_dyn_event(ev) {
+                if (type && ev->ops != type)
+                        continue;
+                if (ev->ops->is_busy(ev)) {
+                        ret = -EBUSY;
+                        goto out;
+                }
+        }
+        for_each_dyn_event_safe(ev, tmp) {
+                if (type && ev->ops != type)
+                        continue;
+                ret = ev->ops->free(ev);
+                if (ret)
+                        break;
+        }
+out:
+        mutex_unlock(&event_mutex);
+
+        return ret;
+}
+
+static int dyn_event_open(struct inode *inode, struct file *file)
+{
+        int ret;
+
+        if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
+                ret = dyn_events_release_all(NULL);
+                if (ret < 0)
+                        return ret;
+        }
+
+        return seq_open(file, &dyn_event_seq_op);
+}
+
+static ssize_t dyn_event_write(struct file *file, const char __user *buffer,
+                                size_t count, loff_t *ppos)
+{
+        return trace_parse_run_command(file, buffer, count, ppos,
+                                       create_dyn_event);
+}
+
+static const struct file_operations dynamic_events_ops = {
+        .owner          = THIS_MODULE,
+        .open           = dyn_event_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = seq_release,
+        .write          = dyn_event_write,
+};
+
+/* Make a tracefs interface for controlling dynamic events */
+static __init int init_dynamic_event(void)
+{
+        struct dentry *d_tracer;
+        struct dentry *entry;
+
+        d_tracer = tracing_init_dentry();
+        if (IS_ERR(d_tracer))
+                return 0;
+
+        entry = tracefs_create_file("dynamic_events", 0644, d_tracer,
+                                    NULL, &dynamic_events_ops);
+
+        /* Event list interface */
+        if (!entry)
+                pr_warn("Could not create tracefs 'dynamic_events' entry\n");
+
+        return 0;
+}
+fs_initcall(init_dynamic_event);