2 files changed, 80 insertions, 1 deletions

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index df9d964c15fc..fa151d49a2ee 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -744,6 +744,12 @@ extern int hw_perf_group_sched_in(struct perf_event *group_leader,
                struct perf_cpu_context *cpuctx,
                struct perf_event_context *ctx, int cpu);
 extern void perf_event_update_userpage(struct perf_event *event);
+extern int perf_event_release_kernel(struct perf_event *event);
+extern struct perf_event *
+perf_event_create_kernel_counter(struct perf_event_attr *attr,
+                                int cpu,
+                                pid_t pid);
+extern u64 perf_event_read_value(struct perf_event *event);
 
 struct perf_sample_data {
         u64                             type;
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 12b5ec39bf97..02d4ff041b01 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -1725,6 +1725,26 @@ static int perf_release(struct inode *inode, struct file *file)
         return 0;
 }
 
+int perf_event_release_kernel(struct perf_event *event)
+{
+        struct perf_event_context *ctx = event->ctx;
+
+        WARN_ON_ONCE(ctx->parent_ctx);
+        mutex_lock(&ctx->mutex);
+        perf_event_remove_from_context(event);
+        mutex_unlock(&ctx->mutex);
+
+        mutex_lock(&event->owner->perf_event_mutex);
+        list_del_init(&event->owner_entry);
+        mutex_unlock(&event->owner->perf_event_mutex);
+        put_task_struct(event->owner);
+
+        free_event(event);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(perf_event_release_kernel);
+
 static int perf_event_read_size(struct perf_event *event)
 {
         int entry = sizeof(u64); /* value */
@@ -1750,7 +1770,7 @@ static int perf_event_read_size(struct perf_event *event)
         return size;
 }
 
-static u64 perf_event_read_value(struct perf_event *event)
+u64 perf_event_read_value(struct perf_event *event)
 {
         struct perf_event *child;
         u64 total = 0;
@@ -1761,6 +1781,7 @@ static u64 perf_event_read_value(struct perf_event *event)
 
         return total;
 }
+EXPORT_SYMBOL_GPL(perf_event_read_value);
 
 static int perf_event_read_entry(struct perf_event *event,
                                    u64 read_format, char __user *buf)
@@ -4638,6 +4659,58 @@ err_put_context:
         return err;
 }
 
+/**
+ * perf_event_create_kernel_counter
+ *
+ * @attr: attributes of the counter to create
+ * @cpu: cpu in which the counter is bound
+ * @pid: task to profile
+ */
+struct perf_event *
+perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
+                                 pid_t pid)
+{
+        struct perf_event *event;
+        struct perf_event_context *ctx;
+        int err;
+
+        /*
+         * Get the target context (task or percpu):
+         */
+
+        ctx = find_get_context(pid, cpu);
+        if (IS_ERR(ctx))
+                return NULL ;
+
+        event = perf_event_alloc(attr, cpu, ctx, NULL,
+                                     NULL, GFP_KERNEL);
+        err = PTR_ERR(event);
+        if (IS_ERR(event))
+                goto err_put_context;
+
+        event->filp = NULL;
+        WARN_ON_ONCE(ctx->parent_ctx);
+        mutex_lock(&ctx->mutex);
+        perf_install_in_context(ctx, event, cpu);
+        ++ctx->generation;
+        mutex_unlock(&ctx->mutex);
+
+        event->owner = current;
+        get_task_struct(current);
+        mutex_lock(&current->perf_event_mutex);
+        list_add_tail(&event->owner_entry, &current->perf_event_list);
+        mutex_unlock(&current->perf_event_mutex);
+
+        return event;
+
+err_put_context:
+        if (err < 0)
+                put_ctx(ctx);
+
+        return NULL;
+}
+EXPORT_SYMBOL_GPL(perf_event_create_kernel_counter);
+
 /*
  * inherit a event from parent task to child task:
  */