Adds bit perf_event_attr::remove_on_exec, to support removing an event
from a task on exec.
This option supports the case where an event is supposed to be
process-wide only, and should not propagate beyond exec, to limit
monitoring to the original process image only.
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
---
v2:
* Add patch to series.
---
include/uapi/linux/perf_event.h | 3 ++-
kernel/events/core.c | 45 +++++++++++++++++++++++++++++++++
2 files changed, 47 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 813efb65fea8..8c5b9f5ad63f 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -390,7 +390,8 @@ struct perf_event_attr {
text_poke : 1, /* include text poke events */
build_id : 1, /* use build id in mmap2 events */
inherit_thread : 1, /* children only inherit if cloned with CLONE_THREAD */
- __reserved_1 : 28;
+ remove_on_exec : 1, /* event is removed from task on exec */
+ __reserved_1 : 27;
union {
__u32 wakeup_events; /* wakeup every n events */
diff --git a/kernel/events/core.c b/kernel/events/core.c
index a8382e6c907c..bc9e6e35e414 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4195,6 +4195,46 @@ static void perf_event_enable_on_exec(int ctxn)
put_ctx(clone_ctx);
}
+static void perf_remove_from_owner(struct perf_event *event);
+static void perf_event_exit_event(struct perf_event *child_event,
+ struct perf_event_context *child_ctx,
+ struct task_struct *child);
+
+/*
+ * Removes all events from the current task that have been marked
+ * remove-on-exec, and feeds their values back to parent events.
+ */
+static void perf_event_remove_on_exec(void)
+{
+ int ctxn;
+
+ for_each_task_context_nr(ctxn) {
+ struct perf_event_context *ctx;
+ struct perf_event *event, *next;
+
+ ctx = perf_pin_task_context(current, ctxn);
+ if (!ctx)
+ continue;
+ mutex_lock(&ctx->mutex);
+
+ list_for_each_entry_safe(event, next, &ctx->event_list, event_entry) {
+ if (!event->attr.remove_on_exec)
+ continue;
+
+ if (!is_kernel_event(event))
+ perf_remove_from_owner(event);
+ perf_remove_from_context(event, DETACH_GROUP);
+ /*
+ * Remove the event and feed back its values to the
+ * parent event.
+ */
+ perf_event_exit_event(event, ctx, current);
+ }
+ mutex_unlock(&ctx->mutex);
+ put_ctx(ctx);
+ }
+}
+
struct perf_read_data {
struct perf_event *event;
bool group;
@@ -7519,6 +7559,8 @@ void perf_event_exec(void)
true);
}
rcu_read_unlock();
+
+ perf_event_remove_on_exec();
}
struct remote_output {
@@ -11600,6 +11642,9 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
if (!attr->inherit && attr->inherit_thread)
return -EINVAL;
+ if (attr->remove_on_exec && attr->enable_on_exec)
+ return -EINVAL;
+
out:
return ret;
--
2.30.1.766.gb4fecdf3b7-goog
