From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Thu, 10 Feb 2022 20:41:58 +0000 (-0500)
Subject: uprobe: implement counter support
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=cc347c39cd5074fe15c54ff8c3d75817f07a1350;p=lttng-modules.git

uprobe: implement counter support

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I46909ecc57a15d5f0c6b58e1f2f254219e55e01d
---

diff --git a/src/probes/lttng-uprobes.c b/src/probes/lttng-uprobes.c
index 5463251a..bf4305f3 100644
--- a/src/probes/lttng-uprobes.c
+++ b/src/probes/lttng-uprobes.c
@@ -22,6 +22,7 @@
 #include <lttng/events-internal.h>
 #include <lttng/tracer.h>
 #include <wrapper/irqflags.h>
+#include <wrapper/rcu.h>
 #include <ringbuffer/frontend_types.h>
 #include <wrapper/vmalloc.h>
 
@@ -31,6 +32,7 @@ int lttng_uprobes_event_handler_pre(struct uprobe_consumer *uc, struct pt_regs *
 	struct lttng_uprobe_handler *uprobe_handler =
 		container_of(uc, struct lttng_uprobe_handler, up_consumer);
 	struct lttng_kernel_event_common *event = uprobe_handler->event;
+	struct lttng_kernel_channel_common *chan_common;
 	struct lttng_kernel_probe_ctx lttng_probe_ctx = {
 		.event = event,
 		.interruptible = !lttng_regs_irqs_disabled(regs),
@@ -39,28 +41,37 @@ int lttng_uprobes_event_handler_pre(struct uprobe_consumer *uc, struct pt_regs *
 		unsigned long ip;
 	} payload;
 
-	switch (event->type) {
-	case LTTNG_KERNEL_EVENT_TYPE_RECORDER:
-	{
-		struct lttng_kernel_event_recorder *event_recorder =
-			container_of(event, struct lttng_kernel_event_recorder, parent);
-		struct lttng_kernel_channel_buffer *chan = event_recorder->chan;
-
-		if (unlikely(!LTTNG_READ_ONCE(chan->parent.session->active)))
-			return 0;
-		if (unlikely(!LTTNG_READ_ONCE(chan->parent.enabled)))
-			return 0;
-		break;
-	}
-	case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER:
-		break;
-	default:
-		WARN_ON_ONCE(1);
-	}
-
 	if (unlikely(!LTTNG_READ_ONCE(event->enabled)))
-		return 0;
+		goto end;
 
+	chan_common = lttng_kernel_get_chan_common_from_event_common(event);
+	if (chan_common) {
+		struct lttng_kernel_session *session = chan_common->session;
+		struct lttng_kernel_id_tracker_rcu *lf;
+
+		if (unlikely(!LTTNG_READ_ONCE(session->active)))
+			goto end;
+		if (unlikely(!LTTNG_READ_ONCE(chan_common->enabled)))
+			goto end;
+		lf = lttng_rcu_dereference(session->pid_tracker.p);
+		if (lf && likely(!lttng_id_tracker_lookup(lf, current->tgid)))
+			goto end;
+		lf = lttng_rcu_dereference(session->vpid_tracker.p);
+		if (lf && likely(!lttng_id_tracker_lookup(lf, task_tgid_vnr(current))))
+			goto end;
+		lf = lttng_rcu_dereference(session->uid_tracker.p);
+		if (lf && likely(!lttng_id_tracker_lookup(lf, from_kuid_munged(&init_user_ns, current_uid()))))
+			goto end;
+		lf = lttng_rcu_dereference(session->vuid_tracker.p);
+		if (lf && likely(!lttng_id_tracker_lookup(lf, from_kuid_munged(current_user_ns(), current_uid()))))
+			goto end;
+		lf = lttng_rcu_dereference(session->gid_tracker.p);
+		if (lf && likely(!lttng_id_tracker_lookup(lf, from_kgid_munged(&init_user_ns, current_gid()))))
+			goto end;
+		lf = lttng_rcu_dereference(session->vgid_tracker.p);
+		if (lf && likely(!lttng_id_tracker_lookup(lf, from_kgid_munged(current_user_ns(), current_gid()))))
+			goto end;
+	}
 	switch (event->type) {
 	case LTTNG_KERNEL_EVENT_TYPE_RECORDER:
 	{
@@ -94,9 +105,21 @@ int lttng_uprobes_event_handler_pre(struct uprobe_consumer *uc, struct pt_regs *
 		event_notifier->notification_send(event_notifier, NULL, NULL, &notif_ctx);
 		break;
 	}
+	case LTTNG_KERNEL_EVENT_TYPE_COUNTER:
+	{
+		struct lttng_kernel_event_counter *event_counter =
+			container_of(event, struct lttng_kernel_event_counter, parent);
+
+		/* uprobes is invoked with preemption enabled. */
+		rcu_read_lock_sched_notrace();
+		(void) event_counter->chan->ops->event_counter_add(event_counter, 1);
+		rcu_read_unlock_sched_notrace();
+		break;
+	}
 	default:
 		WARN_ON_ONCE(1);
 	}
+end:
 	return 0;
 }