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/*
* Copyright (C) 2024 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "src/trace_redaction/redact_sched_switch.h"
#include "src/trace_redaction/proto_util.h"
#include "protos/perfetto/trace/ftrace/ftrace_event.pbzero.h"
#include "protos/perfetto/trace/ftrace/ftrace_event_bundle.pbzero.h"
#include "protos/perfetto/trace/ftrace/sched.pbzero.h"
namespace perfetto::trace_redaction {
// Redact sched switch trace events in an ftrace event bundle:
//
// event {
// timestamp: 6702093744772646
// pid: 0
// sched_switch {
// prev_comm: "swapper/0"
// prev_pid: 0
// prev_prio: 120
// prev_state: 0
// next_comm: "writer"
// next_pid: 23020
// next_prio: 96
// }
// }
//
// In the above message, it should be noted that "event.pid" will always be
// equal to "event.sched_switch.prev_pid".
//
// "ftrace_event_bundle_message" is the ftrace event bundle (contains a
// collection of ftrace event messages) because data in a sched_switch message
// is needed in order to know if the event should be added to the bundle.
RedactSchedSwitch::RedactSchedSwitch()
: FtraceEventRedaction(
protos::pbzero::FtraceEvent::kSchedSwitchFieldNumber) {}
base::Status RedactSchedSwitch::Redact(
const Context& context,
const protos::pbzero::FtraceEvent::Decoder& event,
protozero::ConstBytes bytes,
protos::pbzero::FtraceEvent* event_message) const {
if (!context.package_uid.has_value()) {
return base::ErrStatus("RedactSchedSwitch: missing package uid");
}
if (!context.timeline) {
return base::ErrStatus("RedactSchedSwitch: missing timeline");
}
protos::pbzero::SchedSwitchFtraceEvent::Decoder sched_switch(bytes);
// There must be a prev pid and a next pid. Otherwise, the event is invalid.
// Dropping the event is the safest option.
if (!sched_switch.has_prev_pid() || !sched_switch.has_next_pid()) {
return base::OkStatus();
}
// Avoid making the message until we know that we have prev and next pids.
auto sched_switch_message = event_message->set_sched_switch();
auto prev_slice =
context.timeline->Search(event.timestamp(), sched_switch.prev_pid());
auto next_slice =
context.timeline->Search(event.timestamp(), sched_switch.next_pid());
// To read the fields, move the read head back to the start.
sched_switch.Reset();
for (auto field = sched_switch.ReadField(); field.valid();
field = sched_switch.ReadField()) {
switch (field.id()) {
case protos::pbzero::SchedSwitchFtraceEvent::kNextCommFieldNumber:
if (next_slice.uid == context.package_uid) {
sched_switch_message->set_next_comm(field.as_string());
} else {
sched_switch_message->set_next_comm("");
}
break;
case protos::pbzero::SchedSwitchFtraceEvent::kPrevCommFieldNumber:
if (prev_slice.uid == context.package_uid) {
sched_switch_message->set_prev_comm(field.as_string());
} else {
sched_switch_message->set_prev_comm("");
}
break;
default:
proto_util::AppendField(field, sched_switch_message);
break;
}
}
return base::OkStatus();
}
} // namespace perfetto::trace_redaction
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