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01130e5c9f
https://github.com/mstange/samply is amazing to profile
Electron apps that need visualization of both JS and native
samples in an unified view. However, we cannot use the profiler
once the application is packaged due to restrictions from
entitlements and SIP that will disallow loading the preload library
from samply to exchange the task ports from the launched process.
This changes takes an alternative route inspired by crashpad architecture
where the samply profiler will be bundled as part of the application,
the browser process launches the profiler on demand and performs
mach port exchange via a simple handshake protocol implemented in
950b80e711
Every child process then launched by the browser will send their
task ports via the verified ipc connection the browser process
has created with the samply profiler process.
NB: the --samply-path is for testing purpose, we should remove it
and bundle the samply executable next to chrome_crashpad_handler
when packaging so that evil actors cannot hijack the ipc.
119 lines
3.6 KiB
Plaintext
119 lines
3.6 KiB
Plaintext
// Copyright (c) 2025 Microsoft, Inc.
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// Use of this source code is governed by the MIT license that can be
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// found in the LICENSE file.
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#include "shell/common/mac/samply_profiler_client.h"
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#include <unistd.h>
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#include "base/apple/mach_logging.h"
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#include "base/apple/mach_port_rendezvous.h"
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#include "base/apple/scoped_mach_port.h"
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#include "base/containers/span.h"
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#include "base/logging.h"
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#include "base/numerics/byte_conversions.h"
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#include "shell/common/mac/samply_profiler_types.h"
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namespace electron {
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bool ConnectToSamplyProfiler(mach_port_t profiler_port) {
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if (profiler_port == MACH_PORT_NULL) {
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return false;
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}
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base::apple::ScopedMachReceiveRight reply_port;
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kern_return_t kr = mach_port_allocate(
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mach_task_self(), MACH_PORT_RIGHT_RECEIVE,
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base::apple::ScopedMachReceiveRight::Receiver(reply_port).get());
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if (kr != KERN_SUCCESS) {
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MACH_LOG(WARNING, kr) << "mach_port_allocate for profiler reply";
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return false;
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}
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SamplyMessage msg = {};
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msg.header.msgh_bits =
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MACH_MSGH_BITS_COMPLEX | MACH_MSGH_BITS(MACH_MSG_TYPE_COPY_SEND, 0);
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msg.header.msgh_size = sizeof(SamplyMessage);
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msg.header.msgh_remote_port = profiler_port;
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msg.header.msgh_local_port = MACH_PORT_NULL;
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msg.header.msgh_id = 0;
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msg.body.msgh_descriptor_count = 2;
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msg.reply_port.name = reply_port.get();
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msg.reply_port.disposition = MACH_MSG_TYPE_MAKE_SEND;
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msg.reply_port.type = MACH_MSG_PORT_DESCRIPTOR;
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msg.task_port.name = mach_task_self();
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msg.task_port.disposition = MACH_MSG_TYPE_COPY_SEND;
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msg.task_port.type = MACH_MSG_PORT_DESCRIPTOR;
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msg.magic = kSamplyMagic;
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msg.pid = static_cast<uint32_t>(getpid());
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kr = mach_msg(&msg.header, MACH_SEND_MSG, sizeof(SamplyMessage), 0,
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MACH_PORT_NULL, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
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if (kr != KERN_SUCCESS) {
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MACH_LOG(WARNING, kr) << "mach_msg send to samply profiler";
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return false;
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}
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SamplyReplyBuffer reply = {};
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reply.header.msgh_size = sizeof(SamplyReplyBuffer);
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reply.header.msgh_local_port = reply_port.get();
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kr = mach_msg(&reply.header, MACH_RCV_MSG | MACH_RCV_TIMEOUT, 0,
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sizeof(SamplyReplyBuffer), reply_port.get(), 5000,
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MACH_PORT_NULL);
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if (kr != KERN_SUCCESS) {
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MACH_LOG(WARNING, kr) << "mach_msg receive from samply profiler";
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return false;
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}
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if (reply.header.msgh_size < kSamplyReplyMinSize) {
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LOG(ERROR) << "Samply profiler: reply too small, size="
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<< reply.header.msgh_size
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<< " expected >= " << kSamplyReplyMinSize;
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return false;
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}
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// Read magic and status from bytes[] at known offsets.
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uint32_t magic = base::U32FromNativeEndian(
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base::span(reply.bytes)
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.subspan<kSamplyReplyMagicOffset, sizeof(uint32_t)>());
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uint32_t status = base::U32FromNativeEndian(
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base::span(reply.bytes)
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.subspan<kSamplyReplyStatusOffset, sizeof(uint32_t)>());
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if (magic != kSamplyMagic) {
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LOG(ERROR) << "Samply profiler: invalid reply magic";
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return false;
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}
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if (status != 0) {
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LOG(ERROR) << "Samply profiler: error status " << status;
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return false;
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}
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return true;
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}
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void MaybeConnectToSamplyProfiler() {
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auto* client = base::MachPortRendezvousClient::GetInstance();
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if (!client) {
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// Not available (e.g., no rendezvous server or running standalone)
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return;
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}
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auto profiler_port = client->TakeSendRight(kMachPortKeyProfiler);
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if (!profiler_port.is_valid()) {
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return;
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}
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if (ConnectToSamplyProfiler(profiler_port.get())) {
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VLOG(1) << "Connected to samply profiler (child process)";
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}
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}
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} // namespace electron
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