03fc414908
This is the first piece of the wasm debugging prototype (besides the changes to
add/remove breakpoints in WasmModuleObject made with
e699f39cae).
This changelist adds the infrastructure for a GDB-remote stub that will be used
to manage debugging sessions via the gdb-remote protocol.
It enables the creation and termination of debugging sessions over TCP
connections that are managed in a separate thread.
The logic to actually send, receive and decode GDB-remote packets will be part
of a future changelist.
Build with: v8_enable_wasm_gdb_remote_debugging = true
Run with:
--wasm-gdb-remote Enables Wasm debugging with LLDB
(default: false)
--wasm-gdb-remote-port TCP port to be used for debugging
(default: 8765)
--wasm-pause-waiting-for-debugger Pauses the execution of Wasm code waiting
for a debugger (default: false)
--trace-wasm-gdb-remote Enables tracing of Gdb-remote packets
(default: false)
Note that most of this code is "borrowed" from the code of the Chromium NaCL
GDB-remote stub (located in Chromium in src\native_client\src\trusted\debug_stub).
Implementation details:
- class GdbServer acts as a singleton manager for the gdb-remote stub. It is
instantiated as soon as the first Wasm module is loaded in the Wasm engine.
- class GdbServerThread spawns the worker thread for the TCP connection.
- class Transport manages the socket connection, in a portable way.
- class Session represents a remote debugging session.
- class Target represents a debugging target and it’s the place where the
debugging packets will be processed and will implement the logic to debug
a Wasm engine.
Bug: chromium:1010467
Change-Id: Ib2324e5901f5ae1d855b96b99ef0995d407322b6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1923407
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Paolo Severini <paolosev@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#66379}
74 lines
2.3 KiB
Python
74 lines
2.3 KiB
Python
# Copyright 2019 the V8 project authors. All rights reserved.
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# Use of this source code is governed by a BSD-style license that can be
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# found in the LICENSE file.
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import socket
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import subprocess
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import time
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SOCKET_ADDR = ('localhost', 8765)
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def EnsurePortIsAvailable(addr=SOCKET_ADDR):
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# As a sanity check, check that the TCP port is available by binding to it
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# ourselves (and then unbinding). Otherwise, we could end up talking to an
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# old instance of the GDB stub that is still hanging around, or to some
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# unrelated service that uses the same port number. Of course, there is still
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# a race condition because an unrelated process could bind the port after we
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# unbind.
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sock = socket.socket()
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sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, True)
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sock.bind(addr)
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sock.close()
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class GdbRspConnection(object):
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def __init__(self, addr=SOCKET_ADDR):
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self._socket = self._Connect(addr)
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def _Connect(self, addr):
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# We have to poll because we do not know when the GDB stub has successfully
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# done bind() on the TCP port. This is inherently unreliable.
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timeout_in_seconds = 10
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poll_time_in_seconds = 0.1
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for i in xrange(int(timeout_in_seconds / poll_time_in_seconds)):
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# On Mac OS X, we have to create a new socket FD for each retry.
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sock = socket.socket()
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# Do not delay sending small packets. This significantly speeds up debug
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# stub tests.
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sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, True)
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try:
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sock.connect(addr)
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except socket.error:
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# Retry after a delay.
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time.sleep(poll_time_in_seconds)
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else:
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return sock
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raise Exception('Could not connect to the debug stub in %i seconds'
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% timeout_in_seconds)
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def Close(self):
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self._socket.close()
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def PopenDebugStub(command):
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EnsurePortIsAvailable()
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return subprocess.Popen(command)
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def KillProcess(process):
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if process.returncode is not None:
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# kill() won't work if we've already wait()'ed on the process.
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return
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try:
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process.kill()
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except OSError:
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if sys.platform == 'win32':
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# If process is already terminated, kill() throws
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# "WindowsError: [Error 5] Access is denied" on Windows.
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pass
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else:
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raise
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process.wait()
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