labath created this revision.
labath added reviewers: JDevlieghere, DavidSpickett, mgorny.
labath requested review of this revision.
Herald added a project: LLDB.
This adds a new platform class, whose job is to enable running
(debugging) executables under qemu.
(For general information about qemu, I recommend reading the RFC thread
on lldb-dev
https://lists.llvm.org/pipermail/lldb-dev/2021-October/017106.html.)
This initial patch implements the necessary boilerplate as well as the
minimal amount of functionality needed to actually be able to do
something useful (which, in this case means debugging a fully statically
linked executable).
The knobs necessary to emulate dynamically linked programs, as well as
to control other aspects of qemu operation (the emulated cpu, for
instance) will be added in subsequent patches. Same goes for the ability
to automatically bind to the executables of the emulated architecture.
Currently only two settings are available:
- architecture: the architecture that we should emulate
- emulator-path: the path to the emulator
Even though this patch is relatively small, it doesn't lack subtleties
that are worth calling out explicitly:
- named sockets: qemu supports tcp and unix socket connections, both of them in
the "forward connect" mode (qemu listening, lldb connecting). Forward TCP
connections are impossible to realise in a race-free way. This is the reason
why I chose unix sockets as they have larger, more structured names, which can
guarantee that there are no collisions between concurrent connection attempts.
- the above means that this code will not work on windows. I don't think that's
an issue since user mode qemu does not support windows anyway.
- Right now, I am leaving the code enabled for windows, but maybe it would be
better to disable it (otoh, disabling it means windows developers can't check
they don't break it)
- qemu also does not support macOS, so one could contemplate disabling it there
too. However, macOS does support named sockets, so one can even run the (mock)
qemu tests there, and I think it'd be a shame to lose that.
- some things in this patch are called "Qemu" (the plugin folder, for
instance), while others (e.g., the class) have "QemuUser" in their name. I did
this intentionally to make room for a hypothetical system-mode qemu plugin.
However, that may have been premature...
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D114509
Files:
lldb/packages/Python/lldbsuite/test/gdbclientutils.py
lldb/source/Plugins/Platform/CMakeLists.txt
lldb/source/Plugins/Platform/Qemu/CMakeLists.txt
lldb/source/Plugins/Platform/Qemu/PlatformQemuProperties.td
lldb/source/Plugins/Platform/Qemu/PlatformQemuUser.cpp
lldb/source/Plugins/Platform/Qemu/PlatformQemuUser.h
lldb/test/API/qemu/Makefile
lldb/test/API/qemu/TestQemuLaunch.py
lldb/test/API/qemu/main.c
lldb/test/API/qemu/qemu.py
Index: lldb/test/API/qemu/qemu.py
===================================================================
--- /dev/null
+++ lldb/test/API/qemu/qemu.py
@@ -0,0 +1,38 @@
+from textwrap import dedent
+import argparse
+import socket
+import json
+
+import use_lldb_suite
+from lldbsuite.test.gdbclientutils import *
+
+class MyResponder(MockGDBServerResponder):
+ def cont(self):
+ return "W47"
+
+class FakeEmulator(MockGDBServer):
+ def __init__(self, addr):
+ super().__init__(UnixServerSocket(addr))
+ self.responder = MyResponder()
+
+def main():
+ parser = argparse.ArgumentParser(description=dedent("""\
+ Implements a fake qemu for testing purposes. The executable program
+ is not actually run. Instead a very basic mock process is presented
+ to lldb. The emulated program must accept at least one argument.
+ This should be a path where the emulator will dump its state. This
+ allows us to check the invocation parameters.
+ """))
+ parser.add_argument('-g', metavar="unix-socket", required=True)
+ parser.add_argument('program', help="The program to 'emulate'.")
+ parser.add_argument('state_file', help="Where to dump the emulator state.")
+ parsed, rest = parser.parse_known_args()
+ with open(parsed.state_file, "w") as f:
+ json.dump({"program":parsed.program, "rest":rest}, f)
+
+ emulator = FakeEmulator(parsed.g)
+ emulator.run()
+
+if __name__ == "__main__":
+ main()
+
Index: lldb/test/API/qemu/main.c
===================================================================
--- /dev/null
+++ lldb/test/API/qemu/main.c
@@ -0,0 +1 @@
+int main() {}
Index: lldb/test/API/qemu/TestQemuLaunch.py
===================================================================
--- /dev/null
+++ lldb/test/API/qemu/TestQemuLaunch.py
@@ -0,0 +1,68 @@
+from __future__ import print_function
+import lldb
+import unittest
+import os
+import json
+import stat
+import sys
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+from lldbsuite.test.gdbclientutils import *
+
+
+@skipIfRemote
+@skipIfWindows
+class TestQemuLaunch(TestBase):
+
+ mydir = TestBase.compute_mydir(__file__)
+ NO_DEBUG_INFO_TESTCASE = True
+
+ def setUp(self):
+ super().setUp()
+ self.runCmd("settings set platform.plugin.qemu-user.architecture %s" %
+ self.getArchitecture())
+ emulator = self.getBuildArtifact("qemu.py")
+ with os.fdopen(os.open(emulator, os.O_WRONLY|os.O_CREAT, stat.S_IRWXU),
+ "w") as e:
+ e.write("#! %s\n"%sys.executable)
+ e.write("import runpy\n")
+ e.write("import sys\n")
+ e.write("sys.path = %r\n"%sys.path)
+ e.write("runpy.run_path('%s', run_name='__main__')\n"%
+ self.getSourcePath("qemu.py"))
+ self.runCmd(
+ "settings set platform.plugin.qemu-user.emulator-path '%s'"%emulator)
+
+ def test_basic_launch(self):
+ self.build()
+ exe = self.getBuildArtifact()
+
+ error = lldb.SBError()
+ target = self.dbg.CreateTarget(exe, '', 'qemu-user', False, error)
+ self.assertEqual(target.GetPlatform().GetName(), "qemu-user")
+ self.assertSuccess(error)
+ process = target.LaunchSimple(
+ [self.getBuildArtifact("state.log"), "arg2", "arg3"], None, None)
+ self.assertIsNotNone(process)
+ self.assertEqual(process.GetState(), lldb.eStateExited)
+ self.assertEqual(process.GetExitStatus(), 0x47)
+ with open(self.getBuildArtifact("state.log")) as s:
+ state = json.load(s)
+ self.assertEqual(state["program"], self.getBuildArtifact())
+ self.assertEqual(state["rest"], ["arg2", "arg3"])
+
+ def test_bad_emulator_path(self):
+ self.runCmd(
+ "settings set platform.plugin.qemu-user.emulator-path '%s'"%self.getBuildArtifact("nonexistent.file"))
+
+ self.build()
+ exe = self.getBuildArtifact()
+
+ error = lldb.SBError()
+ target = self.dbg.CreateTarget(exe, '', 'qemu-user', False, error)
+ self.assertEqual(target.GetPlatform().GetName(), "qemu-user")
+ self.assertSuccess(error)
+ info = lldb.SBLaunchInfo([])
+ target.Launch(info, error)
+ self.assertTrue(error.Fail())
+ self.assertIn("doesn't exist", error.GetCString())
Index: lldb/test/API/qemu/Makefile
===================================================================
--- /dev/null
+++ lldb/test/API/qemu/Makefile
@@ -0,0 +1,3 @@
+C_SOURCES := main.c
+
+include Makefile.rules
Index: lldb/source/Plugins/Platform/Qemu/PlatformQemuUser.h
===================================================================
--- /dev/null
+++ lldb/source/Plugins/Platform/Qemu/PlatformQemuUser.h
@@ -0,0 +1,57 @@
+//===-- PlatformQemuUser.h ------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "lldb/Host/Host.h"
+#include "lldb/Host/HostInfo.h"
+#include "lldb/Target/Platform.h"
+
+namespace lldb_private {
+
+class PlatformQemuUser : public Platform {
+public:
+ static void Initialize();
+ static void Terminate();
+
+ static llvm::StringRef GetPluginNameStatic() { return "qemu-user"; }
+ static llvm::StringRef GetPluginDescriptionStatic();
+
+ llvm::StringRef GetPluginName() override { return GetPluginNameStatic(); }
+ llvm::StringRef GetDescription() override {
+ return GetPluginDescriptionStatic();
+ }
+
+ UserIDResolver &GetUserIDResolver() override {
+ return HostInfo::GetUserIDResolver();
+ }
+
+ std::vector<ArchSpec> GetSupportedArchitectures() override;
+
+ lldb::ProcessSP DebugProcess(ProcessLaunchInfo &launch_info,
+ Debugger &debugger, Target &target,
+ Status &error) override;
+
+ lldb::ProcessSP Attach(ProcessAttachInfo &attach_info, Debugger &debugger,
+ Target *target, Status &status) override {
+ status.SetErrorString("Not supported");
+ return nullptr;
+ }
+
+ bool IsConnected() const override { return true; }
+
+ void CalculateTrapHandlerSymbolNames() override {}
+
+ Environment GetEnvironment() override { return Host::GetEnvironment(); }
+
+private:
+ static lldb::PlatformSP CreateInstance(bool force, const ArchSpec *arch);
+ static void DebuggerInitialize(Debugger &debugger);
+
+ PlatformQemuUser() : Platform(/*is_host=*/false) {}
+};
+
+} // namespace lldb_private
Index: lldb/source/Plugins/Platform/Qemu/PlatformQemuUser.cpp
===================================================================
--- /dev/null
+++ lldb/source/Plugins/Platform/Qemu/PlatformQemuUser.cpp
@@ -0,0 +1,148 @@
+//===-- PlatformQemuUser.cpp ----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "Plugins/Platform/Qemu/PlatformQemuUser.h"
+#include "Plugins/Process/gdb-remote/ProcessGDBRemote.h"
+#include "lldb/Core/PluginManager.h"
+#include "lldb/Host/FileSystem.h"
+#include "lldb/Host/ProcessLaunchInfo.h"
+#include "lldb/Interpreter/OptionValueProperties.h"
+#include "lldb/Target/Process.h"
+#include "lldb/Target/Target.h"
+#include "lldb/Utility/Listener.h"
+#include "lldb/Utility/Log.h"
+
+using namespace lldb;
+using namespace lldb_private;
+
+LLDB_PLUGIN_DEFINE_ADV(PlatformQemuUser, PlatformQemu)
+
+#define LLDB_PROPERTIES_platformqemuuser
+#include "PlatformQemuProperties.inc"
+
+enum {
+#define LLDB_PROPERTIES_platformqemuuser
+#include "PlatformQemuPropertiesEnum.inc"
+};
+
+class PluginProperties : public Properties {
+public:
+ PluginProperties() {
+ m_collection_sp = std::make_shared<OptionValueProperties>(
+ ConstString(PlatformQemuUser::GetPluginNameStatic()));
+ m_collection_sp->Initialize(g_platformqemuuser_properties);
+ }
+
+ llvm::StringRef GetArchitecture() {
+ return m_collection_sp->GetPropertyAtIndexAsString(
+ nullptr, ePropertyArchitecture, "");
+ }
+
+ FileSpec GetEmulatorPath() {
+ return m_collection_sp->GetPropertyAtIndexAsFileSpec(nullptr,
+ ePropertyEmulatorPath);
+ }
+};
+
+static PluginProperties &GetGlobalProperties() {
+ static PluginProperties g_settings;
+ return g_settings;
+}
+
+llvm::StringRef PlatformQemuUser::GetPluginDescriptionStatic() {
+ return "Platform for debugging binaries under user mode qemu";
+}
+
+void PlatformQemuUser::Initialize() {
+ PluginManager::RegisterPlugin(
+ GetPluginNameStatic(), GetPluginDescriptionStatic(),
+ PlatformQemuUser::CreateInstance, PlatformQemuUser::DebuggerInitialize);
+}
+
+void PlatformQemuUser::Terminate() {
+ PluginManager::UnregisterPlugin(PlatformQemuUser::CreateInstance);
+}
+
+void PlatformQemuUser::DebuggerInitialize(Debugger &debugger) {
+ if (!PluginManager::GetSettingForPlatformPlugin(
+ debugger, ConstString(GetPluginNameStatic()))) {
+ PluginManager::CreateSettingForPlatformPlugin(
+ debugger, GetGlobalProperties().GetValueProperties(),
+ ConstString("Properties for the qemu-user platform plugin."),
+ /*is_global_property=*/true);
+ }
+}
+
+PlatformSP PlatformQemuUser::CreateInstance(bool force, const ArchSpec *arch) {
+ if (force)
+ return PlatformSP(new PlatformQemuUser());
+ return nullptr;
+}
+
+std::vector<ArchSpec> PlatformQemuUser::GetSupportedArchitectures() {
+ llvm::Triple triple = HostInfo::GetArchitecture().GetTriple();
+ triple.setEnvironment(llvm::Triple::UnknownEnvironment);
+ triple.setArchName(GetGlobalProperties().GetArchitecture());
+ if (triple.getArch() != llvm::Triple::UnknownArch)
+ return {ArchSpec(triple)};
+ return {};
+}
+
+static auto get_arg_range(const Args &args) {
+ return llvm::make_range(args.GetArgumentArrayRef().begin(),
+ args.GetArgumentArrayRef().end());
+}
+
+lldb::ProcessSP PlatformQemuUser::DebugProcess(ProcessLaunchInfo &launch_info,
+ Debugger &debugger,
+ Target &target, Status &error) {
+ Log *log = GetLogIfAnyCategoriesSet(LIBLLDB_LOG_PLATFORM);
+
+ std::string qemu = GetGlobalProperties().GetEmulatorPath().GetPath();
+
+ llvm::SmallString<0> socket_model, socket_path;
+ HostInfo::GetProcessTempDir().GetPath(socket_model);
+ llvm::sys::path::append(socket_model, "qemu-%%%%%%%%.socket");
+ do {
+ llvm::sys::fs::createUniquePath(socket_model, socket_path, false);
+ } while (FileSystem::Instance().Exists(socket_path));
+
+ Args args(
+ {qemu, "-g", socket_path, launch_info.GetExecutableFile().GetPath()});
+ for (size_t i = 1; i < launch_info.GetArguments().size(); ++i)
+ args.AppendArgument(launch_info.GetArguments()[i].ref());
+
+ LLDB_LOG(log, "{0} -> {1}", get_arg_range(launch_info.GetArguments()),
+ get_arg_range(args));
+
+ launch_info.SetArguments(args, true);
+ launch_info.SetLaunchInSeparateProcessGroup(true);
+ launch_info.GetFlags().Clear(eLaunchFlagDebug);
+ launch_info.SetMonitorProcessCallback(ProcessLaunchInfo::NoOpMonitorCallback,
+ false);
+
+ error = Host::LaunchProcess(launch_info);
+ if (error.Fail())
+ return nullptr;
+
+ ProcessSP process_sp = target.CreateProcess(
+ launch_info.GetListener(),
+ process_gdb_remote::ProcessGDBRemote::GetPluginNameStatic(), nullptr,
+ true);
+ ListenerSP listener_sp =
+ Listener::MakeListener("lldb.platform_qemu_user.debugprocess");
+ launch_info.SetHijackListener(listener_sp);
+ Process::ProcessEventHijacker hijacker(*process_sp, listener_sp);
+
+ error = process_sp->ConnectRemote(("unix-connect://" + socket_path).str());
+ if (error.Fail())
+ return nullptr;
+
+ process_sp->WaitForProcessToStop(llvm::None, nullptr, false, listener_sp);
+ return process_sp;
+}
Index: lldb/source/Plugins/Platform/Qemu/PlatformQemuProperties.td
===================================================================
--- /dev/null
+++ lldb/source/Plugins/Platform/Qemu/PlatformQemuProperties.td
@@ -0,0 +1,12 @@
+include "../../../../include/lldb/Core/PropertiesBase.td"
+
+let Definition = "platformqemuuser" in {
+ def Architecture: Property<"architecture", "String">,
+ Global,
+ DefaultStringValue<"">,
+ Desc<"Architecture to emulate.">;
+ def EmulatorPath: Property<"emulator-path", "FileSpec">,
+ Global,
+ DefaultStringValue<"">,
+ Desc<"Path to the emulator binary.">;
+}
Index: lldb/source/Plugins/Platform/Qemu/CMakeLists.txt
===================================================================
--- /dev/null
+++ lldb/source/Plugins/Platform/Qemu/CMakeLists.txt
@@ -0,0 +1,20 @@
+lldb_tablegen(PlatformQemuProperties.inc -gen-lldb-property-defs
+ SOURCE PlatformQemuProperties.td
+ TARGET LLDBPluginPlatformQemuPropertiesGen)
+
+lldb_tablegen(PlatformQemuPropertiesEnum.inc -gen-lldb-property-enum-defs
+ SOURCE PlatformQemuProperties.td
+ TARGET LLDBPluginPlatformQemuPropertiesEnumGen)
+
+add_lldb_library(lldbPluginPlatformQemu PLUGIN
+ PlatformQemuUser.cpp
+
+ LINK_LIBS
+ lldbUtility
+ LINK_COMPONENTS
+ Support
+ )
+
+add_dependencies(lldbPluginPlatformQemu
+ LLDBPluginPlatformQemuPropertiesGen
+ LLDBPluginPlatformQemuPropertiesEnumGen)
Index: lldb/source/Plugins/Platform/CMakeLists.txt
===================================================================
--- lldb/source/Plugins/Platform/CMakeLists.txt
+++ lldb/source/Plugins/Platform/CMakeLists.txt
@@ -6,4 +6,5 @@
add_subdirectory(NetBSD)
add_subdirectory(OpenBSD)
add_subdirectory(POSIX)
+add_subdirectory(Qemu)
add_subdirectory(Windows)
Index: lldb/packages/Python/lldbsuite/test/gdbclientutils.py
===================================================================
--- lldb/packages/Python/lldbsuite/test/gdbclientutils.py
+++ lldb/packages/Python/lldbsuite/test/gdbclientutils.py
@@ -339,7 +339,7 @@
pass
-class ServerSocket:
+class ServerChannel:
"""
A wrapper class for TCP or pty-based server.
"""
@@ -366,22 +366,14 @@
"""Send the data to the connected client."""
-class TCPServerSocket(ServerSocket):
- def __init__(self):
- family, type, proto, _, addr = socket.getaddrinfo(
- "localhost", 0, proto=socket.IPPROTO_TCP)[0]
+class ServerSocket(ServerChannel):
+ def __init__(self, family, type, proto, addr):
self._server_socket = socket.socket(family, type, proto)
self._connection = None
self._server_socket.bind(addr)
self._server_socket.listen(1)
- def get_connect_address(self):
- return "[{}]:{}".format(*self._server_socket.getsockname())
-
- def get_connect_url(self):
- return "connect://" + self.get_connect_address()
-
def close_server(self):
self._server_socket.close()
@@ -409,8 +401,30 @@
assert self._connection is not None
return self._connection.sendall(data)
+class TCPServerSocket(ServerSocket):
+ def __init__(self):
+ family, type, proto, _, addr = socket.getaddrinfo(
+ "localhost", 0, proto=socket.IPPROTO_TCP)[0]
+ super().__init__(family, type, proto, addr)
-class PtyServerSocket(ServerSocket):
+ def get_connect_address(self):
+ return "[{}]:{}".format(*self._server_socket.getsockname())
+
+ def get_connect_url(self):
+ return "connect://" + self.get_connect_address()
+
+class UnixServerSocket(ServerSocket):
+ def __init__(self, addr):
+ super().__init__(socket.AF_UNIX, socket.SOCK_STREAM, 0, addr)
+
+ def get_connect_address(self):
+ return self._server_socket.getsockname()
+
+ def get_connect_url(self):
+ return "unix-connect://" + self.get_connect_address()
+
+
+class PtyServerSocket(ServerChannel):
def __init__(self):
import pty
import tty
@@ -486,6 +500,7 @@
try:
self._socket.accept()
except:
+ traceback.print_exc()
return
self._shouldSendAck = True
self._receivedData = ""
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