[Lldb-commits] [lldb] 70b9822 - [lldb] Add an example of interactive scripted process debugging (NFC)
Med Ismail Bennani via lldb-commits
lldb-commits at lists.llvm.org
Mon Mar 6 13:14:36 PST 2023
Author: Med Ismail Bennani
Date: 2023-03-06T13:14:15-08:00
New Revision: 70b9822ef3b0774609c72d380504c9abfa717f81
URL: https://github.com/llvm/llvm-project/commit/70b9822ef3b0774609c72d380504c9abfa717f81
DIFF: https://github.com/llvm/llvm-project/commit/70b9822ef3b0774609c72d380504c9abfa717f81.diff
LOG: [lldb] Add an example of interactive scripted process debugging (NFC)
This patch is a proof of concept that shows how a scripted process could
be used with real process to perform interactive debugging.
In this example, we run a process that spawns 10 threads. Then, we
create a intermediary scripted process who's job will be to wrap the
real process while intercepting it's process events and dispatching them
back either to the real process or to other child scripted processes.
In this example, we have 2 child scripted processes, with even and odd
thread indices. The goal is to be able to do thread filtering and
explore the various interactive debugging approaches, by letting a child
process running when stopping the other process and inspecting it.
Another approach would be to have the child processes execution in-sync
to force running every child process when one of them starts running.
Signed-off-by: Med Ismail Bennani <medismail.bennani at gmail.com>
Added:
lldb/test/API/functionalities/interactive_scripted_process/Makefile
lldb/test/API/functionalities/interactive_scripted_process/interactive_scripted_process.py
lldb/test/API/functionalities/interactive_scripted_process/main.cpp
Modified:
Removed:
################################################################################
diff --git a/lldb/test/API/functionalities/interactive_scripted_process/Makefile b/lldb/test/API/functionalities/interactive_scripted_process/Makefile
new file mode 100644
index 0000000000000..f2bee8980e62e
--- /dev/null
+++ b/lldb/test/API/functionalities/interactive_scripted_process/Makefile
@@ -0,0 +1,6 @@
+CXXFLAGS=--std=c++17 -g
+
+all: main
+
+clean:
+ rm -rf main *.dSYM
diff --git a/lldb/test/API/functionalities/interactive_scripted_process/interactive_scripted_process.py b/lldb/test/API/functionalities/interactive_scripted_process/interactive_scripted_process.py
new file mode 100644
index 0000000000000..7d354ea2780e0
--- /dev/null
+++ b/lldb/test/API/functionalities/interactive_scripted_process/interactive_scripted_process.py
@@ -0,0 +1,349 @@
+# Usage:
+# ./bin/lldb $LLVM/lldb/test/API/functionalities/interactive_scripted_process/main \
+# -o "br set -p 'Break here'" -o "run" \
+# -o "command script import
+# $LLVM/lldb/test/API/functionalities/interactive_scripted_process/interactive_scripted_process.py" \
+# -o "br set -p 'also break here'" -o 'continue'
+
+import os,json,struct,signal
+
+from threading import Thread
+from typing import Any, Dict
+
+import lldb
+from lldb.plugins.scripted_process import ScriptedProcess
+from lldb.plugins.scripted_process import ScriptedThread
+
+class PassthruScriptedProcess(ScriptedProcess):
+ driving_target = None
+ driving_process = None
+
+ def __init__(self, exe_ctx: lldb.SBExecutionContext, args : lldb.SBStructuredData):
+ super().__init__(exe_ctx, args)
+
+ self.driving_target = None
+ self.driving_process = None
+
+ self.driving_target_idx = args.GetValueForKey("driving_target_idx")
+ if (self.driving_target_idx and self.driving_target_idx.IsValid()):
+ if self.driving_target_idx.GetType() == lldb.eStructuredDataTypeInteger:
+ idx = self.driving_target_idx.GetIntegerValue(42)
+ if self.driving_target_idx.GetType() == lldb.eStructuredDataTypeString:
+ idx = int(self.driving_target_idx.GetStringValue(100))
+ self.driving_target = self.target.GetDebugger().GetTargetAtIndex(idx)
+ self.driving_process = self.driving_target.GetProcess()
+ for driving_thread in self.driving_process:
+ structured_data = lldb.SBStructuredData()
+ structured_data.SetFromJSON(json.dumps({
+ "driving_target_idx" : idx,
+ "thread_idx" : driving_thread.GetIndexID()
+ }))
+
+ self.threads[driving_thread.GetThreadID()] = PassthruScriptedThread(self, structured_data)
+
+ for module in self.driving_target.modules:
+ path = module.file.fullpath
+ load_addr = module.GetObjectFileHeaderAddress().GetLoadAddress(self.driving_target)
+ self.loaded_images.append({"path": path, "load_addr": load_addr})
+
+ def get_memory_region_containing_address(self, addr: int) -> lldb.SBMemoryRegionInfo:
+ mem_region = lldb.SBMemoryRegionInfo()
+ error = self.driving_process.GetMemoryRegionInfo(addr, mem_region)
+ if error.Fail():
+ return None
+ return mem_region
+
+ def read_memory_at_address(self, addr: int, size: int, error: lldb.SBError) -> lldb.SBData:
+ data = lldb.SBData()
+ bytes_read = self.driving_process.ReadMemory(addr, size, error)
+
+ if error.Fail():
+ return data
+
+ data.SetDataWithOwnership(error, bytes_read,
+ self.driving_target.GetByteOrder(),
+ self.driving_target.GetAddressByteSize())
+
+ return data
+
+ def write_memory_at_address(self, addr, data, error):
+ return self.driving_process.WriteMemory(addr,
+ bytearray(data.uint8.all()),
+ error)
+
+ def get_loaded_images(self):
+ return self.loaded_images
+
+ def get_process_id(self) -> int:
+ return 42
+
+ def is_alive(self) -> bool:
+ return True
+
+ def get_scripted_thread_plugin(self):
+ return PassthruScriptedThread.__module__ + "." + PassthruScriptedThread.__name__
+
+class MultiplexedScriptedProcess(PassthruScriptedProcess):
+ def __init__(self, exe_ctx: lldb.SBExecutionContext, args : lldb.SBStructuredData):
+ super().__init__(exe_ctx, args)
+ self.multiplexer = None
+ if isinstance(self.driving_process, lldb.SBProcess) and self.driving_process:
+ parity = args.GetValueForKey("parity")
+ #TODO: Change to Walrus operator (:=) with oneline if assignment
+ # Requires python 3.8
+ val = extract_value_from_structured_data(parity, 0)
+ if val is not None:
+ self.parity = val
+
+ # Turn PassThruScriptedThread into MultiplexedScriptedThread
+ for thread in self.threads.values():
+ thread.__class__ = MultiplexedScriptedThread
+
+ def get_process_id(self):
+ return self.parity + 420
+
+ def launch(self):
+ self.first_launch = True
+ return lldb.SBError()
+
+ def resume(self, should_stop):
+ if self.first_launch:
+ self.first_launch = False
+ return super().resume()
+ else:
+ if not self.multiplexer:
+ error = lldb.SBError()
+ error.SetErrorString("Multiplexer is not set.")
+ return error
+ return self.multiplexer.resume(pid=self.get_process_id())
+
+ def get_threads_info(self):
+ if not self.multiplexer:
+ return super().get_threads_info()
+ return self.multiplexer.get_threads_info(pid=self.get_process_id())
+
+ def get_scripted_thread_plugin(self):
+ return MultiplexedScriptedThread.__module__ + "." + MultiplexedScriptedThread.__name__
+
+class PassthruScriptedThread(ScriptedThread):
+ def __init__(self, process, args):
+ super().__init__(process, args)
+ driving_target_idx = args.GetValueForKey("driving_target_idx")
+ thread_idx = args.GetValueForKey("thread_idx")
+
+ #TODO: Change to Walrus operator (:=) with oneline if assignment
+ # Requires python 3.8
+ val = extract_value_from_structured_data(thread_idx, 0)
+ if val is not None:
+ self.idx = val
+
+ self.driving_target = None
+ self.driving_process = None
+ self.driving_thread = None
+
+ #TODO: Change to Walrus operator (:=) with oneline if assignment
+ # Requires python 3.8
+ val = extract_value_from_structured_data(driving_target_idx, 42)
+ if val is not None:
+ self.driving_target = self.target.GetDebugger().GetTargetAtIndex(val)
+ self.driving_process = self.driving_target.GetProcess()
+ self.driving_thread = self.driving_process.GetThreadByIndexID(self.idx)
+
+ if self.driving_thread:
+ self.id = self.driving_thread.GetThreadID()
+
+ def get_thread_id(self) -> int:
+ return self.id
+
+ def get_name(self) -> str:
+ return PassthruScriptedThread.__name__ + ".thread-" + str(self.idx)
+
+ def get_stop_reason(self) -> Dict[str, Any]:
+ stop_reason = { "type": lldb.eStopReasonInvalid, "data": { }}
+
+ if self.driving_thread and self.driving_thread.IsValid() \
+ and self.get_thread_id() == self.driving_thread.GetThreadID():
+ stop_reason["type"] = lldb.eStopReasonNone
+
+ if self.driving_thread.GetStopReason() != lldb.eStopReasonNone:
+ if 'arm64' in self.scripted_process.arch:
+ stop_reason["type"] = lldb.eStopReasonException
+ stop_reason["data"]["desc"] = self.driving_thread.GetStopDescription(100)
+ elif self.scripted_process.arch == 'x86_64':
+ stop_reason["type"] = lldb.eStopReasonSignal
+ stop_reason["data"]["signal"] = signal.SIGTRAP
+ else:
+ stop_reason["type"] = self.driving_thread.GetStopReason()
+
+ return stop_reason
+
+ def get_register_context(self) -> str:
+ if not self.driving_thread or self.driving_thread.GetNumFrames() == 0:
+ return None
+ frame = self.driving_thread.GetFrameAtIndex(0)
+
+ GPRs = None
+ registerSet = frame.registers # Returns an SBValueList.
+ for regs in registerSet:
+ if 'general purpose' in regs.name.lower():
+ GPRs = regs
+ break
+
+ if not GPRs:
+ return None
+
+ for reg in GPRs:
+ self.register_ctx[reg.name] = int(reg.value, base=16)
+
+ return struct.pack("{}Q".format(len(self.register_ctx)), *self.register_ctx.values())
+
+class MultiplexedScriptedThread(PassthruScriptedThread):
+ def get_name(self) -> str:
+ parity = "Odd" if self.scripted_process.parity % 2 else "Even"
+ return parity + MultiplexedScriptedThread.__name__ + ".thread-" + str(self.idx)
+
+class MultiplexerScriptedProcess(PassthruScriptedProcess):
+ listener = None
+ multiplexed_processes = None
+
+ def wait_for_driving_process_to_stop(self, originator_pid, stop_event_mask):
+ event = lldb.SBEvent()
+
+ done = False
+ while not done:
+ if self.listener.WaitForEvent(5, event):
+ event_mask = event.GetType();
+ if event.BroadcasterMatchesRef(self.driving_process.GetBroadcaster()):
+ if event_mask & lldb.SBProcess.eBroadcastBitStateChanged:
+ done = True;
+ continue
+
+ self.listener.StopListeningForEvents(self.driving_process.GetBroadcaster(),
+ stop_event_mask)
+
+ # Stop multiplexer process
+ mux_process = self.target.GetProcess()
+ mux_process.ForceScriptedState(lldb.eStateRunning);
+ mux_process.ForceScriptedState(lldb.eStateStopped);
+
+ child_process = self.multiplexed_processes[originator_pid]
+ child_process.ForceScriptedState(lldb.eStateRunning);
+ child_process.ForceScriptedState(lldb.eStateStopped);
+
+ def __init__(self, exe_ctx: lldb.SBExecutionContext, args : lldb.SBStructuredData):
+ super().__init__(exe_ctx, args)
+ if isinstance(self.driving_process, lldb.SBProcess) and self.driving_process:
+ self.listener = lldb.SBListener("lldb.listener.multiplexer-scripted-process")
+ self.multiplexed_processes = {}
+
+ def resume(self, should_stop=True, pid=None):
+ if not pid or pid not in self.multiplexed_processes.keys():
+ return super().resume()
+
+ stop_event_mask = lldb.SBProcess.eBroadcastBitInterrupt | lldb.SBProcess.eBroadcastBitStateChanged
+ self.listener.StartListeningForEvents(self.driving_process.GetBroadcaster(),
+ stop_event_mask)
+
+ listener_thread = Thread(target=self.wait_for_driving_process_to_stop,
+ args=[pid, stop_event_mask])
+ listener_thread.start()
+
+ # Resume the driving process
+ self.driving_process.Continue()
+
+ # Update the scripted process state.
+ return lldb.SBError()
+
+ def get_threads_info(self, pid=None):
+ # if not pid or pid not in self.multiplexed_processes.keys():
+ if not pid:
+ return super().get_threads_info()
+ parity = pid % 2
+ return dict(filter(lambda pair: pair[0] % 2 == parity, self.threads.items()))
+
+def multiplex(mux_process, muxed_process):
+ muxed_process.GetScriptedImplementation().multiplexer = mux_process.GetScriptedImplementation()
+ mux_process.GetScriptedImplementation().multiplexed_processes[muxed_process.GetProcessID()] = muxed_process
+
+def launch_scripted_process(target, class_name, dictionary):
+ structured_data = lldb.SBStructuredData()
+ structured_data.SetFromJSON(json.dumps(dictionary))
+
+ launch_info = lldb.SBLaunchInfo(None)
+ launch_info.SetProcessPluginName("ScriptedProcess")
+ launch_info.SetScriptedProcessClassName(class_name)
+ launch_info.SetScriptedProcessDictionary(structured_data)
+
+ error = lldb.SBError()
+ return target.Launch(launch_info, error)
+
+def duplicate_target(driving_target):
+ error = lldb.SBError()
+ exe = driving_target.executable.fullpath
+ triple = driving_target.triple
+ debugger = driving_target.GetDebugger()
+ return debugger.CreateTargetWithFileAndTargetTriple(exe, triple)
+
+def extract_value_from_structured_data(data, default_val):
+ if data and data.IsValid():
+ if data.GetType() == lldb.eStructuredDataTypeInteger:
+ return data.GetIntegerValue(default_val)
+ if data.GetType() == lldb.eStructuredDataTypeString:
+ return int(data.GetStringValue(100))
+ return None
+
+def __lldb_init_module(debugger, dict):
+ def error_out(message):
+ print(message)
+ return
+
+ if not debugger.GetNumTargets() > 0:
+ return error_out("Interactive scripted processes requires one non scripted process.")
+
+ debugger.SetAsync(True)
+
+ driving_target = debugger.GetSelectedTarget()
+ if not driving_target:
+ return error_out("Driving target is invalid")
+
+ driving_process = driving_target.GetProcess()
+ if not driving_process:
+ return error_out("Driving process is invalid")
+
+ # Check that the driving process is stopped somewhere.
+ if not driving_process.state == lldb.eStateStopped:
+ return error_out("Driving process isn't stopped")
+
+ # Create a seconde target for the multiplexer scripted process
+ mux_target = duplicate_target(driving_target)
+ if not mux_target:
+ return error_out("Couldn't duplicate driving target to launch multiplexer scripted process")
+
+ class_name = __name__ + "." + MultiplexerScriptedProcess.__name__
+ dictionary = {'driving_target_idx': debugger.GetIndexOfTarget(driving_target)}
+ mux_process = launch_scripted_process(mux_target, class_name, dictionary)
+ if not mux_process:
+ return error_out("Couldn't launch multiplexer scripted process")
+
+ # Create a target for the multiplexed even scripted process
+ even_target = duplicate_target(driving_target)
+ if not even_target:
+ return error_out("Couldn't duplicate driving target to launch multiplexed even scripted process")
+
+ class_name = __name__ + "." + MultiplexedScriptedProcess.__name__
+ dictionary['parity'] = 0
+ even_process = launch_scripted_process(even_target, class_name, dictionary)
+ if not even_process:
+ return error_out("Couldn't launch multiplexed even scripted process")
+ multiplex(mux_process, even_process)
+
+ # Create a target for the multiplexed odd scripted process
+ odd_target = duplicate_target(driving_target)
+ if not odd_target:
+ return error_out("Couldn't duplicate driving target to launch multiplexed odd scripted process")
+
+ dictionary['parity'] = 1
+ odd_process = launch_scripted_process(odd_target, class_name, dictionary)
+ if not odd_process:
+ return error_out("Couldn't launch multiplexed odd scripted process")
+ multiplex(mux_process, odd_process)
diff --git a/lldb/test/API/functionalities/interactive_scripted_process/main.cpp b/lldb/test/API/functionalities/interactive_scripted_process/main.cpp
new file mode 100644
index 0000000000000..397a154c9c5e2
--- /dev/null
+++ b/lldb/test/API/functionalities/interactive_scripted_process/main.cpp
@@ -0,0 +1,35 @@
+#include <iostream>
+#include <mutex>
+#include <string>
+#include <thread>
+#include <vector>
+
+void spawn_thread(int index) {
+ std::string name = "I'm thread " + std::to_string(index) + " !";
+ bool done = false;
+ std::string state = "Started execution!";
+ while (true) {
+ if (done) // also break here
+ break;
+ }
+
+ state = "Stopped execution!";
+}
+
+int main() {
+ size_t num_threads = 10;
+ std::vector<std::thread> threads;
+
+ for (size_t i = 0; i < num_threads; i++) {
+ threads.push_back(std::thread(spawn_thread, i));
+ }
+
+ std::cout << "Spawned " << threads.size() << " threads!"; // Break here
+
+ for (auto &t : threads) {
+ if (t.joinable())
+ t.join();
+ }
+
+ return 0;
+}
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