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// Copyright 2020 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_DEBUG_WASM_GDB_SERVER_GDB_SERVER_H_
#define V8_DEBUG_WASM_GDB_SERVER_GDB_SERVER_H_
#include <map>
#include <memory>
#include "src/debug/wasm/gdb-server/gdb-server-thread.h"
#include "src/debug/wasm/gdb-server/wasm-module-debug.h"
namespace v8 {
namespace internal {
namespace wasm {
namespace gdb_server {
class TaskRunner;
// class GdbServer acts as a manager for the GDB-remote stub. It is instantiated
// as soon as the first Wasm module is loaded in the Wasm engine and spawns a
// separate thread to accept connections and exchange messages with a debugger.
// It will contain the logic to serve debugger queries and access the state of
// the Wasm engine.
class GdbServer {
public:
// Factory method: creates and returns a GdbServer. Spawns a "GDB-remote"
// thread that will be used to communicate with the debugger.
// May return null on failure.
// This should be called once, the first time a Wasm module is loaded in the
// Wasm engine.
static std::unique_ptr<GdbServer> Create();
// Stops the "GDB-remote" thread and waits for it to complete. This should be
// called once, when the Wasm engine shuts down.
~GdbServer();
// Queries the set of the Wasm modules currently loaded. Each module is
// identified by a unique integer module id.
struct WasmModuleInfo {
uint32_t module_id;
std::string module_name;
};
std::vector<WasmModuleInfo> GetLoadedModules();
// Queries the value of the {index} global value in the Wasm module identified
// by {frame_index}.
//
bool GetWasmGlobal(uint32_t frame_index, uint32_t index, uint8_t* buffer,
uint32_t buffer_size, uint32_t* size);
// Queries the value of the {index} local value in the {frame_index}th stack
// frame in the Wasm module identified by {frame_index}.
//
bool GetWasmLocal(uint32_t frame_index, uint32_t index, uint8_t* buffer,
uint32_t buffer_size, uint32_t* size);
// Queries the value of the {index} value in the operand stack.
//
bool GetWasmStackValue(uint32_t frame_index, uint32_t index, uint8_t* buffer,
uint32_t buffer_size, uint32_t* size);
// Reads {size} bytes, starting from {offset}, from the Memory instance
// associated to the Wasm module identified by {frame_index}.
// Returns the number of bytes copied to {buffer}, or 0 is case of error.
// Note: only one Memory for Module is currently supported.
//
uint32_t GetWasmMemory(uint32_t frame_index, uint32_t offset, uint8_t* buffer,
uint32_t size);
// Reads {size} bytes, starting from the low dword of {address}, from the Code
// space of th Wasm module identified by high dword of {address}.
// Returns the number of bytes copied to {buffer}, or 0 is case of error.
uint32_t GetWasmModuleBytes(wasm_addr_t address, uint8_t* buffer,
uint32_t size);
// Inserts a breakpoint at the offset {offset} of the Wasm module identified
// by {wasm_module_id}.
// Returns true if the breakpoint was successfully added.
bool AddBreakpoint(uint32_t wasm_module_id, uint32_t offset);
// Removes a breakpoint at the offset {offset} of the Wasm module identified
// by {wasm_module_id}.
// Returns true if the breakpoint was successfully removed.
bool RemoveBreakpoint(uint32_t wasm_module_id, uint32_t offset);
// Returns the current call stack as a vector of program counters.
std::vector<wasm_addr_t> GetWasmCallStack() const;
// Manage the set of Isolates for this GdbServer.
void AddIsolate(Isolate* isolate);
void RemoveIsolate(Isolate* isolate);
// Requests that the thread suspend execution at the next Wasm instruction.
void Suspend();
// Handle stepping in wasm functions via the wasm interpreter.
void PrepareStep();
// Called when the target debuggee can resume execution (for example after
// having been suspended on a breakpoint). Terminates the task runner leaving
// all pending tasks in the queue.
void QuitMessageLoopOnPause();
private:
GdbServer();
// When the target debuggee is suspended for a breakpoint or exception, blocks
// the main (isolate) thread and enters in a message loop. Here it waits on a
// queue of Task objects that are posted by the GDB-stub thread and that
// represent queries received from the debugger via the GDB-remote protocol.
void RunMessageLoopOnPause();
// Post a task to run a callback in the isolate thread.
template <typename Callback>
auto RunSyncTask(Callback&& callback) const;
void AddWasmModule(uint32_t module_id, Local<debug::WasmScript> wasm_script);
// Given a Wasm module id, retrieves the corresponding debugging WasmScript
// object.
bool GetModuleDebugHandler(uint32_t module_id,
WasmModuleDebug** wasm_module_debug);
// Returns the debugging target.
Target& GetTarget() const;
// Class DebugDelegate implements the debug::DebugDelegate interface to
// receive notifications when debug events happen in a given isolate, like a
// script being loaded, a breakpoint being hit, an exception being thrown.
class DebugDelegate : public debug::DebugDelegate {
public:
DebugDelegate(Isolate* isolate, GdbServer* gdb_server);
~DebugDelegate();
// debug::DebugDelegate
void ScriptCompiled(Local<debug::Script> script, bool is_live_edited,
bool has_compile_error) override;
void BreakProgramRequested(Local<v8::Context> paused_context,
const std::vector<debug::BreakpointId>&
inspector_break_points_hit) override;
void ExceptionThrown(Local<v8::Context> paused_context,
Local<Value> exception, Local<Value> promise,
bool is_uncaught,
debug::ExceptionType exception_type) override;
bool IsFunctionBlackboxed(Local<debug::Script> script,
const debug::Location& start,
const debug::Location& end) override;
private:
// Calculates module_id as:
// +--------------------+------------------- +
// | DebugDelegate::id_ | Script::Id() |
// +--------------------+------------------- +
// <----- 16 bit -----> <----- 16 bit ----->
uint32_t GetModuleId(uint32_t script_id) const {
DCHECK_LT(script_id, 0x10000);
DCHECK_LT(id_, 0x10000);
return id_ << 16 | script_id;
}
Isolate* isolate_;
uint32_t id_;
GdbServer* gdb_server_;
static std::atomic<uint32_t> id_s;
};
// The GDB-stub thread where all the communication with the debugger happens.
std::unique_ptr<GdbServerThread> thread_;
// Used to transform the queries that arrive in the GDB-stub thread into
// tasks executed in the main (isolate) thread.
std::unique_ptr<TaskRunner> task_runner_;
//////////////////////////////////////////////////////////////////////////////
// Always accessed in the isolate thread.
// Set of breakpoints currently defines in Wasm code.
typedef std::map<uint64_t, int> BreakpointsMap;
BreakpointsMap breakpoints_;
typedef std::map<uint32_t, WasmModuleDebug> ScriptsMap;
ScriptsMap scripts_;
typedef std::map<Isolate*, std::unique_ptr<DebugDelegate>>
IsolateDebugDelegateMap;
IsolateDebugDelegateMap isolate_delegates_;
// End of fields always accessed in the isolate thread.
//////////////////////////////////////////////////////////////////////////////
DISALLOW_COPY_AND_ASSIGN(GdbServer);
};
} // namespace gdb_server
} // namespace wasm
} // namespace internal
} // namespace v8
#endif // V8_DEBUG_WASM_GDB_SERVER_GDB_SERVER_H_
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