paolosev created this revision.
paolosev added reviewers: clayborg, labath.
paolosev added a project: LLDB.
Herald added subscribers: lldb-commits, sunfish, aheejin, jgravelle-google,
sbc100, aprantl, mgorny.
paolosev marked 2 inline comments as done.
paolosev added a comment.
What is the best way to test classes WasmProcessGDBRemote and UnwindWasm?
================
Comment at: lldb/source/Plugins/Process/wasm/ProcessWasm.cpp:92
+ size_t buffer_size, size_t &size) {
+ // TODO(paolosev): Implement in GDBRemoteComunicationClient
+ return false;
----------------
This will be implemented as:
```
return GetGDBRemote().GetWasmLocal(frame_index, index, buf, buffer_size,
size);
```
as soon as `GetWasmLocal` can be added to GDBRemoteCommunicationClient.
================
Comment at: lldb/source/Plugins/Process/wasm/UnwindWasm.cpp:34-35
+
+ IWasmProcess *wasm_process =
+ static_cast<WasmProcessGDBRemote *>(GetThread().GetProcess().get());
+ if (wasm_process)
----------------
This cast works but it is ugly. Is there a better coding pattern I could use
here?
This is the fourth in a series of patches to enable LLDB debugging of
WebAssembly code that runs in a WebAssembly engine. Previous patches added
ObjectFile, SymbolVendor and DynamicLoader plugin classes for Wasm, see:
D71575 <https://reviews.llvm.org/D71575>, D72751
<https://reviews.llvm.org/D72751>, D72650 <https://reviews.llvm.org/D72650>.
The idea is to use the GDB-remote protocol to connect to a Wasm engine that
implements a GDB-remote stub that offers the ability to access the engine
runtime internal state. This patch introduce a new Process plugin //wasm//,
with:
- class `IWasmProcess` that defines the interface with functions to access the
Wasm engine state.
- class `WasmProcessGDBRemote` that inherits from `ProcessGDBRemote` and that
will implement `IWasmProcess` by forwarding requests to the Wasm engine through
a GDBRemote connection.
- class `UnwindWasm` that manages stack unwinding for Wasm.
Note that the GDB-remote protocol needs to be extended with a few Wasm-specific
custom query commands, used to access Wasm-specific constructs like the Wasm
memory, Wasm locals and globals. A patch for this with changes to
`GDBRemoteCommunicationClient` will be proposed separately, like also a patch
to `DWARFExpression` to handle Wasm-specific DWARF location expression
operators, like `DW_OP_WASM_location`.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D78801
Files:
lldb/source/Plugins/CMakeLists.txt
lldb/source/Plugins/Plugins.def.in
lldb/source/Plugins/Process/CMakeLists.txt
lldb/source/Plugins/Process/gdb-remote/GDBRemoteRegisterContext.h
lldb/source/Plugins/Process/wasm/CMakeLists.txt
lldb/source/Plugins/Process/wasm/ProcessWasm.cpp
lldb/source/Plugins/Process/wasm/ProcessWasm.h
lldb/source/Plugins/Process/wasm/UnwindWasm.cpp
lldb/source/Plugins/Process/wasm/UnwindWasm.h
lldb/source/Target/Thread.cpp
Index: lldb/source/Target/Thread.cpp
===================================================================
--- lldb/source/Target/Thread.cpp
+++ lldb/source/Target/Thread.cpp
@@ -7,6 +7,7 @@
//===----------------------------------------------------------------------===//
#include "lldb/Target/Thread.h"
+#include "Plugins/Process/wasm/UnwindWasm.h"
#include "lldb/Breakpoint/BreakpointLocation.h"
#include "lldb/Core/Debugger.h"
#include "lldb/Core/FormatEntity.h"
@@ -1853,8 +1854,13 @@
}
Unwind &Thread::GetUnwinder() {
- if (!m_unwinder_up)
- m_unwinder_up.reset(new UnwindLLDB(*this));
+ if (!m_unwinder_up) {
+ if (CalculateTarget()->GetArchitecture().GetMachine() ==
+ llvm::Triple::wasm32)
+ m_unwinder_up.reset(new wasm::UnwindWasm(*this));
+ else
+ m_unwinder_up.reset(new UnwindLLDB(*this));
+ }
return *m_unwinder_up;
}
Index: lldb/source/Plugins/Process/wasm/UnwindWasm.h
===================================================================
--- /dev/null
+++ lldb/source/Plugins/Process/wasm/UnwindWasm.h
@@ -0,0 +1,49 @@
+//===-- UnwindWasm.h --------------------------------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef lldb_UnwindWasm_h_
+#define lldb_UnwindWasm_h_
+
+#include "lldb/Target/RegisterContext.h"
+#include "lldb/Target/Unwind.h"
+#include <vector>
+
+namespace lldb_private {
+namespace wasm {
+
+class UnwindWasm : public lldb_private::Unwind {
+public:
+ UnwindWasm(lldb_private::Thread &thread)
+ : Unwind(thread), m_frames(), m_unwind_complete(false) {}
+ ~UnwindWasm() override = default;
+
+protected:
+ void DoClear() override {
+ m_frames.clear();
+ m_unwind_complete = false;
+ }
+
+ uint32_t DoGetFrameCount() override;
+
+ bool DoGetFrameInfoAtIndex(uint32_t frame_idx, lldb::addr_t &cfa,
+ lldb::addr_t &pc,
+ bool &behaves_like_zeroth_frame) override;
+ lldb::RegisterContextSP
+ DoCreateRegisterContextForFrame(lldb_private::StackFrame *frame) override;
+
+private:
+ std::vector<lldb::addr_t> m_frames;
+ bool m_unwind_complete;
+
+ DISALLOW_COPY_AND_ASSIGN(UnwindWasm);
+};
+
+} // namespace wasm
+} // namespace lldb_private
+
+#endif // lldb_UnwindWasm_h_
Index: lldb/source/Plugins/Process/wasm/UnwindWasm.cpp
===================================================================
--- /dev/null
+++ lldb/source/Plugins/Process/wasm/UnwindWasm.cpp
@@ -0,0 +1,57 @@
+//===-- UnwindWasm.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 "UnwindWasm.h"
+#include "Plugins/Process/wasm/ProcessWasm.h"
+
+using namespace lldb;
+using namespace lldb_private;
+using namespace process_gdb_remote;
+using namespace wasm;
+
+lldb::RegisterContextSP
+UnwindWasm::DoCreateRegisterContextForFrame(lldb_private::StackFrame *frame) {
+ if (m_frames.size() <= frame->GetFrameIndex()) {
+ return lldb::RegisterContextSP();
+ }
+
+ IWasmProcess *wasm_process =
+ static_cast<WasmProcessGDBRemote *>(frame->CalculateProcess().get());
+ return wasm_process->CreateRegisterContextForFrame(
+ frame, m_frames[frame->GetFrameIndex()]);
+}
+
+uint32_t UnwindWasm::DoGetFrameCount() {
+ if (!m_unwind_complete) {
+ m_unwind_complete = true;
+ m_frames.clear();
+
+ IWasmProcess *wasm_process =
+ static_cast<WasmProcessGDBRemote *>(GetThread().GetProcess().get());
+ if (wasm_process)
+ if (!wasm_process->GetWasmCallStack(m_frames))
+ m_frames.clear();
+ }
+ return m_frames.size();
+}
+
+bool UnwindWasm::DoGetFrameInfoAtIndex(uint32_t frame_idx, lldb::addr_t &cfa,
+ lldb::addr_t &pc,
+ bool &behaves_like_zeroth_frame) {
+ if (m_frames.size() == 0) {
+ DoGetFrameCount();
+ }
+
+ if (frame_idx < m_frames.size()) {
+ behaves_like_zeroth_frame = (frame_idx == 0);
+ cfa = 0;
+ pc = m_frames[frame_idx];
+ return true;
+ }
+ return false;
+}
\ No newline at end of file
Index: lldb/source/Plugins/Process/wasm/ProcessWasm.h
===================================================================
--- /dev/null
+++ lldb/source/Plugins/Process/wasm/ProcessWasm.h
@@ -0,0 +1,97 @@
+//===-- ProcessWasm.h -------------------------------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLDB_SOURCE_PLUGINS_PROCESS_WASM_PROCESSWASM_H
+#define LLDB_SOURCE_PLUGINS_PROCESS_WASM_PROCESSWASM_H
+
+#include "Plugins/Process/gdb-remote/ProcessGDBRemote.h"
+#include "lldb/Target/RegisterContext.h"
+
+namespace lldb_private {
+namespace wasm {
+
+// Interface IWasmProcess provides the access to the Wasm program state
+// retrieved from the Wasm engine.
+struct IWasmProcess {
+ ~IWasmProcess() = default;
+
+ virtual lldb::RegisterContextSP
+ CreateRegisterContextForFrame(StackFrame *frame, lldb::addr_t pc) = 0;
+
+ virtual bool GetWasmLocal(int frame_index, int index, void *buf,
+ size_t buffer_size, size_t &size) = 0;
+
+ virtual bool GetWasmGlobal(int frame_index, int index, void *buf,
+ size_t buffer_size, size_t &size) = 0;
+
+ virtual bool GetWasmStackValue(int frame_index, int index, void *buf,
+ size_t buffer_size, size_t &size) = 0;
+
+ virtual bool WasmReadMemory(int frame_index, lldb::addr_t addr, void *buf,
+ size_t buffer_size) = 0;
+
+ virtual bool GetWasmCallStack(std::vector<lldb::addr_t> &call_stack_pcs) = 0;
+};
+
+class WasmProcessGDBRemote : public process_gdb_remote::ProcessGDBRemote,
+ public IWasmProcess {
+public:
+ WasmProcessGDBRemote(lldb::TargetSP target_sp, lldb::ListenerSP listener_sp);
+
+ ~WasmProcessGDBRemote() override;
+
+ static lldb::ProcessSP CreateInstance(lldb::TargetSP target_sp,
+ lldb::ListenerSP listener_sp,
+ const FileSpec *crash_file_path);
+
+ static void Initialize();
+
+ static void DebuggerInitialize(Debugger &debugger);
+
+ static void Terminate();
+
+ static ConstString GetPluginNameStatic();
+
+ static const char *GetPluginDescriptionStatic();
+
+ // PluginInterface protocol
+ ConstString GetPluginName() override;
+
+ uint32_t GetPluginVersion() override;
+
+ // Process
+ size_t ReadMemory(lldb::addr_t vm_addr, void *buf, size_t size,
+ Status &error) override;
+
+ // IWasmProcess
+ lldb::RegisterContextSP
+ CreateRegisterContextForFrame(StackFrame *frame,
+ lldb::addr_t address) override;
+
+ bool GetWasmLocal(int frame_index, int index, void *buf, size_t buffer_size,
+ size_t &size) override;
+
+ bool GetWasmGlobal(int frame_index, int index, void *buf, size_t buffer_size,
+ size_t &size) override;
+
+ bool GetWasmStackValue(int frame_index, int index, void *buf,
+ size_t buffer_size, size_t &size) override;
+
+ bool WasmReadMemory(int frame_index, lldb::addr_t addr, void *buf,
+ size_t buffer_size) override;
+
+ bool GetWasmCallStack(std::vector<lldb::addr_t> &call_stack_pcs) override;
+
+private:
+ DISALLOW_COPY_AND_ASSIGN(WasmProcessGDBRemote);
+};
+
+} // namespace wasm
+} // namespace lldb_private
+
+#endif // LLDB_SOURCE_PLUGINS_PROCESS_WASM_PROCESSWASM_H
Index: lldb/source/Plugins/Process/wasm/ProcessWasm.cpp
===================================================================
--- /dev/null
+++ lldb/source/Plugins/Process/wasm/ProcessWasm.cpp
@@ -0,0 +1,119 @@
+//===-- ProcessWasm.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 "ProcessWasm.h"
+#include "Plugins/Process/gdb-remote/ThreadGDBRemote.h"
+#include "lldb/Core/PluginManager.h"
+
+using namespace lldb;
+using namespace lldb_private;
+using namespace lldb_private::process_gdb_remote;
+using namespace lldb_private::wasm;
+
+LLDB_PLUGIN_DEFINE(WasmProcessGDBRemote)
+
+// ProcessGDBRemote constructor
+WasmProcessGDBRemote::WasmProcessGDBRemote(lldb::TargetSP target_sp,
+ ListenerSP listener_sp)
+ : ProcessGDBRemote(target_sp, listener_sp) {}
+
+// Destructor
+WasmProcessGDBRemote::~WasmProcessGDBRemote() {}
+
+void WasmProcessGDBRemote::Initialize() {
+ static llvm::once_flag g_once_flag;
+
+ llvm::call_once(g_once_flag, []() {
+ PluginManager::RegisterPlugin(GetPluginNameStatic(),
+ GetPluginDescriptionStatic(), CreateInstance,
+ DebuggerInitialize);
+ });
+}
+
+void WasmProcessGDBRemote::DebuggerInitialize(Debugger &debugger) {
+ ProcessGDBRemote::DebuggerInitialize(debugger);
+}
+
+// PluginInterface
+ConstString WasmProcessGDBRemote::GetPluginName() {
+ return GetPluginNameStatic();
+}
+
+uint32_t WasmProcessGDBRemote::GetPluginVersion() { return 1; }
+
+ConstString WasmProcessGDBRemote::GetPluginNameStatic() {
+ static ConstString g_name("wasm");
+ return g_name;
+}
+
+const char *WasmProcessGDBRemote::GetPluginDescriptionStatic() {
+ return "GDB Remote protocol based WebAssembly debugging plug-in.";
+}
+
+void WasmProcessGDBRemote::Terminate() {
+ PluginManager::UnregisterPlugin(WasmProcessGDBRemote::CreateInstance);
+}
+
+lldb::ProcessSP
+WasmProcessGDBRemote::CreateInstance(lldb::TargetSP target_sp,
+ ListenerSP listener_sp,
+ const FileSpec *crash_file_path) {
+ lldb::ProcessSP process_sp;
+ if (crash_file_path == nullptr)
+ process_sp = std::make_shared<WasmProcessGDBRemote>(target_sp, listener_sp);
+ return process_sp;
+}
+
+size_t WasmProcessGDBRemote::ReadMemory(lldb::addr_t vm_addr, void *buf,
+ size_t size, Status &error) {
+ // TODO(paolosev): Implement in GDBRemoteComunicationClient
+ return false;
+}
+
+lldb::RegisterContextSP
+WasmProcessGDBRemote::CreateRegisterContextForFrame(StackFrame *frame,
+ lldb::addr_t pc) {
+ ThreadGDBRemote *gdb_thread =
+ static_cast<ThreadGDBRemote *>(frame->CalculateThread().get());
+ std::shared_ptr<GDBRemoteRegisterContext> reg_ctx_sp =
+ std::make_shared<GDBRemoteRegisterContext>(
+ *gdb_thread, frame->GetFrameIndex(), m_register_info, false, false);
+ reg_ctx_sp->PrivateSetRegisterValue(0, pc);
+ return reg_ctx_sp;
+}
+
+bool WasmProcessGDBRemote::GetWasmLocal(int frame_index, int index, void *buf,
+ size_t buffer_size, size_t &size) {
+ // TODO(paolosev): Implement in GDBRemoteComunicationClient
+ return false;
+}
+
+bool WasmProcessGDBRemote::GetWasmGlobal(int frame_index, int index, void *buf,
+ size_t buffer_size, size_t &size) {
+ // TODO(paolosev): Implement in GDBRemoteComunicationClient
+ return false;
+}
+
+bool WasmProcessGDBRemote::GetWasmStackValue(int frame_index, int index,
+ void *buf, size_t buffer_size,
+ size_t &size) {
+ // TODO(paolosev): Implement in GDBRemoteComunicationClient
+ return false;
+}
+
+bool WasmProcessGDBRemote::WasmReadMemory(int frame_index, lldb::addr_t addr,
+ void *buf, size_t buffer_size) {
+ // TODO(paolosev): Implement in GDBRemoteComunicationClient
+ return false;
+}
+
+bool WasmProcessGDBRemote::GetWasmCallStack(
+ std::vector<lldb::addr_t> &call_stack_pcs) {
+ // TODO(paolosev): Implement in GDBRemoteComunicationClient
+ return false;
+}
Index: lldb/source/Plugins/Process/wasm/CMakeLists.txt
===================================================================
--- /dev/null
+++ lldb/source/Plugins/Process/wasm/CMakeLists.txt
@@ -0,0 +1,11 @@
+
+add_lldb_library(lldbPluginProcessWasm PLUGIN
+ ProcessWasm.cpp
+ UnwindWasm.cpp
+
+ LINK_LIBS
+ lldbCore
+ ${LLDB_PLUGINS}
+ LINK_COMPONENTS
+ Support
+ )
Index: lldb/source/Plugins/Process/gdb-remote/GDBRemoteRegisterContext.h
===================================================================
--- lldb/source/Plugins/Process/gdb-remote/GDBRemoteRegisterContext.h
+++ lldb/source/Plugins/Process/gdb-remote/GDBRemoteRegisterContext.h
@@ -23,6 +23,11 @@
class StringExtractor;
namespace lldb_private {
+
+namespace wasm {
+class WasmProcessGDBRemote;
+}
+
namespace process_gdb_remote {
class ThreadGDBRemote;
@@ -75,6 +80,7 @@
protected:
friend class ThreadGDBRemote;
+ friend class wasm::WasmProcessGDBRemote;
bool ReadRegisterBytes(const RegisterInfo *reg_info, DataExtractor &data);
Index: lldb/source/Plugins/Process/CMakeLists.txt
===================================================================
--- lldb/source/Plugins/Process/CMakeLists.txt
+++ lldb/source/Plugins/Process/CMakeLists.txt
@@ -17,3 +17,4 @@
add_subdirectory(elf-core)
add_subdirectory(mach-core)
add_subdirectory(minidump)
+add_subdirectory(wasm)
Index: lldb/source/Plugins/Plugins.def.in
===================================================================
--- lldb/source/Plugins/Plugins.def.in
+++ lldb/source/Plugins/Plugins.def.in
@@ -31,6 +31,7 @@
@LLDB_ENUM_PLUGINS@
@LLDB_PROCESS_WINDOWS_PLUGIN@
+@LLDB_PROCESS_WASM_PLUGIN@
@LLDB_PROCESS_GDB_PLUGIN@
#undef LLDB_PLUGIN
Index: lldb/source/Plugins/CMakeLists.txt
===================================================================
--- lldb/source/Plugins/CMakeLists.txt
+++ lldb/source/Plugins/CMakeLists.txt
@@ -30,6 +30,7 @@
# FIXME: ProcessWindowsCommon needs to be initialized after all other process
# plugins but before ProcessGDBRemote.
set(LLDB_PROCESS_WINDOWS_PLUGIN "")
+set(LLDB_PROCESS_WASM_PLUGIN "")
set(LLDB_PROCESS_GDB_PLUGIN "")
foreach(p ${LLDB_ALL_PLUGINS})
@@ -41,6 +42,8 @@
set(LLDB_PROCESS_WINDOWS_PLUGIN "LLDB_PLUGIN(${pStripped})\n")
elseif(${pStripped} STREQUAL "ProcessGDBRemote")
set(LLDB_PROCESS_GDB_PLUGIN "LLDB_PLUGIN(${pStripped})\n")
+ elseif(${pStripped} STREQUAL "ProcessWasm")
+ set(LLDB_PROCESS_WASM_PLUGIN "LLDB_PLUGIN(WasmProcessGDBRemote)\n")
else()
set(LLDB_ENUM_PLUGINS "${LLDB_ENUM_PLUGINS}LLDB_PLUGIN(${pStripped})\n")
endif()
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