[Lldb-commits] [lldb] [lldb] Add WebAssembly Process Plugin (PR #150143)

[David Spickett via lldb-commits]

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@@ -0,0 +1,127 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "ThreadWasm.h"
+#include "lldb/Core/Module.h"
+#include "lldb/Core/PluginManager.h"
+#include "lldb/Core/Value.h"
+#include "lldb/Utility/DataBufferHeap.h"
+
+#include "lldb/Target/UnixSignals.h"
+
+using namespace lldb;
+using namespace lldb_private;
+using namespace lldb_private::process_gdb_remote;
+using namespace lldb_private::wasm;
+
+LLDB_PLUGIN_DEFINE(ProcessWasm)
+
+ProcessWasm::ProcessWasm(lldb::TargetSP target_sp, ListenerSP listener_sp)
+    : ProcessGDBRemote(target_sp, listener_sp) {
+  // Always use Linux signals for Wasm process.
+  m_unix_signals_sp = UnixSignals::Create(ArchSpec{"wasm32-Ant-wasi-wasm"});
+}
+
+void ProcessWasm::Initialize() {
+  static llvm::once_flag g_once_flag;
+
+  llvm::call_once(g_once_flag, []() {
+    PluginManager::RegisterPlugin(GetPluginNameStatic(),
+                                  GetPluginDescriptionStatic(), CreateInstance,
+                                  DebuggerInitialize);
+  });
+}
+
+void ProcessWasm::DebuggerInitialize(Debugger &debugger) {
+  ProcessGDBRemote::DebuggerInitialize(debugger);
+}
+
+llvm::StringRef ProcessWasm::GetPluginName() { return GetPluginNameStatic(); }
+
+llvm::StringRef ProcessWasm::GetPluginNameStatic() { return "wasm"; }
+
+llvm::StringRef ProcessWasm::GetPluginDescriptionStatic() {
+  return "GDB Remote protocol based WebAssembly debugging plug-in.";
+}
+
+void ProcessWasm::Terminate() {
+  PluginManager::UnregisterPlugin(ProcessWasm::CreateInstance);
+}
+
+lldb::ProcessSP ProcessWasm::CreateInstance(lldb::TargetSP target_sp,
+                                            ListenerSP listener_sp,
+                                            const FileSpec *crash_file_path,
+                                            bool can_connect) {
+  if (crash_file_path == nullptr)
+    return std::make_shared<ProcessWasm>(target_sp, listener_sp);
+  return {};
+}
+
+bool ProcessWasm::CanDebug(lldb::TargetSP target_sp,
+                           bool plugin_specified_by_name) {
+  if (plugin_specified_by_name)
+    return true;
+
+  if (Module *exe_module = target_sp->GetExecutableModulePointer()) {
+    if (ObjectFile *exe_objfile = exe_module->GetObjectFile())
+      return exe_objfile->GetArchitecture().GetMachine() ==
+             llvm::Triple::wasm32;
+  }
+  // However, if there is no wasm module, we return false, otherwise,
+  // we might use ProcessWasm to attach gdb remote.
+  return false;
+}
+
+std::shared_ptr<ThreadGDBRemote> ProcessWasm::CreateThread(lldb::tid_t tid) {
+  return std::make_shared<ThreadWasm>(*this, tid);
+}
+
+size_t ProcessWasm::ReadMemory(lldb::addr_t vm_addr, void *buf, size_t size,
+                               Status &error) {
+  wasm_addr_t wasm_addr(vm_addr);
+
+  switch (wasm_addr.GetType()) {
+  case WasmAddressType::Memory:
+  case WasmAddressType::Object:
+    return ProcessGDBRemote::ReadMemory(vm_addr, buf, size, error);
+  case WasmAddressType::Invalid:
+    error.FromErrorStringWithFormat(
+        "Wasm read failed for invalid address 0x%" PRIx64, vm_addr);
+    return 0;
+  }
+}
+
+llvm::Expected<std::vector<lldb::addr_t>>
+ProcessWasm::GetWasmCallStack(lldb::tid_t tid) {
+  StreamString packet;
+  packet.Printf("qWasmCallStack:");
+  packet.Printf("%llx", tid);
+
+  StringExtractorGDBRemote response;
+  if (m_gdb_comm.SendPacketAndWaitForResponse(packet.GetString(), response) !=
+      GDBRemoteCommunication::PacketResult::Success)
+    return llvm::createStringError("failed to send qWasmCallStack");
+
+  if (!response.IsNormalResponse())
+    return llvm::createStringError("failed to get response for qWasmCallStack");
+
+  WritableDataBufferSP data_buffer_sp =
+      std::make_shared<DataBufferHeap>(response.GetStringRef().size() / 2, 0);
+  const size_t bytes = response.GetHexBytes(data_buffer_sp->GetData(), '\xcc');
+  if (bytes == 0 || bytes % sizeof(uint64_t) != 0)
+    return llvm::createStringError("invalid response for qWasmCallStack");
+
+  std::vector<lldb::addr_t> call_stack_pcs;
+  DataExtractor data(data_buffer_sp, GetByteOrder(), GetAddressByteSize());
----------------
DavidSpickett wrote:

I thought I should put my time where my curiosity is, but...

WAMR is not tested for AArch64_BE, does not support s390x (surprisingly) and that leaves MIPS which I don't care to setup tools for - https://github.com/bytecodealliance/wasm-micro-runtime?tab=readme-ov-file#supported-architectures-and-platforms.

Then I looked at the source (Apache 2.0 in case you have professional restrictions) and the endian sent by the debug stub is always little: https://github.com/bytecodealliance/wasm-micro-runtime/blob/d298a66d38960719e17fbe27e8f529d6515bad26/core/iwasm/libraries/debug-engine/handler.c#L249

So if someone did report that memory was backwards on MIPS, AArch64_BE or s390x, that's definitely the runtime's problem.

https://github.com/llvm/llvm-project/pull/150143