a28e7f1aad
Extend support in LLDB for WebAssembly. This PR adds a new Process plugin (ProcessWasm) that extends ProcessGDBRemote for WebAssembly targets. It adds support for WebAssembly's memory model with separate address spaces, and the ability to fetch the call stack from the WebAssembly runtime. I have tested this change with the WebAssembly Micro Runtime (WAMR, https://github.com/bytecodealliance/wasm-micro-runtime) which implements a GDB debug stub and supports the qWasmCallStack packet. ``` (lldb) process connect --plugin wasm connect://localhost:4567 Process 1 stopped * thread #1, name = 'nobody', stop reason = trace frame #0: 0x40000000000001ad wasm32_args.wasm`main: -> 0x40000000000001ad <+3>: global.get 0 0x40000000000001b3 <+9>: i32.const 16 0x40000000000001b5 <+11>: i32.sub 0x40000000000001b6 <+12>: local.set 0 (lldb) b add Breakpoint 1: where = wasm32_args.wasm`add + 28 at test.c:4:12, address = 0x400000000000019c (lldb) c Process 1 resuming Process 1 stopped * thread #1, name = 'nobody', stop reason = breakpoint 1.1 frame #0: 0x400000000000019c wasm32_args.wasm`add(a=<unavailable>, b=<unavailable>) at test.c:4:12 1 int 2 add(int a, int b) 3 { -> 4 return a + b; 5 } 6 7 int (lldb) bt * thread #1, name = 'nobody', stop reason = breakpoint 1.1 * frame #0: 0x400000000000019c wasm32_args.wasm`add(a=<unavailable>, b=<unavailable>) at test.c:4:12 frame #1: 0x40000000000001e5 wasm32_args.wasm`main at test.c:12:12 frame #2: 0x40000000000001fe wasm32_args.wasm ``` This PR is based on an unmerged patch from Paolo Severini: https://reviews.llvm.org/D78801. I intentionally stuck to the foundations to keep this PR small. I have more PRs in the pipeline to support the other features/packets. My motivation for supporting Wasm is to support debugging Swift compiled to WebAssembly: https://www.swift.org/documentation/articles/wasm-getting-started.html
92 lines
3.2 KiB
C++
92 lines
3.2 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLDB_SOURCE_PLUGINS_PROCESS_WASM_PROCESSWASM_H
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#define LLDB_SOURCE_PLUGINS_PROCESS_WASM_PROCESSWASM_H
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#include "Plugins/Process/gdb-remote/ProcessGDBRemote.h"
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namespace lldb_private {
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namespace wasm {
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/// Each WebAssembly module has separated address spaces for Code and Memory.
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/// A WebAssembly module also has a Data section which, when the module is
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/// loaded, gets mapped into a region in the module Memory.
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enum WasmAddressType : uint8_t { Memory = 0x00, Object = 0x01, Invalid = 0xff };
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/// For the purpose of debugging, we can represent all these separated 32-bit
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/// address spaces with a single virtual 64-bit address space. The
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/// wasm_addr_t provides this encoding using bitfields.
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struct wasm_addr_t {
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uint64_t offset : 32;
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uint64_t module_id : 30;
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uint64_t type : 2;
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wasm_addr_t(lldb::addr_t addr)
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: offset(addr & 0x00000000ffffffff),
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module_id((addr & 0x00ffffff00000000) >> 32), type(addr >> 62) {}
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wasm_addr_t(WasmAddressType type, uint32_t module_id, uint32_t offset)
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: offset(offset), module_id(module_id), type(type) {}
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WasmAddressType GetType() { return static_cast<WasmAddressType>(type); }
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operator lldb::addr_t() { return *(uint64_t *)this; }
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};
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static_assert(sizeof(wasm_addr_t) == 8, "");
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/// ProcessWasm provides the access to the Wasm program state
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/// retrieved from the Wasm engine.
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class ProcessWasm : public process_gdb_remote::ProcessGDBRemote {
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public:
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ProcessWasm(lldb::TargetSP target_sp, lldb::ListenerSP listener_sp);
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~ProcessWasm() override = default;
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static lldb::ProcessSP CreateInstance(lldb::TargetSP target_sp,
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lldb::ListenerSP listener_sp,
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const FileSpec *crash_file_path,
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bool can_connect);
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static void Initialize();
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static void DebuggerInitialize(Debugger &debugger);
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static void Terminate();
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static llvm::StringRef GetPluginNameStatic();
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static llvm::StringRef GetPluginDescriptionStatic();
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llvm::StringRef GetPluginName() override;
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size_t ReadMemory(lldb::addr_t vm_addr, void *buf, size_t size,
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Status &error) override;
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bool CanDebug(lldb::TargetSP target_sp,
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bool plugin_specified_by_name) override;
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/// Retrieve the current call stack from the WebAssembly remote process.
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llvm::Expected<std::vector<lldb::addr_t>> GetWasmCallStack(lldb::tid_t tid);
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protected:
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std::shared_ptr<process_gdb_remote::ThreadGDBRemote>
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CreateThread(lldb::tid_t tid) override;
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private:
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friend class UnwindWasm;
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process_gdb_remote::GDBRemoteDynamicRegisterInfoSP &GetRegisterInfo() {
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return m_register_info_sp;
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}
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ProcessWasm(const ProcessWasm &);
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const ProcessWasm &operator=(const ProcessWasm &) = delete;
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};
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} // namespace wasm
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} // namespace lldb_private
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#endif
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