core/debugger: Implement new GDB stub debugger

1 files changed, 382 insertions, 0 deletions

diff --git a/src/core/debugger/gdbstub.cpp b/src/core/debugger/gdbstub.cpp
new file mode 100644
index 000000000..718c45952
--- /dev/null
+++ b/src/core/debugger/gdbstub.cpp
@@ -0,0 +1,382 @@
+// SPDX-FileCopyrightText: Copyright 2022 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <atomic>
+#include <numeric>
+#include <optional>
+#include <thread>
+
+#include <boost/asio.hpp>
+#include <boost/process/async_pipe.hpp>
+
+#include "common/hex_util.h"
+#include "common/logging/log.h"
+#include "common/scope_exit.h"
+#include "core/arm/arm_interface.h"
+#include "core/core.h"
+#include "core/debugger/gdbstub.h"
+#include "core/debugger/gdbstub_arch.h"
+#include "core/hle/kernel/k_page_table.h"
+#include "core/hle/kernel/k_process.h"
+#include "core/hle/kernel/k_thread.h"
+#include "core/loader/loader.h"
+#include "core/memory.h"
+
+namespace Core {
+
+constexpr char GDB_STUB_START = '$';
+constexpr char GDB_STUB_END = '#';
+constexpr char GDB_STUB_ACK = '+';
+constexpr char GDB_STUB_NACK = '-';
+constexpr char GDB_STUB_INT3 = 0x03;
+constexpr int GDB_STUB_SIGTRAP = 5;
+
+constexpr char GDB_STUB_REPLY_ERR[] = "E01";
+constexpr char GDB_STUB_REPLY_OK[] = "OK";
+constexpr char GDB_STUB_REPLY_EMPTY[] = "";
+
+GDBStub::GDBStub(DebuggerBackend& backend_, Core::System& system_)
+    : DebuggerFrontend(backend_), system{system_} {
+    if (system.CurrentProcess()->Is64BitProcess()) {
+        arch = std::make_unique<GDBStubA64>();
+    } else {
+        arch = std::make_unique<GDBStubA32>();
+    }
+}
+
+GDBStub::~GDBStub() = default;
+
+void GDBStub::Connected() {}
+
+void GDBStub::Stopped(Kernel::KThread* thread) {
+    SendReply(arch->ThreadStatus(thread, GDB_STUB_SIGTRAP));
+}
+
+std::vector<DebuggerAction> GDBStub::ClientData(std::span<const u8> data) {
+    std::vector<DebuggerAction> actions;
+    current_command.insert(current_command.end(), data.begin(), data.end());
+
+    while (current_command.size() != 0) {
+        ProcessData(actions);
+    }
+
+    return actions;
+}
+
+void GDBStub::ProcessData(std::vector<DebuggerAction>& actions) {
+    const char c{current_command[0]};
+
+    // Acknowledgement
+    if (c == GDB_STUB_ACK || c == GDB_STUB_NACK) {
+        current_command.erase(current_command.begin());
+        return;
+    }
+
+    // Interrupt
+    if (c == GDB_STUB_INT3) {
+        LOG_INFO(Debug_GDBStub, "Received interrupt");
+        current_command.erase(current_command.begin());
+        actions.push_back(DebuggerAction::Interrupt);
+        SendStatus(GDB_STUB_ACK);
+        return;
+    }
+
+    // Otherwise, require the data to be the start of a command
+    if (c != GDB_STUB_START) {
+        LOG_ERROR(Debug_GDBStub, "Invalid command buffer contents: {}", current_command.data());
+        current_command.clear();
+        SendStatus(GDB_STUB_NACK);
+        return;
+    }
+
+    // Continue reading until command is complete
+    while (CommandEnd() == current_command.end()) {
+        const auto new_data{backend.ReadFromClient()};
+        current_command.insert(current_command.end(), new_data.begin(), new_data.end());
+    }
+
+    // Execute and respond to GDB
+    const auto command{DetachCommand()};
+
+    if (command) {
+        SendStatus(GDB_STUB_ACK);
+        ExecuteCommand(*command, actions);
+    } else {
+        SendStatus(GDB_STUB_NACK);
+    }
+}
+
+void GDBStub::ExecuteCommand(std::string_view packet, std::vector<DebuggerAction>& actions) {
+    LOG_TRACE(Debug_GDBStub, "Executing command: {}", packet);
+
+    if (packet.length() == 0) {
+        SendReply(GDB_STUB_REPLY_ERR);
+        return;
+    }
+
+    std::string_view command{packet.substr(1, packet.size())};
+
+    switch (packet[0]) {
+    case 'H': {
+        Kernel::KThread* thread{nullptr};
+        s64 thread_id{strtoll(command.data() + 1, nullptr, 16)};
+        if (thread_id >= 1) {
+            thread = GetThreadByID(thread_id);
+        }
+
+        if (thread) {
+            SendReply(GDB_STUB_REPLY_OK);
+            backend.SetActiveThread(thread);
+        } else {
+            SendReply(GDB_STUB_REPLY_ERR);
+        }
+        break;
+    }
+    case 'T': {
+        s64 thread_id{strtoll(command.data(), nullptr, 16)};
+        if (GetThreadByID(thread_id)) {
+            SendReply(GDB_STUB_REPLY_OK);
+        } else {
+            SendReply(GDB_STUB_REPLY_ERR);
+        }
+        break;
+    }
+    case 'q':
+        HandleQuery(command);
+        break;
+    case '?':
+        SendReply(arch->ThreadStatus(backend.GetActiveThread(), GDB_STUB_SIGTRAP));
+        break;
+    case 'k':
+        LOG_INFO(Debug_GDBStub, "Shutting down emulation");
+        actions.push_back(DebuggerAction::ShutdownEmulation);
+        break;
+    case 'g':
+        SendReply(arch->ReadRegisters(backend.GetActiveThread()));
+        break;
+    case 'G':
+        arch->WriteRegisters(backend.GetActiveThread(), command);
+        SendReply(GDB_STUB_REPLY_OK);
+        break;
+    case 'p': {
+        const size_t reg{static_cast<size_t>(strtoll(command.data(), nullptr, 16))};
+        SendReply(arch->RegRead(backend.GetActiveThread(), reg));
+        break;
+    }
+    case 'P': {
+        const auto sep{std::find(command.begin(), command.end(), '=') - command.begin() + 1};
+        const size_t reg{static_cast<size_t>(strtoll(command.data(), nullptr, 16))};
+        arch->RegWrite(backend.GetActiveThread(), reg, std::string_view(command).substr(sep));
+        break;
+    }
+    case 'm': {
+        const auto sep{std::find(command.begin(), command.end(), ',') - command.begin() + 1};
+        const size_t addr{static_cast<size_t>(strtoll(command.data(), nullptr, 16))};
+        const size_t size{static_cast<size_t>(strtoll(command.data() + sep, nullptr, 16))};
+
+        if (system.Memory().IsValidVirtualAddressRange(addr, size)) {
+            std::vector<u8> mem(size);
+            system.Memory().ReadBlock(addr, mem.data(), size);
+
+            SendReply(Common::HexToString(mem));
+        } else {
+            SendReply(GDB_STUB_REPLY_ERR);
+        }
+        break;
+    }
+    case 'M': {
+        const auto size_sep{std::find(command.begin(), command.end(), ',') - command.begin() + 1};
+        const auto mem_sep{std::find(command.begin(), command.end(), ':') - command.begin() + 1};
+
+        const size_t addr{static_cast<size_t>(strtoll(command.data(), nullptr, 16))};
+        const size_t size{static_cast<size_t>(strtoll(command.data() + size_sep, nullptr, 16))};
+
+        const auto mem_substr{std::string_view(command).substr(mem_sep)};
+        const auto mem{Common::HexStringToVector(mem_substr, false)};
+
+        if (system.Memory().IsValidVirtualAddressRange(addr, size)) {
+            system.Memory().WriteBlock(addr, mem.data(), size);
+            system.InvalidateCpuInstructionCacheRange(addr, size);
+            SendReply(GDB_STUB_REPLY_OK);
+        } else {
+            SendReply(GDB_STUB_REPLY_ERR);
+        }
+        break;
+    }
+    case 's':
+        actions.push_back(DebuggerAction::StepThread);
+        break;
+    case 'C':
+    case 'c':
+        actions.push_back(DebuggerAction::Continue);
+        break;
+    case 'Z': {
+        const auto addr_sep{std::find(command.begin(), command.end(), ',') - command.begin() + 1};
+        const size_t addr{static_cast<size_t>(strtoll(command.data() + addr_sep, nullptr, 16))};
+
+        if (system.Memory().IsValidVirtualAddress(addr)) {
+            replaced_instructions[addr] = system.Memory().Read32(addr);
+            system.Memory().Write32(addr, arch->BreakpointInstruction());
+            system.InvalidateCpuInstructionCacheRange(addr, sizeof(u32));
+
+            SendReply(GDB_STUB_REPLY_OK);
+        } else {
+            SendReply(GDB_STUB_REPLY_ERR);
+        }
+        break;
+    }
+    case 'z': {
+        const auto addr_sep{std::find(command.begin(), command.end(), ',') - command.begin() + 1};
+        const size_t addr{static_cast<size_t>(strtoll(command.data() + addr_sep, nullptr, 16))};
+
+        const auto orig_insn{replaced_instructions.find(addr)};
+        if (system.Memory().IsValidVirtualAddress(addr) &&
+            orig_insn != replaced_instructions.end()) {
+            system.Memory().Write32(addr, orig_insn->second);
+            system.InvalidateCpuInstructionCacheRange(addr, sizeof(u32));
+            replaced_instructions.erase(addr);
+
+            SendReply(GDB_STUB_REPLY_OK);
+        } else {
+            SendReply(GDB_STUB_REPLY_ERR);
+        }
+        break;
+    }
+    default:
+        SendReply(GDB_STUB_REPLY_EMPTY);
+        break;
+    }
+}
+
+void GDBStub::HandleQuery(std::string_view command) {
+    if (command.starts_with("TStatus")) {
+        // no tracepoint support
+        SendReply("T0");
+    } else if (command.starts_with("Supported")) {
+        SendReply("PacketSize=4000;qXfer:features:read+;qXfer:threads:read+;qXfer:libraries:read+");
+    } else if (command.starts_with("Xfer:features:read:target.xml:")) {
+        const auto offset{command.substr(30)};
+        const auto amount{command.substr(command.find(',') + 1)};
+
+        const auto offset_val{static_cast<u64>(strtoll(offset.data(), nullptr, 16))};
+        const auto amount_val{static_cast<u64>(strtoll(amount.data(), nullptr, 16))};
+        const auto target_xml{arch->GetTargetXML()};
+
+        if (offset_val + amount_val > target_xml.size()) {
+            SendReply("l" + target_xml.substr(offset_val));
+        } else {
+            SendReply("m" + target_xml.substr(offset_val, amount_val));
+        }
+    } else if (command.starts_with("Offsets")) {
+        Loader::AppLoader::Modules modules;
+        system.GetAppLoader().ReadNSOModules(modules);
+
+        const auto main = std::find_if(modules.begin(), modules.end(),
+                                       [](const auto& key) { return key.second == "main"; });
+        if (main != modules.end()) {
+            SendReply(fmt::format("TextSeg={:x}", main->first));
+        } else {
+            SendReply(fmt::format("TextSeg={:x}",
+                                  system.CurrentProcess()->PageTable().GetCodeRegionStart()));
+        }
+    } else if (command.starts_with("fThreadInfo")) {
+        // beginning of list
+        const auto& threads = system.GlobalSchedulerContext().GetThreadList();
+        std::vector<std::string> thread_ids;
+        for (const auto& thread : threads) {
+            thread_ids.push_back(fmt::format("{:x}", thread->GetThreadID()));
+        }
+        SendReply(fmt::format("m{}", fmt::join(thread_ids, ",")));
+    } else if (command.starts_with("sThreadInfo")) {
+        // end of list
+        SendReply("l");
+    } else if (command.starts_with("Xfer:threads:read")) {
+        std::string buffer;
+        buffer += R"(l<?xml version="1.0"?>)";
+        buffer += "<threads>";
+
+        const auto& threads = system.GlobalSchedulerContext().GetThreadList();
+        for (const auto& thread : threads) {
+            buffer +=
+                fmt::format(R"(<thread id="{:x}" core="{:d}" name="Thread {:d}"/>)",
+                            thread->GetThreadID(), thread->GetActiveCore(), thread->GetThreadID());
+        }
+
+        buffer += "</threads>";
+        SendReply(buffer);
+    } else {
+        SendReply(GDB_STUB_REPLY_EMPTY);
+    }
+}
+
+Kernel::KThread* GDBStub::GetThreadByID(u64 thread_id) {
+    const auto& threads{system.GlobalSchedulerContext().GetThreadList()};
+    for (auto* thread : threads) {
+        if (thread->GetThreadID() == thread_id) {
+            return thread;
+        }
+    }
+
+    return nullptr;
+}
+
+std::vector<char>::const_iterator GDBStub::CommandEnd() const {
+    // Find the end marker
+    const auto end{std::find(current_command.begin(), current_command.end(), GDB_STUB_END)};
+
+    // Require the checksum to be present
+    return std::min(end + 2, current_command.end());
+}
+
+std::optional<std::string> GDBStub::DetachCommand() {
+    // Slice the string part from the beginning to the end marker
+    const auto end{CommandEnd()};
+
+    // Extract possible command data
+    std::string data(current_command.data(), end - current_command.begin() + 1);
+
+    // Shift over the remaining contents
+    current_command.erase(current_command.begin(), end + 1);
+
+    // Validate received command
+    if (data[0] != GDB_STUB_START) {
+        LOG_ERROR(Debug_GDBStub, "Invalid start data: {}", data[0]);
+        return std::nullopt;
+    }
+
+    u8 calculated = CalculateChecksum(std::string_view(data).substr(1, data.size() - 4));
+    u8 received = static_cast<u8>(strtoll(data.data() + data.size() - 2, nullptr, 16));
+
+    // Verify checksum
+    if (calculated != received) {
+        LOG_ERROR(Debug_GDBStub, "Checksum mismatch: calculated {:02x}, received {:02x}",
+                  calculated, received);
+        return std::nullopt;
+    }
+
+    return data.substr(1, data.size() - 4);
+}
+
+u8 GDBStub::CalculateChecksum(std::string_view data) {
+    return static_cast<u8>(
+        std::accumulate(data.begin(), data.end(), u8{0}, [](u8 lhs, u8 rhs) { return lhs + rhs; }));
+}
+
+void GDBStub::SendReply(std::string_view data) {
+    const auto output{
+        fmt::format("{}{}{}{:02x}", GDB_STUB_START, data, GDB_STUB_END, CalculateChecksum(data))};
+    LOG_TRACE(Debug_GDBStub, "Writing reply: {}", output);
+
+    // C++ string support is complete rubbish
+    const u8* output_begin = reinterpret_cast<const u8*>(output.data());
+    const u8* output_end = output_begin + output.size();
+    backend.WriteToClient(std::span<const u8>(output_begin, output_end));
+}
+
+void GDBStub::SendStatus(char status) {
+    std::array<u8, 1> buf = {static_cast<u8>(status)};
+    LOG_TRACE(Debug_GDBStub, "Writing status: {}", status);
+    backend.WriteToClient(buf);
+}
+
+} // namespace Core