// 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 std::accumulate(data.begin(), data.end(), u8{0},
[](u8 lhs, u8 rhs) { return static_cast<u8>(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
