// Copyright 2013 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.
// Originally written by Sven Peter <sven@fail0verflow.com> for anergistic.
#include <csignal>
#include <cstdarg>
#include <cstdio>
#include <cstring>
#include <fcntl.h>
#include <map>
#include <numeric>
#ifdef _MSC_VER
#include <WinSock2.h>
#include <ws2tcpip.h>
#include <common/x64/abi.h>
#include <io.h>
#include <iphlpapi.h>
#define SHUT_RDWR 2
#else
#include <sys/select.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <unistd.h>
#endif
#include "common/logging/log.h"
#include "common/string_util.h"
#include <core/arm/arm_interface.h>
#include "core/core.h"
#include "core/memory.h"
#include "gdbstub.h"
const int GDB_BUFFER_SIZE = 10000;
const char GDB_STUB_START = '$';
const char GDB_STUB_END = '#';
const char GDB_STUB_ACK = '+';
const char GDB_STUB_NACK = '-';
#ifndef SIGTRAP
const u32 SIGTRAP = 5;
#endif
#ifndef SIGTERM
const u32 SIGTERM = 15;
#endif
#ifndef MSG_WAITALL
const u32 MSG_WAITALL = 8;
#endif
const u32 R0_REGISTER = 0;
const u32 R15_REGISTER = 15;
const u32 CSPR_REGISTER = 25;
namespace GDBStub {
static int gdbserver_socket = -1;
static u8 command_buffer[GDB_BUFFER_SIZE];
static u32 command_length;
static u32 latest_signal = 0;
static u32 send_signal = 0;
static u32 step_break = 0;
static bool memory_break = false;
// Binding to a port within the reserved ports range (0-1023) requires root permissions,
// so default to a port outside of that range.
static u16 gdbstub_port = 24689;
static bool halt_loop = true;
static bool step_loop = false;
std::atomic<bool> g_server_enabled(false);
#ifdef _WIN32
WSADATA InitData;
#endif
struct Breakpoint {
bool active;
PAddr addr;
u32 len;
};
static std::map<u32, Breakpoint> breakpoints_execute;
static std::map<u32, Breakpoint> breakpoints_read;
static std::map<u32, Breakpoint> breakpoints_write;
/**
* Turns hex string character into the equivalent byte.
*
* @param hex Input hex character to be turned into byte.
*/
static u8 HexCharToValue(u8 hex) {
if (hex >= '0' && hex <= '9') {
return hex - '0';
} else if (hex >= 'a' && hex <= 'f') {
return hex - 'a' + 0xA;
} else if (hex >= 'A' && hex <= 'F') {
return hex - 'A' + 0xA;
}
LOG_ERROR(Debug_GDBStub, "Invalid nibble: %c (%02x)\n", hex, hex);
return 0;
}
/**
* Turn nibble of byte into hex string character.
*
* @param n Nibble to be turned into hex character.
*/
static u8 NibbleToHex(u8 n) {
n &= 0xF;
if (n < 0xA) {
return '0' + n;
} else {
return 'A' + n - 0xA;
}
}
/**
* Converts input array of u8 bytes into their equivalent hex string characters.
*
* @param dest Pointer to buffer to store output hex string characters.
* @param src Pointer to array of u8 bytes.
* @param len Length of src array.
*/
static void MemToHex(u8* dest, u8* src, u32 len) {
while (len-- > 0) {
u8 tmp = *src++;
*dest++ = NibbleToHex(tmp >> 4);
*dest++ = NibbleToHex(tmp);
}
}
/**
* Converts input hex string characters into an array of equivalent of u8 bytes.
*
* @param dest Pointer to buffer to store u8 bytes.
* @param src Pointer to array of output hex string characters.
* @param len Length of src array.
*/
static void HexToMem(u8* dest, u8* src, u32 len) {
while (len-- > 0) {
*dest++ = (HexCharToValue(src[0]) << 4) | HexCharToValue(src[1]);
src += 2;
}
}
/**
* Convert a u32 into a hex string.
*
* @param dest Pointer to buffer to store output hex string characters.
*/
static void IntToHex(u8* dest, u32 v) {
for (int i = 0; i < 8; i += 2) {
dest[i + 1] = NibbleToHex(v >> (4 * i));
dest[i] = NibbleToHex(v >> (4 * (i + 1)));
}
}
/**
* Convert a hex string into a u32.
*
* @param src Pointer to hex string.
*/
static u32 HexToInt(u8* src) {
u32 output = 0;
for (int i = 0; i < 8; i += 2) {
output = (output << 4) | HexCharToValue(src[7 - i - 1]);
output = (output << 4) | HexCharToValue(src[7 - i]);
}
return output;
}
/// Read a byte from the gdb client.
static u8 ReadByte() {
u8 c;
size_t received_size = recv(gdbserver_socket, reinterpret_cast<char*>(&c), 1, MSG_WAITALL);
if (received_size != 1) {
LOG_ERROR(Debug_GDBStub, "recv failed : %ld", received_size);
Deinit();
}
return c;
}
/// Calculate the checksum of the current command buffer.
static u8 CalculateChecksum(u8 *buffer, u32 length) {
return static_cast<u8>(std::accumulate(buffer, buffer + length, 0, std::plus<u8>()));
}
/**
* Get the list of breakpoints for a given breakpoint type.
*
* @param type Type of breakpoint list.
*/
static std::map<u32, Breakpoint>& GetBreakpointList(BreakpointType type) {
switch (type) {
case BreakpointType::Execute:
return breakpoints_execute;
case BreakpointType::Read:
return breakpoints_read;
case BreakpointType::Write:
return breakpoints_write;
default:
return breakpoints_read;
}
}
/**
* Remove the breakpoint from the given address of the specified type.
*
* @param type Type of breakpoint.
* @param addr Address of breakpoint.
*/
static void RemoveBreakpoint(BreakpointType type, PAddr addr) {
std::map<u32, Breakpoint>& p = GetBreakpointList(type);
auto bp = p.find(addr);
if (bp != p.end()) {
LOG_DEBUG(Debug_GDBStub, "gdb: removed a breakpoint: %08x bytes at %08x of type %d\n", bp->second.len, bp->second.addr, type);
p.erase(addr);
}
}
PAddr GetNextBreakpointFromAddress(PAddr addr, BreakpointType type) {
std::map<u32, Breakpoint>& p = GetBreakpointList(type);
auto next_breakpoint = p.lower_bound(addr);
u32 breakpoint = -1;
if (next_breakpoint != p.end())
breakpoint = next_breakpoint->first;
return breakpoint;
}
bool CheckBreakpoint(PAddr addr, BreakpointType type) {
if (!IsConnected()) {
return false;
}
std::map<u32, Breakpoint>& p = GetBreakpointList(type);
auto bp = p.find(addr);
if (bp != p.end()) {
u32 len = bp->second.len;
// IDA Pro defaults to 4-byte breakpoints for all non-hardware breakpoints
// no matter if it's a 4-byte or 2-byte instruction. When you execute a
// Thumb instruction with a 4-byte breakpoint set, it will set a breakpoint on
// two instructions instead of the single instruction you placed the breakpoint
// on. So, as a way to make sure that execution breakpoints are only breaking
// on the instruction that was specified, set the length of an execution
// breakpoint to 1. This should be fine since the CPU should never begin executing
// an instruction anywhere except the beginning of the instruction.
if (type == BreakpointType::Execute) {
len = 1;
}
if (bp->second.active && (addr >= bp->second.addr && addr < bp->second.addr + len)) {
LOG_DEBUG(Debug_GDBStub, "Found breakpoint type %d @ %08x, range: %08x - %08x (%d bytes)\n", type, addr, bp->second.addr, bp->second.addr + len, len);
return true;
}
}
return false;
}
/**
* Send packet to gdb client.
*
* @param packet Packet to be sent to client.
*/
static void SendPacket(const char packet) {
size_t sent_size = send(gdbserver_socket, &packet, 1, 0);
if (sent_size != 1) {
LOG_ERROR(Debug_GDBStub, "send failed");
}
}
/**
* Send reply to gdb client.
*
* @param reply Reply to be sent to client.
*/
static void SendReply(const char* reply) {
if (!IsConnected()) {
return;
}
memset(command_buffer, 0, sizeof(command_buffer));
command_length = strlen(reply);
if (command_length + 4 > sizeof(command_buffer)) {
LOG_ERROR(Debug_GDBStub, "command_buffer overflow in SendReply");
}
memcpy(command_buffer + 1, reply, command_length);
u8 checksum = CalculateChecksum(command_buffer, command_length + 1);
command_buffer[0] = GDB_STUB_START;
command_buffer[command_length + 1] = GDB_STUB_END;
command_buffer[command_length + 2] = NibbleToHex(checksum >> 4);
command_buffer[command_length + 3] = NibbleToHex(checksum);
u8* ptr = command_buffer;
u32 left = command_length + 4;
while (left > 0) {
int sent_size = send(gdbserver_socket, reinterpret_cast<char*>(ptr), left, 0);
if (sent_size < 0) {
LOG_ERROR(Debug_GDBStub, "gdb: send failed");
return Deinit();
}
left -= sent_size;
ptr += sent_size;
}
}
/// Handle query command from gdb client.
static void HandleQuery() {
LOG_DEBUG(Debug_GDBStub, "gdb: query '%s'\n", command_buffer + 1);
if (!strcmp(reinterpret_cast<const char*>(command_buffer + 1), "TStatus")) {
SendReply("T0");
} else {
SendReply("");
}
}
/// Handle set thread command from gdb client.
static void HandleSetThread() {
if (memcmp(command_buffer, "Hg0", 3) == 0 ||
memcmp(command_buffer, "Hc-1", 4) == 0 ||
memcmp(command_buffer, "Hc0", 4) == 0 ||
memcmp(command_buffer, "Hc1", 4) == 0) {
return SendReply("OK");
}
SendReply("E01");
}
/// Create and send signal packet.
static void HandleSignal() {
std::string buffer = Common::StringFromFormat("T%02x%02x:%08x;%02x:%08x;", latest_signal, 15, htonl(Core::g_app_core->GetPC()), 13, htonl(Core::g_app_core->GetReg(13)));
LOG_DEBUG(Debug_GDBStub, "Response: %s", buffer.c_str());
SendReply(buffer.c_str());
}
/**
* Set signal and send packet to client through HandleSignal if signal flag is set using SendSignal.
*
* @param signal Signal to be sent to client.
*/
int SendSignal(u32 signal) {
if (gdbserver_socket == -1) {
return 1;
}
latest_signal = signal;
if (send_signal) {
HandleSignal();
send_signal = 0;
}
return 0;
}
/// Read command from gdb client.
static void ReadCommand() {
command_length = 0;
memset(command_buffer, 0, sizeof(command_buffer));
u8 c = ReadByte();
if (c == '+') {
//ignore ack
return;
} else if (c == 0x03) {
LOG_INFO(Debug_GDBStub, "gdb: found break command\n");
halt_loop = true;
send_signal = 1;
SendSignal(SIGTRAP);
return;
} else if (c != GDB_STUB_START) {
LOG_DEBUG(Debug_GDBStub, "gdb: read invalid byte %02x\n", c);
return;
}
while ((c = ReadByte()) != GDB_STUB_END) {
command_buffer[command_length++] = c;
if (command_length == sizeof(command_buffer)) {
LOG_ERROR(Debug_GDBStub, "gdb: command_buffer overflow\n");
SendPacket(GDB_STUB_NACK);
return;
}
}
u8 checksum_received = HexCharToValue(ReadByte()) << 4;
checksum_received |= HexCharToValue(ReadByte());
u8 checksum_calculated = CalculateChecksum(command_buffer, command_length);
if (checksum_received != checksum_calculated) {
LOG_ERROR(Debug_GDBStub, "gdb: invalid checksum: calculated %02x and read %02x for $%s# (length: %d)\n",
checksum_calculated, checksum_received, command_buffer, command_length);
command_length = 0;
SendPacket(GDB_STUB_NACK);
return;
}
SendPacket(GDB_STUB_ACK);
}
/// Check if there is data to be read from the gdb client.
static bool IsDataAvailable() {
if (!IsConnected()) {
return false;
}
fd_set fd_socket;
FD_ZERO(&fd_socket);
FD_SET(gdbserver_socket, &fd_socket);
struct timeval t;
t.tv_sec = 0;
t.tv_usec = 0;
if (select(gdbserver_socket + 1, &fd_socket, nullptr, nullptr, &t) < 0) {
LOG_ERROR(Debug_GDBStub, "select failed");
return false;
}
return FD_ISSET(gdbserver_socket, &fd_socket);
}
/// Send requested register to gdb client.
static void ReadRegister() {
static u8 reply[64];
memset(reply, 0, sizeof(reply));
u32 id = HexCharToValue(command_buffer[1]);
if (command_buffer[2] != '\0') {
id <<= 4;
id |= HexCharToValue(command_buffer[2]);
}
if (id >= R0_REGISTER && id <= R15_REGISTER) {
IntToHex(reply, Core::g_app_core->GetReg(id));
} else if (id == CSPR_REGISTER) {
IntToHex(reply, Core::g_app_core->GetCPSR());
} else {
return SendReply("E01");
}
SendReply(reinterpret_cast<char*>(reply));
}
/// Send all registers to the gdb client.
static void ReadRegisters() {
static u8 buffer[GDB_BUFFER_SIZE - 4];
memset(buffer, 0, sizeof(buffer));
u8* bufptr = buffer;
for (int i = 0; i <= CSPR_REGISTER; i++) {
if (i <= R15_REGISTER) {
IntToHex(bufptr + i * 8, Core::g_app_core->GetReg(i));
} else if (i == CSPR_REGISTER) {
IntToHex(bufptr + i * 8, Core::g_app_core->GetCPSR());
} else {
IntToHex(bufptr + i * 8, 0);
IntToHex(bufptr + (i + 1) * 8, 0);
i++; // These registers seem to be all 64bit instead of 32bit, so skip two instead of one
}
}
SendReply(reinterpret_cast<char*>(buffer));
}
/// Modify data of register specified by gdb client.
static void WriteRegister() {
u8* buffer_ptr = command_buffer + 3;
u32 id = HexCharToValue(command_buffer[1]);
if (command_buffer[2] != '=') {
++buffer_ptr;
id <<= 4;
id |= HexCharToValue(command_buffer[2]);
}
if (id >= R0_REGISTER && id <= R15_REGISTER) {
Core::g_app_core->SetReg(id, HexToInt(buffer_ptr));
} else if (id == CSPR_REGISTER) {
Core::g_app_core->SetCPSR(HexToInt(buffer_ptr));
} else {
return SendReply("E01");
}
SendReply("OK");
}
/// Modify all registers with data received from the client.
static void WriteRegisters() {
u8* buffer_ptr = command_buffer + 1;
if (command_buffer[0] != 'G')
return SendReply("E01");
for (int i = 0; i <= CSPR_REGISTER; i++) {
if (i <= R15_REGISTER) {
Core::g_app_core->SetReg(i, HexToInt(buffer_ptr + i * 8));
} else if (i == CSPR_REGISTER) {
Core::g_app_core->SetCPSR(HexToInt(buffer_ptr + i * 8));
} else {
i++; // These registers seem to be all 64bit instead of 32bit, so skip two instead of one
}
}
SendReply("OK");
}
/// Read location in memory specified by gdb client.
static void ReadMemory() {
static u8 reply[GDB_BUFFER_SIZE - 4];
int i = 1;
PAddr addr = 0;
while (command_buffer[i] != ',') {
addr = (addr << 4) | HexCharToValue(command_buffer[i++]);
}
i++;
u32 len = 0;
while (i < command_length) {
len = (len << 4) | HexCharToValue(command_buffer[i++]);
}
if (len * 2 > sizeof(reply)) {
SendReply("E01");
}
u8* data = Memory::GetPointer(addr);
if (!data) {
return SendReply("E0");
}
MemToHex(reply, data, len);
reply[len * 2] = '\0';
SendReply(reinterpret_cast<char*>(reply));
}
/// Modify location in memory with data received from the gdb client.
static void WriteMemory() {
int i = 1;
PAddr addr = 0;
while (command_buffer[i] != ',') {
addr = (addr << 4) | HexCharToValue(command_buffer[i++]);
}
i++;
u32 len = 0;
while (command_buffer[i] != ':') {
len = (len << 4) | HexCharToValue(command_buffer[i++]);
}
u8* dst = Memory::GetPointer(addr);
if (!dst) {
return SendReply("E00");
}
HexToMem(dst, command_buffer + i + 1, len);
SendReply("OK");
}
void Break(bool is_memory_break) {
if (!halt_loop) {
halt_loop = true;
send_signal = 1;
SendSignal(SIGTRAP);
}
memory_break = is_memory_break;
}
/// Tell the CPU that it should perform a single step.
static void Step() {
step_loop = true;
halt_loop = true;
send_signal = 1;
step_break = 1;
SendSignal(SIGTRAP);
}
bool IsMemoryBreak() {
if (IsConnected()) {
return false;
}
return memory_break;
}
/// Tell the CPU to continue executing.
static void Continue() {
memory_break = false;
step_break = 0;
step_loop = false;
halt_loop = false;
}
/**
* Commit breakpoint to list of breakpoints.
*
* @param type Type of breakpoint.
* @param addr Address of breakpoint.
* @param len Length of breakpoint.
*/
bool CommitBreakpoint(BreakpointType type, PAddr addr, u32 len) {
std::map<u32, Breakpoint>& p = GetBreakpointList(type);
Breakpoint breakpoint;
breakpoint.active = true;
breakpoint.addr = addr;
breakpoint.len = len;
p.insert({ addr, breakpoint });
LOG_DEBUG(Debug_GDBStub, "gdb: added %d breakpoint: %08x bytes at %08x\n", type, breakpoint.len, breakpoint.addr);
return true;
}
/// Handle add breakpoint command from gdb client.
static void AddBreakpoint() {
BreakpointType type;
u8 type_id = HexCharToValue(command_buffer[1]);
switch (type_id) {
case 0:
case 1:
type = BreakpointType::Execute;
break;
case 2:
type = BreakpointType::Write;
break;
case 3:
type = BreakpointType::Read;
break;
case 4:
type = BreakpointType::Access;
break;
default:
return SendReply("E01");
}
int i = 3;
PAddr addr = 0;
while (command_buffer[i] != ',') {
addr = addr << 4 | HexCharToValue(command_buffer[i++]);
}
i++;
u32 len = 0;
while (i < command_length) {
len = len << 4 | HexCharToValue(command_buffer[i++]);
}
if (type == BreakpointType::Access) {
// Access is made up of Read and Write types, so add both breakpoints
type = BreakpointType::Read;
if (!CommitBreakpoint(type, addr, len)) {
return SendReply("E02");
}
type = BreakpointType::Write;
}
if (!CommitBreakpoint(type, addr, len)) {
return SendReply("E02");
}
SendReply("OK");
}
/// Handle remove breakpoint command from gdb client.
static void RemoveBreakpoint() {
BreakpointType type;
u8 type_id = HexCharToValue(command_buffer[1]);
switch (type_id) {
case 0:
case 1:
type = BreakpointType::Execute;
break;
case 2:
type = BreakpointType::Write;
break;
case 3:
type = BreakpointType::Read;
break;
case 4:
type = BreakpointType::Access;
break;
default:
return SendReply("E01");
}
int i = 3;
PAddr addr = 0;
while (command_buffer[i] != ',') {
addr = (addr << 4) | HexCharToValue(command_buffer[i++]);
}
i++;
u32 len = 0;
while (i < command_length) {
len = (len << 4) | HexCharToValue(command_buffer[i++]);
}
if (type == BreakpointType::Access) {
// Access is made up of Read and Write types, so add both breakpoints
type = BreakpointType::Read;
RemoveBreakpoint(type, addr);
type = BreakpointType::Write;
}
RemoveBreakpoint(type, addr);
SendReply("OK");
}
void HandlePacket() {
if (!IsConnected()) {
return;
}
if (!IsDataAvailable()) {
return;
}
ReadCommand();
if (command_length == 0) {
return;
}
LOG_DEBUG(Debug_GDBStub, "Packet: %s", command_buffer);
switch (command_buffer[0]) {
case 'q':
HandleQuery();
break;
case 'H':
HandleSetThread();
break;
case '?':
HandleSignal();
break;
case 'k':
Deinit();
LOG_INFO(Debug_GDBStub, "killed by gdb");
return;
case 'g':
ReadRegisters();
break;
case 'G':
WriteRegisters();
break;
case 'p':
ReadRegister();
break;
case 'P':
WriteRegister();
break;
case 'm':
ReadMemory();
break;
case 'M':
WriteMemory();
break;
case 's':
Step();
return;
case 'C':
case 'c':
Continue();
return;
case 'z':
RemoveBreakpoint();
break;
case 'Z':
AddBreakpoint();
break;
default:
SendReply("");
break;
}
}
void SetServerPort(u16 port) {
gdbstub_port = port;
}
void ToggleServer(bool status) {
if (status) {
g_server_enabled = status;
// Start server
if (!IsConnected() && Core::g_sys_core != nullptr) {
Init();
}
}
else {
// Stop server
if (IsConnected()) {
Deinit();
}
g_server_enabled = status;
}
}
void Init(u16 port) {
if (!g_server_enabled) {
// Set the halt loop to false in case the user enabled the gdbstub mid-execution.
// This way the CPU can still execute normally.
halt_loop = false;
step_loop = false;
return;
}
// Setup initial gdbstub status
halt_loop = true;
step_loop = false;
breakpoints_execute.clear();
breakpoints_read.clear();
breakpoints_write.clear();
// Start gdb server
LOG_INFO(Debug_GDBStub, "Starting GDB server on port %d...", port);
sockaddr_in saddr_server = {};
saddr_server.sin_family = AF_INET;
saddr_server.sin_port = htons(port);
saddr_server.sin_addr.s_addr = INADDR_ANY;
#ifdef _WIN32
WSAStartup(MAKEWORD(2, 2), &InitData);
#endif
int tmpsock = socket(PF_INET, SOCK_STREAM, 0);
if (tmpsock == -1) {
LOG_ERROR(Debug_GDBStub, "Failed to create gdb socket");
}
const sockaddr* server_addr = reinterpret_cast<const sockaddr*>(&saddr_server);
socklen_t server_addrlen = sizeof(saddr_server);
if (bind(tmpsock, server_addr, server_addrlen) < 0) {
LOG_ERROR(Debug_GDBStub, "Failed to bind gdb socket");
}
if (listen(tmpsock, 1) < 0) {
LOG_ERROR(Debug_GDBStub, "Failed to listen to gdb socket");
}
// Wait for gdb to connect
LOG_INFO(Debug_GDBStub, "Waiting for gdb to connect...\n");
sockaddr_in saddr_client;
sockaddr* client_addr = reinterpret_cast<sockaddr*>(&saddr_client);
socklen_t client_addrlen = sizeof(saddr_client);
gdbserver_socket = accept(tmpsock, client_addr, &client_addrlen);
if (gdbserver_socket < 0) {
// In the case that we couldn't start the server for whatever reason, just start CPU execution like normal.
halt_loop = false;
step_loop = false;
LOG_ERROR(Debug_GDBStub, "Failed to accept gdb client");
}
else {
LOG_INFO(Debug_GDBStub, "Client connected.\n");
saddr_client.sin_addr.s_addr = ntohl(saddr_client.sin_addr.s_addr);
}
// Clean up temporary socket if it's still alive at this point.
if (tmpsock != -1) {
shutdown(tmpsock, SHUT_RDWR);
}
}
void Init() {
Init(gdbstub_port);
}
void Deinit() {
if (!g_server_enabled) {
return;
}
LOG_INFO(Debug_GDBStub, "Stopping GDB ...");
if (gdbserver_socket != -1) {
shutdown(gdbserver_socket, SHUT_RDWR);
gdbserver_socket = -1;
}
#ifdef _WIN32
WSACleanup();
#endif
LOG_INFO(Debug_GDBStub, "GDB stopped.");
}
bool IsConnected() {
return g_server_enabled && gdbserver_socket != -1;
}
bool GetCpuHaltFlag() {
return halt_loop;
}
bool GetCpuStepFlag() {
return step_loop;
}
void SetCpuStepFlag(bool is_step) {
step_loop = is_step;
}
};
