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#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include <algorithm>
#include <cassert>
#include <cstdio>
#include <vector>
#include "disasm.h"
#include "sim.h"
#include "gdbserver.h"
template <typename T>
unsigned int circular_buffer_t<T>::size() const
{
if (end >= start)
return end - start;
else
return end + capacity - start;
}
template <typename T>
void circular_buffer_t<T>::consume(unsigned int bytes)
{
start = (start + bytes) % capacity;
}
template <typename T>
unsigned int circular_buffer_t<T>::contiguous_empty_size() const
{
if (end >= start)
if (start == 0)
return capacity - end - 1;
else
return capacity - end;
else
return start - end - 1;
}
template <typename T>
unsigned int circular_buffer_t<T>::contiguous_data_size() const
{
if (end >= start)
return end - start;
else
return capacity - start;
}
template <typename T>
void circular_buffer_t<T>::data_added(unsigned int bytes)
{
end += bytes;
assert(end <= capacity);
if (end == capacity)
end = 0;
}
template <typename T>
void circular_buffer_t<T>::reset()
{
start = 0;
end = 0;
}
template <typename T>
void circular_buffer_t<T>::append(const T *src, unsigned int count)
{
unsigned int copy = std::min(count, contiguous_empty_size());
memcpy(contiguous_empty(), src, copy * sizeof(T));
data_added(copy);
count -= copy;
if (count > 0) {
assert(count < contiguous_empty_size());
memcpy(contiguous_empty(), src, count * sizeof(T));
data_added(count);
}
}
// Code inspired by/copied from OpenOCD server/server.c.
gdbserver_t::gdbserver_t(uint16_t port, sim_t *sim) :
sim(sim),
client_fd(0),
recv_buf(64 * 1024), send_buf(64 * 1024)
{
socket_fd = socket(AF_INET, SOCK_STREAM, 0);
if (socket_fd == -1) {
fprintf(stderr, "error creating socket: %s\n", strerror(errno));
abort();
}
int so_reuseaddr_option = 1;
setsockopt(socket_fd,
SOL_SOCKET,
SO_REUSEADDR,
(void *)&so_reuseaddr_option,
sizeof(int));
int oldopts = fcntl(socket_fd, F_GETFL, 0);
fcntl(socket_fd, F_SETFL, oldopts | O_NONBLOCK);
struct sockaddr_in sin;
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = INADDR_ANY;
sin.sin_port = htons(port);
if (bind(socket_fd, (struct sockaddr *)&sin, sizeof(sin)) == -1) {
fprintf(stderr, "couldn't bind to socket: %s\n", strerror(errno));
abort();
}
/* These setsockopt()s must happen before the listen() */
int window_size = 128 * 1024;
setsockopt(socket_fd, SOL_SOCKET, SO_SNDBUF,
(char *)&window_size, sizeof(window_size));
setsockopt(socket_fd, SOL_SOCKET, SO_RCVBUF,
(char *)&window_size, sizeof(window_size));
if (listen(socket_fd, 1) == -1) {
fprintf(stderr, "couldn't listen on socket: %s\n", strerror(errno));
abort();
}
}
void gdbserver_t::accept()
{
struct sockaddr client_addr;
socklen_t address_size = sizeof(client_addr);
client_fd = ::accept(socket_fd, &client_addr, &address_size);
if (client_fd == -1) {
if (errno == EAGAIN) {
// We'll try again in the next call.
} else {
fprintf(stderr, "failed to accept on socket: %s (%d)\n", strerror(errno), errno);
abort();
}
} else {
int oldopts = fcntl(client_fd, F_GETFL, 0);
fcntl(client_fd, F_SETFL, oldopts | O_NONBLOCK);
expect_ack = false;
extended_mode = false;
// gdb wants the core to be halted when it attaches.
processor_t *p = sim->get_core(0);
p->set_halted(true);
}
}
void gdbserver_t::read()
{
// Reading from a non-blocking socket still blocks if there is no data
// available.
size_t count = recv_buf.contiguous_empty_size();
assert(count > 0);
ssize_t bytes = ::read(client_fd, recv_buf.contiguous_empty(), count);
if (bytes == -1) {
if (errno == EAGAIN) {
// We'll try again the next call.
} else {
fprintf(stderr, "failed to read on socket: %s (%d)\n", strerror(errno), errno);
abort();
}
} else if (bytes == 0) {
// The remote disconnected.
client_fd = 0;
processor_t *p = sim->get_core(0);
p->set_halted(false);
recv_buf.reset();
send_buf.reset();
} else {
recv_buf.data_added(bytes);
}
}
void gdbserver_t::write()
{
if (send_buf.empty())
return;
while (!send_buf.empty()) {
unsigned int count = send_buf.contiguous_data_size();
assert(count > 0);
ssize_t bytes = ::write(client_fd, send_buf.contiguous_data(), count);
if (bytes == -1) {
fprintf(stderr, "failed to write to socket: %s (%d)\n", strerror(errno), errno);
abort();
} else if (bytes == 0) {
// Client can't take any more data right now.
break;
} else {
printf("wrote %ld bytes: ", bytes);
for (unsigned int i = 0; i < bytes; i++) {
printf("%c", send_buf[i]);
}
printf("\n");
send_buf.consume(bytes);
}
}
}
void print_packet(const std::vector<uint8_t> &packet)
{
for (uint8_t c : packet) {
if (c >= ' ' and c <= '~')
fprintf(stderr, "%c", c);
else
fprintf(stderr, "\\x%x", c);
}
fprintf(stderr, "\n");
}
uint8_t compute_checksum(const std::vector<uint8_t> &packet)
{
uint8_t checksum = 0;
for (auto i = packet.begin() + 1; i != packet.end() - 3; i++ ) {
checksum += *i;
}
return checksum;
}
uint8_t character_hex_value(uint8_t character)
{
if (character >= '0' && character <= '9')
return character - '0';
if (character >= 'a' && character <= 'f')
return 10 + character - 'a';
if (character >= 'A' && character <= 'F')
return 10 + character - 'A';
return 0xff;
}
uint8_t extract_checksum(const std::vector<uint8_t> &packet)
{
return character_hex_value(*(packet.end() - 1)) +
16 * character_hex_value(*(packet.end() - 2));
}
void gdbserver_t::process_requests()
{
// See https://sourceware.org/gdb/onlinedocs/gdb/Remote-Protocol.html
while (!recv_buf.empty()) {
std::vector<uint8_t> packet;
for (unsigned int i = 0; i < recv_buf.size(); i++) {
uint8_t b = recv_buf[i];
if (packet.empty() && expect_ack && b == '+') {
recv_buf.consume(1);
break;
}
if (packet.empty() && b == 3) {
fprintf(stderr, "Received interrupt\n");
recv_buf.consume(1);
handle_interrupt();
break;
}
if (b == '$') {
// Start of new packet.
if (!packet.empty()) {
fprintf(stderr, "Received malformed %ld-byte packet from debug client: ", packet.size());
print_packet(packet);
recv_buf.consume(i);
break;
}
}
packet.push_back(b);
// Packets consist of $<packet-data>#<checksum>
// where <checksum> is
if (packet.size() >= 4 &&
packet[packet.size()-3] == '#') {
handle_packet(packet);
recv_buf.consume(i+1);
break;
}
}
// There's a partial packet in the buffer. Wait until we get more data to
// process it.
if (packet.size()) {
break;
}
}
}
void gdbserver_t::handle_halt_reason(const std::vector<uint8_t> &packet)
{
send_packet("S00");
}
void gdbserver_t::handle_general_registers_read(const std::vector<uint8_t> &packet)
{
// Register order that gdb expects is:
// "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7",
// "x8", "x9", "x10", "x11", "x12", "x13", "x14", "x15",
// "x16", "x17", "x18", "x19", "x20", "x21", "x22", "x23",
// "x24", "x25", "x26", "x27", "x28", "x29", "x30", "x31",
// "pc",
// "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7",
// "f8", "f9", "f10", "f11", "f12", "f13", "f14", "f15",
// "f16", "f17", "f18", "f19", "f20", "f21", "f22", "f23",
// "f24", "f25", "f26", "f27", "f28", "f29", "f30", "f31",
// Each byte of register data is described by two hex digits. The bytes with
// the register are transmitted in target byte order. The size of each
// register and their position within the ‘g’ packet are determined by the
// gdb internal gdbarch functions DEPRECATED_REGISTER_RAW_SIZE and
// gdbarch_register_name.
send("$");
running_checksum = 0;
processor_t *p = sim->get_core(0);
for (int r = 0; r < 32; r++) {
send(p->state.XPR[r]);
}
send_running_checksum();
expect_ack = true;
}
uint64_t consume_hex_number(std::vector<uint8_t>::const_iterator &iter,
std::vector<uint8_t>::const_iterator end)
{
uint64_t value = 0;
while (iter != end) {
uint8_t c = *iter;
uint64_t c_value = character_hex_value(c);
if (c_value > 15)
break;
iter++;
value <<= 4;
value += c_value;
}
return value;
}
void gdbserver_t::handle_register_read(const std::vector<uint8_t> &packet)
{
// p n
// Register order that gdb expects is:
// "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7",
// "x8", "x9", "x10", "x11", "x12", "x13", "x14", "x15",
// "x16", "x17", "x18", "x19", "x20", "x21", "x22", "x23",
// "x24", "x25", "x26", "x27", "x28", "x29", "x30", "x31",
// "pc",
// "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7",
// "f8", "f9", "f10", "f11", "f12", "f13", "f14", "f15",
// "f16", "f17", "f18", "f19", "f20", "f21", "f22", "f23",
// "f24", "f25", "f26", "f27", "f28", "f29", "f30", "f31",
std::vector<uint8_t>::const_iterator iter = packet.begin() + 2;
unsigned int n = consume_hex_number(iter, packet.end());
if (*iter != '#')
return send_packet("E16"); // EINVAL
processor_t *p = sim->get_core(0);
send("$");
running_checksum = 0;
if (n < 32) {
send(p->state.XPR[n]);
} else if (n == 0x20) {
send(p->state.pc);
} else {
send("E16"); // EINVAL
}
send_running_checksum();
expect_ack = true;
}
void gdbserver_t::handle_memory_read(const std::vector<uint8_t> &packet)
{
// m addr,length
std::vector<uint8_t>::const_iterator iter = packet.begin() + 2;
reg_t address = consume_hex_number(iter, packet.end());
if (*iter != ',')
return send_packet("E16"); // EINVAL
iter++;
reg_t length = consume_hex_number(iter, packet.end());
if (*iter != '#')
return send_packet("E16"); // EINVAL
send("$");
running_checksum = 0;
char buffer[3];
processor_t *p = sim->get_core(0);
mmu_t* mmu = sim->debug_mmu;
for (reg_t i = 0; i < length; i++) {
sprintf(buffer, "%02x", mmu->load_uint8(address + i));
send(buffer);
}
send_running_checksum();
}
void gdbserver_t::handle_memory_binary_write(const std::vector<uint8_t> &packet)
{
// X addr,length:XX...
std::vector<uint8_t>::const_iterator iter = packet.begin() + 2;
reg_t address = consume_hex_number(iter, packet.end());
if (*iter != ',')
return send_packet("E16"); // EINVAL
iter++;
reg_t length = consume_hex_number(iter, packet.end());
if (*iter != ':')
return send_packet("E16"); // EINVAL
iter++;
processor_t *p = sim->get_core(0);
mmu_t* mmu = sim->debug_mmu;
for (unsigned int i = 0; i < length; i++) {
if (iter == packet.end()) {
return send_packet("E16"); // EINVAL
}
mmu->store_uint8(address + i, *iter);
iter++;
}
if (*iter != '#')
return send_packet("E4b"); // EOVERFLOW
send_packet("OK");
}
void gdbserver_t::handle_continue(const std::vector<uint8_t> &packet)
{
// c [addr]
processor_t *p = sim->get_core(0);
if (packet[2] != '#') {
std::vector<uint8_t>::const_iterator iter = packet.begin() + 2;
p->state.pc = consume_hex_number(iter, packet.end());
if (*iter != '#')
return send_packet("E16"); // EINVAL
}
p->set_halted(false);
}
void gdbserver_t::handle_kill(const std::vector<uint8_t> &packet)
{
// k
// The exact effect of this packet is not specified.
// Looks like OpenOCD disconnects?
// TODO
}
void gdbserver_t::handle_extended(const std::vector<uint8_t> &packet)
{
// Enable extended mode. In extended mode, the remote server is made
// persistent. The ‘R’ packet is used to restart the program being debugged.
send_packet("OK");
extended_mode = true;
}
void gdbserver_t::handle_packet(const std::vector<uint8_t> &packet)
{
if (compute_checksum(packet) != extract_checksum(packet)) {
fprintf(stderr, "Received %ld-byte packet with invalid checksum\n", packet.size());
fprintf(stderr, "Computed checksum: %x\n", compute_checksum(packet));
print_packet(packet);
send("-");
return;
}
fprintf(stderr, "Received %ld-byte packet from debug client: ", packet.size());
print_packet(packet);
send("+");
switch (packet[1]) {
case '!':
return handle_extended(packet);
case '?':
return handle_halt_reason(packet);
case 'g':
return handle_general_registers_read(packet);
case 'k':
return handle_kill(packet);
case 'm':
return handle_memory_read(packet);
// case 'M':
// return handle_memory_write(packet);
case 'X':
return handle_memory_binary_write(packet);
case 'p':
return handle_register_read(packet);
case 'c':
return handle_continue(packet);
}
// Not supported.
fprintf(stderr, "** Unsupported packet: ");
print_packet(packet);
send_packet("");
}
void gdbserver_t::handle_interrupt()
{
processor_t *p = sim->get_core(0);
p->set_halted(true);
send_packet("S02"); // Pretend program received SIGINT.
}
void gdbserver_t::handle()
{
if (client_fd > 0) {
this->read();
this->write();
} else {
this->accept();
}
this->process_requests();
}
void gdbserver_t::send(const char* msg)
{
unsigned int length = strlen(msg);
for (const char *c = msg; *c; c++)
running_checksum += *c;
send_buf.append((const uint8_t *) msg, length);
}
void gdbserver_t::send(uint64_t value)
{
char buffer[3];
for (unsigned int i = 0; i < 8; i++) {
sprintf(buffer, "%02x", (int) (value & 0xff));
send(buffer);
value >>= 8;
}
}
void gdbserver_t::send(uint32_t value)
{
char buffer[3];
for (unsigned int i = 0; i < 4; i++) {
sprintf(buffer, "%02x", (int) (value & 0xff));
send(buffer);
value >>= 8;
}
}
void gdbserver_t::send_packet(const char* data)
{
send("$");
running_checksum = 0;
send(data);
send_running_checksum();
expect_ack = true;
}
void gdbserver_t::send_running_checksum()
{
char checksum_string[4];
sprintf(checksum_string, "#%02x", running_checksum);
send(checksum_string);
}
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