/*
* Copyright (C) 2008 Stefan Hajnoczi <stefanha@gmail.com>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/**
* @file
*
* GDB stub for remote debugging
*
*/
#include <stdlib.h>
#include <stddef.h>
#include <stdio.h>
#include <ctype.h>
#include <assert.h>
#include <gpxe/process.h>
#include <gpxe/serial.h>
#include "gdbmach.h"
enum {
POSIX_EINVAL = 0x1c /* used to report bad arguments to GDB */
};
struct gdbstub {
int signo;
gdbreg_t *regs;
int exit_handler; /* leave interrupt handler */
void ( * parse ) ( struct gdbstub *stub, char ch );
uint8_t cksum1;
/* Buffer for payload data when parsing a packet. Once the
* packet has been received, this buffer is used to hold
* the reply payload. */
char payload [ 256 ];
int len;
};
/* Packet parser states */
static void gdbstub_state_new ( struct gdbstub *stub, char ch );
static void gdbstub_state_data ( struct gdbstub *stub, char ch );
static void gdbstub_state_cksum1 ( struct gdbstub *stub, char ch );
static void gdbstub_state_cksum2 ( struct gdbstub *stub, char ch );
static void gdbstub_state_wait_ack ( struct gdbstub *stub, char ch );
static uint8_t gdbstub_from_hex_digit ( char ch ) {
return ( isdigit ( ch ) ? ch - '0' : tolower ( ch ) - 'a' + 0xa ) & 0xf;
}
static uint8_t gdbstub_to_hex_digit ( uint8_t b ) {
b &= 0xf;
return ( b < 0xa ? '0' : 'a' - 0xa ) + b;
}
static void gdbstub_from_hex_buf ( char *dst, char *src, int len ) {
while ( len-- > 0 ) {
*dst = gdbstub_from_hex_digit ( *src++ );
if ( len-- > 0 ) {
*dst = (*dst << 4) | gdbstub_from_hex_digit ( *src++ );
}
dst++;
}
}
static void gdbstub_to_hex_buf ( char *dst, char *src, int len ) {
while ( len-- > 0 ) {
*dst++ = gdbstub_to_hex_digit ( *src >> 4 );
*dst++ = gdbstub_to_hex_digit ( *src++ );
}
}
static uint8_t gdbstub_cksum ( char *data, int len ) {
uint8_t cksum = 0;
while ( len-- > 0 ) {
cksum += ( uint8_t ) *data++;
}
return cksum;
}
static int gdbstub_getchar ( struct gdbstub *stub ) {
if ( stub->exit_handler ) {
return -1;
}
return serial_getc();
}
static void gdbstub_putchar ( struct gdbstub * stub __unused, char ch ) {
serial_putc ( ch );
}
static void gdbstub_tx_packet ( struct gdbstub *stub ) {
uint8_t cksum = gdbstub_cksum ( stub->payload, stub->len );
int i;
gdbstub_putchar ( stub, '$' );
for ( i = 0; i < stub->len; i++ ) {
gdbstub_putchar ( stub, stub->payload [ i ] );
}
gdbstub_putchar ( stub, '#' );
gdbstub_putchar ( stub, gdbstub_to_hex_digit ( cksum >> 4 ) );
gdbstub_putchar ( stub, gdbstub_to_hex_digit ( cksum ) );
stub->parse = gdbstub_state_wait_ack;
}
/* GDB commands */
static void gdbstub_send_ok ( struct gdbstub *stub ) {
stub->payload [ 0 ] = 'O';
stub->payload [ 1 ] = 'K';
stub->len = 2;
gdbstub_tx_packet ( stub );
}
static void gdbstub_send_num_packet ( struct gdbstub *stub, char reply, int num ) {
stub->payload [ 0 ] = reply;
stub->payload [ 1 ] = gdbstub_to_hex_digit ( ( char ) num >> 4 );
stub->payload [ 2 ] = gdbstub_to_hex_digit ( ( char ) num );
stub->len = 3;
gdbstub_tx_packet ( stub );
}
/* Format is arg1,arg2,...,argn:data where argn are hex integers and data is not an argument */
static int gdbstub_get_packet_args ( struct gdbstub *stub, unsigned long *args, int nargs, int *stop_idx ) {
int i;
char ch = 0;
int argc = 0;
unsigned long val = 0;
for ( i = 1; i < stub->len && argc < nargs; i++ ) {
ch = stub->payload [ i ];
if ( ch == ':' ) {
break;
} else if ( ch == ',' ) {
args [ argc++ ] = val;
val = 0;
} else {
val = ( val << 4 ) | gdbstub_from_hex_digit ( ch );
}
}
if ( stop_idx ) {
*stop_idx = i;
}
if ( argc < nargs ) {
args [ argc++ ] = val;
}
return ( ( i == stub->len || ch == ':' ) && argc == nargs );
}
static void gdbstub_send_errno ( struct gdbstub *stub, int errno ) {
gdbstub_send_num_packet ( stub, 'E', errno );
}
static void gdbstub_report_signal ( struct gdbstub *stub ) {
gdbstub_send_num_packet ( stub, 'S', stub->signo );
}
static void gdbstub_read_regs ( struct gdbstub *stub ) {
gdbstub_to_hex_buf ( stub->payload, ( char * ) stub->regs, GDBMACH_SIZEOF_REGS );
stub->len = GDBMACH_SIZEOF_REGS * 2;
gdbstub_tx_packet ( stub );
}
static void gdbstub_write_regs ( struct gdbstub *stub ) {
if ( stub->len != 1 + GDBMACH_SIZEOF_REGS * 2 ) {
gdbstub_send_errno ( stub, POSIX_EINVAL );
return;
}
gdbstub_from_hex_buf ( ( char * ) stub->regs, &stub->payload [ 1 ], stub->len );
gdbstub_send_ok ( stub );
}
static void gdbstub_read_mem ( struct gdbstub *stub ) {
unsigned long args [ 2 ];
if ( !gdbstub_get_packet_args ( stub, args, sizeof args / sizeof args [ 0 ], NULL ) ) {
gdbstub_send_errno ( stub, POSIX_EINVAL );
return;
}
args [ 1 ] = ( args [ 1 ] < sizeof stub->payload / 2 ) ? args [ 1 ] : sizeof stub->payload / 2;
gdbstub_to_hex_buf ( stub->payload, ( char * ) args [ 0 ], args [ 1 ] );
stub->len = args [ 1 ] * 2;
gdbstub_tx_packet ( stub );
}
static void gdbstub_write_mem ( struct gdbstub *stub ) {
unsigned long args [ 2 ];
int colon;
if ( !gdbstub_get_packet_args ( stub, args, sizeof args / sizeof args [ 0 ], &colon ) ||
colon >= stub->len || stub->payload [ colon ] != ':' ||
( stub->len - colon - 1 ) % 2 != 0 ) {
gdbstub_send_errno ( stub, POSIX_EINVAL );
return;
}
gdbstub_from_hex_buf ( ( char * ) args [ 0 ], &stub->payload [ colon + 1 ], stub->len - colon - 1 );
gdbstub_send_ok ( stub );
}
static void gdbstub_continue ( struct gdbstub *stub, int single_step ) {
gdbreg_t pc;
if ( stub->len > 1 && gdbstub_get_packet_args ( stub, &pc, 1, NULL ) ) {
gdbmach_set_pc ( stub->regs, pc );
}
gdbmach_set_single_step ( stub->regs, single_step );
stub->exit_handler = 1;
/* Reply will be sent when we hit the next breakpoint or interrupt */
}
static void gdbstub_rx_packet ( struct gdbstub *stub ) {
switch ( stub->payload [ 0 ] ) {
case '?':
gdbstub_report_signal ( stub );
break;
case 'g':
gdbstub_read_regs ( stub );
break;
case 'G':
gdbstub_write_regs ( stub );
break;
case 'm':
gdbstub_read_mem ( stub );
break;
case 'M':
gdbstub_write_mem ( stub );
break;
case 'c':
gdbstub_continue ( stub, 0 );
break;
case 's':
gdbstub_continue ( stub, 1 );
break;
default:
stub->len = 0;
gdbstub_tx_packet ( stub );
break;
}
}
/* GDB packet parser */
static void gdbstub_state_new ( struct gdbstub *stub, char ch ) {
if ( ch == '$' ) {
stub->len = 0;
stub->parse = gdbstub_state_data;
}
}
static void gdbstub_state_data ( struct gdbstub *stub, char ch ) {
if ( ch == '#' ) {
stub->parse = gdbstub_state_cksum1;
} else if ( ch == '$' ) {
stub->len = 0; /* retry new packet */
} else {
/* If the length exceeds our buffer, let the checksum fail */
if ( stub->len < ( int ) sizeof stub->payload ) {
stub->payload [ stub->len++ ] = ch;
}
}
}
static void gdbstub_state_cksum1 ( struct gdbstub *stub, char ch ) {
stub->cksum1 = gdbstub_from_hex_digit ( ch ) << 4;
stub->parse = gdbstub_state_cksum2;
}
static void gdbstub_state_cksum2 ( struct gdbstub *stub, char ch ) {
uint8_t their_cksum;
uint8_t our_cksum;
stub->parse = gdbstub_state_new;
their_cksum = stub->cksum1 + gdbstub_from_hex_digit ( ch );
our_cksum = gdbstub_cksum ( stub->payload, stub->len );
if ( their_cksum == our_cksum ) {
gdbstub_putchar ( stub, '+' );
if ( stub->len > 0 ) {
gdbstub_rx_packet ( stub );
}
} else {
gdbstub_putchar ( stub, '-' );
}
}
static void gdbstub_state_wait_ack ( struct gdbstub *stub, char ch ) {
if ( ch == '+' ) {
stub->parse = gdbstub_state_new;
} else if ( ch == '-' ) {
gdbstub_tx_packet ( stub ); /* retransmit */
}
}
static void gdbstub_parse ( struct gdbstub *stub, char ch ) {
stub->parse ( stub, ch );
}
static struct gdbstub stub = {
.parse = gdbstub_state_new
};
__cdecl void gdbstub_handler ( int signo, gdbreg_t *regs ) {
int ch;
stub.signo = signo;
stub.regs = regs;
stub.exit_handler = 0;
gdbstub_report_signal ( &stub );
while ( ( ch = gdbstub_getchar( &stub ) ) != -1 ) {
gdbstub_parse ( &stub, ch );
}
}
/* Activity monitor to detect packets from GDB when we are not active */
static void gdbstub_activity_step ( struct process *process __unused ) {
if ( serial_ischar() ) {
gdbmach_breakpoint();
}
}
struct process gdbstub_activity_process __permanent_process = {
.step = gdbstub_activity_step,
};
