1/* 2 * Copyright (C) 2008 Stefan Hajnoczi <stefanha@gmail.com>. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License as 6 * published by the Free Software Foundation; either version 2 of the 7 * License, or any later version. 8 * 9 * This program is distributed in the hope that it will be useful, but 10 * WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 * General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, write to the Free Software 16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 17 */ 18 19/** 20 * @file 21 * 22 * GDB stub for remote debugging 23 * 24 */ 25 26#include <stdlib.h> 27#include <stdio.h> 28#include <string.h> 29#include <ctype.h> 30#include <byteswap.h> 31#include <gpxe/gdbstub.h> 32#include "gdbmach.h" 33 34enum { 35 POSIX_EINVAL = 0x1c, /* used to report bad arguments to GDB */ 36 SIZEOF_PAYLOAD = 256, /* buffer size of GDB payload data */ 37}; 38 39struct gdbstub { 40 struct gdb_transport *trans; 41 int exit_handler; /* leave interrupt handler */ 42 43 int signo; 44 gdbreg_t *regs; 45 46 void ( * parse ) ( struct gdbstub *stub, char ch ); 47 uint8_t cksum1; 48 49 /* Buffer for payload data when parsing a packet. Once the 50 * packet has been received, this buffer is used to hold 51 * the reply payload. */ 52 char buf [ SIZEOF_PAYLOAD + 4 ]; /* $...PAYLOAD...#XX */ 53 char *payload; /* start of payload */ 54 int len; /* length of payload */ 55}; 56 57/* Packet parser states */ 58static void gdbstub_state_new ( struct gdbstub *stub, char ch ); 59static void gdbstub_state_data ( struct gdbstub *stub, char ch ); 60static void gdbstub_state_cksum1 ( struct gdbstub *stub, char ch ); 61static void gdbstub_state_cksum2 ( struct gdbstub *stub, char ch ); 62static void gdbstub_state_wait_ack ( struct gdbstub *stub, char ch ); 63 64static uint8_t gdbstub_from_hex_digit ( char ch ) { 65 return ( isdigit ( ch ) ? ch - '0' : tolower ( ch ) - 'a' + 0xa ) & 0xf; 66} 67 68static uint8_t gdbstub_to_hex_digit ( uint8_t b ) { 69 b &= 0xf; 70 return ( b < 0xa ? '0' : 'a' - 0xa ) + b; 71} 72 73/* 74 * To make reading/writing device memory atomic, we check for 75 * 2- or 4-byte aligned operations and handle them specially. 76 */ 77 78static void gdbstub_from_hex_buf ( char *dst, char *src, int lenbytes ) { 79 if ( lenbytes == 2 && ( ( unsigned long ) dst & 0x1 ) == 0 ) { 80 uint16_t i = gdbstub_from_hex_digit ( src [ 2 ] ) << 12 | 81 gdbstub_from_hex_digit ( src [ 3 ] ) << 8 | 82 gdbstub_from_hex_digit ( src [ 0 ] ) << 4 | 83 gdbstub_from_hex_digit ( src [ 1 ] ); 84 * ( uint16_t * ) dst = cpu_to_le16 ( i ); 85 } else if ( lenbytes == 4 && ( ( unsigned long ) dst & 0x3 ) == 0 ) { 86 uint32_t i = gdbstub_from_hex_digit ( src [ 6 ] ) << 28 | 87 gdbstub_from_hex_digit ( src [ 7 ] ) << 24 | 88 gdbstub_from_hex_digit ( src [ 4 ] ) << 20 | 89 gdbstub_from_hex_digit ( src [ 5 ] ) << 16 | 90 gdbstub_from_hex_digit ( src [ 2 ] ) << 12 | 91 gdbstub_from_hex_digit ( src [ 3 ] ) << 8 | 92 gdbstub_from_hex_digit ( src [ 0 ] ) << 4 | 93 gdbstub_from_hex_digit ( src [ 1 ] ); 94 * ( uint32_t * ) dst = cpu_to_le32 ( i ); 95 } else { 96 while ( lenbytes-- > 0 ) { 97 *dst++ = gdbstub_from_hex_digit ( src [ 0 ] ) << 4 | 98 gdbstub_from_hex_digit ( src [ 1 ] ); 99 src += 2; 100 } 101 } 102} 103 104static void gdbstub_to_hex_buf ( char *dst, char *src, int lenbytes ) { 105 if ( lenbytes == 2 && ( ( unsigned long ) src & 0x1 ) == 0 ) { 106 uint16_t i = cpu_to_le16 ( * ( uint16_t * ) src ); 107 dst [ 0 ] = gdbstub_to_hex_digit ( i >> 4 ); 108 dst [ 1 ] = gdbstub_to_hex_digit ( i ); 109 dst [ 2 ] = gdbstub_to_hex_digit ( i >> 12 ); 110 dst [ 3 ] = gdbstub_to_hex_digit ( i >> 8 ); 111 } else if ( lenbytes == 4 && ( ( unsigned long ) src & 0x3 ) == 0 ) { 112 uint32_t i = cpu_to_le32 ( * ( uint32_t * ) src ); 113 dst [ 0 ] = gdbstub_to_hex_digit ( i >> 4 ); 114 dst [ 1 ] = gdbstub_to_hex_digit ( i ); 115 dst [ 2 ] = gdbstub_to_hex_digit ( i >> 12 ); 116 dst [ 3 ] = gdbstub_to_hex_digit ( i >> 8 ); 117 dst [ 4 ] = gdbstub_to_hex_digit ( i >> 20 ); 118 dst [ 5 ] = gdbstub_to_hex_digit ( i >> 16); 119 dst [ 6 ] = gdbstub_to_hex_digit ( i >> 28 ); 120 dst [ 7 ] = gdbstub_to_hex_digit ( i >> 24 ); 121 } else { 122 while ( lenbytes-- > 0 ) { 123 *dst++ = gdbstub_to_hex_digit ( *src >> 4 ); 124 *dst++ = gdbstub_to_hex_digit ( *src ); 125 src++; 126 } 127 } 128} 129 130static uint8_t gdbstub_cksum ( char *data, int len ) { 131 uint8_t cksum = 0; 132 while ( len-- > 0 ) { 133 cksum += ( uint8_t ) *data++; 134 } 135 return cksum; 136} 137 138static void gdbstub_tx_packet ( struct gdbstub *stub ) { 139 uint8_t cksum = gdbstub_cksum ( stub->payload, stub->len ); 140 stub->buf [ 0 ] = '$'; 141 stub->buf [ stub->len + 1 ] = '#'; 142 stub->buf [ stub->len + 2 ] = gdbstub_to_hex_digit ( cksum >> 4 ); 143 stub->buf [ stub->len + 3 ] = gdbstub_to_hex_digit ( cksum ); 144 stub->trans->send ( stub->buf, stub->len + 4 ); 145 stub->parse = gdbstub_state_wait_ack; 146} 147 148/* GDB commands */ 149static void gdbstub_send_ok ( struct gdbstub *stub ) { 150 stub->payload [ 0 ] = 'O'; 151 stub->payload [ 1 ] = 'K'; 152 stub->len = 2; 153 gdbstub_tx_packet ( stub ); 154} 155 156static void gdbstub_send_num_packet ( struct gdbstub *stub, char reply, int num ) { 157 stub->payload [ 0 ] = reply; 158 stub->payload [ 1 ] = gdbstub_to_hex_digit ( ( char ) num >> 4 ); 159 stub->payload [ 2 ] = gdbstub_to_hex_digit ( ( char ) num ); 160 stub->len = 3; 161 gdbstub_tx_packet ( stub ); 162} 163 164/* Format is arg1,arg2,...,argn:data where argn are hex integers and data is not an argument */ 165static int gdbstub_get_packet_args ( struct gdbstub *stub, unsigned long *args, int nargs, int *stop_idx ) { 166 int i; 167 char ch = 0; 168 int argc = 0; 169 unsigned long val = 0; 170 for ( i = 1; i < stub->len && argc < nargs; i++ ) { 171 ch = stub->payload [ i ]; 172 if ( ch == ':' ) { 173 break; 174 } else if ( ch == ',' ) { 175 args [ argc++ ] = val; 176 val = 0; 177 } else { 178 val = ( val << 4 ) | gdbstub_from_hex_digit ( ch ); 179 } 180 } 181 if ( stop_idx ) { 182 *stop_idx = i; 183 } 184 if ( argc < nargs ) { 185 args [ argc++ ] = val; 186 } 187 return ( ( i == stub->len || ch == ':' ) && argc == nargs ); 188} 189 190static void gdbstub_send_errno ( struct gdbstub *stub, int errno ) { 191 gdbstub_send_num_packet ( stub, 'E', errno ); 192} 193 194static void gdbstub_report_signal ( struct gdbstub *stub ) { 195 gdbstub_send_num_packet ( stub, 'S', stub->signo ); 196} 197 198static void gdbstub_read_regs ( struct gdbstub *stub ) { 199 gdbstub_to_hex_buf ( stub->payload, ( char * ) stub->regs, GDBMACH_SIZEOF_REGS ); 200 stub->len = GDBMACH_SIZEOF_REGS * 2; 201 gdbstub_tx_packet ( stub ); 202} 203 204static void gdbstub_write_regs ( struct gdbstub *stub ) { 205 if ( stub->len != 1 + GDBMACH_SIZEOF_REGS * 2 ) { 206 gdbstub_send_errno ( stub, POSIX_EINVAL ); 207 return; 208 } 209 gdbstub_from_hex_buf ( ( char * ) stub->regs, &stub->payload [ 1 ], GDBMACH_SIZEOF_REGS ); 210 gdbstub_send_ok ( stub ); 211} 212 213static void gdbstub_read_mem ( struct gdbstub *stub ) { 214 unsigned long args [ 2 ]; 215 if ( !gdbstub_get_packet_args ( stub, args, sizeof args / sizeof args [ 0 ], NULL ) ) { 216 gdbstub_send_errno ( stub, POSIX_EINVAL ); 217 return; 218 } 219 args [ 1 ] = ( args [ 1 ] < SIZEOF_PAYLOAD / 2 ) ? args [ 1 ] : SIZEOF_PAYLOAD / 2; 220 gdbstub_to_hex_buf ( stub->payload, ( char * ) args [ 0 ], args [ 1 ] ); 221 stub->len = args [ 1 ] * 2; 222 gdbstub_tx_packet ( stub ); 223} 224 225static void gdbstub_write_mem ( struct gdbstub *stub ) { 226 unsigned long args [ 2 ]; 227 int colon; 228 if ( !gdbstub_get_packet_args ( stub, args, sizeof args / sizeof args [ 0 ], &colon ) || 229 colon >= stub->len || stub->payload [ colon ] != ':' || 230 ( stub->len - colon - 1 ) % 2 != 0 ) { 231 gdbstub_send_errno ( stub, POSIX_EINVAL ); 232 return; 233 } 234 gdbstub_from_hex_buf ( ( char * ) args [ 0 ], &stub->payload [ colon + 1 ], ( stub->len - colon - 1 ) / 2 ); 235 gdbstub_send_ok ( stub ); 236} 237 238static void gdbstub_continue ( struct gdbstub *stub, int single_step ) { 239 gdbreg_t pc; 240 if ( stub->len > 1 && gdbstub_get_packet_args ( stub, &pc, 1, NULL ) ) { 241 gdbmach_set_pc ( stub->regs, pc ); 242 } 243 gdbmach_set_single_step ( stub->regs, single_step ); 244 stub->exit_handler = 1; 245 /* Reply will be sent when we hit the next breakpoint or interrupt */ 246} 247 248static void gdbstub_breakpoint ( struct gdbstub *stub ) { 249 unsigned long args [ 3 ]; 250 int enable = stub->payload [ 0 ] == 'Z' ? 1 : 0; 251 if ( !gdbstub_get_packet_args ( stub, args, sizeof args / sizeof args [ 0 ], NULL ) ) { 252 gdbstub_send_errno ( stub, POSIX_EINVAL ); 253 return; 254 } 255 if ( gdbmach_set_breakpoint ( args [ 0 ], args [ 1 ], args [ 2 ], enable ) ) { 256 gdbstub_send_ok ( stub ); 257 } else { 258 /* Not supported */ 259 stub->len = 0; 260 gdbstub_tx_packet ( stub ); 261 } 262} 263 264static void gdbstub_rx_packet ( struct gdbstub *stub ) { 265 switch ( stub->payload [ 0 ] ) { 266 case '?': 267 gdbstub_report_signal ( stub ); 268 break; 269 case 'g': 270 gdbstub_read_regs ( stub ); 271 break; 272 case 'G': 273 gdbstub_write_regs ( stub ); 274 break; 275 case 'm': 276 gdbstub_read_mem ( stub ); 277 break; 278 case 'M': 279 gdbstub_write_mem ( stub ); 280 break; 281 case 'c': /* Continue */ 282 case 'k': /* Kill */ 283 case 's': /* Step */ 284 case 'D': /* Detach */ 285 gdbstub_continue ( stub, stub->payload [ 0 ] == 's' ); 286 if ( stub->payload [ 0 ] == 'D' ) { 287 gdbstub_send_ok ( stub ); 288 } 289 break; 290 case 'Z': /* Insert breakpoint */ 291 case 'z': /* Remove breakpoint */ 292 gdbstub_breakpoint ( stub ); 293 break; 294 default: 295 stub->len = 0; 296 gdbstub_tx_packet ( stub ); 297 break; 298 } 299} 300 301/* GDB packet parser */ 302static void gdbstub_state_new ( struct gdbstub *stub, char ch ) { 303 if ( ch == '$' ) { 304 stub->len = 0; 305 stub->parse = gdbstub_state_data; 306 } 307} 308 309static void gdbstub_state_data ( struct gdbstub *stub, char ch ) { 310 if ( ch == '#' ) { 311 stub->parse = gdbstub_state_cksum1; 312 } else if ( ch == '$' ) { 313 stub->len = 0; /* retry new packet */ 314 } else { 315 /* If the length exceeds our buffer, let the checksum fail */ 316 if ( stub->len < SIZEOF_PAYLOAD ) { 317 stub->payload [ stub->len++ ] = ch; 318 } 319 } 320} 321 322static void gdbstub_state_cksum1 ( struct gdbstub *stub, char ch ) { 323 stub->cksum1 = gdbstub_from_hex_digit ( ch ) << 4; 324 stub->parse = gdbstub_state_cksum2; 325} 326 327static void gdbstub_state_cksum2 ( struct gdbstub *stub, char ch ) { 328 uint8_t their_cksum; 329 uint8_t our_cksum; 330 331 stub->parse = gdbstub_state_new; 332 their_cksum = stub->cksum1 + gdbstub_from_hex_digit ( ch ); 333 our_cksum = gdbstub_cksum ( stub->payload, stub->len ); 334 if ( their_cksum == our_cksum ) { 335 stub->trans->send ( "+", 1 ); 336 if ( stub->len > 0 ) { 337 gdbstub_rx_packet ( stub ); 338 } 339 } else { 340 stub->trans->send ( "-", 1 ); 341 } 342} 343 344static void gdbstub_state_wait_ack ( struct gdbstub *stub, char ch ) { 345 if ( ch == '+' ) { 346 stub->parse = gdbstub_state_new; 347 } else { 348 /* This retransmit is very aggressive but necessary to keep 349 * in sync with GDB. */ 350 gdbstub_tx_packet ( stub ); 351 } 352} 353 354static void gdbstub_parse ( struct gdbstub *stub, char ch ) { 355 stub->parse ( stub, ch ); 356} 357 358static struct gdbstub stub = { 359 .parse = gdbstub_state_new 360}; 361 362void gdbstub_handler ( int signo, gdbreg_t *regs ) { 363 char packet [ SIZEOF_PAYLOAD + 4 ]; 364 size_t len, i; 365 366 /* A transport must be set up */ 367 if ( !stub.trans ) { 368 return; 369 } 370 371 stub.signo = signo; 372 stub.regs = regs; 373 stub.exit_handler = 0; 374 gdbstub_report_signal ( &stub ); 375 while ( !stub.exit_handler && ( len = stub.trans->recv ( packet, sizeof ( packet ) ) ) > 0 ) { 376 for ( i = 0; i < len; i++ ) { 377 gdbstub_parse ( &stub, packet [ i ] ); 378 } 379 } 380} 381 382struct gdb_transport *find_gdb_transport ( const char *name ) { 383 struct gdb_transport *trans; 384 385 for_each_table_entry ( trans, GDB_TRANSPORTS ) { 386 if ( strcmp ( trans->name, name ) == 0 ) { 387 return trans; 388 } 389 } 390 return NULL; 391} 392 393void gdbstub_start ( struct gdb_transport *trans ) { 394 stub.trans = trans; 395 stub.payload = &stub.buf [ 1 ]; 396 gdbmach_breakpoint(); 397} 398