iPXE
gdbstub.c
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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., 51 Franklin Street, Fifth Floor, Boston, MA
17  * 02110-1301, USA.
18  *
19  * You can also choose to distribute this program under the terms of
20  * the Unmodified Binary Distribution Licence (as given in the file
21  * COPYING.UBDL), provided that you have satisfied its requirements.
22  */
23 
24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
25 
26 /**
27  * @file
28  *
29  * GDB stub for remote debugging
30  *
31  */
32 
33 #include <stdlib.h>
34 #include <stdio.h>
35 #include <string.h>
36 #include <ctype.h>
37 #include <byteswap.h>
38 #include <ipxe/gdbstub.h>
39 #include "gdbmach.h"
40 
41 enum {
42  POSIX_EINVAL = 0x1c, /* used to report bad arguments to GDB */
43  SIZEOF_PAYLOAD = 512, /* buffer size of GDB payload data */
44 };
45 
46 struct gdbstub {
48  int exit_handler; /* leave interrupt handler */
49 
50  int signo;
52 
53  void ( * parse ) ( struct gdbstub *stub, char ch );
55 
56  /* Buffer for payload data when parsing a packet. Once the
57  * packet has been received, this buffer is used to hold
58  * the reply payload. */
59  char buf [ SIZEOF_PAYLOAD + 4 ]; /* $...PAYLOAD...#XX */
60  char *payload; /* start of payload */
61  int len; /* length of payload */
62 };
63 
64 /* Packet parser states */
65 static void gdbstub_state_new ( struct gdbstub *stub, char ch );
66 static void gdbstub_state_data ( struct gdbstub *stub, char ch );
67 static void gdbstub_state_cksum1 ( struct gdbstub *stub, char ch );
68 static void gdbstub_state_cksum2 ( struct gdbstub *stub, char ch );
69 static void gdbstub_state_wait_ack ( struct gdbstub *stub, char ch );
70 
72  return ( isdigit ( ch ) ? ch - '0' : tolower ( ch ) - 'a' + 0xa ) & 0xf;
73 }
74 
76  b &= 0xf;
77  return ( b < 0xa ? '0' : 'a' - 0xa ) + b;
78 }
79 
80 /*
81  * To make reading/writing device memory atomic, we check for
82  * 2- or 4-byte aligned operations and handle them specially.
83  */
84 
85 static void gdbstub_from_hex_buf ( char *dst, char *src, int lenbytes ) {
86  if ( lenbytes == 2 && ( ( unsigned long ) dst & 0x1 ) == 0 ) {
87  uint16_t i = gdbstub_from_hex_digit ( src [ 2 ] ) << 12 |
88  gdbstub_from_hex_digit ( src [ 3 ] ) << 8 |
89  gdbstub_from_hex_digit ( src [ 0 ] ) << 4 |
90  gdbstub_from_hex_digit ( src [ 1 ] );
91  * ( uint16_t * ) dst = cpu_to_le16 ( i );
92  } else if ( lenbytes == 4 && ( ( unsigned long ) dst & 0x3 ) == 0 ) {
93  uint32_t i = gdbstub_from_hex_digit ( src [ 6 ] ) << 28 |
94  gdbstub_from_hex_digit ( src [ 7 ] ) << 24 |
95  gdbstub_from_hex_digit ( src [ 4 ] ) << 20 |
96  gdbstub_from_hex_digit ( src [ 5 ] ) << 16 |
97  gdbstub_from_hex_digit ( src [ 2 ] ) << 12 |
98  gdbstub_from_hex_digit ( src [ 3 ] ) << 8 |
99  gdbstub_from_hex_digit ( src [ 0 ] ) << 4 |
100  gdbstub_from_hex_digit ( src [ 1 ] );
101  * ( uint32_t * ) dst = cpu_to_le32 ( i );
102  } else {
103  while ( lenbytes-- > 0 ) {
104  *dst++ = gdbstub_from_hex_digit ( src [ 0 ] ) << 4 |
105  gdbstub_from_hex_digit ( src [ 1 ] );
106  src += 2;
107  }
108  }
109 }
110 
111 static void gdbstub_to_hex_buf ( char *dst, char *src, int lenbytes ) {
112  if ( lenbytes == 2 && ( ( unsigned long ) src & 0x1 ) == 0 ) {
113  uint16_t i = cpu_to_le16 ( * ( uint16_t * ) src );
114  dst [ 0 ] = gdbstub_to_hex_digit ( i >> 4 );
115  dst [ 1 ] = gdbstub_to_hex_digit ( i );
116  dst [ 2 ] = gdbstub_to_hex_digit ( i >> 12 );
117  dst [ 3 ] = gdbstub_to_hex_digit ( i >> 8 );
118  } else if ( lenbytes == 4 && ( ( unsigned long ) src & 0x3 ) == 0 ) {
119  uint32_t i = cpu_to_le32 ( * ( uint32_t * ) src );
120  dst [ 0 ] = gdbstub_to_hex_digit ( i >> 4 );
121  dst [ 1 ] = gdbstub_to_hex_digit ( i );
122  dst [ 2 ] = gdbstub_to_hex_digit ( i >> 12 );
123  dst [ 3 ] = gdbstub_to_hex_digit ( i >> 8 );
124  dst [ 4 ] = gdbstub_to_hex_digit ( i >> 20 );
125  dst [ 5 ] = gdbstub_to_hex_digit ( i >> 16);
126  dst [ 6 ] = gdbstub_to_hex_digit ( i >> 28 );
127  dst [ 7 ] = gdbstub_to_hex_digit ( i >> 24 );
128  } else {
129  while ( lenbytes-- > 0 ) {
130  *dst++ = gdbstub_to_hex_digit ( *src >> 4 );
131  *dst++ = gdbstub_to_hex_digit ( *src );
132  src++;
133  }
134  }
135 }
136 
137 static uint8_t gdbstub_cksum ( char *data, int len ) {
138  uint8_t cksum = 0;
139  while ( len-- > 0 ) {
140  cksum += ( uint8_t ) *data++;
141  }
142  return cksum;
143 }
144 
145 static void gdbstub_tx_packet ( struct gdbstub *stub ) {
146  uint8_t cksum = gdbstub_cksum ( stub->payload, stub->len );
147  stub->buf [ 0 ] = '$';
148  stub->buf [ stub->len + 1 ] = '#';
149  stub->buf [ stub->len + 2 ] = gdbstub_to_hex_digit ( cksum >> 4 );
150  stub->buf [ stub->len + 3 ] = gdbstub_to_hex_digit ( cksum );
151  stub->trans->send ( stub->buf, stub->len + 4 );
153 }
154 
155 /* GDB commands */
156 static void gdbstub_send_ok ( struct gdbstub *stub ) {
157  stub->payload [ 0 ] = 'O';
158  stub->payload [ 1 ] = 'K';
159  stub->len = 2;
161 }
162 
163 static void gdbstub_send_num_packet ( struct gdbstub *stub, char reply, int num ) {
164  stub->payload [ 0 ] = reply;
165  stub->payload [ 1 ] = gdbstub_to_hex_digit ( ( char ) num >> 4 );
166  stub->payload [ 2 ] = gdbstub_to_hex_digit ( ( char ) num );
167  stub->len = 3;
169 }
170 
171 /* Format is arg1,arg2,...,argn:data where argn are hex integers and data is not an argument */
172 static int gdbstub_get_packet_args ( struct gdbstub *stub, unsigned long *args, int nargs, int *stop_idx ) {
173  int i;
174  char ch = 0;
175  int argc = 0;
176  unsigned long val = 0;
177  for ( i = 1; i < stub->len && argc < nargs; i++ ) {
178  ch = stub->payload [ i ];
179  if ( ch == ':' ) {
180  break;
181  } else if ( ch == ',' ) {
182  args [ argc++ ] = val;
183  val = 0;
184  } else {
185  val = ( val << 4 ) | gdbstub_from_hex_digit ( ch );
186  }
187  }
188  if ( stop_idx ) {
189  *stop_idx = i;
190  }
191  if ( argc < nargs ) {
192  args [ argc++ ] = val;
193  }
194  return ( ( i == stub->len || ch == ':' ) && argc == nargs );
195 }
196 
197 static void gdbstub_send_errno ( struct gdbstub *stub, int errno ) {
199 }
200 
201 static void gdbstub_report_signal ( struct gdbstub *stub ) {
203 }
204 
205 static void gdbstub_read_regs ( struct gdbstub *stub ) {
209 }
210 
211 static void gdbstub_write_regs ( struct gdbstub *stub ) {
212  if ( stub->len != 1 + GDBMACH_SIZEOF_REGS * 2 ) {
214  return;
215  }
216  gdbstub_from_hex_buf ( ( char * ) stub->regs, &stub->payload [ 1 ], GDBMACH_SIZEOF_REGS );
217  gdbstub_send_ok ( stub );
218 }
219 
220 static void gdbstub_read_mem ( struct gdbstub *stub ) {
221  unsigned long args [ 2 ];
222  if ( !gdbstub_get_packet_args ( stub, args, sizeof args / sizeof args [ 0 ], NULL ) ) {
224  return;
225  }
226  args [ 1 ] = ( args [ 1 ] < SIZEOF_PAYLOAD / 2 ) ? args [ 1 ] : SIZEOF_PAYLOAD / 2;
227  gdbstub_to_hex_buf ( stub->payload, ( char * ) args [ 0 ], args [ 1 ] );
228  stub->len = args [ 1 ] * 2;
230 }
231 
232 static void gdbstub_write_mem ( struct gdbstub *stub ) {
233  unsigned long args [ 2 ];
234  int colon;
235  if ( !gdbstub_get_packet_args ( stub, args, sizeof args / sizeof args [ 0 ], &colon ) ||
236  colon >= stub->len || stub->payload [ colon ] != ':' ||
237  ( stub->len - colon - 1 ) % 2 != 0 ) {
239  return;
240  }
241  gdbstub_from_hex_buf ( ( char * ) args [ 0 ], &stub->payload [ colon + 1 ], ( stub->len - colon - 1 ) / 2 );
242  gdbstub_send_ok ( stub );
243 }
244 
245 static void gdbstub_continue ( struct gdbstub *stub, int single_step ) {
246  gdbreg_t pc;
247  if ( stub->len > 1 && gdbstub_get_packet_args ( stub, &pc, 1, NULL ) ) {
248  gdbmach_set_pc ( stub->regs, pc );
249  }
250  gdbmach_set_single_step ( stub->regs, single_step );
251  stub->exit_handler = 1;
252  /* Reply will be sent when we hit the next breakpoint or interrupt */
253 }
254 
255 static void gdbstub_breakpoint ( struct gdbstub *stub ) {
256  unsigned long args [ 3 ];
257  int enable = stub->payload [ 0 ] == 'Z' ? 1 : 0;
258  int rc;
259 
260  if ( !gdbstub_get_packet_args ( stub, args, sizeof args / sizeof args [ 0 ], NULL ) ) {
262  return;
263  }
264  if ( ( rc = gdbmach_set_breakpoint ( args [ 0 ], args [ 1 ],
265  args [ 2 ], enable ) ) != 0 ) {
266  /* Not supported */
267  stub->len = 0;
269  return;
270  }
271  gdbstub_send_ok ( stub );
272 }
273 
274 static void gdbstub_rx_packet ( struct gdbstub *stub ) {
275  switch ( stub->payload [ 0 ] ) {
276  case '?':
278  break;
279  case 'g':
281  break;
282  case 'G':
284  break;
285  case 'm':
287  break;
288  case 'M':
290  break;
291  case 'c': /* Continue */
292  case 'k': /* Kill */
293  case 's': /* Step */
294  case 'D': /* Detach */
295  gdbstub_continue ( stub, stub->payload [ 0 ] == 's' );
296  if ( stub->payload [ 0 ] == 'D' ) {
297  gdbstub_send_ok ( stub );
298  }
299  break;
300  case 'Z': /* Insert breakpoint */
301  case 'z': /* Remove breakpoint */
303  break;
304  default:
305  stub->len = 0;
307  break;
308  }
309 }
310 
311 /* GDB packet parser */
312 static void gdbstub_state_new ( struct gdbstub *stub, char ch ) {
313  if ( ch == '$' ) {
314  stub->len = 0;
316  }
317 }
318 
319 static void gdbstub_state_data ( struct gdbstub *stub, char ch ) {
320  if ( ch == '#' ) {
322  } else if ( ch == '$' ) {
323  stub->len = 0; /* retry new packet */
324  } else {
325  /* If the length exceeds our buffer, let the checksum fail */
326  if ( stub->len < SIZEOF_PAYLOAD ) {
327  stub->payload [ stub->len++ ] = ch;
328  }
329  }
330 }
331 
332 static void gdbstub_state_cksum1 ( struct gdbstub *stub, char ch ) {
333  stub->cksum1 = gdbstub_from_hex_digit ( ch ) << 4;
335 }
336 
337 static void gdbstub_state_cksum2 ( struct gdbstub *stub, char ch ) {
338  uint8_t their_cksum;
339  uint8_t our_cksum;
340 
342  their_cksum = stub->cksum1 + gdbstub_from_hex_digit ( ch );
343  our_cksum = gdbstub_cksum ( stub->payload, stub->len );
344  if ( their_cksum == our_cksum ) {
345  stub->trans->send ( "+", 1 );
346  if ( stub->len > 0 ) {
348  }
349  } else {
350  stub->trans->send ( "-", 1 );
351  }
352 }
353 
354 static void gdbstub_state_wait_ack ( struct gdbstub *stub, char ch ) {
355  if ( ch == '+' ) {
357  } else {
358  /* This retransmit is very aggressive but necessary to keep
359  * in sync with GDB. */
361  }
362 }
363 
364 static void gdbstub_parse ( struct gdbstub *stub, char ch ) {
365  stub->parse ( stub, ch );
366 }
367 
368 static struct gdbstub stub = {
370 };
371 
373  char packet [ SIZEOF_PAYLOAD + 4 ];
374  size_t len, i;
375 
376  /* A transport must be set up */
377  if ( !stub.trans ) {
378  return;
379  }
380 
381  stub.signo = signo;
382  stub.regs = regs;
383  stub.exit_handler = 0;
385  while ( !stub.exit_handler && ( len = stub.trans->recv ( packet, sizeof ( packet ) ) ) > 0 ) {
386  for ( i = 0; i < len; i++ ) {
387  gdbstub_parse ( &stub, packet [ i ] );
388  }
389  }
390 }
391 
392 struct gdb_transport *find_gdb_transport ( const char *name ) {
393  struct gdb_transport *trans;
394 
396  if ( strcmp ( trans->name, name ) == 0 ) {
397  return trans;
398  }
399  }
400  return NULL;
401 }
402 
403 void gdbstub_start ( struct gdb_transport *trans ) {
404  stub.trans = trans;
405  stub.payload = &stub.buf [ 1 ];
406  gdbmach_init();
408 }
GDB architecture specifics.
struct arbelprm_rc_send_wqe rc
Definition: arbel.h:14
const char * name
Definition: ath9k_hw.c:1984
unsigned short uint16_t
Definition: stdint.h:11
static uint8_t gdbstub_cksum(char *data, int len)
Definition: gdbstub.c:137
static void gdbstub_state_wait_ack(struct gdbstub *stub, char ch)
Definition: gdbstub.c:354
struct gdb_transport * find_gdb_transport(const char *name)
Look up GDB transport by name.
Definition: gdbstub.c:392
static void gdbmach_breakpoint(void)
Definition: gdbmach.h:64
const char * name
Transport name.
Definition: gdbstub.h:22
void(* parse)(struct gdbstub *stub, char ch)
Definition: gdbstub.c:53
static void gdbstub_state_cksum2(struct gdbstub *stub, char ch)
Definition: gdbstub.c:337
static void gdbmach_set_single_step(gdbreg_t *regs, int step)
Definition: gdbmach.h:59
static void gdbstub_send_num_packet(struct gdbstub *stub, char reply, int num)
Definition: gdbstub.c:163
static void gdbstub_state_cksum1(struct gdbstub *stub, char ch)
Definition: gdbstub.c:332
int gdbmach_set_breakpoint(int type, unsigned long addr, size_t len, int enable)
Set hardware breakpoint.
Definition: gdbmach.c:134
void gdbmach_init(void)
Initialise GDB.
Definition: gdbmach.c:242
unsigned long gdbreg_t
Definition: gdbmach.h:15
Character types.
static void gdbstub_state_data(struct gdbstub *stub, char ch)
Definition: gdbstub.c:319
static void gdbstub_continue(struct gdbstub *stub, int single_step)
Definition: gdbstub.c:245
static void gdbstub_report_signal(struct gdbstub *stub)
Definition: gdbstub.c:201
static void gdbmach_set_pc(gdbreg_t *regs, gdbreg_t pc)
Definition: gdbmach.h:55
uint8_t ch
Definition: registers.h:83
int signo
Definition: gdbstub.c:50
static int gdbstub_get_packet_args(struct gdbstub *stub, unsigned long *args, int nargs, int *stop_idx)
Definition: gdbstub.c:172
static int isdigit(int character)
Check if character is a decimal digit.
Definition: ctype.h:18
static void gdbstub_write_regs(struct gdbstub *stub)
Definition: gdbstub.c:211
char * payload
Definition: gdbstub.c:60
int exit_handler
Definition: gdbstub.c:48
static void gdbstub_tx_packet(struct gdbstub *stub)
Definition: gdbstub.c:145
int errno
Global "last error" number.
Definition: errno.c:20
static void gdbstub_read_regs(struct gdbstub *stub)
Definition: gdbstub.c:205
static int tolower(int character)
Convert character to lower case.
Definition: ctype.h:97
static uint8_t gdbstub_from_hex_digit(char ch)
Definition: gdbstub.c:71
static void gdbstub_breakpoint(struct gdbstub *stub)
Definition: gdbstub.c:255
char buf[SIZEOF_PAYLOAD+4]
Definition: gdbstub.c:59
#define cpu_to_le32(value)
Definition: byteswap.h:107
char unsigned long * num
Definition: xenstore.h:17
static void gdbstub_send_errno(struct gdbstub *stub, int errno)
Definition: gdbstub.c:197
static __always_inline void off_t userptr_t src
Definition: efi_uaccess.h:66
struct gdb_transport * trans
Definition: gdbstub.c:47
static struct gdbstub stub
Definition: gdbstub.c:368
void gdbstub_start(struct gdb_transport *trans)
Break into the debugger using the given transport.
Definition: gdbstub.c:403
uint8_t cksum1
Definition: gdbstub.c:54
#define for_each_table_entry(pointer, table)
Iterate through all entries within a linker table.
Definition: tables.h:358
void gdbstub_handler(int signo, gdbreg_t *regs)
Interrupt handler.
Definition: gdbstub.c:372
static void gdbstub_write_mem(struct gdbstub *stub)
Definition: gdbstub.c:232
unsigned char uint8_t
Definition: stdint.h:10
gdbreg_t * regs
Definition: gdbstub.c:51
static void gdbstub_read_mem(struct gdbstub *stub)
Definition: gdbstub.c:220
unsigned int uint32_t
Definition: stdint.h:12
static void gdbstub_send_ok(struct gdbstub *stub)
Definition: gdbstub.c:156
struct i386_regs regs
Definition: registers.h:15
void __asmcall int val
Definition: setjmp.h:28
GDB remote debugging.
static void gdbstub_parse(struct gdbstub *stub, char ch)
Definition: gdbstub.c:364
uint32_t len
Length.
Definition: ena.h:14
static uint8_t gdbstub_to_hex_digit(uint8_t b)
Definition: gdbstub.c:75
int strcmp(const char *first, const char *second)
Compare strings.
Definition: string.c:157
static void gdbstub_rx_packet(struct gdbstub *stub)
Definition: gdbstub.c:274
size_t(* recv)(char *buf, size_t len)
Perform a blocking read.
Definition: gdbstub.h:40
#define cpu_to_le16(value)
Definition: byteswap.h:106
int len
Definition: gdbstub.c:61
FILE_LICENCE(GPL2_OR_LATER_OR_UBDL)
#define GDB_TRANSPORTS
Definition: gdbstub.h:50
struct arbelprm_port_state_change_st data
Message.
Definition: arbel.h:12
static void gdbstub_to_hex_buf(char *dst, char *src, int lenbytes)
Definition: gdbstub.c:111
void(* send)(const char *buf, size_t len)
Write, may block.
Definition: gdbstub.h:47
static void gdbstub_from_hex_buf(char *dst, char *src, int lenbytes)
Definition: gdbstub.c:85
#define NULL
NULL pointer (VOID *)
Definition: Base.h:362
String functions.
A transport mechanism for the GDB protocol.
Definition: gdbstub.h:20
static void gdbstub_state_new(struct gdbstub *stub, char ch)
Definition: gdbstub.c:312