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 
40 enum {
41  POSIX_EINVAL = 0x1c, /* used to report bad arguments to GDB */
42  SIZEOF_PAYLOAD = 512, /* buffer size of GDB payload data */
43 };
44 
45 struct gdbstub {
47  int exit_handler; /* leave interrupt handler */
48 
49  int signo;
51 
52  void ( * parse ) ( struct gdbstub *stub, char ch );
54 
55  /* Buffer for payload data when parsing a packet. Once the
56  * packet has been received, this buffer is used to hold
57  * the reply payload. */
58  char buf [ SIZEOF_PAYLOAD + 4 ]; /* $...PAYLOAD...#XX */
59  char *payload; /* start of payload */
60  int len; /* length of payload */
61 };
62 
63 /* Packet parser states */
64 static void gdbstub_state_new ( struct gdbstub *stub, char ch );
65 static void gdbstub_state_data ( struct gdbstub *stub, char ch );
66 static void gdbstub_state_cksum1 ( struct gdbstub *stub, char ch );
67 static void gdbstub_state_cksum2 ( struct gdbstub *stub, char ch );
68 static void gdbstub_state_wait_ack ( struct gdbstub *stub, char ch );
69 
71  return ( isdigit ( ch ) ? ch - '0' : tolower ( ch ) - 'a' + 0xa ) & 0xf;
72 }
73 
75  b &= 0xf;
76  return ( b < 0xa ? '0' : 'a' - 0xa ) + b;
77 }
78 
79 /*
80  * To make reading/writing device memory atomic, we check for
81  * 2- or 4-byte aligned operations and handle them specially.
82  */
83 
84 static void gdbstub_from_hex_buf ( char *dst, char *src, int lenbytes ) {
85  if ( lenbytes == 2 && ( ( unsigned long ) dst & 0x1 ) == 0 ) {
86  uint16_t i = gdbstub_from_hex_digit ( src [ 2 ] ) << 12 |
87  gdbstub_from_hex_digit ( src [ 3 ] ) << 8 |
88  gdbstub_from_hex_digit ( src [ 0 ] ) << 4 |
89  gdbstub_from_hex_digit ( src [ 1 ] );
90  * ( uint16_t * ) dst = cpu_to_le16 ( i );
91  } else if ( lenbytes == 4 && ( ( unsigned long ) dst & 0x3 ) == 0 ) {
92  uint32_t i = gdbstub_from_hex_digit ( src [ 6 ] ) << 28 |
93  gdbstub_from_hex_digit ( src [ 7 ] ) << 24 |
94  gdbstub_from_hex_digit ( src [ 4 ] ) << 20 |
95  gdbstub_from_hex_digit ( src [ 5 ] ) << 16 |
96  gdbstub_from_hex_digit ( src [ 2 ] ) << 12 |
97  gdbstub_from_hex_digit ( src [ 3 ] ) << 8 |
98  gdbstub_from_hex_digit ( src [ 0 ] ) << 4 |
99  gdbstub_from_hex_digit ( src [ 1 ] );
100  * ( uint32_t * ) dst = cpu_to_le32 ( i );
101  } else {
102  while ( lenbytes-- > 0 ) {
103  *dst++ = gdbstub_from_hex_digit ( src [ 0 ] ) << 4 |
104  gdbstub_from_hex_digit ( src [ 1 ] );
105  src += 2;
106  }
107  }
108 }
109 
110 static void gdbstub_to_hex_buf ( char *dst, char *src, int lenbytes ) {
111  if ( lenbytes == 2 && ( ( unsigned long ) src & 0x1 ) == 0 ) {
112  uint16_t i = cpu_to_le16 ( * ( uint16_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  } else if ( lenbytes == 4 && ( ( unsigned long ) src & 0x3 ) == 0 ) {
118  uint32_t i = cpu_to_le32 ( * ( uint32_t * ) src );
119  dst [ 0 ] = gdbstub_to_hex_digit ( i >> 4 );
120  dst [ 1 ] = gdbstub_to_hex_digit ( i );
121  dst [ 2 ] = gdbstub_to_hex_digit ( i >> 12 );
122  dst [ 3 ] = gdbstub_to_hex_digit ( i >> 8 );
123  dst [ 4 ] = gdbstub_to_hex_digit ( i >> 20 );
124  dst [ 5 ] = gdbstub_to_hex_digit ( i >> 16);
125  dst [ 6 ] = gdbstub_to_hex_digit ( i >> 28 );
126  dst [ 7 ] = gdbstub_to_hex_digit ( i >> 24 );
127  } else {
128  while ( lenbytes-- > 0 ) {
129  *dst++ = gdbstub_to_hex_digit ( *src >> 4 );
130  *dst++ = gdbstub_to_hex_digit ( *src );
131  src++;
132  }
133  }
134 }
135 
136 static uint8_t gdbstub_cksum ( char *data, int len ) {
137  uint8_t cksum = 0;
138  while ( len-- > 0 ) {
139  cksum += ( uint8_t ) *data++;
140  }
141  return cksum;
142 }
143 
144 static void gdbstub_tx_packet ( struct gdbstub *stub ) {
145  uint8_t cksum = gdbstub_cksum ( stub->payload, stub->len );
146  stub->buf [ 0 ] = '$';
147  stub->buf [ stub->len + 1 ] = '#';
148  stub->buf [ stub->len + 2 ] = gdbstub_to_hex_digit ( cksum >> 4 );
149  stub->buf [ stub->len + 3 ] = gdbstub_to_hex_digit ( cksum );
150  stub->trans->send ( stub->buf, stub->len + 4 );
152 }
153 
154 /* GDB commands */
155 static void gdbstub_send_ok ( struct gdbstub *stub ) {
156  stub->payload [ 0 ] = 'O';
157  stub->payload [ 1 ] = 'K';
158  stub->len = 2;
160 }
161 
162 static void gdbstub_send_num_packet ( struct gdbstub *stub, char reply, int num ) {
163  stub->payload [ 0 ] = reply;
164  stub->payload [ 1 ] = gdbstub_to_hex_digit ( ( char ) num >> 4 );
165  stub->payload [ 2 ] = gdbstub_to_hex_digit ( ( char ) num );
166  stub->len = 3;
168 }
169 
170 /* Format is arg1,arg2,...,argn:data where argn are hex integers and data is not an argument */
171 static int gdbstub_get_packet_args ( struct gdbstub *stub, unsigned long *args, int nargs, int *stop_idx ) {
172  int i;
173  char ch = 0;
174  int argc = 0;
175  unsigned long val = 0;
176  for ( i = 1; i < stub->len && argc < nargs; i++ ) {
177  ch = stub->payload [ i ];
178  if ( ch == ':' ) {
179  break;
180  } else if ( ch == ',' ) {
181  args [ argc++ ] = val;
182  val = 0;
183  } else {
184  val = ( val << 4 ) | gdbstub_from_hex_digit ( ch );
185  }
186  }
187  if ( stop_idx ) {
188  *stop_idx = i;
189  }
190  if ( argc < nargs ) {
191  args [ argc++ ] = val;
192  }
193  return ( ( i == stub->len || ch == ':' ) && argc == nargs );
194 }
195 
196 static void gdbstub_send_errno ( struct gdbstub *stub, int errno ) {
198 }
199 
200 static void gdbstub_report_signal ( struct gdbstub *stub ) {
202 }
203 
204 static void gdbstub_read_regs ( struct gdbstub *stub ) {
208 }
209 
210 static void gdbstub_write_regs ( struct gdbstub *stub ) {
211  if ( stub->len != 1 + GDBMACH_SIZEOF_REGS * 2 ) {
213  return;
214  }
215  gdbstub_from_hex_buf ( ( char * ) stub->regs, &stub->payload [ 1 ], GDBMACH_SIZEOF_REGS );
216  gdbstub_send_ok ( stub );
217 }
218 
219 static void gdbstub_read_mem ( struct gdbstub *stub ) {
220  unsigned long args [ 2 ];
221  if ( !gdbstub_get_packet_args ( stub, args, sizeof args / sizeof args [ 0 ], NULL ) ) {
223  return;
224  }
225  args [ 1 ] = ( args [ 1 ] < SIZEOF_PAYLOAD / 2 ) ? args [ 1 ] : SIZEOF_PAYLOAD / 2;
226  gdbstub_to_hex_buf ( stub->payload, ( char * ) args [ 0 ], args [ 1 ] );
227  stub->len = args [ 1 ] * 2;
229 }
230 
231 static void gdbstub_write_mem ( struct gdbstub *stub ) {
232  unsigned long args [ 2 ];
233  int colon;
234  if ( !gdbstub_get_packet_args ( stub, args, sizeof args / sizeof args [ 0 ], &colon ) ||
235  colon >= stub->len || stub->payload [ colon ] != ':' ||
236  ( stub->len - colon - 1 ) % 2 != 0 ) {
238  return;
239  }
240  gdbstub_from_hex_buf ( ( char * ) args [ 0 ], &stub->payload [ colon + 1 ], ( stub->len - colon - 1 ) / 2 );
241  gdbstub_send_ok ( stub );
242 }
243 
244 static void gdbstub_continue ( struct gdbstub *stub, int single_step ) {
245  gdbreg_t pc;
246  if ( stub->len > 1 && gdbstub_get_packet_args ( stub, &pc, 1, NULL ) ) {
247  gdbmach_set_pc ( stub->regs, pc );
248  }
249  gdbmach_set_single_step ( stub->regs, single_step );
250  stub->exit_handler = 1;
251  /* Reply will be sent when we hit the next breakpoint or interrupt */
252 }
253 
254 static void gdbstub_breakpoint ( struct gdbstub *stub ) {
255  unsigned long args [ 3 ];
256  int enable = stub->payload [ 0 ] == 'Z' ? 1 : 0;
257  int rc;
258 
259  if ( !gdbstub_get_packet_args ( stub, args, sizeof args / sizeof args [ 0 ], NULL ) ) {
261  return;
262  }
263  if ( ( rc = gdbmach_set_breakpoint ( args [ 0 ], args [ 1 ],
264  args [ 2 ], enable ) ) != 0 ) {
265  /* Not supported */
266  stub->len = 0;
268  return;
269  }
270  gdbstub_send_ok ( stub );
271 }
272 
273 static void gdbstub_rx_packet ( struct gdbstub *stub ) {
274  switch ( stub->payload [ 0 ] ) {
275  case '?':
277  break;
278  case 'g':
280  break;
281  case 'G':
283  break;
284  case 'm':
286  break;
287  case 'M':
289  break;
290  case 'c': /* Continue */
291  case 'k': /* Kill */
292  case 's': /* Step */
293  case 'D': /* Detach */
294  gdbstub_continue ( stub, stub->payload [ 0 ] == 's' );
295  if ( stub->payload [ 0 ] == 'D' ) {
296  gdbstub_send_ok ( stub );
297  }
298  break;
299  case 'Z': /* Insert breakpoint */
300  case 'z': /* Remove breakpoint */
302  break;
303  default:
304  stub->len = 0;
306  break;
307  }
308 }
309 
310 /* GDB packet parser */
311 static void gdbstub_state_new ( struct gdbstub *stub, char ch ) {
312  if ( ch == '$' ) {
313  stub->len = 0;
315  }
316 }
317 
318 static void gdbstub_state_data ( struct gdbstub *stub, char ch ) {
319  if ( ch == '#' ) {
321  } else if ( ch == '$' ) {
322  stub->len = 0; /* retry new packet */
323  } else {
324  /* If the length exceeds our buffer, let the checksum fail */
325  if ( stub->len < SIZEOF_PAYLOAD ) {
326  stub->payload [ stub->len++ ] = ch;
327  }
328  }
329 }
330 
331 static void gdbstub_state_cksum1 ( struct gdbstub *stub, char ch ) {
332  stub->cksum1 = gdbstub_from_hex_digit ( ch ) << 4;
334 }
335 
336 static void gdbstub_state_cksum2 ( struct gdbstub *stub, char ch ) {
337  uint8_t their_cksum;
338  uint8_t our_cksum;
339 
341  their_cksum = stub->cksum1 + gdbstub_from_hex_digit ( ch );
342  our_cksum = gdbstub_cksum ( stub->payload, stub->len );
343  if ( their_cksum == our_cksum ) {
344  stub->trans->send ( "+", 1 );
345  if ( stub->len > 0 ) {
347  }
348  } else {
349  stub->trans->send ( "-", 1 );
350  }
351 }
352 
353 static void gdbstub_state_wait_ack ( struct gdbstub *stub, char ch ) {
354  if ( ch == '+' ) {
356  } else {
357  /* This retransmit is very aggressive but necessary to keep
358  * in sync with GDB. */
360  }
361 }
362 
363 static void gdbstub_parse ( struct gdbstub *stub, char ch ) {
364  stub->parse ( stub, ch );
365 }
366 
367 static struct gdbstub stub = {
369 };
370 
372  char packet [ SIZEOF_PAYLOAD + 4 ];
373  size_t len, i;
374 
375  /* A transport must be set up */
376  if ( !stub.trans ) {
377  return;
378  }
379 
380  stub.signo = signo;
381  stub.regs = regs;
382  stub.exit_handler = 0;
384  while ( !stub.exit_handler && ( len = stub.trans->recv ( packet, sizeof ( packet ) ) ) > 0 ) {
385  for ( i = 0; i < len; i++ ) {
386  gdbstub_parse ( &stub, packet [ i ] );
387  }
388  }
389 }
390 
391 struct gdb_transport *find_gdb_transport ( const char *name ) {
392  struct gdb_transport *trans;
393 
395  if ( strcmp ( trans->name, name ) == 0 ) {
396  return trans;
397  }
398  }
399  return NULL;
400 }
401 
402 void gdbstub_start ( struct gdb_transport *trans ) {
403  stub.trans = trans;
404  stub.payload = &stub.buf [ 1 ];
405  gdbmach_init();
407 }
static const void * src
Definition: string.h:47
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:136
static void gdbstub_state_wait_ack(struct gdbstub *stub, char ch)
Definition: gdbstub.c:353
void __asmcall int val
Definition: setjmp.h:12
struct gdb_transport * find_gdb_transport(const char *name)
Look up GDB transport by name.
Definition: gdbstub.c:391
unsigned long gdbreg_t
Definition: gdbmach.h:15
const char * name
Transport name.
Definition: gdbstub.h:22
void(* parse)(struct gdbstub *stub, char ch)
Definition: gdbstub.c:52
static void gdbstub_state_cksum2(struct gdbstub *stub, char ch)
Definition: gdbstub.c:336
static void gdbmach_breakpoint(void)
Definition: gdbmach.h:64
static void gdbstub_send_num_packet(struct gdbstub *stub, char reply, int num)
Definition: gdbstub.c:162
static void gdbstub_state_cksum1(struct gdbstub *stub, char ch)
Definition: gdbstub.c:331
int gdbmach_set_breakpoint(int type, unsigned long addr, size_t len, int enable)
Set hardware breakpoint.
Definition: gdbmach.c:133
void gdbmach_init(void)
Initialise GDB.
Definition: gdbmach.c:241
Character types.
static void gdbstub_state_data(struct gdbstub *stub, char ch)
Definition: gdbstub.c:318
static void gdbstub_continue(struct gdbstub *stub, int single_step)
Definition: gdbstub.c:244
static void gdbstub_report_signal(struct gdbstub *stub)
Definition: gdbstub.c:200
uint8_t ch
Definition: registers.h:83
int signo
Definition: gdbstub.c:49
uint32_t num
Definition: multiboot.h:12
static int gdbstub_get_packet_args(struct gdbstub *stub, unsigned long *args, int nargs, int *stop_idx)
Definition: gdbstub.c:171
static int isdigit(int character)
Check if character is a decimal digit.
Definition: ctype.h:29
static void gdbstub_write_regs(struct gdbstub *stub)
Definition: gdbstub.c:210
char * payload
Definition: gdbstub.c:59
int exit_handler
Definition: gdbstub.c:47
static void gdbstub_tx_packet(struct gdbstub *stub)
Definition: gdbstub.c:144
int errno
Global "last error" number.
Definition: errno.c:20
static void gdbstub_read_regs(struct gdbstub *stub)
Definition: gdbstub.c:204
static int tolower(int character)
Convert character to lower case.
Definition: ctype.h:108
static uint8_t gdbstub_from_hex_digit(char ch)
Definition: gdbstub.c:70
static void gdbstub_breakpoint(struct gdbstub *stub)
Definition: gdbstub.c:254
char buf[SIZEOF_PAYLOAD+4]
Definition: gdbstub.c:58
#define cpu_to_le32(value)
Definition: byteswap.h:107
static void gdbstub_send_errno(struct gdbstub *stub, int errno)
Definition: gdbstub.c:196
struct gdb_transport * trans
Definition: gdbstub.c:46
static struct gdbstub stub
Definition: gdbstub.c:367
void gdbstub_start(struct gdb_transport *trans)
Break into the debugger using the given transport.
Definition: gdbstub.c:402
uint8_t cksum1
Definition: gdbstub.c:53
#define for_each_table_entry(pointer, table)
Iterate through all entries within a linker table.
Definition: tables.h:385
void gdbstub_handler(int signo, gdbreg_t *regs)
Interrupt handler.
Definition: gdbstub.c:371
static void gdbstub_write_mem(struct gdbstub *stub)
Definition: gdbstub.c:231
unsigned char uint8_t
Definition: stdint.h:10
gdbreg_t * regs
Definition: gdbstub.c:50
static void gdbstub_read_mem(struct gdbstub *stub)
Definition: gdbstub.c:219
unsigned int uint32_t
Definition: stdint.h:12
static void gdbstub_send_ok(struct gdbstub *stub)
Definition: gdbstub.c:155
struct i386_regs regs
Definition: registers.h:15
GDB remote debugging.
static void gdbstub_parse(struct gdbstub *stub, char ch)
Definition: gdbstub.c:363
static uint8_t gdbstub_to_hex_digit(uint8_t b)
Definition: gdbstub.c:74
int strcmp(const char *first, const char *second)
Compare strings.
Definition: string.c:173
static void gdbstub_rx_packet(struct gdbstub *stub)
Definition: gdbstub.c:273
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
static void gdbmach_set_pc(gdbreg_t *regs, gdbreg_t pc)
Definition: gdbmach.h:55
uint8_t data[48]
Additional event data.
Definition: ena.h:22
int len
Definition: gdbstub.c:60
FILE_LICENCE(GPL2_OR_LATER_OR_UBDL)
static void gdbmach_set_single_step(gdbreg_t *regs, int step)
Definition: gdbmach.h:59
#define GDB_TRANSPORTS
Definition: gdbstub.h:50
static void gdbstub_to_hex_buf(char *dst, char *src, int lenbytes)
Definition: gdbstub.c:110
void(* send)(const char *buf, size_t len)
Write, may block.
Definition: gdbstub.h:47
uint32_t len
Length.
Definition: ena.h:14
static void gdbstub_from_hex_buf(char *dst, char *src, int lenbytes)
Definition: gdbstub.c:84
#define NULL
NULL pointer (VOID *)
Definition: Base.h:321
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:311