FreeBSD/Linux Kernel Cross Reference
sys/kern/kgdb_stub.c
1 /* $NetBSD: kgdb_stub.c,v 1.17 2004/03/23 13:22:03 junyoung Exp $ */
2
3 /*
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This software was developed by the Computer Systems Engineering group
8 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
9 * contributed to Berkeley.
10 *
11 * All advertising materials mentioning features or use of this software
12 * must display the following acknowledgement:
13 * This product includes software developed by the University of
14 * California, Lawrence Berkeley Laboratories.
15 *
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
18 * are met:
19 * 1. Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer.
21 * 2. Redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution.
24 * 3. Neither the name of the University nor the names of its contributors
25 * may be used to endorse or promote products derived from this software
26 * without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * SUCH DAMAGE.
39 *
40 * @(#)kgdb_stub.c 8.4 (Berkeley) 1/12/94
41 */
42
43 /*
44 * "Stub" to allow remote CPU to debug over a serial line using gdb.
45 */
46
47 #include <sys/cdefs.h>
48 __KERNEL_RCSID(0, "$NetBSD: kgdb_stub.c,v 1.17 2004/03/23 13:22:03 junyoung Exp $");
49
50 #include "opt_kgdb.h"
51
52 #include <sys/param.h>
53 #include <sys/systm.h>
54 #include <sys/kgdb.h>
55
56 #undef DEBUG_KGDB
57
58 #ifdef DEBUG_KGDB
59 #define DPRINTF(x) printf x
60 #else
61 #define DPRINTF(x)
62 #endif
63
64 /* XXX: Maybe these should be in the MD files? */
65 #ifndef KGDB_DEV
66 #define KGDB_DEV NODEV
67 #endif
68 #ifndef KGDB_DEVRATE
69 #define KGDB_DEVRATE 19200
70 #endif
71
72 int kgdb_dev = KGDB_DEV; /* remote debugging device (NODEV if none) */
73 int kgdb_rate = KGDB_DEVRATE; /* remote debugging baud rate */
74 int kgdb_active = 0; /* remote debugging active if != 0 */
75 int kgdb_debug_init = 0; /* != 0 waits for remote at system init */
76 int kgdb_debug_panic = 0; /* != 0 waits for remote on panic */
77 label_t *kgdb_recover = 0;
78
79 static void kgdb_copy(void *, void *, int);
80 /* static void kgdb_zero(void *, int); */
81 static void kgdb_send(u_char *);
82 static int kgdb_recv(u_char *, int);
83 static int digit2i(u_char);
84 static u_char i2digit(int);
85 static void mem2hex(void *, void *, int);
86 static u_char *hex2mem(void *, u_char *, int);
87 static vaddr_t hex2i(u_char **);
88
89 static int (*kgdb_getc)(void *);
90 static void (*kgdb_putc)(void *, int);
91 static void *kgdb_ioarg;
92
93 /* KGDB_BUFLEN must be at least (2*KGDB_NUMREGS*sizeof(kgdb_reg_t)+1) */
94 static u_char buffer[KGDB_BUFLEN];
95 static kgdb_reg_t gdb_regs[KGDB_NUMREGS];
96
97 #define GETC() ((*kgdb_getc)(kgdb_ioarg))
98 #define PUTC(c) ((*kgdb_putc)(kgdb_ioarg, c))
99
100 /*
101 * db_trap_callback can be hooked by MD port code to handle special
102 * cases such as disabling hardware watchdogs while in kgdb. Name
103 * is shared with DDB.
104 */
105 void (*db_trap_callback)(int);
106
107 /*
108 * This little routine exists simply so that bcopy() can be debugged.
109 */
110 static void
111 kgdb_copy(vsrc, vdst, len)
112 void *vsrc, *vdst;
113 int len;
114 {
115 char *src = vsrc;
116 char *dst = vdst;
117
118 while (--len >= 0)
119 *dst++ = *src++;
120 }
121
122 #if 0
123 /* ditto for bzero */
124 static void
125 kgdb_zero(vptr, len)
126 void *vptr;
127 int len;
128 {
129 char *ptr = vptr;
130
131 while (--len >= 0)
132 *ptr++ = (char) 0;
133 }
134 #endif
135
136 /*
137 * Convert a hex digit into an integer.
138 * This returns -1 if the argument passed is no
139 * valid hex digit.
140 */
141 static int
142 digit2i(c)
143 u_char c;
144 {
145 if (c >= '' && c <= '9')
146 return (c - '');
147 else if (c >= 'a' && c <= 'f')
148 return (c - 'a' + 10);
149 else if (c >= 'A' && c <= 'F')
150
151 return (c - 'A' + 10);
152 else
153 return (-1);
154 }
155
156 /*
157 * Convert the low 4 bits of an integer into
158 * an hex digit.
159 */
160 static u_char
161 i2digit(n)
162 int n;
163 {
164 return ("0123456789abcdef"[n & 0x0f]);
165 }
166
167 /*
168 * Convert a byte array into an hex string.
169 */
170 static void
171 mem2hex(vdst, vsrc, len)
172 void *vdst, *vsrc;
173 int len;
174 {
175 u_char *dst = vdst;
176 u_char *src = vsrc;
177
178 while (len--) {
179 *dst++ = i2digit(*src >> 4);
180 *dst++ = i2digit(*src++);
181 }
182 *dst = '\0';
183 }
184
185 /*
186 * Convert an hex string into a byte array.
187 * This returns a pointer to the character following
188 * the last valid hex digit. If the string ends in
189 * the middle of a byte, NULL is returned.
190 */
191 static u_char *
192 hex2mem(vdst, src, maxlen)
193 void *vdst;
194 u_char *src;
195 int maxlen;
196 {
197 u_char *dst = vdst;
198 int msb, lsb;
199
200 while (*src && maxlen--) {
201 msb = digit2i(*src++);
202 if (msb < 0)
203 return (src - 1);
204 lsb = digit2i(*src++);
205 if (lsb < 0)
206 return (NULL);
207 *dst++ = (msb << 4) | lsb;
208 }
209 return (src);
210 }
211
212 /*
213 * Convert an hex string into an integer.
214 * This returns a pointer to the character following
215 * the last valid hex digit.
216 */
217 static vaddr_t
218 hex2i(srcp)
219 u_char **srcp;
220 {
221 char *src = *srcp;
222 vaddr_t r = 0;
223 int nibble;
224
225 while ((nibble = digit2i(*src)) >= 0) {
226 r *= 16;
227 r += nibble;
228 src++;
229 }
230 *srcp = src;
231 return (r);
232 }
233
234 /*
235 * Send a packet.
236 */
237 static void
238 kgdb_send(bp)
239 u_char *bp;
240 {
241 u_char *p;
242 u_char csum, c;
243
244 DPRINTF(("kgdb_send: %s\n", bp));
245 do {
246 p = bp;
247 PUTC(KGDB_START);
248 for (csum = 0; (c = *p); p++) {
249 PUTC(c);
250 csum += c;
251 }
252 PUTC(KGDB_END);
253 PUTC(i2digit(csum >> 4));
254 PUTC(i2digit(csum));
255 } while ((c = GETC() & 0x7f) == KGDB_BADP);
256 }
257
258 /*
259 * Receive a packet.
260 */
261 static int
262 kgdb_recv(bp, maxlen)
263 u_char *bp;
264 int maxlen;
265 {
266 u_char *p;
267 int c, csum, tmpcsum;
268 int len;
269
270 DPRINTF(("kgdb_recv: "));
271 do {
272 p = bp;
273 csum = len = 0;
274 while ((c = GETC()) != KGDB_START)
275 DPRINTF(("%c",c));
276 DPRINTF(("%c Start ",c));
277
278 while ((c = GETC()) != KGDB_END && len < maxlen) {
279 DPRINTF(("%c",c));
280 c &= 0x7f;
281 csum += c;
282 *p++ = c;
283 len++;
284 }
285 csum &= 0xff;
286 *p = '\0';
287 DPRINTF(("%c End ", c));
288
289 if (len >= maxlen) {
290 DPRINTF(("Long- "));
291 PUTC(KGDB_BADP);
292 continue;
293 }
294 tmpcsum = csum;
295
296 c = GETC();
297 DPRINTF(("%c",c));
298 csum -= digit2i(c) * 16;
299 c = GETC();
300 DPRINTF(("%c",c));
301 csum -= digit2i(c);
302
303 if (csum == 0) {
304 DPRINTF(("Good+ "));
305 PUTC(KGDB_GOODP);
306 /* Sequence present? */
307 if (bp[2] == ':') {
308 DPRINTF(("Seq %c%c ", bp[0], bp[1]));
309 PUTC(bp[0]);
310 PUTC(bp[1]);
311 len -= 3;
312 kgdb_copy(bp + 3, bp, len);
313 }
314 break;
315 }
316 DPRINTF((" Bad(wanted %x, off by %d)- ", tmpcsum, csum));
317 PUTC(KGDB_BADP);
318 } while (1);
319 DPRINTF(("kgdb_recv: %s\n", bp));
320 return (len);
321 }
322
323 /*
324 * This is called by the appropriate tty driver.
325 */
326 void
327 kgdb_attach(getfn, putfn, ioarg)
328 int (*getfn)(void *);
329 void (*putfn)(void *, int);
330 void *ioarg;
331 {
332 kgdb_getc = getfn;
333 kgdb_putc = putfn;
334 kgdb_ioarg = ioarg;
335 }
336
337 /*
338 * This function does all command processing for interfacing to
339 * a remote gdb. Note that the error codes are ignored by gdb
340 * at present, but might eventually become meaningful. (XXX)
341 * It might makes sense to use POSIX errno values, because
342 * that is what the gdb/remote.c functions want to return.
343 */
344 int
345 kgdb_trap(type, regs)
346 int type;
347 db_regs_t *regs;
348 {
349 label_t jmpbuf;
350 vaddr_t addr;
351 size_t len;
352 u_char *p;
353
354 if (kgdb_dev < 0 || kgdb_getc == NULL) {
355 /* not debugging */
356 return (0);
357 }
358
359 db_clear_single_step(regs);
360
361 if (db_trap_callback) db_trap_callback(1);
362
363 /* Detect and recover from unexpected traps. */
364 if (kgdb_recover != 0) {
365 printf("kgdb: caught trap 0x%x at %p\n",
366 type, (void*)PC_REGS(regs));
367 kgdb_send("E0E"); /* 14==EFAULT */
368 longjmp(kgdb_recover);
369 }
370
371 /*
372 * The first entry to this function is normally through
373 * a breakpoint trap in kgdb_connect(), in which case we
374 * must advance past the breakpoint because gdb will not.
375 *
376 * Machines vary as to where they leave the PC after a
377 * breakpoint trap. Those that leave the PC set to the
378 * address of the trap instruction (i.e. pc532) will not
379 * define FIXUP_PC_AFTER_BREAK(), and therefore will just
380 * advance the PC. On machines that leave the PC set to
381 * the instruction after the trap, FIXUP_PC_AFTER_BREAK
382 * will be defined to back-up the PC, so that after the
383 * "first-time" part of the if statement below has run,
384 * the PC will be the same as it was on entry.
385 *
386 * On the first entry here, we expect that gdb is not yet
387 * listening to us, so just enter the interaction loop.
388 * After the debugger is "active" (connected) it will be
389 * waiting for a "signaled" message from us.
390 */
391 if (kgdb_active == 0) {
392 if (!IS_BREAKPOINT_TRAP(type, 0)) {
393 /* No debugger active -- let trap handle this. */
394 if (db_trap_callback) db_trap_callback(0);
395 return (0);
396 }
397 /* Make the PC point at the breakpoint... */
398 #ifdef FIXUP_PC_AFTER_BREAK
399 FIXUP_PC_AFTER_BREAK(regs);
400 #endif
401 /* ... and then advance past it. */
402 #ifdef PC_ADVANCE
403 PC_ADVANCE(regs);
404 #else
405 PC_REGS(regs) += BKPT_SIZE;
406 #endif
407 kgdb_active = 1;
408 } else {
409 /* Tell remote host that an exception has occurred. */
410 sprintf(buffer, "S%02x", kgdb_signal(type));
411 kgdb_send(buffer);
412 }
413
414 /* Stick frame regs into our reg cache. */
415 kgdb_getregs(regs, gdb_regs);
416
417 /*
418 * Interact with gdb until it lets us go.
419 * If we cause a trap, resume here.
420 */
421 (void)setjmp((kgdb_recover = &jmpbuf));
422 for (;;) {
423 kgdb_recv(buffer, sizeof(buffer));
424 switch (buffer[0]) {
425
426 default:
427 /* Unknown command. */
428 kgdb_send("");
429 continue;
430
431 case KGDB_SIGNAL:
432 /*
433 * if this command came from a running gdb,
434 * answer it -- the other guy has no way of
435 * knowing if we're in or out of this loop
436 * when he issues a "remote-signal".
437 */
438 sprintf(buffer, "S%02x", kgdb_signal(type));
439 kgdb_send(buffer);
440 continue;
441
442 case KGDB_REG_R:
443 mem2hex(buffer, gdb_regs, sizeof(gdb_regs));
444 kgdb_send(buffer);
445 continue;
446
447 case KGDB_REG_W:
448 p = hex2mem(gdb_regs, buffer + 1, sizeof(gdb_regs));
449 if (p == NULL || *p != '\0')
450 kgdb_send("E01");
451 else {
452 kgdb_setregs(regs, gdb_regs);
453 kgdb_send("OK");
454 }
455 continue;
456
457 case KGDB_MEM_R:
458 p = buffer + 1;
459 addr = hex2i(&p);
460 if (*p++ != ',') {
461 kgdb_send("E02");
462 continue;
463 }
464 len = hex2i(&p);
465 if (*p != '\0') {
466 kgdb_send("E03");
467 continue;
468 }
469 if (len > sizeof(buffer) / 2) {
470 kgdb_send("E04");
471 continue;
472 }
473 if (kgdb_acc(addr, len) == 0) {
474 kgdb_send("E05");
475 continue;
476 }
477 db_read_bytes(addr, (size_t)len,
478 (char *)buffer + sizeof(buffer) / 2);
479 mem2hex(buffer, buffer + sizeof(buffer) / 2, len);
480 kgdb_send(buffer);
481 continue;
482
483 case KGDB_MEM_W:
484 p = buffer + 1;
485 addr = hex2i(&p);
486 if (*p++ != ',') {
487 kgdb_send("E06");
488 continue;
489 }
490 len = hex2i(&p);
491 if (*p++ != ':') {
492 kgdb_send("E07");
493 continue;
494 }
495 if (len > (sizeof(buffer) - (p - buffer))) {
496 kgdb_send("E08");
497 continue;
498 }
499 p = hex2mem(buffer, p, sizeof(buffer));
500 if (p == NULL) {
501 kgdb_send("E09");
502 continue;
503 }
504 if (kgdb_acc(addr, len) == 0) {
505 kgdb_send("E0A");
506 continue;
507 }
508 db_write_bytes(addr, (size_t)len, (char *)buffer);
509 kgdb_send("OK");
510 continue;
511
512 case KGDB_DETACH:
513 case KGDB_KILL:
514 kgdb_active = 0;
515 printf("kgdb detached\n");
516 db_clear_single_step(regs);
517 kgdb_send("OK");
518 goto out;
519
520 case KGDB_CONT:
521 if (buffer[1]) {
522 p = buffer + 1;
523 addr = hex2i(&p);
524 if (*p) {
525 kgdb_send("E0B");
526 continue;
527 }
528 PC_REGS(regs) = addr;
529 DPRINTF(("kgdb: continuing at %08lx\n", addr));
530
531 } else {
532 DPRINTF((
533 "kgdb: continuing at old address %08lx\n",
534 (vaddr_t)PC_REGS(regs)));
535 }
536
537 db_clear_single_step(regs);
538 goto out;
539
540 case KGDB_STEP:
541 if (buffer[1]) {
542 p = buffer + 1;
543 addr = hex2i(&p);
544 if (*p) {
545 kgdb_send("E0B");
546 continue;
547 }
548 PC_REGS(regs) = addr;
549 }
550 db_set_single_step(regs);
551 goto out;
552 }
553 }
554 out:
555 if (db_trap_callback) db_trap_callback(0);
556 kgdb_recover = 0;
557 return (1);
558 }
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