2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2004 Marcel Moolenaar
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
32 #include <sys/param.h>
33 #include <sys/systm.h>
35 #include <sys/kernel.h>
38 #include <sys/reboot.h>
41 #include <machine/gdb_machdep.h>
42 #include <machine/kdb.h>
45 #include <gdb/gdb_int.h>
47 SYSCTL_NODE(_debug, OID_AUTO, gdb, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
50 static dbbe_init_f gdb_init;
51 static dbbe_trap_f gdb_trap;
53 KDB_BACKEND(gdb, gdb_init, NULL, NULL, gdb_trap);
55 static struct gdb_dbgport null_gdb_dbgport;
56 DATA_SET(gdb_dbgport_set, null_gdb_dbgport);
57 SET_DECLARE(gdb_dbgport_set, struct gdb_dbgport);
59 struct gdb_dbgport *gdb_cur = NULL;
60 int gdb_listening = 0;
61 bool gdb_ackmode = true;
63 static unsigned char gdb_bindata[64];
66 bool gdb_return_to_ddb = false;
72 struct gdb_dbgport *dp, **iter;
77 SET_FOREACH(iter, gdb_dbgport_set) {
79 pri = (dp->gdb_probe != NULL) ? dp->gdb_probe() : -1;
80 dp->gdb_active = (pri >= 0) ? 0 : -1;
86 if (gdb_cur != NULL) {
87 printf("GDB: debug ports:");
88 SET_FOREACH(iter, gdb_dbgport_set) {
90 if (dp->gdb_active == 0)
91 printf(" %s", dp->gdb_name);
95 printf("GDB: no debug ports present\n");
96 if (gdb_cur != NULL) {
98 printf("GDB: current port: %s\n", gdb_cur->gdb_name);
100 if (gdb_cur != NULL) {
101 cur_pri = (boothowto & RB_GDB) ? 2 : 0;
109 gdb_do_mem_search(void)
113 const unsigned char *found;
115 if (gdb_rx_varhex(&addr) || gdb_rx_char() != ';' ||
116 gdb_rx_varhex(&size) || gdb_rx_char() != ';' ||
117 gdb_rx_bindata(gdb_bindata, sizeof(gdb_bindata), &patlen)) {
121 if (gdb_search_mem((char *)(uintptr_t)addr, size, gdb_bindata,
128 gdb_tx_hex((intmax_t)(uintptr_t)found, 8);
136 gdb_do_threadinfo(struct thread **thr_iter)
138 static struct thread * const done_sentinel = (void *)(uintptr_t)1;
139 static const size_t tidsz_hex = sizeof(lwpid_t) * 2;
142 if (*thr_iter == NULL) {
147 if (*thr_iter == done_sentinel) {
156 *thr_iter != NULL && gdb_txbuf_has_capacity(tidsz_hex + 1);
157 *thr_iter = kdb_thr_next(*thr_iter), tds_sent++) {
160 gdb_tx_varhex((*thr_iter)->td_tid);
164 * Can't send EOF and "some" in same packet, so set a sentinel to send
165 * EOF when GDB asks us next.
167 if (*thr_iter == NULL && tds_sent > 0)
168 *thr_iter = done_sentinel;
174 #define BIT(n) (1ull << (n))
187 static const char * const gdb_feature_names[] = {
188 [GDB_MULTIPROCESS] = "multiprocess",
189 [GDB_SWBREAK] = "swbreak",
190 [GDB_HWBREAK] = "hwbreak",
191 [GDB_QRELOCINSN] = "qRelocInsn",
192 [GDB_FORK_EVENTS] = "fork-events",
193 [GDB_VFORK_EVENTS] = "vfork-events",
194 [GDB_EXEC_EVENTS] = "exec-events",
195 [GDB_VCONT_SUPPORTED] = "vContSupported",
196 [GDB_QTHREADEVENTS] = "QThreadEvents",
197 [GDB_NO_RESUMED] = "no-resumed",
200 gdb_do_qsupported(uint32_t *feat)
202 char *tok, *delim, ok;
205 /* Parse supported host features */
207 switch (gdb_rx_char()) {
216 while (gdb_rxsz > 0) {
218 delim = strchrnul(gdb_rxp, ';');
219 toklen = (delim - tok);
223 if (*delim != '\0') {
232 ok = tok[toklen - 1];
233 if (ok != '-' && ok != '+') {
235 * GDB only has one KV-pair feature, and we don't
236 * support it, so ignore and move on.
238 if (strchr(tok, '=') != NULL)
240 /* Not a KV-pair, and not a +/- flag? Malformed. */
245 tok[toklen - 1] = '\0';
247 for (i = 0; i < nitems(gdb_feature_names); i++)
248 if (strcmp(gdb_feature_names[i], tok) == 0)
251 if (i == nitems(gdb_feature_names)) {
252 /* Unknown GDB feature. */
260 /* Send a supported feature list back */
263 gdb_tx_str("PacketSize");
266 * We don't buffer framing bytes, but we do need to retain a byte for a
269 gdb_tx_varhex(GDB_BUFSZ + strlen("$#nn") - 1);
271 gdb_tx_str(";qXfer:threads:read+");
274 * If the debugport is a reliable transport, request No Ack mode from
275 * the server. The server may or may not choose to enter No Ack mode.
276 * https://sourceware.org/gdb/onlinedocs/gdb/Packet-Acknowledgment.html
278 if (gdb_cur->gdb_dbfeatures & GDB_DBGP_FEAT_RELIABLE)
279 gdb_tx_str(";QStartNoAckMode+");
282 * Future consideration:
295 * A qXfer_context provides a vaguely generic way to generate a multi-packet
296 * response on the fly, making some assumptions about the size of sbuf writes
297 * vs actual packet length constraints. A non-byzantine gdb host should allow
298 * hundreds of bytes per packet or more.
300 * Upper layers are considered responsible for escaping the four forbidden
301 * characters '# $ } *'.
303 struct qXfer_context {
308 char xfer_buf[GDB_BUFSZ];
312 qXfer_drain(void *v, const char *buf, int len)
314 struct qXfer_context *qx;
322 * Overflow. We lost some message. Maybe the packet size is
323 * ridiculously small.
325 printf("%s: Overflow in qXfer detected.\n", __func__);
329 qx->last_offset += len;
337 memcpy(gdb_txp, buf, len);
345 init_qXfer_ctx(struct qXfer_context *qx, uintmax_t len)
348 /* Protocol (max) length field includes framing overhead. */
349 if (len < sizeof("$m#nn"))
353 len = ummin(len, GDB_BUFSZ - 1);
357 qx->lastmessage = false;
358 sbuf_new(&qx->sb, qx->xfer_buf, len, SBUF_FIXEDLEN);
359 sbuf_set_drain(&qx->sb, qXfer_drain, qx);
364 * Squashes special XML and GDB characters down to _. Sorry.
367 qXfer_escape_xmlattr_str(char *dst, size_t dstlen, const char *src)
369 static const char *forbidden = "#$}*";
374 for (i = 0; i < dstlen - 1 && *src != 0; src++, i++) {
376 /* XML attr filter */
379 /* We assume attributes will be "" quoted. */
380 if (c == '<' || c == '&' || c == '"')
384 if (strchr(forbidden, c) != NULL) {
386 * It would be nice to escape these properly, but to do
387 * it correctly we need to escape them in the transmit
388 * layer, potentially doubling our buffer requirements.
389 * For now, avoid breaking the protocol by squashing
390 * them to underscore.
401 printf("XXX%s: overflow; API misuse\n", __func__);
407 * Dynamically generate qXfer:threads document, one packet at a time.
409 * The format is loosely described[0], although it does not seem that the
410 * <?xml?> mentioned on that page is required.
412 * [0]: https://sourceware.org/gdb/current/onlinedocs/gdb/Thread-List-Format.html
415 do_qXfer_threads_read(void)
419 struct qXfer_context qXfer;
420 /* Kludgy state machine */
423 XML_START_THREAD, /* '<thread' */
424 XML_THREAD_ID, /* ' id="xxx"' */
425 XML_THREAD_CORE, /* ' core="yyy"' */
426 XML_THREAD_NAME, /* ' name="zzz"' */
427 XML_THREAD_EXTRA, /* '> ...' */
428 XML_END_THREAD, /* '</thread>' */
429 XML_SENT_END_THREADS, /* '</threads>' */
432 static char td_name_escape[MAXCOMLEN * 2 + 1];
434 const char *name_src;
435 uintmax_t offset, len;
438 /* Annex part must be empty. */
439 if (gdb_rx_char() != ':')
440 goto misformed_request;
442 if (gdb_rx_varhex(&offset) != 0 ||
443 gdb_rx_char() != ',' ||
444 gdb_rx_varhex(&len) != 0)
445 goto misformed_request;
448 * Validate resume xfers.
451 if (offset != ctx.qXfer.last_offset) {
452 printf("%s: Resumed offset %ju != expected %zu\n",
453 __func__, offset, ctx.qXfer.last_offset);
457 ctx.qXfer.flushed = false;
461 ctx.iter = kdb_thr_first();
462 ctx.next_step = XML_START_THREAD;
463 error = init_qXfer_ctx(&ctx.qXfer, len);
467 sbuf_cat(&ctx.qXfer.sb, "<threads>");
470 while (!ctx.qXfer.flushed && ctx.iter != NULL) {
471 switch (ctx.next_step) {
472 case XML_START_THREAD:
473 ctx.next_step = XML_THREAD_ID;
474 sbuf_cat(&ctx.qXfer.sb, "<thread");
478 ctx.next_step = XML_THREAD_CORE;
479 sbuf_printf(&ctx.qXfer.sb, " id=\"%jx\"",
480 (uintmax_t)ctx.iter->td_tid);
483 case XML_THREAD_CORE:
484 ctx.next_step = XML_THREAD_NAME;
485 if (ctx.iter->td_oncpu != NOCPU) {
486 sbuf_printf(&ctx.qXfer.sb, " core=\"%d\"",
491 case XML_THREAD_NAME:
492 ctx.next_step = XML_THREAD_EXTRA;
494 if (ctx.iter->td_name[0] != 0)
495 name_src = ctx.iter->td_name;
496 else if (ctx.iter->td_proc != NULL &&
497 ctx.iter->td_proc->p_comm[0] != 0)
498 name_src = ctx.iter->td_proc->p_comm;
502 qXfer_escape_xmlattr_str(td_name_escape,
503 sizeof(td_name_escape), name_src);
504 sbuf_printf(&ctx.qXfer.sb, " name=\"%s\"",
508 case XML_THREAD_EXTRA:
509 ctx.next_step = XML_END_THREAD;
511 sbuf_putc(&ctx.qXfer.sb, '>');
513 if (ctx.iter->td_state == TDS_RUNNING)
514 sbuf_cat(&ctx.qXfer.sb, "Running");
515 else if (ctx.iter->td_state == TDS_RUNQ)
516 sbuf_cat(&ctx.qXfer.sb, "RunQ");
517 else if (ctx.iter->td_state == TDS_CAN_RUN)
518 sbuf_cat(&ctx.qXfer.sb, "CanRun");
519 else if (TD_ON_LOCK(ctx.iter))
520 sbuf_cat(&ctx.qXfer.sb, "Blocked");
521 else if (TD_IS_SLEEPING(ctx.iter))
522 sbuf_cat(&ctx.qXfer.sb, "Sleeping");
523 else if (TD_IS_SWAPPED(ctx.iter))
524 sbuf_cat(&ctx.qXfer.sb, "Swapped");
525 else if (TD_AWAITING_INTR(ctx.iter))
526 sbuf_cat(&ctx.qXfer.sb, "IthreadWait");
527 else if (TD_IS_SUSPENDED(ctx.iter))
528 sbuf_cat(&ctx.qXfer.sb, "Suspended");
530 sbuf_cat(&ctx.qXfer.sb, "???");
534 ctx.next_step = XML_START_THREAD;
535 sbuf_cat(&ctx.qXfer.sb, "</thread>");
536 ctx.iter = kdb_thr_next(ctx.iter);
540 * This one isn't part of the looping state machine,
541 * but GCC complains if you leave an enum value out of the
544 case XML_SENT_END_THREADS:
549 if (ctx.qXfer.flushed)
552 if (ctx.next_step != XML_SENT_END_THREADS) {
553 ctx.next_step = XML_SENT_END_THREADS;
554 sbuf_cat(&ctx.qXfer.sb, "</threads>");
556 if (ctx.qXfer.flushed)
559 ctx.qXfer.lastmessage = true;
560 sbuf_finish(&ctx.qXfer.sb);
561 sbuf_delete(&ctx.qXfer.sb);
562 ctx.qXfer.last_offset = 0;
567 * GDB "General-Query-Packets.html" qXfer-read anchor specifically
568 * documents an E00 code for malformed requests or invalid annex.
569 * Non-zero codes indicate invalid offset or "error reading the data."
578 * A set of standardized transfers from "special data areas."
580 * We've already matched on "qXfer:" and advanced the rx packet buffer past
581 * that bit. Parse out the rest of the packet and generate an appropriate
587 if (!gdb_rx_equal("threads:"))
590 if (!gdb_rx_equal("read:"))
593 do_qXfer_threads_read();
602 gdb_handle_detach(void)
604 kdb_cpu_clear_singlestep();
607 if (gdb_cur->gdb_dbfeatures & GDB_DBGP_FEAT_WANTTERM)
611 if (!gdb_return_to_ddb)
614 gdb_return_to_ddb = false;
616 if (kdb_dbbe_select("ddb") != 0)
617 printf("The ddb backend could not be selected.\n");
622 gdb_trap(int type, int code)
625 struct thread *thr_iter;
627 uint32_t host_features;
629 prev_jb = kdb_jmpbuf(jb);
630 if (setjmp(jb) != 0) {
631 printf("%s bailing, hopefully back to ddb!\n", __func__);
633 (void)kdb_jmpbuf(prev_jb);
641 * Send a T packet. We currently do not support watchpoints (the
642 * awatch, rwatch or watch elements).
645 gdb_tx_hex(gdb_cpu_signal(type, code), 2);
646 gdb_tx_varhex(GDB_REG_PC);
648 gdb_tx_reg(GDB_REG_PC);
650 gdb_tx_str("thread:");
651 gdb_tx_varhex((long)kdb_thread->td_tid);
653 gdb_tx_end(); /* XXX check error condition. */
656 while (gdb_rx_begin() == 0) {
657 /* printf("GDB: got '%s'\n", gdb_rxp); */
658 switch (gdb_rx_char()) {
659 case '?': /* Last signal. */
661 gdb_tx_hex(gdb_cpu_signal(type, code), 2);
662 gdb_tx_str("thread:");
663 gdb_tx_varhex((long)kdb_thread->td_tid);
667 case 'c': { /* Continue. */
670 if (!gdb_rx_varhex(&addr)) {
672 gdb_cpu_setreg(GDB_REG_PC, &pc);
674 kdb_cpu_clear_singlestep();
678 case 'C': { /* Continue with signal. */
681 if (!gdb_rx_varhex(&sig) && gdb_rx_char() == ';' &&
682 !gdb_rx_varhex(&addr)) {
684 gdb_cpu_setreg(GDB_REG_PC, &pc);
686 kdb_cpu_clear_singlestep();
690 case 'D': { /* Detach */
695 case 'g': { /* Read registers. */
698 for (r = 0; r < GDB_NREGS; r++)
703 case 'G': /* Write registers. */
706 case 'H': { /* Set thread. */
710 /* Ignore 'g' (general) or 'c' (continue) flag. */
711 (void) gdb_rx_char();
713 if (gdb_rx_varhex(&tid)) {
718 thr = kdb_thr_lookup(tid);
728 case 'k': /* Kill request. */
731 case 'm': { /* Read memory. */
732 uintmax_t addr, size;
733 if (gdb_rx_varhex(&addr) || gdb_rx_char() != ',' ||
734 gdb_rx_varhex(&size)) {
739 if (gdb_tx_mem((char *)(uintptr_t)addr, size))
745 case 'M': { /* Write memory. */
746 uintmax_t addr, size;
747 if (gdb_rx_varhex(&addr) || gdb_rx_char() != ',' ||
748 gdb_rx_varhex(&size) || gdb_rx_char() != ':') {
752 if (gdb_rx_mem((char *)(uintptr_t)addr, size) == 0)
758 case 'P': { /* Write register. */
762 if (gdb_rx_varhex(®) || gdb_rx_char() != '=' ||
763 !gdb_rx_mem(val, gdb_cpu_regsz(reg))) {
767 gdb_cpu_setreg(reg, val);
771 case 'q': /* General query. */
772 if (gdb_rx_equal("C")) {
775 gdb_tx_varhex((long)kdb_thread->td_tid);
777 } else if (gdb_rx_equal("Supported")) {
778 gdb_do_qsupported(&host_features);
779 } else if (gdb_rx_equal("fThreadInfo")) {
780 thr_iter = kdb_thr_first();
781 gdb_do_threadinfo(&thr_iter);
782 } else if (gdb_rx_equal("sThreadInfo")) {
783 gdb_do_threadinfo(&thr_iter);
784 } else if (gdb_rx_equal("Xfer:")) {
786 } else if (gdb_rx_equal("Search:memory:")) {
789 } else if (gdb_rx_equal("Offsets")) {
790 gdb_cpu_do_offsets();
792 } else if (!gdb_cpu_query())
796 if (gdb_rx_equal("StartNoAckMode")) {
797 if ((gdb_cur->gdb_dbfeatures &
798 GDB_DBGP_FEAT_RELIABLE) == 0) {
800 * Shouldn't happen if we didn't
801 * advertise support. Reject.
811 case 's': { /* Step. */
814 if (!gdb_rx_varhex(&addr)) {
816 gdb_cpu_setreg(GDB_REG_PC, &pc);
818 kdb_cpu_set_singlestep();
822 case 'S': { /* Step with signal. */
825 if (!gdb_rx_varhex(&sig) && gdb_rx_char() == ';' &&
826 !gdb_rx_varhex(&addr)) {
828 gdb_cpu_setreg(GDB_REG_PC, &pc);
830 kdb_cpu_set_singlestep();
834 case 'T': { /* Thread alive. */
836 if (gdb_rx_varhex(&tid)) {
840 if (kdb_thr_lookup(tid) != NULL)
847 /* Empty command. Treat as unknown command. */
850 /* Unknown command. Send empty response. */
855 (void)kdb_jmpbuf(prev_jb);