/*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2004 Marcel Moolenaar * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include #include #include #include #include SYSCTL_NODE(_debug, OID_AUTO, gdb, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, "GDB settings"); static dbbe_init_f gdb_init; static dbbe_trap_f gdb_trap; KDB_BACKEND(gdb, gdb_init, NULL, NULL, gdb_trap); static struct gdb_dbgport null_gdb_dbgport; DATA_SET(gdb_dbgport_set, null_gdb_dbgport); SET_DECLARE(gdb_dbgport_set, struct gdb_dbgport); struct gdb_dbgport *gdb_cur = NULL; int gdb_listening = 0; bool gdb_ackmode = true; static unsigned char gdb_bindata[64]; #ifdef DDB bool gdb_return_to_ddb = false; #endif static int gdb_init(void) { struct gdb_dbgport *dp, **iter; int cur_pri, pri; gdb_cur = NULL; cur_pri = -1; SET_FOREACH(iter, gdb_dbgport_set) { dp = *iter; pri = (dp->gdb_probe != NULL) ? dp->gdb_probe() : -1; dp->gdb_active = (pri >= 0) ? 0 : -1; if (pri > cur_pri) { cur_pri = pri; gdb_cur = dp; } } if (gdb_cur != NULL) { printf("GDB: debug ports:"); SET_FOREACH(iter, gdb_dbgport_set) { dp = *iter; if (dp->gdb_active == 0) printf(" %s", dp->gdb_name); } printf("\n"); } else printf("GDB: no debug ports present\n"); if (gdb_cur != NULL) { gdb_cur->gdb_init(); printf("GDB: current port: %s\n", gdb_cur->gdb_name); } if (gdb_cur != NULL) { cur_pri = (boothowto & RB_GDB) ? 2 : 0; gdb_consinit(); } else cur_pri = -1; return (cur_pri); } static void gdb_do_mem_search(void) { size_t patlen; intmax_t addr, size; const unsigned char *found; if (gdb_rx_varhex(&addr) || gdb_rx_char() != ';' || gdb_rx_varhex(&size) || gdb_rx_char() != ';' || gdb_rx_bindata(gdb_bindata, sizeof(gdb_bindata), &patlen)) { gdb_tx_err(EINVAL); return; } if (gdb_search_mem((char *)(uintptr_t)addr, size, gdb_bindata, patlen, &found)) { if (found == 0ULL) gdb_tx_begin('0'); else { gdb_tx_begin('1'); gdb_tx_char(','); gdb_tx_hex((intmax_t)(uintptr_t)found, 8); } gdb_tx_end(); } else gdb_tx_err(EIO); } static void gdb_do_threadinfo(struct thread **thr_iter) { static struct thread * const done_sentinel = (void *)(uintptr_t)1; static const size_t tidsz_hex = sizeof(lwpid_t) * 2; size_t tds_sent; if (*thr_iter == NULL) { gdb_tx_err(ENXIO); return; } if (*thr_iter == done_sentinel) { gdb_tx_begin('l'); *thr_iter = NULL; goto sendit; } gdb_tx_begin('m'); for (tds_sent = 0; *thr_iter != NULL && gdb_txbuf_has_capacity(tidsz_hex + 1); *thr_iter = kdb_thr_next(*thr_iter), tds_sent++) { if (tds_sent > 0) gdb_tx_char(','); gdb_tx_varhex((*thr_iter)->td_tid); } /* * Can't send EOF and "some" in same packet, so set a sentinel to send * EOF when GDB asks us next. */ if (*thr_iter == NULL && tds_sent > 0) *thr_iter = done_sentinel; sendit: gdb_tx_end(); } #define BIT(n) (1ull << (n)) enum { GDB_MULTIPROCESS, GDB_SWBREAK, GDB_HWBREAK, GDB_QRELOCINSN, GDB_FORK_EVENTS, GDB_VFORK_EVENTS, GDB_EXEC_EVENTS, GDB_VCONT_SUPPORTED, GDB_QTHREADEVENTS, GDB_NO_RESUMED, }; static const char * const gdb_feature_names[] = { [GDB_MULTIPROCESS] = "multiprocess", [GDB_SWBREAK] = "swbreak", [GDB_HWBREAK] = "hwbreak", [GDB_QRELOCINSN] = "qRelocInsn", [GDB_FORK_EVENTS] = "fork-events", [GDB_VFORK_EVENTS] = "vfork-events", [GDB_EXEC_EVENTS] = "exec-events", [GDB_VCONT_SUPPORTED] = "vContSupported", [GDB_QTHREADEVENTS] = "QThreadEvents", [GDB_NO_RESUMED] = "no-resumed", }; static void gdb_do_qsupported(uint32_t *feat) { char *tok, *delim, ok; size_t i, toklen; /* Parse supported host features */ *feat = 0; switch (gdb_rx_char()) { case ':': break; case EOF: goto nofeatures; default: goto error; } while (gdb_rxsz > 0) { tok = gdb_rxp; delim = strchrnul(gdb_rxp, ';'); toklen = (delim - tok); gdb_rxp += toklen; gdb_rxsz -= toklen; if (*delim != '\0') { *delim = '\0'; gdb_rxp += 1; gdb_rxsz -= 1; } if (toklen < 2) goto error; ok = tok[toklen - 1]; if (ok != '-' && ok != '+') { /* * GDB only has one KV-pair feature, and we don't * support it, so ignore and move on. */ if (strchr(tok, '=') != NULL) continue; /* Not a KV-pair, and not a +/- flag? Malformed. */ goto error; } if (ok != '+') continue; tok[toklen - 1] = '\0'; for (i = 0; i < nitems(gdb_feature_names); i++) if (strcmp(gdb_feature_names[i], tok) == 0) break; if (i == nitems(gdb_feature_names)) { /* Unknown GDB feature. */ continue; } *feat |= BIT(i); } nofeatures: /* Send a supported feature list back */ gdb_tx_begin(0); gdb_tx_str("PacketSize"); gdb_tx_char('='); /* * We don't buffer framing bytes, but we do need to retain a byte for a * trailing nul. */ gdb_tx_varhex(GDB_BUFSZ + strlen("$#nn") - 1); gdb_tx_str(";qXfer:threads:read+"); /* * If the debugport is a reliable transport, request No Ack mode from * the server. The server may or may not choose to enter No Ack mode. * https://sourceware.org/gdb/onlinedocs/gdb/Packet-Acknowledgment.html */ if (gdb_cur->gdb_dbfeatures & GDB_DBGP_FEAT_RELIABLE) gdb_tx_str(";QStartNoAckMode+"); /* * Future consideration: * - vCont * - multiprocess */ gdb_tx_end(); return; error: *feat = 0; gdb_tx_err(EINVAL); } /* * A qXfer_context provides a vaguely generic way to generate a multi-packet * response on the fly, making some assumptions about the size of sbuf writes * vs actual packet length constraints. A non-byzantine gdb host should allow * hundreds of bytes per packet or more. * * Upper layers are considered responsible for escaping the four forbidden * characters '# $ } *'. */ struct qXfer_context { struct sbuf sb; size_t last_offset; bool flushed; bool lastmessage; char xfer_buf[GDB_BUFSZ]; }; static int qXfer_drain(void *v, const char *buf, int len) { struct qXfer_context *qx; if (len < 0) return (-EINVAL); qx = v; if (qx->flushed) { /* * Overflow. We lost some message. Maybe the packet size is * ridiculously small. */ printf("%s: Overflow in qXfer detected.\n", __func__); return (-ENOBUFS); } qx->last_offset += len; qx->flushed = true; if (qx->lastmessage) gdb_tx_begin('l'); else gdb_tx_begin('m'); memcpy(gdb_txp, buf, len); gdb_txp += len; gdb_tx_end(); return (len); } static int init_qXfer_ctx(struct qXfer_context *qx, uintmax_t len) { /* Protocol (max) length field includes framing overhead. */ if (len < sizeof("$m#nn")) return (ENOSPC); len -= 4; len = ummin(len, GDB_BUFSZ - 1); qx->last_offset = 0; qx->flushed = false; qx->lastmessage = false; sbuf_new(&qx->sb, qx->xfer_buf, len, SBUF_FIXEDLEN); sbuf_set_drain(&qx->sb, qXfer_drain, qx); return (0); } /* * Squashes special XML and GDB characters down to _. Sorry. */ static void qXfer_escape_xmlattr_str(char *dst, size_t dstlen, const char *src) { static const char *forbidden = "#$}*"; size_t i; char c; for (i = 0; i < dstlen - 1 && *src != 0; src++, i++) { c = *src; /* XML attr filter */ if (c < 32) c = '_'; /* We assume attributes will be "" quoted. */ if (c == '<' || c == '&' || c == '"') c = '_'; /* GDB escape. */ if (strchr(forbidden, c) != NULL) { /* * It would be nice to escape these properly, but to do * it correctly we need to escape them in the transmit * layer, potentially doubling our buffer requirements. * For now, avoid breaking the protocol by squashing * them to underscore. */ #if 0 *dst++ = '}'; c ^= 0x20; #endif c = '_'; } *dst++ = c; } if (*src != 0) printf("XXX%s: overflow; API misuse\n", __func__); *dst = 0; } /* * Dynamically generate qXfer:threads document, one packet at a time. * * The format is loosely described[0], although it does not seem that the * mentioned on that page is required. * * [0]: https://sourceware.org/gdb/current/onlinedocs/gdb/Thread-List-Format.html */ static void do_qXfer_threads_read(void) { /* Kludgy context */ static struct { struct qXfer_context qXfer; /* Kludgy state machine */ struct thread *iter; enum { XML_START_THREAD, /* ' ...' */ XML_END_THREAD, /* '' */ XML_SENT_END_THREADS, /* '' */ } next_step; } ctx; static char td_name_escape[MAXCOMLEN * 2 + 1]; const char *name_src; uintmax_t offset, len; int error; /* Annex part must be empty. */ if (gdb_rx_char() != ':') goto misformed_request; if (gdb_rx_varhex(&offset) != 0 || gdb_rx_char() != ',' || gdb_rx_varhex(&len) != 0) goto misformed_request; /* * Validate resume xfers. */ if (offset != 0) { if (offset != ctx.qXfer.last_offset) { printf("%s: Resumed offset %ju != expected %zu\n", __func__, offset, ctx.qXfer.last_offset); error = ESPIPE; goto request_error; } ctx.qXfer.flushed = false; } if (offset == 0) { ctx.iter = kdb_thr_first(); ctx.next_step = XML_START_THREAD; error = init_qXfer_ctx(&ctx.qXfer, len); if (error != 0) goto request_error; sbuf_cat(&ctx.qXfer.sb, ""); } while (!ctx.qXfer.flushed && ctx.iter != NULL) { switch (ctx.next_step) { case XML_START_THREAD: ctx.next_step = XML_THREAD_ID; sbuf_cat(&ctx.qXfer.sb, "td_tid); continue; case XML_THREAD_CORE: ctx.next_step = XML_THREAD_NAME; if (ctx.iter->td_oncpu != NOCPU) { sbuf_printf(&ctx.qXfer.sb, " core=\"%d\"", ctx.iter->td_oncpu); } continue; case XML_THREAD_NAME: ctx.next_step = XML_THREAD_EXTRA; if (ctx.iter->td_name[0] != 0) name_src = ctx.iter->td_name; else if (ctx.iter->td_proc != NULL && ctx.iter->td_proc->p_comm[0] != 0) name_src = ctx.iter->td_proc->p_comm; else continue; qXfer_escape_xmlattr_str(td_name_escape, sizeof(td_name_escape), name_src); sbuf_printf(&ctx.qXfer.sb, " name=\"%s\"", td_name_escape); continue; case XML_THREAD_EXTRA: ctx.next_step = XML_END_THREAD; sbuf_putc(&ctx.qXfer.sb, '>'); if (TD_GET_STATE(ctx.iter) == TDS_RUNNING) sbuf_cat(&ctx.qXfer.sb, "Running"); else if (TD_GET_STATE(ctx.iter) == TDS_RUNQ) sbuf_cat(&ctx.qXfer.sb, "RunQ"); else if (TD_GET_STATE(ctx.iter) == TDS_CAN_RUN) sbuf_cat(&ctx.qXfer.sb, "CanRun"); else if (TD_ON_LOCK(ctx.iter)) sbuf_cat(&ctx.qXfer.sb, "Blocked"); else if (TD_IS_SLEEPING(ctx.iter)) sbuf_cat(&ctx.qXfer.sb, "Sleeping"); else if (TD_IS_SWAPPED(ctx.iter)) sbuf_cat(&ctx.qXfer.sb, "Swapped"); else if (TD_AWAITING_INTR(ctx.iter)) sbuf_cat(&ctx.qXfer.sb, "IthreadWait"); else if (TD_IS_SUSPENDED(ctx.iter)) sbuf_cat(&ctx.qXfer.sb, "Suspended"); else sbuf_cat(&ctx.qXfer.sb, "???"); continue; case XML_END_THREAD: ctx.next_step = XML_START_THREAD; sbuf_cat(&ctx.qXfer.sb, ""); ctx.iter = kdb_thr_next(ctx.iter); continue; /* * This one isn't part of the looping state machine, * but GCC complains if you leave an enum value out of the * select. */ case XML_SENT_END_THREADS: /* NOTREACHED */ break; } } if (ctx.qXfer.flushed) return; if (ctx.next_step != XML_SENT_END_THREADS) { ctx.next_step = XML_SENT_END_THREADS; sbuf_cat(&ctx.qXfer.sb, ""); } if (ctx.qXfer.flushed) return; ctx.qXfer.lastmessage = true; sbuf_finish(&ctx.qXfer.sb); sbuf_delete(&ctx.qXfer.sb); ctx.qXfer.last_offset = 0; return; misformed_request: /* * GDB "General-Query-Packets.html" qXfer-read anchor specifically * documents an E00 code for malformed requests or invalid annex. * Non-zero codes indicate invalid offset or "error reading the data." */ error = 0; request_error: gdb_tx_err(error); return; } /* * A set of standardized transfers from "special data areas." * * We've already matched on "qXfer:" and advanced the rx packet buffer past * that bit. Parse out the rest of the packet and generate an appropriate * response. */ static void do_qXfer(void) { if (!gdb_rx_equal("threads:")) goto unrecognized; if (!gdb_rx_equal("read:")) goto unrecognized; do_qXfer_threads_read(); return; unrecognized: gdb_tx_empty(); return; } static void gdb_handle_detach(void) { kdb_cpu_clear_singlestep(); gdb_listening = 0; if (gdb_cur->gdb_dbfeatures & GDB_DBGP_FEAT_WANTTERM) gdb_cur->gdb_term(); #ifdef DDB if (!gdb_return_to_ddb) return; gdb_return_to_ddb = false; if (kdb_dbbe_select("ddb") != 0) printf("The ddb backend could not be selected.\n"); #endif } static int gdb_trap(int type, int code) { jmp_buf jb; struct thread *thr_iter; void *prev_jb; uint32_t host_features; prev_jb = kdb_jmpbuf(jb); if (setjmp(jb) != 0) { printf("%s bailing, hopefully back to ddb!\n", __func__); gdb_listening = 0; (void)kdb_jmpbuf(prev_jb); return (1); } gdb_listening = 0; gdb_ackmode = true; /* * Send a T packet. We currently do not support watchpoints (the * awatch, rwatch or watch elements). */ gdb_tx_begin('T'); gdb_tx_hex(gdb_cpu_signal(type, code), 2); gdb_tx_varhex(GDB_REG_PC); gdb_tx_char(':'); gdb_tx_reg(GDB_REG_PC); gdb_tx_char(';'); gdb_tx_str("thread:"); gdb_tx_varhex((long)kdb_thread->td_tid); gdb_tx_char(';'); gdb_tx_end(); /* XXX check error condition. */ thr_iter = NULL; while (gdb_rx_begin() == 0) { /* printf("GDB: got '%s'\n", gdb_rxp); */ switch (gdb_rx_char()) { case '?': /* Last signal. */ gdb_tx_begin('T'); gdb_tx_hex(gdb_cpu_signal(type, code), 2); gdb_tx_str("thread:"); gdb_tx_varhex((long)kdb_thread->td_tid); gdb_tx_char(';'); gdb_tx_end(); break; case 'c': { /* Continue. */ uintmax_t addr; register_t pc; if (!gdb_rx_varhex(&addr)) { pc = addr; gdb_cpu_setreg(GDB_REG_PC, &pc); } kdb_cpu_clear_singlestep(); gdb_listening = 1; return (1); } case 'C': { /* Continue with signal. */ uintmax_t addr, sig; register_t pc; if (!gdb_rx_varhex(&sig) && gdb_rx_char() == ';' && !gdb_rx_varhex(&addr)) { pc = addr; gdb_cpu_setreg(GDB_REG_PC, &pc); } kdb_cpu_clear_singlestep(); gdb_listening = 1; return (1); } case 'D': { /* Detach */ gdb_tx_ok(); gdb_handle_detach(); return (1); } case 'g': { /* Read registers. */ size_t r; gdb_tx_begin(0); for (r = 0; r < GDB_NREGS; r++) gdb_tx_reg(r); gdb_tx_end(); break; } case 'G': { /* Write registers. */ char *val; bool success; size_t r; for (success = true, r = 0; r < GDB_NREGS; r++) { val = gdb_rxp; if (!gdb_rx_mem(val, gdb_cpu_regsz(r))) { gdb_tx_err(EINVAL); success = false; break; } gdb_cpu_setreg(r, val); } if (success) gdb_tx_ok(); break; } case 'H': { /* Set thread. */ intmax_t tid; struct thread *thr; /* Ignore 'g' (general) or 'c' (continue) flag. */ (void) gdb_rx_char(); if (gdb_rx_varhex(&tid)) { gdb_tx_err(EINVAL); break; } if (tid > 0) { thr = kdb_thr_lookup(tid); if (thr == NULL) { gdb_tx_err(ENOENT); break; } kdb_thr_select(thr); } gdb_tx_ok(); break; } case 'k': /* Kill request. */ gdb_handle_detach(); return (1); case 'm': { /* Read memory. */ uintmax_t addr, size; if (gdb_rx_varhex(&addr) || gdb_rx_char() != ',' || gdb_rx_varhex(&size)) { gdb_tx_err(EINVAL); break; } gdb_tx_begin(0); if (gdb_tx_mem((char *)(uintptr_t)addr, size)) gdb_tx_end(); else gdb_tx_err(EIO); break; } case 'M': { /* Write memory. */ uintmax_t addr, size; if (gdb_rx_varhex(&addr) || gdb_rx_char() != ',' || gdb_rx_varhex(&size) || gdb_rx_char() != ':') { gdb_tx_err(EINVAL); break; } if (gdb_rx_mem((char *)(uintptr_t)addr, size) == 0) gdb_tx_err(EIO); else gdb_tx_ok(); break; } case 'p': { /* Read register. */ uintmax_t reg; if (gdb_rx_varhex(®)) { gdb_tx_err(EINVAL); break; } gdb_tx_begin(0); gdb_tx_reg(reg); gdb_tx_end(); break; } case 'P': { /* Write register. */ char *val; uintmax_t reg; val = gdb_rxp; if (gdb_rx_varhex(®) || gdb_rx_char() != '=' || !gdb_rx_mem(val, gdb_cpu_regsz(reg))) { gdb_tx_err(EINVAL); break; } gdb_cpu_setreg(reg, val); gdb_tx_ok(); break; } case 'q': /* General query. */ if (gdb_rx_equal("C")) { gdb_tx_begin('Q'); gdb_tx_char('C'); gdb_tx_varhex((long)kdb_thread->td_tid); gdb_tx_end(); } else if (gdb_rx_equal("Supported")) { gdb_do_qsupported(&host_features); } else if (gdb_rx_equal("fThreadInfo")) { thr_iter = kdb_thr_first(); gdb_do_threadinfo(&thr_iter); } else if (gdb_rx_equal("sThreadInfo")) { gdb_do_threadinfo(&thr_iter); } else if (gdb_rx_equal("Xfer:")) { do_qXfer(); } else if (gdb_rx_equal("Search:memory:")) { gdb_do_mem_search(); #ifdef __powerpc__ } else if (gdb_rx_equal("Offsets")) { gdb_cpu_do_offsets(); #endif } else if (!gdb_cpu_query()) gdb_tx_empty(); break; case 'Q': if (gdb_rx_equal("StartNoAckMode")) { if ((gdb_cur->gdb_dbfeatures & GDB_DBGP_FEAT_RELIABLE) == 0) { /* * Shouldn't happen if we didn't * advertise support. Reject. */ gdb_tx_empty(); break; } gdb_ackmode = false; gdb_tx_ok(); } else gdb_tx_empty(); break; case 's': { /* Step. */ uintmax_t addr; register_t pc; if (!gdb_rx_varhex(&addr)) { pc = addr; gdb_cpu_setreg(GDB_REG_PC, &pc); } kdb_cpu_set_singlestep(); gdb_listening = 1; return (1); } case 'S': { /* Step with signal. */ uintmax_t addr, sig; register_t pc; if (!gdb_rx_varhex(&sig) && gdb_rx_char() == ';' && !gdb_rx_varhex(&addr)) { pc = addr; gdb_cpu_setreg(GDB_REG_PC, &pc); } kdb_cpu_set_singlestep(); gdb_listening = 1; return (1); } case 'T': { /* Thread alive. */ intmax_t tid; if (gdb_rx_varhex(&tid)) { gdb_tx_err(EINVAL); break; } if (kdb_thr_lookup(tid) != NULL) gdb_tx_ok(); else gdb_tx_err(ENOENT); break; } case EOF: /* Empty command. Treat as unknown command. */ /* FALLTHROUGH */ default: /* Unknown command. Send empty response. */ gdb_tx_empty(); break; } } (void)kdb_jmpbuf(prev_jb); return (0); }