1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2006 Sam Leffler 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 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. 16 * 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. 27 */ 28 29 /* 30 * Support for redirecting console msgs to gdb. We register 31 * a pseudo console to hook cnputc and send stuff to the gdb 32 * port. The only trickiness here is buffering output so this 33 * isn't dog slow. 34 */ 35 36 #include <sys/param.h> 37 #include <sys/systm.h> 38 #include <sys/cons.h> 39 #include <sys/kdb.h> 40 #include <sys/kernel.h> 41 #include <sys/malloc.h> 42 #include <sys/reboot.h> 43 #include <sys/sysctl.h> 44 45 #include <machine/gdb_machdep.h> 46 #include <machine/kdb.h> 47 48 #include <gdb/gdb.h> 49 #include <gdb/gdb_int.h> 50 51 struct gdbcons { 52 int npending; 53 /* /2 for hex conversion, -6 for protocol glue */ 54 char buf[GDB_BUFSZ/2 - 6]; 55 struct callout flush; 56 }; 57 static struct gdbcons state = { -1 }; 58 59 static int gdbcons_enable = 0; 60 SYSCTL_INT(_debug_gdb, OID_AUTO, cons, CTLFLAG_RWTUN, &gdbcons_enable, 0, 61 "copy console messages to GDB"); 62 /* Legacy sysctl alias */ 63 SYSCTL_INT(_debug, OID_AUTO, gdbcons, CTLFLAG_RWTUN, &gdbcons_enable, 64 0, "copy console messages to GDB"); 65 66 static void 67 gdb_cnprobe(struct consdev *cp) 68 { 69 sprintf(cp->cn_name, "gdb"); 70 cp->cn_pri = CN_LOW; /* XXX no way to say "write only" */ 71 } 72 73 static void 74 gdb_cninit(struct consdev *cp) 75 { 76 struct gdbcons *c = &state; 77 78 /* setup tx buffer and callout */ 79 if (c->npending == -1) { 80 c->npending = 0; 81 callout_init(&c->flush, 1); 82 cp->cn_arg = c; 83 } 84 } 85 86 static void 87 gdb_cnterm(struct consdev *cp) 88 { 89 } 90 91 static void 92 gdb_cngrab(struct consdev *cp) 93 { 94 } 95 96 static void 97 gdb_cnungrab(struct consdev *cp) 98 { 99 } 100 101 static int 102 gdb_cngetc(struct consdev *cp) 103 { 104 return -1; 105 } 106 107 static void 108 gdb_tx_puthex(int c) 109 { 110 const char *hex = "0123456789abcdef"; 111 112 gdb_tx_char(hex[(c>>4)&0xf]); 113 gdb_tx_char(hex[(c>>0)&0xf]); 114 } 115 116 static void 117 gdb_cnflush(void *arg) 118 { 119 struct gdbcons *gc = arg; 120 int i; 121 122 gdb_tx_begin('O'); 123 for (i = 0; i < gc->npending; i++) 124 gdb_tx_puthex(gc->buf[i]); 125 gdb_tx_end(); 126 gc->npending = 0; 127 } 128 129 /* 130 * This glop is to figure out when it's safe to use callouts 131 * to defer buffer flushing. There's probably a better way 132 * and/or an earlier point in the boot process when it's ok. 133 */ 134 static int calloutok = 0; 135 static void 136 oktousecallout(void *data __unused) 137 { 138 calloutok = 1; 139 } 140 SYSINIT(gdbhack, SI_SUB_LAST, SI_ORDER_MIDDLE, oktousecallout, NULL); 141 142 static void 143 gdb_cnputc(struct consdev *cp, int c) 144 { 145 struct gdbcons *gc; 146 147 if (gdbcons_enable && gdb_cur != NULL && gdb_listening) { 148 gc = cp->cn_arg; 149 if (gc->npending != 0) { 150 /* 151 * Cancel any pending callout and flush the 152 * buffer if there's no space for this byte. 153 */ 154 if (calloutok) 155 callout_stop(&gc->flush); 156 if (gc->npending == sizeof(gc->buf)) 157 gdb_cnflush(gc); 158 } 159 gc->buf[gc->npending++] = c; 160 /* 161 * Flush on end of line; this is especially helpful 162 * during boot when we don't have callouts to flush 163 * the buffer. Otherwise we defer flushing; a 1/4 164 * second is a guess. 165 */ 166 if (c == '\n') 167 gdb_cnflush(gc); 168 else if (calloutok) 169 callout_reset(&gc->flush, hz/4, gdb_cnflush, gc); 170 } 171 } 172 173 CONSOLE_DRIVER(gdb); 174 175 /* 176 * Our console device only gets attached if the system is booted 177 * with RB_MULTIPLE set so gdb_init also calls us to attach the 178 * console so we're setup regardless. 179 */ 180 void 181 gdb_consinit(void) 182 { 183 gdb_cnprobe(&gdb_consdev); 184 gdb_cninit(&gdb_consdev); 185 cnadd(&gdb_consdev); 186 } 187