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/cdefs.h> 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/cons.h> 40 #include <sys/kdb.h> 41 #include <sys/kernel.h> 42 #include <sys/malloc.h> 43 #include <sys/reboot.h> 44 #include <sys/sysctl.h> 45 46 #include <machine/gdb_machdep.h> 47 #include <machine/kdb.h> 48 49 #include <gdb/gdb.h> 50 #include <gdb/gdb_int.h> 51 52 struct gdbcons { 53 int npending; 54 /* /2 for hex conversion, -6 for protocol glue */ 55 char buf[GDB_BUFSZ/2 - 6]; 56 struct callout flush; 57 }; 58 static struct gdbcons state = { -1 }; 59 60 static int gdbcons_enable = 0; 61 SYSCTL_INT(_debug_gdb, OID_AUTO, cons, CTLFLAG_RWTUN, &gdbcons_enable, 0, 62 "copy console messages to GDB"); 63 /* Legacy sysctl alias */ 64 SYSCTL_INT(_debug, OID_AUTO, gdbcons, CTLFLAG_RWTUN, &gdbcons_enable, 65 0, "copy console messages to GDB"); 66 67 static void 68 gdb_cnprobe(struct consdev *cp) 69 { 70 sprintf(cp->cn_name, "gdb"); 71 cp->cn_pri = CN_LOW; /* XXX no way to say "write only" */ 72 } 73 74 static void 75 gdb_cninit(struct consdev *cp) 76 { 77 struct gdbcons *c = &state; 78 79 /* setup tx buffer and callout */ 80 if (c->npending == -1) { 81 c->npending = 0; 82 callout_init(&c->flush, 1); 83 cp->cn_arg = c; 84 } 85 } 86 87 static void 88 gdb_cnterm(struct consdev *cp) 89 { 90 } 91 92 static void 93 gdb_cngrab(struct consdev *cp) 94 { 95 } 96 97 static void 98 gdb_cnungrab(struct consdev *cp) 99 { 100 } 101 102 static int 103 gdb_cngetc(struct consdev *cp) 104 { 105 return -1; 106 } 107 108 static void 109 gdb_tx_puthex(int c) 110 { 111 const char *hex = "0123456789abcdef"; 112 113 gdb_tx_char(hex[(c>>4)&0xf]); 114 gdb_tx_char(hex[(c>>0)&0xf]); 115 } 116 117 static void 118 gdb_cnflush(void *arg) 119 { 120 struct gdbcons *gc = arg; 121 int i; 122 123 gdb_tx_begin('O'); 124 for (i = 0; i < gc->npending; i++) 125 gdb_tx_puthex(gc->buf[i]); 126 gdb_tx_end(); 127 gc->npending = 0; 128 } 129 130 /* 131 * This glop is to figure out when it's safe to use callouts 132 * to defer buffer flushing. There's probably a better way 133 * and/or an earlier point in the boot process when it's ok. 134 */ 135 static int calloutok = 0; 136 static void 137 oktousecallout(void *data __unused) 138 { 139 calloutok = 1; 140 } 141 SYSINIT(gdbhack, SI_SUB_LAST, SI_ORDER_MIDDLE, oktousecallout, NULL); 142 143 static void 144 gdb_cnputc(struct consdev *cp, int c) 145 { 146 struct gdbcons *gc; 147 148 if (gdbcons_enable && gdb_cur != NULL && gdb_listening) { 149 gc = cp->cn_arg; 150 if (gc->npending != 0) { 151 /* 152 * Cancel any pending callout and flush the 153 * buffer if there's no space for this byte. 154 */ 155 if (calloutok) 156 callout_stop(&gc->flush); 157 if (gc->npending == sizeof(gc->buf)) 158 gdb_cnflush(gc); 159 } 160 gc->buf[gc->npending++] = c; 161 /* 162 * Flush on end of line; this is especially helpful 163 * during boot when we don't have callouts to flush 164 * the buffer. Otherwise we defer flushing; a 1/4 165 * second is a guess. 166 */ 167 if (c == '\n') 168 gdb_cnflush(gc); 169 else if (calloutok) 170 callout_reset(&gc->flush, hz/4, gdb_cnflush, gc); 171 } 172 } 173 174 CONSOLE_DRIVER(gdb); 175 176 /* 177 * Our console device only gets attached if the system is booted 178 * with RB_MULTIPLE set so gdb_init also calls us to attach the 179 * console so we're setup regardless. 180 */ 181 void 182 gdb_consinit(void) 183 { 184 gdb_cnprobe(&gdb_consdev); 185 gdb_cninit(&gdb_consdev); 186 cnadd(&gdb_consdev); 187 } 188