1 /*- 2 * Copyright (c) 2006 Sam Leffler 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 /* 28 * Support for redirecting console msgs to gdb. We register 29 * a pseudo console to hook cnputc and send stuff to the gdb 30 * port. The only trickiness here is buffering output so this 31 * isn't dog slow. 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD$"); 36 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, OID_AUTO, gdbcons, CTLFLAG_RW, &gdbcons_enable, 62 0, "copy console messages to gdb"); 63 TUNABLE_INT("debug.gdbcons", &gdbcons_enable); 64 65 static void 66 gdb_cnprobe(struct consdev *cp) 67 { 68 sprintf(cp->cn_name, "gdb"); 69 cp->cn_pri = CN_LOW; /* XXX no way to say "write only" */ 70 } 71 72 static void 73 gdb_cninit(struct consdev *cp) 74 { 75 struct gdbcons *c = &state; 76 77 /* setup tx buffer and callout */ 78 if (c->npending == -1) { 79 c->npending = 0; 80 callout_init(&c->flush, CALLOUT_MPSAFE); 81 cp->cn_arg = c; 82 } 83 } 84 85 static int 86 gdb_nogetc(struct consdev *cp) 87 { 88 return -1; 89 } 90 91 static void 92 gdb_tx_puthex(int c) 93 { 94 const char *hex = "0123456789abcdef"; 95 96 gdb_tx_char(hex[(c>>4)&0xf]); 97 gdb_tx_char(hex[(c>>0)&0xf]); 98 } 99 100 static void 101 gdb_cnflush(void *arg) 102 { 103 struct gdbcons *gc = arg; 104 int i; 105 106 gdb_tx_begin('O'); 107 for (i = 0; i < gc->npending; i++) 108 gdb_tx_puthex(gc->buf[i]); 109 gdb_tx_end(); 110 gc->npending = 0; 111 } 112 113 /* 114 * This glop is to figure out when it's safe to use callouts 115 * to defer buffer flushing. There's probably a better way 116 * and/or an earlier point in the boot process when it's ok. 117 */ 118 static int calloutok = 0; 119 static void 120 oktousecallout(void *data __unused) 121 { 122 calloutok = 1; 123 } 124 SYSINIT(gdbhack, SI_SUB_RUN_SCHEDULER, SI_ORDER_ANY, oktousecallout, NULL) 125 126 static void 127 gdb_cnputc(struct consdev *cp, int c) 128 { 129 struct gdbcons *gc; 130 131 if (gdbcons_enable && gdb_cur != NULL && gdb_listening) { 132 gc = cp->cn_arg; 133 if (gc->npending != 0) { 134 /* 135 * Cancel any pending callout and flush the 136 * buffer if there's no space for this byte. 137 */ 138 if (calloutok) 139 callout_stop(&gc->flush); 140 if (gc->npending == sizeof(gc->buf)) 141 gdb_cnflush(gc); 142 } 143 gc->buf[gc->npending++] = c; 144 /* 145 * Flush on end of line; this is especially helpful 146 * during boot when we don't have callouts to flush 147 * the buffer. Otherwise we defer flushing; a 1/4 148 * second is a guess. 149 */ 150 if (c == '\n') 151 gdb_cnflush(gc); 152 else if (calloutok) 153 callout_reset(&gc->flush, hz/4, gdb_cnflush, gc); 154 } 155 } 156 157 /* NB: no get interface, we supply nogetc for checkc too */ 158 CONS_DRIVER(gdb, gdb_cnprobe, gdb_cninit, NULL, gdb_nogetc, gdb_nogetc, 159 gdb_cnputc, NULL); 160 161 /* 162 * Our console device only gets attached if the system is booted 163 * with RB_MULTIPLE set so gdb_init also calls us to attach the 164 * console so we're setup regardless. 165 */ 166 void 167 gdb_consinit(void) 168 { 169 gdb_cnprobe(&gdb_consdev); 170 gdb_cninit(&gdb_consdev); 171 cnadd(&gdb_consdev); 172 } 173