2 * SPDX-License-Identifier: BSD-2-Clause
4 * Copyright (c) 2006 Sam Leffler
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.
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
36 #include <sys/cdefs.h>
37 #include <sys/param.h>
38 #include <sys/systm.h>
41 #include <sys/kernel.h>
42 #include <sys/malloc.h>
43 #include <sys/reboot.h>
44 #include <sys/sysctl.h>
46 #include <machine/gdb_machdep.h>
47 #include <machine/kdb.h>
50 #include <gdb/gdb_int.h>
54 /* /2 for hex conversion, -6 for protocol glue */
55 char buf[GDB_BUFSZ/2 - 6];
58 static struct gdbcons state = { -1 };
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");
68 gdb_cnprobe(struct consdev *cp)
70 sprintf(cp->cn_name, "gdb");
71 cp->cn_pri = CN_LOW; /* XXX no way to say "write only" */
75 gdb_cninit(struct consdev *cp)
77 struct gdbcons *c = &state;
79 /* setup tx buffer and callout */
80 if (c->npending == -1) {
82 callout_init(&c->flush, 1);
88 gdb_cnterm(struct consdev *cp)
93 gdb_cngrab(struct consdev *cp)
98 gdb_cnungrab(struct consdev *cp)
103 gdb_cngetc(struct consdev *cp)
111 const char *hex = "0123456789abcdef";
113 gdb_tx_char(hex[(c>>4)&0xf]);
114 gdb_tx_char(hex[(c>>0)&0xf]);
118 gdb_cnflush(void *arg)
120 struct gdbcons *gc = arg;
124 for (i = 0; i < gc->npending; i++)
125 gdb_tx_puthex(gc->buf[i]);
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.
135 static int calloutok = 0;
137 oktousecallout(void *data __unused)
141 SYSINIT(gdbhack, SI_SUB_LAST, SI_ORDER_MIDDLE, oktousecallout, NULL);
144 gdb_cnputc(struct consdev *cp, int c)
148 if (gdbcons_enable && gdb_cur != NULL && gdb_listening) {
150 if (gc->npending != 0) {
152 * Cancel any pending callout and flush the
153 * buffer if there's no space for this byte.
156 callout_stop(&gc->flush);
157 if (gc->npending == sizeof(gc->buf))
160 gc->buf[gc->npending++] = c;
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
170 callout_reset(&gc->flush, hz/4, gdb_cnflush, gc);
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.
184 gdb_cnprobe(&gdb_consdev);
185 gdb_cninit(&gdb_consdev);