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
51struct 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};
57static struct gdbcons state = { -1 };
58
59static	int gdbcons_enable = 0;
60SYSCTL_INT(_debug_gdb, OID_AUTO, cons, CTLFLAG_RWTUN, &gdbcons_enable, 0,
61	"copy console messages to GDB");
62/* Legacy sysctl alias */
63SYSCTL_INT(_debug, OID_AUTO, gdbcons, CTLFLAG_RWTUN, &gdbcons_enable,
64	0, "copy console messages to GDB");
65
66static void
67gdb_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
73static void
74gdb_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
86static void
87gdb_cnterm(struct consdev *cp)
88{
89}
90
91static void
92gdb_cngrab(struct consdev *cp)
93{
94}
95
96static void
97gdb_cnungrab(struct consdev *cp)
98{
99}
100
101static int
102gdb_cngetc(struct consdev *cp)
103{
104	return -1;
105}
106
107static void
108gdb_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
116static void
117gdb_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 */
134static int calloutok = 0;
135static void
136oktousecallout(void *data __unused)
137{
138	calloutok = 1;
139}
140SYSINIT(gdbhack, SI_SUB_LAST, SI_ORDER_MIDDLE, oktousecallout, NULL);
141
142static void
143gdb_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
173CONSOLE_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 */
180void
181gdb_consinit(void)
182{
183	gdb_cnprobe(&gdb_consdev);
184	gdb_cninit(&gdb_consdev);
185	cnadd(&gdb_consdev);
186}
187