FreeBSD/Linux Kernel Cross Reference
sys/gdb/gdb_cons.c
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: src/sys/gdb/gdb_cons.c,v 1.3 2008/03/16 13:02:04 rwatson Exp $");
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 void
86 gdb_cnterm(struct consdev *cp)
87 {
88 }
89
90 static int
91 gdb_cngetc(struct consdev *cp)
92 {
93 return -1;
94 }
95
96 static void
97 gdb_tx_puthex(int c)
98 {
99 const char *hex = "0123456789abcdef";
100
101 gdb_tx_char(hex[(c>>4)&0xf]);
102 gdb_tx_char(hex[(c>>0)&0xf]);
103 }
104
105 static void
106 gdb_cnflush(void *arg)
107 {
108 struct gdbcons *gc = arg;
109 int i;
110
111 gdb_tx_begin('O');
112 for (i = 0; i < gc->npending; i++)
113 gdb_tx_puthex(gc->buf[i]);
114 gdb_tx_end();
115 gc->npending = 0;
116 }
117
118 /*
119 * This glop is to figure out when it's safe to use callouts
120 * to defer buffer flushing. There's probably a better way
121 * and/or an earlier point in the boot process when it's ok.
122 */
123 static int calloutok = 0;
124 static void
125 oktousecallout(void *data __unused)
126 {
127 calloutok = 1;
128 }
129 SYSINIT(gdbhack, SI_SUB_RUN_SCHEDULER, SI_ORDER_ANY, oktousecallout, NULL);
130
131 static void
132 gdb_cnputc(struct consdev *cp, int c)
133 {
134 struct gdbcons *gc;
135
136 if (gdbcons_enable && gdb_cur != NULL && gdb_listening) {
137 gc = cp->cn_arg;
138 if (gc->npending != 0) {
139 /*
140 * Cancel any pending callout and flush the
141 * buffer if there's no space for this byte.
142 */
143 if (calloutok)
144 callout_stop(&gc->flush);
145 if (gc->npending == sizeof(gc->buf))
146 gdb_cnflush(gc);
147 }
148 gc->buf[gc->npending++] = c;
149 /*
150 * Flush on end of line; this is especially helpful
151 * during boot when we don't have callouts to flush
152 * the buffer. Otherwise we defer flushing; a 1/4
153 * second is a guess.
154 */
155 if (c == '\n')
156 gdb_cnflush(gc);
157 else if (calloutok)
158 callout_reset(&gc->flush, hz/4, gdb_cnflush, gc);
159 }
160 }
161
162 CONSOLE_DRIVER(gdb);
163
164 /*
165 * Our console device only gets attached if the system is booted
166 * with RB_MULTIPLE set so gdb_init also calls us to attach the
167 * console so we're setup regardless.
168 */
169 void
170 gdb_consinit(void)
171 {
172 gdb_cnprobe(&gdb_consdev);
173 gdb_cninit(&gdb_consdev);
174 cnadd(&gdb_consdev);
175 }
176
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