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: releng/11.2/sys/gdb/gdb_cons.c 283291 2015-05-22 17:05:21Z jkim $");
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_RWTUN, &gdbcons_enable,
62 0, "copy console messages to GDB");
63
64 static void
65 gdb_cnprobe(struct consdev *cp)
66 {
67 sprintf(cp->cn_name, "gdb");
68 cp->cn_pri = CN_LOW; /* XXX no way to say "write only" */
69 }
70
71 static void
72 gdb_cninit(struct consdev *cp)
73 {
74 struct gdbcons *c = &state;
75
76 /* setup tx buffer and callout */
77 if (c->npending == -1) {
78 c->npending = 0;
79 callout_init(&c->flush, 1);
80 cp->cn_arg = c;
81 }
82 }
83
84 static void
85 gdb_cnterm(struct consdev *cp)
86 {
87 }
88
89 static void
90 gdb_cngrab(struct consdev *cp)
91 {
92 }
93
94 static void
95 gdb_cnungrab(struct consdev *cp)
96 {
97 }
98
99 static int
100 gdb_cngetc(struct consdev *cp)
101 {
102 return -1;
103 }
104
105 static void
106 gdb_tx_puthex(int c)
107 {
108 const char *hex = "0123456789abcdef";
109
110 gdb_tx_char(hex[(c>>4)&0xf]);
111 gdb_tx_char(hex[(c>>0)&0xf]);
112 }
113
114 static void
115 gdb_cnflush(void *arg)
116 {
117 struct gdbcons *gc = arg;
118 int i;
119
120 gdb_tx_begin('O');
121 for (i = 0; i < gc->npending; i++)
122 gdb_tx_puthex(gc->buf[i]);
123 gdb_tx_end();
124 gc->npending = 0;
125 }
126
127 /*
128 * This glop is to figure out when it's safe to use callouts
129 * to defer buffer flushing. There's probably a better way
130 * and/or an earlier point in the boot process when it's ok.
131 */
132 static int calloutok = 0;
133 static void
134 oktousecallout(void *data __unused)
135 {
136 calloutok = 1;
137 }
138 SYSINIT(gdbhack, SI_SUB_LAST, SI_ORDER_MIDDLE, oktousecallout, NULL);
139
140 static void
141 gdb_cnputc(struct consdev *cp, int c)
142 {
143 struct gdbcons *gc;
144
145 if (gdbcons_enable && gdb_cur != NULL && gdb_listening) {
146 gc = cp->cn_arg;
147 if (gc->npending != 0) {
148 /*
149 * Cancel any pending callout and flush the
150 * buffer if there's no space for this byte.
151 */
152 if (calloutok)
153 callout_stop(&gc->flush);
154 if (gc->npending == sizeof(gc->buf))
155 gdb_cnflush(gc);
156 }
157 gc->buf[gc->npending++] = c;
158 /*
159 * Flush on end of line; this is especially helpful
160 * during boot when we don't have callouts to flush
161 * the buffer. Otherwise we defer flushing; a 1/4
162 * second is a guess.
163 */
164 if (c == '\n')
165 gdb_cnflush(gc);
166 else if (calloutok)
167 callout_reset(&gc->flush, hz/4, gdb_cnflush, gc);
168 }
169 }
170
171 CONSOLE_DRIVER(gdb);
172
173 /*
174 * Our console device only gets attached if the system is booted
175 * with RB_MULTIPLE set so gdb_init also calls us to attach the
176 * console so we're setup regardless.
177 */
178 void
179 gdb_consinit(void)
180 {
181 gdb_cnprobe(&gdb_consdev);
182 gdb_cninit(&gdb_consdev);
183 cnadd(&gdb_consdev);
184 }
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