xref: /freebsd/sbin/ddb/ddb_capture.c (revision a466cc55373fc3cf86837f09da729535b57e69a1)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2008 Robert N. M. Watson
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  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31 
32 #include <sys/types.h>
33 #include <sys/sysctl.h>
34 
35 #include <err.h>
36 #include <errno.h>
37 #include <fcntl.h>
38 #include <kvm.h>
39 #include <limits.h>
40 #include <stdio.h>
41 #include <stdlib.h>
42 #include <string.h>
43 #include <sysexits.h>
44 #include <unistd.h>
45 
46 #include "ddb.h"
47 
48 /*
49  * Interface with the ddb(4) capture buffer of a live kernel using sysctl, or
50  * for a crash dump using libkvm.
51  */
52 #define	SYSCTL_DDB_CAPTURE_BUFOFF	"debug.ddb.capture.bufoff"
53 #define	SYSCTL_DDB_CAPTURE_BUFSIZE	"debug.ddb.capture.bufsize"
54 #define	SYSCTL_DDB_CAPTURE_MAXBUFSIZE	"debug.ddb.capture.maxbufsize"
55 #define	SYSCTL_DDB_CAPTURE_DATA		"debug.ddb.capture.data"
56 #define	SYSCTL_DDB_CAPTURE_INPROGRESS	"debug.ddb.capture.inprogress"
57 
58 static struct nlist namelist[] = {
59 #define X_DB_CAPTURE_BUF	0
60 	{ .n_name = "_db_capture_buf" },
61 #define X_DB_CAPTURE_BUFSIZE	1
62 	{ .n_name = "_db_capture_bufsize" },
63 #define X_DB_CAPTURE_MAXBUFSIZE	2
64 	{ .n_name = "_db_capture_maxbufsize" },
65 #define X_DB_CAPTURE_BUFOFF	3
66 	{ .n_name = "_db_capture_bufoff" },
67 #define	X_DB_CAPTURE_INPROGRESS	4
68 	{ .n_name = "_db_capture_inprogress" },
69 	{ .n_name = "" },
70 };
71 
72 static int
73 kread(kvm_t *kvm, void *kvm_pointer, void *address, size_t size,
74     size_t offset)
75 {
76 	ssize_t ret;
77 
78 	ret = kvm_read(kvm, (unsigned long)kvm_pointer + offset, address,
79 	    size);
80 	if (ret < 0 || (size_t)ret != size)
81 		return (-1);
82 	return (0);
83 }
84 
85 static int
86 kread_symbol(kvm_t *kvm, int read_index, void *address, size_t size,
87     size_t offset)
88 {
89 	ssize_t ret;
90 
91 	ret = kvm_read(kvm, namelist[read_index].n_value + offset, address, size);
92 	if (ret < 0 || (size_t)ret != size)
93 		return (-1);
94 	return (0);
95 }
96 
97 static void
98 ddb_capture_print_kvm(kvm_t *kvm)
99 {
100 	u_int db_capture_bufoff;
101 	char *buffer, *db_capture_buf;
102 
103 	if (kread_symbol(kvm, X_DB_CAPTURE_BUF, &db_capture_buf,
104 	    sizeof(db_capture_buf), 0) < 0)
105 		errx(-1, "kvm: unable to read db_capture_buf");
106 
107 	if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff,
108 	    sizeof(db_capture_bufoff), 0) < 0)
109 		errx(-1, "kvm: unable to read db_capture_bufoff");
110 
111 	buffer = malloc(db_capture_bufoff + 1);
112 	if (buffer == NULL)
113 		err(-1, "malloc: db_capture_bufoff (%u)",
114 		    db_capture_bufoff);
115 	bzero(buffer, db_capture_bufoff + 1);
116 
117 	if (kread(kvm, db_capture_buf, buffer, db_capture_bufoff, 0) < 0)
118 		errx(-1, "kvm: unable to read buffer");
119 
120 	printf("%s\n", buffer);
121 	free(buffer);
122 }
123 
124 static void
125 ddb_capture_print_sysctl(void)
126 {
127 	size_t buflen, len;
128 	char *buffer;
129 	int ret;
130 
131 repeat:
132 	if (sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, NULL, &buflen, NULL, 0) < 0)
133 		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA);
134 	if (buflen == 0)
135 		return;
136 	buffer = malloc(buflen);
137 	if (buffer == NULL)
138 		err(EX_OSERR, "malloc");
139 	bzero(buffer, buflen);
140 	len = buflen;
141 	ret = sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, buffer, &len, NULL, 0);
142 	if (ret < 0 && errno != ENOMEM)
143 		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA);
144 	if (ret < 0) {
145 		free(buffer);
146 		goto repeat;
147 	}
148 
149 	printf("%s\n", buffer);
150 	free(buffer);
151 }
152 
153 static void
154 ddb_capture_status_kvm(kvm_t *kvm)
155 {
156 	u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress;
157 
158 	if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff,
159 	    sizeof(db_capture_bufoff), 0) < 0)
160 		errx(-1, "kvm: unable to read db_capture_bufoff");
161 	if (kread_symbol(kvm, X_DB_CAPTURE_BUFSIZE, &db_capture_bufsize,
162 	    sizeof(db_capture_bufsize), 0) < 0)
163 		errx(-1, "kvm: unable to read db_capture_bufsize");
164 	if (kread_symbol(kvm, X_DB_CAPTURE_INPROGRESS,
165 	    &db_capture_inprogress, sizeof(db_capture_inprogress), 0) < 0)
166 		err(-1, "kvm: unable to read db_capture_inprogress");
167 	printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize);
168 	if (db_capture_inprogress)
169 		printf("capture is on\n");
170 	else
171 		printf("capture is off\n");
172 
173 }
174 
175 static void
176 ddb_capture_status_sysctl(void)
177 {
178 	u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress;
179 	size_t len;
180 
181 	len = sizeof(db_capture_bufoff);
182 	if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFOFF, &db_capture_bufoff, &len,
183 	    NULL, 0) < 0)
184 		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFOFF);
185 	len = sizeof(db_capture_bufoff);
186 	if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFSIZE, &db_capture_bufsize,
187 	    &len, NULL, 0) < 0)
188 		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFSIZE);
189 	len = sizeof(db_capture_inprogress);
190 	if (sysctlbyname(SYSCTL_DDB_CAPTURE_INPROGRESS,
191 	    &db_capture_inprogress, &len, NULL, 0) < 0)
192 		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_INPROGRESS);
193 	printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize);
194 	if (db_capture_inprogress)
195 		printf("capture is on\n");
196 	else
197 		printf("capture is off\n");
198 }
199 
200 void
201 ddb_capture(int argc, char *argv[])
202 {
203 	char *mflag, *nflag, errbuf[_POSIX2_LINE_MAX];
204 	kvm_t *kvm;
205 	int ch;
206 
207 	mflag = NULL;
208 	nflag = NULL;
209 	kvm = NULL;
210 	while ((ch = getopt(argc, argv, "M:N:")) != -1) {
211 		switch (ch) {
212 		case 'M':
213 			mflag = optarg;
214 			break;
215 
216 		case 'N':
217 			nflag = optarg;
218 			break;
219 
220 		default:
221 			usage();
222 		}
223 	}
224 	argc -= optind;
225 	argv += optind;
226 
227 	if (argc != 1)
228 		usage();
229 
230 	if (mflag != NULL) {
231 		kvm = kvm_openfiles(nflag, mflag, NULL, O_RDONLY, errbuf);
232 		if (kvm == NULL)
233 			errx(-1, "ddb_capture: kvm_openfiles: %s", errbuf);
234 		if (kvm_nlist(kvm, namelist) != 0)
235 			errx(-1, "ddb_capture: kvm_nlist");
236 	} else if (nflag != NULL)
237 		usage();
238 	if (strcmp(argv[0], "print") == 0) {
239 		if (kvm != NULL)
240 			ddb_capture_print_kvm(kvm);
241 		else
242 			ddb_capture_print_sysctl();
243 	} else if (strcmp(argv[0], "status") == 0) {
244 		if (kvm != NULL)
245 			ddb_capture_status_kvm(kvm);
246 		else
247 			ddb_capture_status_sysctl();
248 	} else
249 		usage();
250 }
251