xref: /freebsd/sbin/ddb/ddb_capture.c (revision 32e86a82f54826f14ea381affa6674db3aa3b5ae)
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/types.h>
30 #include <sys/sysctl.h>
31 
32 #include <err.h>
33 #include <errno.h>
34 #include <fcntl.h>
35 #include <kvm.h>
36 #include <limits.h>
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include <string.h>
40 #include <sysexits.h>
41 #include <unistd.h>
42 
43 #include "ddb.h"
44 
45 /*
46  * Interface with the ddb(4) capture buffer of a live kernel using sysctl, or
47  * for a crash dump using libkvm.
48  */
49 #define	SYSCTL_DDB_CAPTURE_BUFOFF	"debug.ddb.capture.bufoff"
50 #define	SYSCTL_DDB_CAPTURE_BUFSIZE	"debug.ddb.capture.bufsize"
51 #define	SYSCTL_DDB_CAPTURE_MAXBUFSIZE	"debug.ddb.capture.maxbufsize"
52 #define	SYSCTL_DDB_CAPTURE_DATA		"debug.ddb.capture.data"
53 #define	SYSCTL_DDB_CAPTURE_INPROGRESS	"debug.ddb.capture.inprogress"
54 
55 static struct nlist namelist[] = {
56 #define X_DB_CAPTURE_BUF	0
57 	{ .n_name = "_db_capture_buf" },
58 #define X_DB_CAPTURE_BUFSIZE	1
59 	{ .n_name = "_db_capture_bufsize" },
60 #define X_DB_CAPTURE_MAXBUFSIZE	2
61 	{ .n_name = "_db_capture_maxbufsize" },
62 #define X_DB_CAPTURE_BUFOFF	3
63 	{ .n_name = "_db_capture_bufoff" },
64 #define	X_DB_CAPTURE_INPROGRESS	4
65 	{ .n_name = "_db_capture_inprogress" },
66 	{ .n_name = "" },
67 };
68 
69 static int
kread(kvm_t * kvm,void * kvm_pointer,void * address,size_t size,size_t offset)70 kread(kvm_t *kvm, void *kvm_pointer, void *address, size_t size,
71     size_t offset)
72 {
73 	ssize_t ret;
74 
75 	ret = kvm_read(kvm, (unsigned long)kvm_pointer + offset, address,
76 	    size);
77 	if (ret < 0 || (size_t)ret != size)
78 		return (-1);
79 	return (0);
80 }
81 
82 static int
kread_symbol(kvm_t * kvm,int read_index,void * address,size_t size,size_t offset)83 kread_symbol(kvm_t *kvm, int read_index, void *address, size_t size,
84     size_t offset)
85 {
86 	ssize_t ret;
87 
88 	ret = kvm_read(kvm, namelist[read_index].n_value + offset, address, size);
89 	if (ret < 0 || (size_t)ret != size)
90 		return (-1);
91 	return (0);
92 }
93 
94 static void
ddb_capture_print_kvm(kvm_t * kvm)95 ddb_capture_print_kvm(kvm_t *kvm)
96 {
97 	u_int db_capture_bufoff;
98 	char *buffer, *db_capture_buf;
99 
100 	if (kread_symbol(kvm, X_DB_CAPTURE_BUF, &db_capture_buf,
101 	    sizeof(db_capture_buf), 0) < 0)
102 		errx(-1, "kvm: unable to read db_capture_buf");
103 
104 	if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff,
105 	    sizeof(db_capture_bufoff), 0) < 0)
106 		errx(-1, "kvm: unable to read db_capture_bufoff");
107 
108 	buffer = malloc(db_capture_bufoff + 1);
109 	if (buffer == NULL)
110 		err(-1, "malloc: db_capture_bufoff (%u)",
111 		    db_capture_bufoff);
112 	bzero(buffer, db_capture_bufoff + 1);
113 
114 	if (kread(kvm, db_capture_buf, buffer, db_capture_bufoff, 0) < 0)
115 		errx(-1, "kvm: unable to read buffer");
116 
117 	printf("%s\n", buffer);
118 	free(buffer);
119 }
120 
121 static void
ddb_capture_print_sysctl(void)122 ddb_capture_print_sysctl(void)
123 {
124 	size_t buflen, len;
125 	char *buffer;
126 	int ret;
127 
128 repeat:
129 	if (sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, NULL, &buflen, NULL, 0) < 0)
130 		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA);
131 	if (buflen == 0)
132 		return;
133 	buffer = malloc(buflen);
134 	if (buffer == NULL)
135 		err(EX_OSERR, "malloc");
136 	bzero(buffer, buflen);
137 	len = buflen;
138 	ret = sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, buffer, &len, NULL, 0);
139 	if (ret < 0 && errno != ENOMEM)
140 		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA);
141 	if (ret < 0) {
142 		free(buffer);
143 		goto repeat;
144 	}
145 
146 	printf("%s\n", buffer);
147 	free(buffer);
148 }
149 
150 static void
ddb_capture_status_kvm(kvm_t * kvm)151 ddb_capture_status_kvm(kvm_t *kvm)
152 {
153 	u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress;
154 
155 	if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff,
156 	    sizeof(db_capture_bufoff), 0) < 0)
157 		errx(-1, "kvm: unable to read db_capture_bufoff");
158 	if (kread_symbol(kvm, X_DB_CAPTURE_BUFSIZE, &db_capture_bufsize,
159 	    sizeof(db_capture_bufsize), 0) < 0)
160 		errx(-1, "kvm: unable to read db_capture_bufsize");
161 	if (kread_symbol(kvm, X_DB_CAPTURE_INPROGRESS,
162 	    &db_capture_inprogress, sizeof(db_capture_inprogress), 0) < 0)
163 		err(-1, "kvm: unable to read db_capture_inprogress");
164 	printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize);
165 	if (db_capture_inprogress)
166 		printf("capture is on\n");
167 	else
168 		printf("capture is off\n");
169 
170 }
171 
172 static void
ddb_capture_status_sysctl(void)173 ddb_capture_status_sysctl(void)
174 {
175 	u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress;
176 	size_t len;
177 
178 	len = sizeof(db_capture_bufoff);
179 	if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFOFF, &db_capture_bufoff, &len,
180 	    NULL, 0) < 0)
181 		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFOFF);
182 	len = sizeof(db_capture_bufoff);
183 	if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFSIZE, &db_capture_bufsize,
184 	    &len, NULL, 0) < 0)
185 		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFSIZE);
186 	len = sizeof(db_capture_inprogress);
187 	if (sysctlbyname(SYSCTL_DDB_CAPTURE_INPROGRESS,
188 	    &db_capture_inprogress, &len, NULL, 0) < 0)
189 		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_INPROGRESS);
190 	printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize);
191 	if (db_capture_inprogress)
192 		printf("capture is on\n");
193 	else
194 		printf("capture is off\n");
195 }
196 
197 void
ddb_capture(int argc,char * argv[])198 ddb_capture(int argc, char *argv[])
199 {
200 	char *mflag, *nflag, errbuf[_POSIX2_LINE_MAX];
201 	kvm_t *kvm;
202 	int ch;
203 
204 	mflag = NULL;
205 	nflag = NULL;
206 	kvm = NULL;
207 	while ((ch = getopt(argc, argv, "M:N:")) != -1) {
208 		switch (ch) {
209 		case 'M':
210 			mflag = optarg;
211 			break;
212 
213 		case 'N':
214 			nflag = optarg;
215 			break;
216 
217 		default:
218 			usage();
219 		}
220 	}
221 	argc -= optind;
222 	argv += optind;
223 
224 	if (argc != 1)
225 		usage();
226 
227 	if (mflag != NULL) {
228 		kvm = kvm_openfiles(nflag, mflag, NULL, O_RDONLY, errbuf);
229 		if (kvm == NULL)
230 			errx(-1, "ddb_capture: kvm_openfiles: %s", errbuf);
231 		if (kvm_nlist(kvm, namelist) != 0)
232 			errx(-1, "ddb_capture: kvm_nlist");
233 	} else if (nflag != NULL)
234 		usage();
235 	if (strcmp(argv[0], "print") == 0) {
236 		if (kvm != NULL)
237 			ddb_capture_print_kvm(kvm);
238 		else
239 			ddb_capture_print_sysctl();
240 	} else if (strcmp(argv[0], "status") == 0) {
241 		if (kvm != NULL)
242 			ddb_capture_status_kvm(kvm);
243 		else
244 			ddb_capture_status_sysctl();
245 	} else
246 		usage();
247 }
248