ddb_capture.c revision 198820
1/*- 2 * Copyright (c) 2008 Robert N. M. Watson 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 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27#include <sys/cdefs.h> 28__FBSDID("$FreeBSD: head/sbin/ddb/ddb_capture.c 198820 2009-11-02 20:18:50Z jhb $"); 29 30#include <sys/types.h> 31#include <sys/sysctl.h> 32 33#include <err.h> 34#include <errno.h> 35#include <fcntl.h> 36#include <kvm.h> 37#include <limits.h> 38#include <stdio.h> 39#include <stdlib.h> 40#include <string.h> 41#include <sysexits.h> 42#include <unistd.h> 43 44#include "ddb.h" 45 46/* 47 * Interface with the ddb(4) capture buffer of a live kernel using sysctl, or 48 * for a crash dump using libkvm. 49 */ 50#define SYSCTL_DDB_CAPTURE_BUFOFF "debug.ddb.capture.bufoff" 51#define SYSCTL_DDB_CAPTURE_BUFSIZE "debug.ddb.capture.bufsize" 52#define SYSCTL_DDB_CAPTURE_MAXBUFSIZE "debug.ddb.capture.maxbufsize" 53#define SYSCTL_DDB_CAPTURE_DATA "debug.ddb.capture.data" 54#define SYSCTL_DDB_CAPTURE_INPROGRESS "debug.ddb.capture.inprogress" 55 56static struct nlist namelist[] = { 57#define X_DB_CAPTURE_BUF 0 58 { .n_name = "_db_capture_buf" }, 59#define X_DB_CAPTURE_BUFSIZE 1 60 { .n_name = "_db_capture_bufsize" }, 61#define X_DB_CAPTURE_MAXBUFSIZE 2 62 { .n_name = "_db_capture_maxbufsize" }, 63#define X_DB_CAPTURE_BUFOFF 3 64 { .n_name = "_db_capture_bufoff" }, 65#define X_DB_CAPTURE_INPROGRESS 4 66 { .n_name = "_db_capture_inprogress" }, 67 { .n_name = "" }, 68}; 69 70static int 71kread(kvm_t *kvm, void *kvm_pointer, void *address, size_t size, 72 size_t offset) 73{ 74 ssize_t ret; 75 76 ret = kvm_read(kvm, (unsigned long)kvm_pointer + offset, address, 77 size); 78 if (ret < 0 || (size_t)ret != size) 79 return (-1); 80 return (0); 81} 82 83static int 84kread_symbol(kvm_t *kvm, int index, void *address, size_t size, 85 size_t offset) 86{ 87 ssize_t ret; 88 89 ret = kvm_read(kvm, namelist[index].n_value + offset, address, size); 90 if (ret < 0 || (size_t)ret != size) 91 return (-1); 92 return (0); 93} 94 95static void 96ddb_capture_print_kvm(kvm_t *kvm) 97{ 98 u_int db_capture_bufoff; 99 char *buffer, *db_capture_buf; 100 101 if (kread_symbol(kvm, X_DB_CAPTURE_BUF, &db_capture_buf, 102 sizeof(db_capture_buf), 0) < 0) 103 errx(-1, "kvm: unable to read db_capture_buf"); 104 105 if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff, 106 sizeof(db_capture_bufoff), 0) < 0) 107 errx(-1, "kvm: unable to read db_capture_bufoff"); 108 109 buffer = malloc(db_capture_bufoff + 1); 110 if (buffer == NULL) 111 err(-1, "malloc: db_capture_bufoff (%u)", 112 db_capture_bufoff); 113 bzero(buffer, db_capture_bufoff + 1); 114 115 if (kread(kvm, db_capture_buf, buffer, db_capture_bufoff, 0) < 0) 116 errx(-1, "kvm: unable to read buffer"); 117 118 printf("%s\n", buffer); 119 free(buffer); 120} 121 122static void 123ddb_capture_print_sysctl(void) 124{ 125 size_t buflen, len; 126 char *buffer; 127 int ret; 128 129repeat: 130 if (sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, NULL, &buflen, NULL, 0) < 0) 131 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA); 132 if (buflen == 0) 133 return; 134 buffer = malloc(buflen); 135 if (buffer == NULL) 136 err(EX_OSERR, "malloc"); 137 bzero(buffer, buflen); 138 len = buflen; 139 ret = sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, buffer, &len, NULL, 0); 140 if (ret < 0 && errno != ENOMEM) 141 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA); 142 if (ret < 0) { 143 free(buffer); 144 goto repeat; 145 } 146 147 printf("%s\n", buffer); 148 free(buffer); 149} 150 151static void 152ddb_capture_status_kvm(kvm_t *kvm) 153{ 154 u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress; 155 156 if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff, 157 sizeof(db_capture_bufoff), 0) < 0) 158 errx(-1, "kvm: unable to read db_capture_bufoff"); 159 if (kread_symbol(kvm, X_DB_CAPTURE_BUFSIZE, &db_capture_bufsize, 160 sizeof(db_capture_bufsize), 0) < 0) 161 errx(-1, "kvm: unable to read db_capture_bufsize"); 162 if (kread_symbol(kvm, X_DB_CAPTURE_INPROGRESS, 163 &db_capture_inprogress, sizeof(db_capture_inprogress), 0) < 0) 164 err(-1, "kvm: unable to read db_capture_inprogress"); 165 printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize); 166 if (db_capture_inprogress) 167 printf("capture is on\n"); 168 else 169 printf("capture is off\n"); 170 171} 172 173static void 174ddb_capture_status_sysctl(void) 175{ 176 u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress; 177 size_t len; 178 179 len = sizeof(db_capture_bufoff); 180 if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFOFF, &db_capture_bufoff, &len, 181 NULL, 0) < 0) 182 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFOFF); 183 len = sizeof(db_capture_bufoff); 184 if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFSIZE, &db_capture_bufsize, 185 &len, NULL, 0) < 0) 186 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFSIZE); 187 len = sizeof(db_capture_inprogress); 188 if (sysctlbyname(SYSCTL_DDB_CAPTURE_INPROGRESS, 189 &db_capture_inprogress, &len, NULL, 0) < 0) 190 err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_INPROGRESS); 191 printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize); 192 if (db_capture_inprogress) 193 printf("capture is on\n"); 194 else 195 printf("capture is off\n"); 196} 197 198void 199ddb_capture(int argc, char *argv[]) 200{ 201 char *mflag, *nflag, errbuf[_POSIX2_LINE_MAX]; 202 kvm_t *kvm; 203 int ch; 204 205 mflag = NULL; 206 nflag = NULL; 207 kvm = NULL; 208 while ((ch = getopt(argc, argv, "M:N:")) != -1) { 209 switch (ch) { 210 case 'M': 211 mflag = optarg; 212 break; 213 214 case 'N': 215 nflag = optarg; 216 break; 217 218 default: 219 usage(); 220 } 221 } 222 argc -= optind; 223 argv += optind; 224 225 if (argc != 1) 226 usage(); 227 228 if (mflag != NULL) { 229 kvm = kvm_openfiles(nflag, mflag, NULL, O_RDONLY, errbuf); 230 if (kvm == NULL) 231 errx(-1, "ddb_capture: kvm_openfiles: %s", errbuf); 232 if (kvm_nlist(kvm, namelist) != 0) 233 errx(-1, "ddb_capture: kvm_nlist"); 234 } else if (nflag != NULL) 235 usage(); 236 if (strcmp(argv[0], "print") == 0) { 237 if (kvm != NULL) 238 ddb_capture_print_kvm(kvm); 239 else 240 ddb_capture_print_sysctl(); 241 } else if (strcmp(argv[0], "status") == 0) { 242 if (kvm != NULL) 243 ddb_capture_status_kvm(kvm); 244 else 245 ddb_capture_status_sysctl(); 246 } else 247 usage(); 248} 249