2 * Copyright (c) 2007 Robert N. M. Watson
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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
28 * Kernel text-dump support: write a series of text files to the dump
29 * partition for later recovery, including captured DDB output, kernel
30 * configuration, message buffer, and panic message. This allows for a more
31 * compact representation of critical debugging information than traditional
32 * binary dumps, as well as allowing dump information to be used without
33 * access to kernel symbols, source code, etc.
38 * Crash dumps are aligned to the end of the dump or swap partition in order
39 * to minimize the chances of swap duing fsck eating into the dump. However,
40 * unlike a memory dump, we don't know the size of the textdump a priori, so
41 * can't just write it out sequentially in order from a known starting point
42 * calculated with respect to the end of the partition. In order to address
43 * this, we actually write out the textdump in reverse block order, allowing
44 * us to directly align it to the end of the partition and then write out the
45 * dump header and trailer before and after it once done. savecore(8) must
46 * know to reverse the order of the blocks in order to produce a readable
49 * Data is written out in the ustar file format so that we can write data
50 * incrementally as a stream without reference to previous files.
55 * - Allow subsystems to register to submit files for inclusion in the text
56 * dump in a generic way.
59 #include <sys/cdefs.h>
60 __FBSDID("$FreeBSD$");
62 #include "opt_config.h"
66 #include <sys/param.h>
68 #include <sys/kernel.h>
69 #include <sys/kerneldump.h>
70 #include <sys/msgbuf.h>
71 #include <sys/sysctl.h>
72 #include <sys/systm.h>
75 #include <ddb/db_lex.h>
77 static SYSCTL_NODE(_debug_ddb, OID_AUTO, textdump, CTLFLAG_RW, 0,
78 "DDB textdump options");
81 * Don't touch the first SIZEOF_METADATA bytes on the dump device. This is
82 * to protect us from metadata and metadata from us.
84 #define SIZEOF_METADATA (64*1024)
87 * Data is written out as a series of files in the ustar tar format. ustar
88 * is a simple streamed format consiting of a series of files prefixed with
89 * headers, and all padded to 512-byte block boundaries, which maps
90 * conveniently to our requirements.
93 char uh_filename[100];
101 char uh_linkfile[100];
108 char uh_filenameprefix[155];
113 * Various size assertions -- pretty much everything must be one block in
116 CTASSERT(sizeof(struct kerneldumpheader) == TEXTDUMP_BLOCKSIZE);
117 CTASSERT(sizeof(struct ustar_header) == TEXTDUMP_BLOCKSIZE);
120 * Is a textdump scheduled? If so, the shutdown code will invoke our dumpsys
121 * routine instead of the machine-dependent kernel dump routine.
123 #ifdef TEXTDUMP_PREFERRED
124 int textdump_pending = 1;
126 int textdump_pending = 0;
128 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, pending, CTLFLAG_RW,
129 &textdump_pending, 0,
130 "Perform textdump instead of regular kernel dump.");
133 * Various constants for tar headers and contents.
135 #define TAR_USER "root"
136 #define TAR_GROUP "wheel"
139 #define TAR_MODE "0600"
140 #define TAR_USTAR "ustar"
142 #define TAR_CONFIG_FILENAME "config.txt" /* Kernel configuration. */
143 #define TAR_MSGBUF_FILENAME "msgbuf.txt" /* Kernel messsage buffer. */
144 #define TAR_PANIC_FILENAME "panic.txt" /* Panic message. */
145 #define TAR_VERSION_FILENAME "version.txt" /* Kernel version. */
148 * Configure which files will be dumped.
150 #ifdef INCLUDE_CONFIG_FILE
151 static int textdump_do_config = 1;
152 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_config, CTLFLAG_RW,
153 &textdump_do_config, 0, "Dump kernel configuration in textdump");
156 static int textdump_do_ddb = 1;
157 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_ddb, CTLFLAG_RW,
158 &textdump_do_ddb, 0, "Dump DDB captured output in textdump");
160 static int textdump_do_msgbuf = 1;
161 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_msgbuf, CTLFLAG_RW,
162 &textdump_do_msgbuf, 0, "Dump kernel message buffer in textdump");
164 static int textdump_do_panic = 1;
165 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_panic, CTLFLAG_RW,
166 &textdump_do_panic, 0, "Dump kernel panic message in textdump");
168 static int textdump_do_version = 1;
169 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_version, CTLFLAG_RW,
170 &textdump_do_version, 0, "Dump kernel version string in textdump");
173 * State related to incremental writing of blocks to disk.
175 static off_t textdump_offset; /* Offset of next sequential write. */
176 static int textdump_error; /* Carried write error, if any. */
179 * Statically allocate space to prepare block-sized headers and data.
181 char textdump_block_buffer[TEXTDUMP_BLOCKSIZE];
182 static struct kerneldumpheader kdh;
185 * Calculate and fill in the checksum for a ustar header.
188 ustar_checksum(struct ustar_header *uhp)
193 for (i = 0; i < sizeof(uhp->uh_sum); i++)
194 uhp->uh_sum[i] = ' ';
196 for (i = 0; i < sizeof(*uhp); i++)
197 sum += ((u_char *)uhp)[i];
198 snprintf(uhp->uh_sum, sizeof(uhp->uh_sum), "%6o", sum);
202 * Each file in the tarball has a block-sized header with its name and other,
203 * largely hard-coded, properties.
206 textdump_mkustar(char *block_buffer, const char *filename, u_int size)
208 struct ustar_header *uhp;
210 #ifdef TEXTDUMP_VERBOSE
211 if (textdump_error == 0)
212 printf("textdump: creating '%s'.\n", filename);
214 uhp = (struct ustar_header *)block_buffer;
215 bzero(uhp, sizeof(*uhp));
216 strlcpy(uhp->uh_filename, filename, sizeof(uhp->uh_filename));
217 strlcpy(uhp->uh_mode, TAR_MODE, sizeof(uhp->uh_mode));
218 snprintf(uhp->uh_size, sizeof(uhp->uh_size), "%o", size);
219 strlcpy(uhp->uh_tar_owner, TAR_UID, sizeof(uhp->uh_tar_owner));
220 strlcpy(uhp->uh_tar_group, TAR_GID, sizeof(uhp->uh_tar_group));
221 strlcpy(uhp->uh_owner, TAR_USER, sizeof(uhp->uh_owner));
222 strlcpy(uhp->uh_group, TAR_GROUP, sizeof(uhp->uh_group));
223 snprintf(uhp->uh_mtime, sizeof(uhp->uh_mtime), "%lo",
224 (unsigned long)time_second);
226 strlcpy(uhp->uh_ustar, TAR_USTAR, sizeof(uhp->uh_ustar));
231 * textdump_writeblock() writes TEXTDUMP_BLOCKSIZE-sized blocks of data to
232 * the space between di->mediaoffset and di->mediaoffset + di->mediasize. It
233 * accepts an offset relative to di->mediaoffset. If we're carrying any
234 * error from previous I/O, return that error and don't continue to try to
235 * write. Most writers ignore the error and forge ahead on the basis that
236 * there's not much you can do.
239 textdump_writeblock(struct dumperinfo *di, off_t offset, char *buffer)
243 return (textdump_error);
244 if (offset + TEXTDUMP_BLOCKSIZE > di->mediasize)
246 if (offset < SIZEOF_METADATA)
248 textdump_error = dump_write(di, buffer, 0, offset + di->mediaoffset,
251 printf("textdump_writeblock: offset %jd, error %d\n", (intmax_t)offset,
253 return (textdump_error);
257 * Interfaces to save and restore the dump offset, so that printers can go
258 * back to rewrite a header if required, while avoiding their knowing about
259 * the global layout of the blocks.
261 * If we ever want to support writing textdumps to tape or other
262 * stream-oriented target, we'll need to remove this.
265 textdump_saveoff(off_t *offsetp)
268 *offsetp = textdump_offset;
272 textdump_restoreoff(off_t offset)
275 textdump_offset = offset;
279 * Interface to write the "next block" relative to the current offset; since
280 * we write backwards from the end of the partition, we subtract, but there's
281 * no reason for the caller to know this.
284 textdump_writenextblock(struct dumperinfo *di, char *buffer)
288 error = textdump_writeblock(di, textdump_offset, buffer);
289 textdump_offset -= TEXTDUMP_BLOCKSIZE;
293 #ifdef INCLUDE_CONFIG_FILE
294 extern char kernconfstring[];
297 * Dump kernel configuration.
300 textdump_dump_config(struct dumperinfo *di)
302 u_int count, fullblocks, len;
304 len = strlen(kernconfstring);
305 textdump_mkustar(textdump_block_buffer, TAR_CONFIG_FILENAME, len);
306 (void)textdump_writenextblock(di, textdump_block_buffer);
309 * Write out all full blocks directly from the string, and handle any
310 * left-over bits by copying it to out to the local buffer and
313 fullblocks = len / TEXTDUMP_BLOCKSIZE;
314 for (count = 0; count < fullblocks; count++)
315 (void)textdump_writenextblock(di, kernconfstring + count *
317 if (len % TEXTDUMP_BLOCKSIZE != 0) {
318 bzero(textdump_block_buffer, TEXTDUMP_BLOCKSIZE);
319 bcopy(kernconfstring + count * TEXTDUMP_BLOCKSIZE,
320 textdump_block_buffer, len % TEXTDUMP_BLOCKSIZE);
321 (void)textdump_writenextblock(di, textdump_block_buffer);
324 #endif /* INCLUDE_CONFIG_FILE */
327 * Dump kernel message buffer.
330 textdump_dump_msgbuf(struct dumperinfo *di)
332 off_t end_offset, tarhdr_offset;
333 u_int i, len, offset, seq, total_len;
337 * Write out a dummy tar header to advance the offset; we'll rewrite
338 * it later once we know the true size.
340 textdump_saveoff(&tarhdr_offset);
341 textdump_mkustar(textdump_block_buffer, TAR_MSGBUF_FILENAME, 0);
342 (void)textdump_writenextblock(di, textdump_block_buffer);
345 * Copy out the data in small chunks, but don't copy nuls that may be
346 * present if the message buffer has not yet completely filled at
351 msgbuf_peekbytes(msgbufp, NULL, 0, &seq);
352 while ((len = msgbuf_peekbytes(msgbufp, buf, sizeof(buf), &seq)) > 0) {
353 for (i = 0; i < len; i++) {
356 textdump_block_buffer[offset] = buf[i];
358 if (offset != sizeof(textdump_block_buffer))
360 (void)textdump_writenextblock(di,
361 textdump_block_buffer);
366 total_len += offset; /* Without the zero-padding. */
368 bzero(textdump_block_buffer + offset,
369 sizeof(textdump_block_buffer) - offset);
370 (void)textdump_writenextblock(di, textdump_block_buffer);
374 * Rewrite tar header to reflect how much was actually written.
376 textdump_saveoff(&end_offset);
377 textdump_restoreoff(tarhdr_offset);
378 textdump_mkustar(textdump_block_buffer, TAR_MSGBUF_FILENAME,
380 (void)textdump_writenextblock(di, textdump_block_buffer);
381 textdump_restoreoff(end_offset);
385 textdump_dump_panic(struct dumperinfo *di)
390 * Write out tar header -- we store up to one block of panic message.
392 len = min(strlen(panicstr), TEXTDUMP_BLOCKSIZE);
393 textdump_mkustar(textdump_block_buffer, TAR_PANIC_FILENAME, len);
394 (void)textdump_writenextblock(di, textdump_block_buffer);
397 * Zero-pad the panic string and write out block.
399 bzero(textdump_block_buffer, sizeof(textdump_block_buffer));
400 bcopy(panicstr, textdump_block_buffer, len);
401 (void)textdump_writenextblock(di, textdump_block_buffer);
405 textdump_dump_version(struct dumperinfo *di)
410 * Write out tar header -- at most one block of version information.
412 len = min(strlen(version), TEXTDUMP_BLOCKSIZE);
413 textdump_mkustar(textdump_block_buffer, TAR_VERSION_FILENAME, len);
414 (void)textdump_writenextblock(di, textdump_block_buffer);
417 * Zero pad the version string and write out block.
419 bzero(textdump_block_buffer, sizeof(textdump_block_buffer));
420 bcopy(version, textdump_block_buffer, len);
421 (void)textdump_writenextblock(di, textdump_block_buffer);
425 * Commit text dump to disk.
428 textdump_dumpsys(struct dumperinfo *di)
430 off_t dumplen, trailer_offset;
432 if (di->blocksize != TEXTDUMP_BLOCKSIZE) {
433 printf("Dump partition block size (%ju) not textdump "
434 "block size (%ju)", (uintmax_t)di->blocksize,
435 (uintmax_t)TEXTDUMP_BLOCKSIZE);
440 * We don't know a priori how large the dump will be, but we do know
441 * that we need to reserve space for metadata and that we need two
442 * dump headers. Also leave room for one ustar header and one block
445 if (di->mediasize < SIZEOF_METADATA + 2 * sizeof(kdh)) {
446 printf("Insufficient space on dump partition for minimal textdump.\n");
452 * Position the start of the dump so that we'll write the kernel dump
453 * trailer immediately before the end of the partition, and then work
454 * our way back. We will rewrite this header later to reflect the
455 * true size if things go well.
457 textdump_offset = di->mediasize - sizeof(kdh);
458 textdump_saveoff(&trailer_offset);
459 mkdumpheader(&kdh, TEXTDUMPMAGIC, KERNELDUMP_TEXT_VERSION, 0, TEXTDUMP_BLOCKSIZE);
460 (void)textdump_writenextblock(di, (char *)&kdh);
463 * Write a series of files in ustar format.
467 #ifdef INCLUDE_CONFIG_FILE
468 if (textdump_do_config)
469 textdump_dump_config(di);
471 if (textdump_do_msgbuf)
472 textdump_dump_msgbuf(di);
473 if (textdump_do_panic && panicstr != NULL)
474 textdump_dump_panic(di);
475 if (textdump_do_version)
476 textdump_dump_version(di);
479 * Now that we know the true size, we can write out the header, then
480 * seek back to the end and rewrite the trailer with the correct
483 dumplen = trailer_offset - (textdump_offset + TEXTDUMP_BLOCKSIZE);
484 mkdumpheader(&kdh, TEXTDUMPMAGIC, KERNELDUMP_TEXT_VERSION, dumplen,
486 (void)textdump_writenextblock(di, (char *)&kdh);
487 textdump_restoreoff(trailer_offset);
488 (void)textdump_writenextblock(di, (char *)&kdh);
491 * Terminate the dump, report any errors, and clear the pending flag.
493 if (textdump_error == 0)
494 (void)dump_write(di, NULL, 0, 0, 0);
495 if (textdump_error == ENOSPC)
496 printf("Textdump: Insufficient space on dump partition\n");
497 else if (textdump_error != 0)
498 printf("Textdump: Error %d writing dump\n", textdump_error);
500 printf("Textdump complete.\n");
501 textdump_pending = 0;
505 * DDB(4) command to manage textdumps:
507 * textdump set - request a textdump
508 * textdump status - print DDB output textdump status
509 * textdump unset - clear textdump request
512 db_textdump_usage(void)
515 db_printf("textdump [unset|set|status|dump]\n");
519 db_textdump_cmd(db_expr_t addr, bool have_addr, db_expr_t count, char *modif)
528 if (db_read_token() != tEOL) {
532 if (strcmp(db_tok_string, "set") == 0) {
533 textdump_pending = 1;
534 db_printf("textdump set\n");
535 } else if (strcmp(db_tok_string, "status") == 0) {
536 if (textdump_pending)
537 db_printf("textdump is set\n");
539 db_printf("textdump is not set\n");
540 } else if (strcmp(db_tok_string, "unset") == 0) {
541 textdump_pending = 0;
542 db_printf("textdump unset\n");
543 } else if (strcmp(db_tok_string, "dump") == 0) {
544 textdump_pending = 1;