2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2007 Robert N. M. Watson
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
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.
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
30 * Kernel text-dump support: write a series of text files to the dump
31 * partition for later recovery, including captured DDB output, kernel
32 * configuration, message buffer, and panic message. This allows for a more
33 * compact representation of critical debugging information than traditional
34 * binary dumps, as well as allowing dump information to be used without
35 * access to kernel symbols, source code, etc.
40 * Crash dumps are aligned to the end of the dump or swap partition in order
41 * to minimize the chances of swap duing fsck eating into the dump. However,
42 * unlike a memory dump, we don't know the size of the textdump a priori, so
43 * can't just write it out sequentially in order from a known starting point
44 * calculated with respect to the end of the partition. In order to address
45 * this, we actually write out the textdump in reverse block order, allowing
46 * us to directly align it to the end of the partition and then write out the
47 * dump header and trailer before and after it once done. savecore(8) must
48 * know to reverse the order of the blocks in order to produce a readable
51 * Data is written out in the ustar file format so that we can write data
52 * incrementally as a stream without reference to previous files.
57 * - Allow subsystems to register to submit files for inclusion in the text
58 * dump in a generic way.
61 #include <sys/cdefs.h>
62 __FBSDID("$FreeBSD$");
64 #include "opt_config.h"
68 #include <sys/param.h>
70 #include <sys/kernel.h>
71 #include <sys/kerneldump.h>
72 #include <sys/msgbuf.h>
73 #include <sys/sysctl.h>
74 #include <sys/systm.h>
77 #include <ddb/db_lex.h>
79 static SYSCTL_NODE(_debug_ddb, OID_AUTO, textdump, CTLFLAG_RW, 0,
80 "DDB textdump options");
83 * Don't touch the first SIZEOF_METADATA bytes on the dump device. This is
84 * to protect us from metadata and metadata from us.
86 #define SIZEOF_METADATA (64*1024)
89 * Data is written out as a series of files in the ustar tar format. ustar
90 * is a simple streamed format consiting of a series of files prefixed with
91 * headers, and all padded to 512-byte block boundaries, which maps
92 * conveniently to our requirements.
95 char uh_filename[100];
103 char uh_linkfile[100];
110 char uh_filenameprefix[155];
115 * Various size assertions -- pretty much everything must be one block in
118 CTASSERT(sizeof(struct kerneldumpheader) == TEXTDUMP_BLOCKSIZE);
119 CTASSERT(sizeof(struct ustar_header) == TEXTDUMP_BLOCKSIZE);
122 * Is a textdump scheduled? If so, the shutdown code will invoke our dumpsys
123 * routine instead of the machine-dependent kernel dump routine.
125 #ifdef TEXTDUMP_PREFERRED
126 int textdump_pending = 1;
128 int textdump_pending = 0;
130 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, pending, CTLFLAG_RW,
131 &textdump_pending, 0,
132 "Perform textdump instead of regular kernel dump.");
135 * Various constants for tar headers and contents.
137 #define TAR_USER "root"
138 #define TAR_GROUP "wheel"
141 #define TAR_MODE "0600"
142 #define TAR_USTAR "ustar"
144 #define TAR_CONFIG_FILENAME "config.txt" /* Kernel configuration. */
145 #define TAR_MSGBUF_FILENAME "msgbuf.txt" /* Kernel messsage buffer. */
146 #define TAR_PANIC_FILENAME "panic.txt" /* Panic message. */
147 #define TAR_VERSION_FILENAME "version.txt" /* Kernel version. */
150 * Configure which files will be dumped.
152 #ifdef INCLUDE_CONFIG_FILE
153 static int textdump_do_config = 1;
154 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_config, CTLFLAG_RW,
155 &textdump_do_config, 0, "Dump kernel configuration in textdump");
158 static int textdump_do_ddb = 1;
159 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_ddb, CTLFLAG_RW,
160 &textdump_do_ddb, 0, "Dump DDB captured output in textdump");
162 static int textdump_do_msgbuf = 1;
163 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_msgbuf, CTLFLAG_RW,
164 &textdump_do_msgbuf, 0, "Dump kernel message buffer in textdump");
166 static int textdump_do_panic = 1;
167 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_panic, CTLFLAG_RW,
168 &textdump_do_panic, 0, "Dump kernel panic message in textdump");
170 static int textdump_do_version = 1;
171 SYSCTL_INT(_debug_ddb_textdump, OID_AUTO, do_version, CTLFLAG_RW,
172 &textdump_do_version, 0, "Dump kernel version string in textdump");
175 * State related to incremental writing of blocks to disk.
177 static off_t textdump_offset; /* Offset of next sequential write. */
178 static int textdump_error; /* Carried write error, if any. */
181 * Statically allocate space to prepare block-sized headers and data.
183 char textdump_block_buffer[TEXTDUMP_BLOCKSIZE];
184 static struct kerneldumpheader kdh;
187 * Calculate and fill in the checksum for a ustar header.
190 ustar_checksum(struct ustar_header *uhp)
195 for (i = 0; i < sizeof(uhp->uh_sum); i++)
196 uhp->uh_sum[i] = ' ';
198 for (i = 0; i < sizeof(*uhp); i++)
199 sum += ((u_char *)uhp)[i];
200 snprintf(uhp->uh_sum, sizeof(uhp->uh_sum), "%6o", sum);
204 * Each file in the tarball has a block-sized header with its name and other,
205 * largely hard-coded, properties.
208 textdump_mkustar(char *block_buffer, const char *filename, u_int size)
210 struct ustar_header *uhp;
212 #ifdef TEXTDUMP_VERBOSE
213 if (textdump_error == 0)
214 printf("textdump: creating '%s'.\n", filename);
216 uhp = (struct ustar_header *)block_buffer;
217 bzero(uhp, sizeof(*uhp));
218 strlcpy(uhp->uh_filename, filename, sizeof(uhp->uh_filename));
219 strlcpy(uhp->uh_mode, TAR_MODE, sizeof(uhp->uh_mode));
220 snprintf(uhp->uh_size, sizeof(uhp->uh_size), "%o", size);
221 strlcpy(uhp->uh_tar_owner, TAR_UID, sizeof(uhp->uh_tar_owner));
222 strlcpy(uhp->uh_tar_group, TAR_GID, sizeof(uhp->uh_tar_group));
223 strlcpy(uhp->uh_owner, TAR_USER, sizeof(uhp->uh_owner));
224 strlcpy(uhp->uh_group, TAR_GROUP, sizeof(uhp->uh_group));
225 snprintf(uhp->uh_mtime, sizeof(uhp->uh_mtime), "%lo",
226 (unsigned long)time_second);
228 strlcpy(uhp->uh_ustar, TAR_USTAR, sizeof(uhp->uh_ustar));
233 * textdump_writeblock() writes TEXTDUMP_BLOCKSIZE-sized blocks of data to
234 * the space between di->mediaoffset and di->mediaoffset + di->mediasize. It
235 * accepts an offset relative to di->mediaoffset. If we're carrying any
236 * error from previous I/O, return that error and don't continue to try to
237 * write. Most writers ignore the error and forge ahead on the basis that
238 * there's not much you can do.
241 textdump_writeblock(struct dumperinfo *di, off_t offset, char *buffer)
245 return (textdump_error);
246 if (offset + TEXTDUMP_BLOCKSIZE > di->mediasize)
248 if (offset < SIZEOF_METADATA)
250 textdump_error = dump_write(di, buffer, 0, offset + di->mediaoffset,
253 printf("textdump_writeblock: offset %jd, error %d\n", (intmax_t)offset,
255 return (textdump_error);
259 * Interfaces to save and restore the dump offset, so that printers can go
260 * back to rewrite a header if required, while avoiding their knowing about
261 * the global layout of the blocks.
263 * If we ever want to support writing textdumps to tape or other
264 * stream-oriented target, we'll need to remove this.
267 textdump_saveoff(off_t *offsetp)
270 *offsetp = textdump_offset;
274 textdump_restoreoff(off_t offset)
277 textdump_offset = offset;
281 * Interface to write the "next block" relative to the current offset; since
282 * we write backwards from the end of the partition, we subtract, but there's
283 * no reason for the caller to know this.
286 textdump_writenextblock(struct dumperinfo *di, char *buffer)
290 error = textdump_writeblock(di, textdump_offset, buffer);
291 textdump_offset -= TEXTDUMP_BLOCKSIZE;
295 #ifdef INCLUDE_CONFIG_FILE
296 extern char kernconfstring[];
299 * Dump kernel configuration.
302 textdump_dump_config(struct dumperinfo *di)
304 u_int count, fullblocks, len;
306 len = strlen(kernconfstring);
307 textdump_mkustar(textdump_block_buffer, TAR_CONFIG_FILENAME, len);
308 (void)textdump_writenextblock(di, textdump_block_buffer);
311 * Write out all full blocks directly from the string, and handle any
312 * left-over bits by copying it to out to the local buffer and
315 fullblocks = len / TEXTDUMP_BLOCKSIZE;
316 for (count = 0; count < fullblocks; count++)
317 (void)textdump_writenextblock(di, kernconfstring + count *
319 if (len % TEXTDUMP_BLOCKSIZE != 0) {
320 bzero(textdump_block_buffer, TEXTDUMP_BLOCKSIZE);
321 bcopy(kernconfstring + count * TEXTDUMP_BLOCKSIZE,
322 textdump_block_buffer, len % TEXTDUMP_BLOCKSIZE);
323 (void)textdump_writenextblock(di, textdump_block_buffer);
326 #endif /* INCLUDE_CONFIG_FILE */
329 * Dump kernel message buffer.
332 textdump_dump_msgbuf(struct dumperinfo *di)
334 off_t end_offset, tarhdr_offset;
335 u_int i, len, offset, seq, total_len;
339 * Write out a dummy tar header to advance the offset; we'll rewrite
340 * it later once we know the true size.
342 textdump_saveoff(&tarhdr_offset);
343 textdump_mkustar(textdump_block_buffer, TAR_MSGBUF_FILENAME, 0);
344 (void)textdump_writenextblock(di, textdump_block_buffer);
347 * Copy out the data in small chunks, but don't copy nuls that may be
348 * present if the message buffer has not yet completely filled at
353 msgbuf_peekbytes(msgbufp, NULL, 0, &seq);
354 while ((len = msgbuf_peekbytes(msgbufp, buf, sizeof(buf), &seq)) > 0) {
355 for (i = 0; i < len; i++) {
358 textdump_block_buffer[offset] = buf[i];
360 if (offset != sizeof(textdump_block_buffer))
362 (void)textdump_writenextblock(di,
363 textdump_block_buffer);
368 total_len += offset; /* Without the zero-padding. */
370 bzero(textdump_block_buffer + offset,
371 sizeof(textdump_block_buffer) - offset);
372 (void)textdump_writenextblock(di, textdump_block_buffer);
376 * Rewrite tar header to reflect how much was actually written.
378 textdump_saveoff(&end_offset);
379 textdump_restoreoff(tarhdr_offset);
380 textdump_mkustar(textdump_block_buffer, TAR_MSGBUF_FILENAME,
382 (void)textdump_writenextblock(di, textdump_block_buffer);
383 textdump_restoreoff(end_offset);
387 textdump_dump_panic(struct dumperinfo *di)
392 * Write out tar header -- we store up to one block of panic message.
394 len = min(strlen(panicstr), TEXTDUMP_BLOCKSIZE);
395 textdump_mkustar(textdump_block_buffer, TAR_PANIC_FILENAME, len);
396 (void)textdump_writenextblock(di, textdump_block_buffer);
399 * Zero-pad the panic string and write out block.
401 bzero(textdump_block_buffer, sizeof(textdump_block_buffer));
402 bcopy(panicstr, textdump_block_buffer, len);
403 (void)textdump_writenextblock(di, textdump_block_buffer);
407 textdump_dump_version(struct dumperinfo *di)
412 * Write out tar header -- at most one block of version information.
414 len = min(strlen(version), TEXTDUMP_BLOCKSIZE);
415 textdump_mkustar(textdump_block_buffer, TAR_VERSION_FILENAME, len);
416 (void)textdump_writenextblock(di, textdump_block_buffer);
419 * Zero pad the version string and write out block.
421 bzero(textdump_block_buffer, sizeof(textdump_block_buffer));
422 bcopy(version, textdump_block_buffer, len);
423 (void)textdump_writenextblock(di, textdump_block_buffer);
427 * Commit text dump to disk.
430 textdump_dumpsys(struct dumperinfo *di)
432 struct kerneldumpcrypto *kdc;
433 off_t dumplen, trailer_offset;
435 if (di->blocksize != TEXTDUMP_BLOCKSIZE) {
436 printf("Dump partition block size (%ju) not textdump "
437 "block size (%ju)", (uintmax_t)di->blocksize,
438 (uintmax_t)TEXTDUMP_BLOCKSIZE);
443 * We don't know a priori how large the dump will be, but we do know
444 * that we need to reserve space for metadata and that we need two
445 * dump headers. Also leave room for one ustar header and one block
448 if (di->mediasize < SIZEOF_METADATA + 2 * sizeof(kdh)) {
449 printf("Insufficient space on dump partition for minimal textdump.\n");
455 * Disable EKCD because we don't provide encrypted textdumps.
461 * Position the start of the dump so that we'll write the kernel dump
462 * trailer immediately before the end of the partition, and then work
463 * our way back. We will rewrite this header later to reflect the
464 * true size if things go well.
466 textdump_offset = di->mediasize - sizeof(kdh);
467 textdump_saveoff(&trailer_offset);
468 dump_init_header(di, &kdh, TEXTDUMPMAGIC, KERNELDUMP_TEXT_VERSION, 0);
469 (void)textdump_writenextblock(di, (char *)&kdh);
472 * Write a series of files in ustar format.
476 #ifdef INCLUDE_CONFIG_FILE
477 if (textdump_do_config)
478 textdump_dump_config(di);
480 if (textdump_do_msgbuf)
481 textdump_dump_msgbuf(di);
482 if (textdump_do_panic && panicstr != NULL)
483 textdump_dump_panic(di);
484 if (textdump_do_version)
485 textdump_dump_version(di);
488 * Now that we know the true size, we can write out the header, then
489 * seek back to the end and rewrite the trailer with the correct
492 dumplen = trailer_offset - (textdump_offset + TEXTDUMP_BLOCKSIZE);
493 dump_init_header(di, &kdh, TEXTDUMPMAGIC, KERNELDUMP_TEXT_VERSION,
495 (void)textdump_writenextblock(di, (char *)&kdh);
496 textdump_restoreoff(trailer_offset);
497 (void)textdump_writenextblock(di, (char *)&kdh);
500 * Terminate the dump, report any errors, and clear the pending flag.
502 if (textdump_error == 0)
503 (void)dump_write(di, NULL, 0, 0, 0);
504 if (textdump_error == ENOSPC)
505 printf("Textdump: Insufficient space on dump partition\n");
506 else if (textdump_error != 0)
507 printf("Textdump: Error %d writing dump\n", textdump_error);
509 printf("Textdump complete.\n");
510 textdump_pending = 0;
513 * Restore EKCD status.
519 * DDB(4) command to manage textdumps:
521 * textdump set - request a textdump
522 * textdump status - print DDB output textdump status
523 * textdump unset - clear textdump request
526 db_textdump_usage(void)
529 db_printf("textdump [unset|set|status|dump]\n");
533 db_textdump_cmd(db_expr_t addr, bool have_addr, db_expr_t count, char *modif)
542 if (db_read_token() != tEOL) {
546 if (strcmp(db_tok_string, "set") == 0) {
547 textdump_pending = 1;
548 db_printf("textdump set\n");
549 } else if (strcmp(db_tok_string, "status") == 0) {
550 if (textdump_pending)
551 db_printf("textdump is set\n");
553 db_printf("textdump is not set\n");
554 } else if (strcmp(db_tok_string, "unset") == 0) {
555 textdump_pending = 0;
556 db_printf("textdump unset\n");
557 } else if (strcmp(db_tok_string, "dump") == 0) {
558 textdump_pending = 1;