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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Persistent Storage - platform driver interface parts.4 *5 * Copyright (C) 2007-2008 Google, Inc.6 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>7 */8 9#define pr_fmt(fmt) "pstore: " fmt10 11#include <linux/atomic.h>12#include <linux/types.h>13#include <linux/errno.h>14#include <linux/init.h>15#include <linux/kmsg_dump.h>16#include <linux/console.h>17#include <linux/mm.h>18#include <linux/module.h>19#include <linux/pstore.h>20#include <linux/string.h>21#include <linux/timer.h>22#include <linux/slab.h>23#include <linux/uaccess.h>24#include <linux/jiffies.h>25#include <linux/vmalloc.h>26#include <linux/workqueue.h>27#include <linux/zlib.h>28 29#include "internal.h"30 31/*32 * We defer making "oops" entries appear in pstore - see33 * whether the system is actually still running well enough34 * to let someone see the entry35 */36static int pstore_update_ms = -1;37module_param_named(update_ms, pstore_update_ms, int, 0600);38MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "39 "(default is -1, which means runtime updates are disabled; "40 "enabling this option may not be safe; it may lead to further "41 "corruption on Oopses)");42 43/* Names should be in the same order as the enum pstore_type_id */44static const char * const pstore_type_names[] = {45 "dmesg",46 "mce",47 "console",48 "ftrace",49 "rtas",50 "powerpc-ofw",51 "powerpc-common",52 "pmsg",53 "powerpc-opal",54};55 56static int pstore_new_entry;57 58static void pstore_timefunc(struct timer_list *);59static DEFINE_TIMER(pstore_timer, pstore_timefunc);60 61static void pstore_dowork(struct work_struct *);62static DECLARE_WORK(pstore_work, pstore_dowork);63 64/*65 * psinfo_lock protects "psinfo" during calls to66 * pstore_register(), pstore_unregister(), and67 * the filesystem mount/unmount routines.68 */69static DEFINE_MUTEX(psinfo_lock);70struct pstore_info *psinfo;71 72static char *backend;73module_param(backend, charp, 0444);74MODULE_PARM_DESC(backend, "specific backend to use");75 76/*77 * pstore no longer implements compression via the crypto API, and only78 * supports zlib deflate compression implemented using the zlib library79 * interface. This removes additional complexity which is hard to justify for a80 * diagnostic facility that has to operate in conditions where the system may81 * have become unstable. Zlib deflate is comparatively small in terms of code82 * size, and compresses ASCII text comparatively well. In terms of compression83 * speed, deflate is not the best performer but for recording the log output on84 * a kernel panic, this is not considered critical.85 *86 * The only remaining arguments supported by the compress= module parameter are87 * 'deflate' and 'none'. To retain compatibility with existing installations,88 * all other values are logged and replaced with 'deflate'.89 */90static char *compress = "deflate";91module_param(compress, charp, 0444);92MODULE_PARM_DESC(compress, "compression to use");93 94/* How much of the kernel log to snapshot */95unsigned long kmsg_bytes = CONFIG_PSTORE_DEFAULT_KMSG_BYTES;96module_param(kmsg_bytes, ulong, 0444);97MODULE_PARM_DESC(kmsg_bytes, "amount of kernel log to snapshot (in bytes)");98 99static void *compress_workspace;100 101/*102 * Compression is only used for dmesg output, which consists of low-entropy103 * ASCII text, and so we can assume worst-case 60%.104 */105#define DMESG_COMP_PERCENT 60106 107static char *big_oops_buf;108static size_t max_compressed_size;109 110void pstore_set_kmsg_bytes(int bytes)111{112 kmsg_bytes = bytes;113}114 115/* Tag each group of saved records with a sequence number */116static int oopscount;117 118const char *pstore_type_to_name(enum pstore_type_id type)119{120 BUILD_BUG_ON(ARRAY_SIZE(pstore_type_names) != PSTORE_TYPE_MAX);121 122 if (WARN_ON_ONCE(type >= PSTORE_TYPE_MAX))123 return "unknown";124 125 return pstore_type_names[type];126}127EXPORT_SYMBOL_GPL(pstore_type_to_name);128 129enum pstore_type_id pstore_name_to_type(const char *name)130{131 int i;132 133 for (i = 0; i < PSTORE_TYPE_MAX; i++) {134 if (!strcmp(pstore_type_names[i], name))135 return i;136 }137 138 return PSTORE_TYPE_MAX;139}140EXPORT_SYMBOL_GPL(pstore_name_to_type);141 142static void pstore_timer_kick(void)143{144 if (pstore_update_ms < 0)145 return;146 147 mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));148}149 150static bool pstore_cannot_block_path(enum kmsg_dump_reason reason)151{152 /*153 * In case of NMI path, pstore shouldn't be blocked154 * regardless of reason.155 */156 if (in_nmi())157 return true;158 159 switch (reason) {160 /* In panic case, other cpus are stopped by smp_send_stop(). */161 case KMSG_DUMP_PANIC:162 /*163 * Emergency restart shouldn't be blocked by spinning on164 * pstore_info::buf_lock.165 */166 case KMSG_DUMP_EMERG:167 return true;168 default:169 return false;170 }171}172 173static int pstore_compress(const void *in, void *out,174 unsigned int inlen, unsigned int outlen)175{176 struct z_stream_s zstream = {177 .next_in = in,178 .avail_in = inlen,179 .next_out = out,180 .avail_out = outlen,181 .workspace = compress_workspace,182 };183 int ret;184 185 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS))186 return -EINVAL;187 188 ret = zlib_deflateInit2(&zstream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,189 -MAX_WBITS, DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY);190 if (ret != Z_OK)191 return -EINVAL;192 193 ret = zlib_deflate(&zstream, Z_FINISH);194 if (ret != Z_STREAM_END)195 return -EINVAL;196 197 ret = zlib_deflateEnd(&zstream);198 if (ret != Z_OK)199 pr_warn_once("zlib_deflateEnd() failed: %d\n", ret);200 201 return zstream.total_out;202}203 204static void allocate_buf_for_compression(void)205{206 size_t compressed_size;207 char *buf;208 209 /* Skip if not built-in or compression disabled. */210 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !compress ||211 !strcmp(compress, "none")) {212 compress = NULL;213 return;214 }215 216 if (strcmp(compress, "deflate")) {217 pr_err("Unsupported compression '%s', falling back to deflate\n",218 compress);219 compress = "deflate";220 }221 222 /*223 * The compression buffer only needs to be as large as the maximum224 * uncompressed record size, since any record that would be expanded by225 * compression is just stored uncompressed.226 */227 compressed_size = (psinfo->bufsize * 100) / DMESG_COMP_PERCENT;228 buf = kvzalloc(compressed_size, GFP_KERNEL);229 if (!buf) {230 pr_err("Failed %zu byte compression buffer allocation for: %s\n",231 psinfo->bufsize, compress);232 return;233 }234 235 compress_workspace =236 vmalloc(zlib_deflate_workspacesize(MAX_WBITS, DEF_MEM_LEVEL));237 if (!compress_workspace) {238 pr_err("Failed to allocate zlib deflate workspace\n");239 kvfree(buf);240 return;241 }242 243 /* A non-NULL big_oops_buf indicates compression is available. */244 big_oops_buf = buf;245 max_compressed_size = compressed_size;246 247 pr_info("Using crash dump compression: %s\n", compress);248}249 250static void free_buf_for_compression(void)251{252 if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && compress_workspace) {253 vfree(compress_workspace);254 compress_workspace = NULL;255 }256 257 kvfree(big_oops_buf);258 big_oops_buf = NULL;259 max_compressed_size = 0;260}261 262void pstore_record_init(struct pstore_record *record,263 struct pstore_info *psinfo)264{265 memset(record, 0, sizeof(*record));266 267 record->psi = psinfo;268 269 /* Report zeroed timestamp if called before timekeeping has resumed. */270 record->time = ns_to_timespec64(ktime_get_real_fast_ns());271}272 273/*274 * callback from kmsg_dump. Save as much as we can (up to kmsg_bytes) from the275 * end of the buffer.276 */277static void pstore_dump(struct kmsg_dumper *dumper,278 struct kmsg_dump_detail *detail)279{280 struct kmsg_dump_iter iter;281 unsigned long total = 0;282 const char *why;283 unsigned int part = 1;284 unsigned long flags = 0;285 int saved_ret = 0;286 int ret;287 288 why = kmsg_dump_reason_str(detail->reason);289 290 if (pstore_cannot_block_path(detail->reason)) {291 if (!raw_spin_trylock_irqsave(&psinfo->buf_lock, flags)) {292 pr_err("dump skipped in %s path because of concurrent dump\n",293 in_nmi() ? "NMI" : why);294 return;295 }296 } else {297 raw_spin_lock_irqsave(&psinfo->buf_lock, flags);298 }299 300 kmsg_dump_rewind(&iter);301 302 oopscount++;303 while (total < kmsg_bytes) {304 char *dst;305 size_t dst_size;306 int header_size;307 int zipped_len = -1;308 size_t dump_size;309 struct pstore_record record;310 311 pstore_record_init(&record, psinfo);312 record.type = PSTORE_TYPE_DMESG;313 record.count = oopscount;314 record.reason = detail->reason;315 record.part = part;316 record.buf = psinfo->buf;317 318 dst = big_oops_buf ?: psinfo->buf;319 dst_size = max_compressed_size ?: psinfo->bufsize;320 321 /* Write dump header. */322 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,323 oopscount, part);324 dst_size -= header_size;325 326 /* Write dump contents. */327 if (!kmsg_dump_get_buffer(&iter, true, dst + header_size,328 dst_size, &dump_size))329 break;330 331 if (big_oops_buf) {332 zipped_len = pstore_compress(dst, psinfo->buf,333 header_size + dump_size,334 psinfo->bufsize);335 336 if (zipped_len > 0) {337 record.compressed = true;338 record.size = zipped_len;339 } else {340 /*341 * Compression failed, so the buffer is most342 * likely filled with binary data that does not343 * compress as well as ASCII text. Copy as much344 * of the uncompressed data as possible into345 * the pstore record, and discard the rest.346 */347 record.size = psinfo->bufsize;348 memcpy(psinfo->buf, dst, psinfo->bufsize);349 }350 } else {351 record.size = header_size + dump_size;352 }353 354 ret = psinfo->write(&record);355 if (ret == 0 && detail->reason == KMSG_DUMP_OOPS) {356 pstore_new_entry = 1;357 pstore_timer_kick();358 } else {359 /* Preserve only the first non-zero returned value. */360 if (!saved_ret)361 saved_ret = ret;362 }363 364 total += record.size;365 part++;366 }367 raw_spin_unlock_irqrestore(&psinfo->buf_lock, flags);368 369 if (saved_ret) {370 pr_err_once("backend (%s) writing error (%d)\n", psinfo->name,371 saved_ret);372 }373}374 375static struct kmsg_dumper pstore_dumper = {376 .dump = pstore_dump,377};378 379/*380 * Register with kmsg_dump to save last part of console log on panic.381 */382static void pstore_register_kmsg(void)383{384 kmsg_dump_register(&pstore_dumper);385}386 387static void pstore_unregister_kmsg(void)388{389 kmsg_dump_unregister(&pstore_dumper);390}391 392#ifdef CONFIG_PSTORE_CONSOLE393static void pstore_console_write(struct console *con, const char *s, unsigned c)394{395 struct pstore_record record;396 397 if (!c)398 return;399 400 pstore_record_init(&record, psinfo);401 record.type = PSTORE_TYPE_CONSOLE;402 403 record.buf = (char *)s;404 record.size = c;405 psinfo->write(&record);406}407 408static struct console pstore_console = {409 .write = pstore_console_write,410 .index = -1,411};412 413static void pstore_register_console(void)414{415 /* Show which backend is going to get console writes. */416 strscpy(pstore_console.name, psinfo->name,417 sizeof(pstore_console.name));418 /*419 * Always initialize flags here since prior unregister_console()420 * calls may have changed settings (specifically CON_ENABLED).421 */422 pstore_console.flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME;423 register_console(&pstore_console);424}425 426static void pstore_unregister_console(void)427{428 unregister_console(&pstore_console);429}430#else431static void pstore_register_console(void) {}432static void pstore_unregister_console(void) {}433#endif434 435static int pstore_write_user_compat(struct pstore_record *record,436 const char __user *buf)437{438 int ret = 0;439 440 if (record->buf)441 return -EINVAL;442 443 record->buf = vmemdup_user(buf, record->size);444 if (IS_ERR(record->buf)) {445 ret = PTR_ERR(record->buf);446 goto out;447 }448 449 ret = record->psi->write(record);450 451 kvfree(record->buf);452out:453 record->buf = NULL;454 455 return unlikely(ret < 0) ? ret : record->size;456}457 458/*459 * platform specific persistent storage driver registers with460 * us here. If pstore is already mounted, call the platform461 * read function right away to populate the file system. If not462 * then the pstore mount code will call us later to fill out463 * the file system.464 */465int pstore_register(struct pstore_info *psi)466{467 char *new_backend;468 469 if (backend && strcmp(backend, psi->name)) {470 pr_warn("backend '%s' already in use: ignoring '%s'\n",471 backend, psi->name);472 return -EBUSY;473 }474 475 /* Sanity check flags. */476 if (!psi->flags) {477 pr_warn("backend '%s' must support at least one frontend\n",478 psi->name);479 return -EINVAL;480 }481 482 /* Check for required functions. */483 if (!psi->read || !psi->write) {484 pr_warn("backend '%s' must implement read() and write()\n",485 psi->name);486 return -EINVAL;487 }488 489 new_backend = kstrdup(psi->name, GFP_KERNEL);490 if (!new_backend)491 return -ENOMEM;492 493 mutex_lock(&psinfo_lock);494 if (psinfo) {495 pr_warn("backend '%s' already loaded: ignoring '%s'\n",496 psinfo->name, psi->name);497 mutex_unlock(&psinfo_lock);498 kfree(new_backend);499 return -EBUSY;500 }501 502 if (!psi->write_user)503 psi->write_user = pstore_write_user_compat;504 psinfo = psi;505 mutex_init(&psinfo->read_mutex);506 raw_spin_lock_init(&psinfo->buf_lock);507 508 if (psi->flags & PSTORE_FLAGS_DMESG)509 allocate_buf_for_compression();510 511 pstore_get_records(0);512 513 if (psi->flags & PSTORE_FLAGS_DMESG) {514 pstore_dumper.max_reason = psinfo->max_reason;515 pstore_register_kmsg();516 }517 if (psi->flags & PSTORE_FLAGS_CONSOLE)518 pstore_register_console();519 if (psi->flags & PSTORE_FLAGS_FTRACE)520 pstore_register_ftrace();521 if (psi->flags & PSTORE_FLAGS_PMSG)522 pstore_register_pmsg();523 524 /* Start watching for new records, if desired. */525 pstore_timer_kick();526 527 /*528 * Update the module parameter backend, so it is visible529 * through /sys/module/pstore/parameters/backend530 */531 backend = new_backend;532 533 pr_info("Registered %s as persistent store backend\n", psi->name);534 535 mutex_unlock(&psinfo_lock);536 return 0;537}538EXPORT_SYMBOL_GPL(pstore_register);539 540void pstore_unregister(struct pstore_info *psi)541{542 /* It's okay to unregister nothing. */543 if (!psi)544 return;545 546 mutex_lock(&psinfo_lock);547 548 /* Only one backend can be registered at a time. */549 if (WARN_ON(psi != psinfo)) {550 mutex_unlock(&psinfo_lock);551 return;552 }553 554 /* Unregister all callbacks. */555 if (psi->flags & PSTORE_FLAGS_PMSG)556 pstore_unregister_pmsg();557 if (psi->flags & PSTORE_FLAGS_FTRACE)558 pstore_unregister_ftrace();559 if (psi->flags & PSTORE_FLAGS_CONSOLE)560 pstore_unregister_console();561 if (psi->flags & PSTORE_FLAGS_DMESG)562 pstore_unregister_kmsg();563 564 /* Stop timer and make sure all work has finished. */565 del_timer_sync(&pstore_timer);566 flush_work(&pstore_work);567 568 /* Remove all backend records from filesystem tree. */569 pstore_put_backend_records(psi);570 571 free_buf_for_compression();572 573 psinfo = NULL;574 kfree(backend);575 backend = NULL;576 577 pr_info("Unregistered %s as persistent store backend\n", psi->name);578 mutex_unlock(&psinfo_lock);579}580EXPORT_SYMBOL_GPL(pstore_unregister);581 582static void decompress_record(struct pstore_record *record,583 struct z_stream_s *zstream)584{585 int ret;586 int unzipped_len;587 char *unzipped, *workspace;588 size_t max_uncompressed_size;589 590 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !record->compressed)591 return;592 593 /* Only PSTORE_TYPE_DMESG support compression. */594 if (record->type != PSTORE_TYPE_DMESG) {595 pr_warn("ignored compressed record type %d\n", record->type);596 return;597 }598 599 /* Missing compression buffer means compression was not initialized. */600 if (!zstream->workspace) {601 pr_warn("no decompression method initialized!\n");602 return;603 }604 605 ret = zlib_inflateReset(zstream);606 if (ret != Z_OK) {607 pr_err("zlib_inflateReset() failed, ret = %d!\n", ret);608 return;609 }610 611 /* Allocate enough space to hold max decompression and ECC. */612 max_uncompressed_size = 3 * psinfo->bufsize;613 workspace = kvzalloc(max_uncompressed_size + record->ecc_notice_size,614 GFP_KERNEL);615 if (!workspace)616 return;617 618 zstream->next_in = record->buf;619 zstream->avail_in = record->size;620 zstream->next_out = workspace;621 zstream->avail_out = max_uncompressed_size;622 623 ret = zlib_inflate(zstream, Z_FINISH);624 if (ret != Z_STREAM_END) {625 pr_err_ratelimited("zlib_inflate() failed, ret = %d!\n", ret);626 kvfree(workspace);627 return;628 }629 630 unzipped_len = zstream->total_out;631 632 /* Append ECC notice to decompressed buffer. */633 memcpy(workspace + unzipped_len, record->buf + record->size,634 record->ecc_notice_size);635 636 /* Copy decompressed contents into an minimum-sized allocation. */637 unzipped = kvmemdup(workspace, unzipped_len + record->ecc_notice_size,638 GFP_KERNEL);639 kvfree(workspace);640 if (!unzipped)641 return;642 643 /* Swap out compressed contents with decompressed contents. */644 kvfree(record->buf);645 record->buf = unzipped;646 record->size = unzipped_len;647 record->compressed = false;648}649 650/*651 * Read all the records from one persistent store backend. Create652 * files in our filesystem. Don't warn about -EEXIST errors653 * when we are re-scanning the backing store looking to add new654 * error records.655 */656void pstore_get_backend_records(struct pstore_info *psi,657 struct dentry *root, int quiet)658{659 int failed = 0;660 unsigned int stop_loop = 65536;661 struct z_stream_s zstream = {};662 663 if (!psi || !root)664 return;665 666 if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && compress) {667 zstream.workspace = kvmalloc(zlib_inflate_workspacesize(),668 GFP_KERNEL);669 zlib_inflateInit2(&zstream, -DEF_WBITS);670 }671 672 mutex_lock(&psi->read_mutex);673 if (psi->open && psi->open(psi))674 goto out;675 676 /*677 * Backend callback read() allocates record.buf. decompress_record()678 * may reallocate record.buf. On success, pstore_mkfile() will keep679 * the record.buf, so free it only on failure.680 */681 for (; stop_loop; stop_loop--) {682 struct pstore_record *record;683 int rc;684 685 record = kzalloc(sizeof(*record), GFP_KERNEL);686 if (!record) {687 pr_err("out of memory creating record\n");688 break;689 }690 pstore_record_init(record, psi);691 692 record->size = psi->read(record);693 694 /* No more records left in backend? */695 if (record->size <= 0) {696 kfree(record);697 break;698 }699 700 decompress_record(record, &zstream);701 rc = pstore_mkfile(root, record);702 if (rc) {703 /* pstore_mkfile() did not take record, so free it. */704 kvfree(record->buf);705 kfree(record->priv);706 kfree(record);707 if (rc != -EEXIST || !quiet)708 failed++;709 }710 }711 if (psi->close)712 psi->close(psi);713out:714 mutex_unlock(&psi->read_mutex);715 716 if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && compress) {717 if (zlib_inflateEnd(&zstream) != Z_OK)718 pr_warn("zlib_inflateEnd() failed\n");719 kvfree(zstream.workspace);720 }721 722 if (failed)723 pr_warn("failed to create %d record(s) from '%s'\n",724 failed, psi->name);725 if (!stop_loop)726 pr_err("looping? Too many records seen from '%s'\n",727 psi->name);728}729 730static void pstore_dowork(struct work_struct *work)731{732 pstore_get_records(1);733}734 735static void pstore_timefunc(struct timer_list *unused)736{737 if (pstore_new_entry) {738 pstore_new_entry = 0;739 schedule_work(&pstore_work);740 }741 742 pstore_timer_kick();743}744 745static int __init pstore_init(void)746{747 int ret;748 749 ret = pstore_init_fs();750 if (ret)751 free_buf_for_compression();752 753 return ret;754}755late_initcall(pstore_init);756 757static void __exit pstore_exit(void)758{759 pstore_exit_fs();760}761module_exit(pstore_exit)762 763MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");764MODULE_DESCRIPTION("Persistent Storage - platform driver interface");765MODULE_LICENSE("GPL");766