// SPDX-License-Identifier: GPL-2.0-only
/*
* Persistent Storage - platform driver interface parts.
*
* Copyright (C) 2007-2008 Google, Inc.
* Copyright (C) 2010 Intel Corporation <[email protected]>
*/
#define pr_fmt(fmt) "pstore: " fmt
#include <linux/atomic.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kmsg_dump.h>
#include <linux/console.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/pstore.h>
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/jiffies.h>
#include <linux/vmalloc.h>
#include <linux/workqueue.h>
#include <linux/zlib.h>
#include "internal.h"
/*
* We defer making "oops" entries appear in pstore - see
* whether the system is actually still running well enough
* to let someone see the entry
*/
static int pstore_update_ms = -1;
module_param_named(update_ms, pstore_update_ms, int, 0600);
MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
"(default is -1, which means runtime updates are disabled; "
"enabling this option may not be safe; it may lead to further "
"corruption on Oopses)");
/* Names should be in the same order as the enum pstore_type_id */
static const char * const pstore_type_names[] = {
"dmesg",
"mce",
"console",
"ftrace",
"rtas",
"powerpc-ofw",
"powerpc-common",
"pmsg",
"powerpc-opal",
};
static int pstore_new_entry;
static void pstore_timefunc(struct timer_list *);
static DEFINE_TIMER(pstore_timer, pstore_timefunc);
static void pstore_dowork(struct work_struct *);
static DECLARE_WORK(pstore_work, pstore_dowork);
/*
* psinfo_lock protects "psinfo" during calls to
* pstore_register(), pstore_unregister(), and
* the filesystem mount/unmount routines.
*/
static DEFINE_MUTEX(psinfo_lock);
struct pstore_info *psinfo;
static char *backend;
module_param(backend, charp, 0444);
MODULE_PARM_DESC(backend, "specific backend to use");
/*
* pstore no longer implements compression via the crypto API, and only
* supports zlib deflate compression implemented using the zlib library
* interface. This removes additional complexity which is hard to justify for a
* diagnostic facility that has to operate in conditions where the system may
* have become unstable. Zlib deflate is comparatively small in terms of code
* size, and compresses ASCII text comparatively well. In terms of compression
* speed, deflate is not the best performer but for recording the log output on
* a kernel panic, this is not considered critical.
*
* The only remaining arguments supported by the compress= module parameter are
* 'deflate' and 'none'. To retain compatibility with existing installations,
* all other values are logged and replaced with 'deflate'.
*/
static char *compress = "deflate";
module_param(compress, charp, 0444);
MODULE_PARM_DESC(compress, "compression to use");
/* How much of the kernel log to snapshot */
unsigned long kmsg_bytes = CONFIG_PSTORE_DEFAULT_KMSG_BYTES;
module_param(kmsg_bytes, ulong, 0444);
MODULE_PARM_DESC(kmsg_bytes, "amount of kernel log to snapshot (in bytes)");
static void *compress_workspace;
/*
* Compression is only used for dmesg output, which consists of low-entropy
* ASCII text, and so we can assume worst-case 60%.
*/
#define DMESG_COMP_PERCENT 60
static char *big_oops_buf;
static size_t max_compressed_size;
void pstore_set_kmsg_bytes(int bytes)
{
kmsg_bytes = bytes;
}
/* Tag each group of saved records with a sequence number */
static int oopscount;
const char *pstore_type_to_name(enum pstore_type_id type)
{
BUILD_BUG_ON(ARRAY_SIZE(pstore_type_names) != PSTORE_TYPE_MAX);
if (WARN_ON_ONCE(type >= PSTORE_TYPE_MAX))
return "unknown";
return pstore_type_names[type];
}
EXPORT_SYMBOL_GPL(pstore_type_to_name);
enum pstore_type_id pstore_name_to_type(const char *name)
{
int i;
for (i = 0; i < PSTORE_TYPE_MAX; i++) {
if (!strcmp(pstore_type_names[i], name))
return i;
}
return PSTORE_TYPE_MAX;
}
EXPORT_SYMBOL_GPL(pstore_name_to_type);
static void pstore_timer_kick(void)
{
if (pstore_update_ms < 0)
return;
mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
}
static bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
{
/*
* In case of NMI path, pstore shouldn't be blocked
* regardless of reason.
*/
if (in_nmi())
return true;
switch (reason) {
/* In panic case, other cpus are stopped by smp_send_stop(). */
case KMSG_DUMP_PANIC:
/*
* Emergency restart shouldn't be blocked by spinning on
* pstore_info::buf_lock.
*/
case KMSG_DUMP_EMERG:
return true;
default:
return false;
}
}
static int pstore_compress(const void *in, void *out,
unsigned int inlen, unsigned int outlen)
{
struct z_stream_s zstream = {
.next_in = in,
.avail_in = inlen,
.next_out = out,
.avail_out = outlen,
.workspace = compress_workspace,
};
int ret;
if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS))
return -EINVAL;
ret = zlib_deflateInit2(&zstream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
-MAX_WBITS, DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY);
if (ret != Z_OK)
return -EINVAL;
ret = zlib_deflate(&zstream, Z_FINISH);
if (ret != Z_STREAM_END)
return -EINVAL;
ret = zlib_deflateEnd(&zstream);
if (ret != Z_OK)
pr_warn_once("zlib_deflateEnd() failed: %d\n", ret);
return zstream.total_out;
}
static void allocate_buf_for_compression(void)
{
size_t compressed_size;
char *buf;
/* Skip if not built-in or compression disabled. */
if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !compress ||
!strcmp(compress, "none")) {
compress = NULL;
return;
}
if (strcmp(compress, "deflate")) {
pr_err("Unsupported compression '%s', falling back to deflate\n",
compress);
compress = "deflate";
}
/*
* The compression buffer only needs to be as large as the maximum
* uncompressed record size, since any record that would be expanded by
* compression is just stored uncompressed.
*/
compressed_size = (psinfo->bufsize * 100) / DMESG_COMP_PERCENT;
buf = kvzalloc(compressed_size, GFP_KERNEL);
if (!buf) {
pr_err("Failed %zu byte compression buffer allocation for: %s\n",
psinfo->bufsize, compress);
return;
}
compress_workspace =
vmalloc(zlib_deflate_workspacesize(MAX_WBITS, DEF_MEM_LEVEL));
if (!compress_workspace) {
pr_err("Failed to allocate zlib deflate workspace\n");
kvfree(buf);
return;
}
/* A non-NULL big_oops_buf indicates compression is available. */
big_oops_buf = buf;
max_compressed_size = compressed_size;
pr_info("Using crash dump compression: %s\n", compress);
}
static void free_buf_for_compression(void)
{
if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && compress_workspace) {
vfree(compress_workspace);
compress_workspace = NULL;
}
kvfree(big_oops_buf);
big_oops_buf = NULL;
max_compressed_size = 0;
}
void pstore_record_init(struct pstore_record *record,
struct pstore_info *psinfo)
{
memset(record, 0, sizeof(*record));
record->psi = psinfo;
/* Report zeroed timestamp if called before timekeeping has resumed. */
record->time = ns_to_timespec64(ktime_get_real_fast_ns());
}
/*
* callback from kmsg_dump. Save as much as we can (up to kmsg_bytes) from the
* end of the buffer.
*/
static void pstore_dump(struct kmsg_dumper *dumper,
struct kmsg_dump_detail *detail)
{
struct kmsg_dump_iter iter;
unsigned long total = 0;
const char *why;
unsigned int part = 1;
unsigned long flags = 0;
int saved_ret = 0;
int ret;
why = kmsg_dump_reason_str(detail->reason);
if (pstore_cannot_block_path(detail->reason)) {
if (!raw_spin_trylock_irqsave(&psinfo->buf_lock, flags)) {
pr_err("dump skipped in %s path because of concurrent dump\n",
in_nmi() ? "NMI" : why);
return;
}
} else {
raw_spin_lock_irqsave(&psinfo->buf_lock, flags);
}
kmsg_dump_rewind(&iter);
oopscount++;
while (total < kmsg_bytes) {
char *dst;
size_t dst_size;
int header_size;
int zipped_len = -1;
size_t dump_size;
struct pstore_record record;
pstore_record_init(&record, psinfo);
record.type = PSTORE_TYPE_DMESG;
record.count = oopscount;
record.reason = detail->reason;
record.part = part;
record.buf = psinfo->buf;
dst = big_oops_buf ?: psinfo->buf;
dst_size = max_compressed_size ?: psinfo->bufsize;
/* Write dump header. */
header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
oopscount, part);
dst_size -= header_size;
/* Write dump contents. */
if (!kmsg_dump_get_buffer(&iter, true, dst + header_size,
dst_size, &dump_size))
break;
if (big_oops_buf) {
zipped_len = pstore_compress(dst, psinfo->buf,
header_size + dump_size,
psinfo->bufsize);
if (zipped_len > 0) {
record.compressed = true;
record.size = zipped_len;
} else {
/*
* Compression failed, so the buffer is most
* likely filled with binary data that does not
* compress as well as ASCII text. Copy as much
* of the uncompressed data as possible into
* the pstore record, and discard the rest.
*/
record.size = psinfo->bufsize;
memcpy(psinfo->buf, dst, psinfo->bufsize);
}
} else {
record.size = header_size + dump_size;
}
ret = psinfo->write(&record);
if (ret == 0 && detail->reason == KMSG_DUMP_OOPS) {
pstore_new_entry = 1;
pstore_timer_kick();
} else {
/* Preserve only the first non-zero returned value. */
if (!saved_ret)
saved_ret = ret;
}
total += record.size;
part++;
}
raw_spin_unlock_irqrestore(&psinfo->buf_lock, flags);
if (saved_ret) {
pr_err_once("backend (%s) writing error (%d)\n", psinfo->name,
saved_ret);
}
}
static struct kmsg_dumper pstore_dumper = {
.dump = pstore_dump,
};
/*
* Register with kmsg_dump to save last part of console log on panic.
*/
static void pstore_register_kmsg(void)
{
kmsg_dump_register(&pstore_dumper);
}
static void pstore_unregister_kmsg(void)
{
kmsg_dump_unregister(&pstore_dumper);
}
#ifdef CONFIG_PSTORE_CONSOLE
static void pstore_console_write(struct console *con, const char *s, unsigned c)
{
struct pstore_record record;
if (!c)
return;
pstore_record_init(&record, psinfo);
record.type = PSTORE_TYPE_CONSOLE;
record.buf = (char *)s;
record.size = c;
psinfo->write(&record);
}
static struct console pstore_console = {
.write = pstore_console_write,
.index = -1,
};
static void pstore_register_console(void)
{
/* Show which backend is going to get console writes. */
strscpy(pstore_console.name, psinfo->name,
sizeof(pstore_console.name));
/*
* Always initialize flags here since prior unregister_console()
* calls may have changed settings (specifically CON_ENABLED).
*/
pstore_console.flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME;
register_console(&pstore_console);
}
static void pstore_unregister_console(void)
{
unregister_console(&pstore_console);
}
#else
static void pstore_register_console(void) {}
static void pstore_unregister_console(void) {}
#endif
static int pstore_write_user_compat(struct pstore_record *record,
const char __user *buf)
{
int ret = 0;
if (record->buf)
return -EINVAL;
record->buf = vmemdup_user(buf, record->size);
if (IS_ERR(record->buf)) {
ret = PTR_ERR(record->buf);
goto out;
}
ret = record->psi->write(record);
kvfree(record->buf);
out:
record->buf = NULL;
return unlikely(ret < 0) ? ret : record->size;
}
/*
* platform specific persistent storage driver registers with
* us here. If pstore is already mounted, call the platform
* read function right away to populate the file system. If not
* then the pstore mount code will call us later to fill out
* the file system.
*/
int pstore_register(struct pstore_info *psi)
{
char *new_backend;
if (backend && strcmp(backend, psi->name)) {
pr_warn("backend '%s' already in use: ignoring '%s'\n",
backend, psi->name);
return -EBUSY;
}
/* Sanity check flags. */
if (!psi->flags) {
pr_warn("backend '%s' must support at least one frontend\n",
psi->name);
return -EINVAL;
}
/* Check for required functions. */
if (!psi->read || !psi->write) {
pr_warn("backend '%s' must implement read() and write()\n",
psi->name);
return -EINVAL;
}
new_backend = kstrdup(psi->name, GFP_KERNEL);
if (!new_backend)
return -ENOMEM;
mutex_lock(&psinfo_lock);
if (psinfo) {
pr_warn("backend '%s' already loaded: ignoring '%s'\n",
psinfo->name, psi->name);
mutex_unlock(&psinfo_lock);
kfree(new_backend);
return -EBUSY;
}
if (!psi->write_user)
psi->write_user = pstore_write_user_compat;
psinfo = psi;
mutex_init(&psinfo->read_mutex);
raw_spin_lock_init(&psinfo->buf_lock);
if (psi->flags & PSTORE_FLAGS_DMESG)
allocate_buf_for_compression();
pstore_get_records(0);
if (psi->flags & PSTORE_FLAGS_DMESG) {
pstore_dumper.max_reason = psinfo->max_reason;
pstore_register_kmsg();
}
if (psi->flags & PSTORE_FLAGS_CONSOLE)
pstore_register_console();
if (psi->flags & PSTORE_FLAGS_FTRACE)
pstore_register_ftrace();
if (psi->flags & PSTORE_FLAGS_PMSG)
pstore_register_pmsg();
/* Start watching for new records, if desired. */
pstore_timer_kick();
/*
* Update the module parameter backend, so it is visible
* through /sys/module/pstore/parameters/backend
*/
backend = new_backend;
pr_info("Registered %s as persistent store backend\n", psi->name);
mutex_unlock(&psinfo_lock);
return 0;
}
EXPORT_SYMBOL_GPL(pstore_register);
void pstore_unregister(struct pstore_info *psi)
{
/* It's okay to unregister nothing. */
if (!psi)
return;
mutex_lock(&psinfo_lock);
/* Only one backend can be registered at a time. */
if (WARN_ON(psi != psinfo)) {
mutex_unlock(&psinfo_lock);
return;
}
/* Unregister all callbacks. */
if (psi->flags & PSTORE_FLAGS_PMSG)
pstore_unregister_pmsg();
if (psi->flags & PSTORE_FLAGS_FTRACE)
pstore_unregister_ftrace();
if (psi->flags & PSTORE_FLAGS_CONSOLE)
pstore_unregister_console();
if (psi->flags & PSTORE_FLAGS_DMESG)
pstore_unregister_kmsg();
/* Stop timer and make sure all work has finished. */
del_timer_sync(&pstore_timer);
flush_work(&pstore_work);
/* Remove all backend records from filesystem tree. */
pstore_put_backend_records(psi);
free_buf_for_compression();
psinfo = NULL;
kfree(backend);
backend = NULL;
pr_info("Unregistered %s as persistent store backend\n", psi->name);
mutex_unlock(&psinfo_lock);
}
EXPORT_SYMBOL_GPL(pstore_unregister);
static void decompress_record(struct pstore_record *record,
struct z_stream_s *zstream)
{
int ret;
int unzipped_len;
char *unzipped, *workspace;
size_t max_uncompressed_size;
if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !record->compressed)
return;
/* Only PSTORE_TYPE_DMESG support compression. */
if (record->type != PSTORE_TYPE_DMESG) {
pr_warn("ignored compressed record type %d\n", record->type);
return;
}
/* Missing compression buffer means compression was not initialized. */
if (!zstream->workspace) {
pr_warn("no decompression method initialized!\n");
return;
}
ret = zlib_inflateReset(zstream);
if (ret != Z_OK) {
pr_err("zlib_inflateReset() failed, ret = %d!\n", ret);
return;
}
/* Allocate enough space to hold max decompression and ECC. */
max_uncompressed_size = 3 * psinfo->bufsize;
workspace = kvzalloc(max_uncompressed_size + record->ecc_notice_size,
GFP_KERNEL);
if (!workspace)
return;
zstream->next_in = record->buf;
zstream->avail_in = record->size;
zstream->next_out = workspace;
zstream->avail_out = max_uncompressed_size;
ret = zlib_inflate(zstream, Z_FINISH);
if (ret != Z_STREAM_END) {
pr_err_ratelimited("zlib_inflate() failed, ret = %d!\n", ret);
kvfree(workspace);
return;
}
unzipped_len = zstream->total_out;
/* Append ECC notice to decompressed buffer. */
memcpy(workspace + unzipped_len, record->buf + record->size,
record->ecc_notice_size);
/* Copy decompressed contents into an minimum-sized allocation. */
unzipped = kvmemdup(workspace, unzipped_len + record->ecc_notice_size,
GFP_KERNEL);
kvfree(workspace);
if (!unzipped)
return;
/* Swap out compressed contents with decompressed contents. */
kvfree(record->buf);
record->buf = unzipped;
record->size = unzipped_len;
record->compressed = false;
}
/*
* Read all the records from one persistent store backend. Create
* files in our filesystem. Don't warn about -EEXIST errors
* when we are re-scanning the backing store looking to add new
* error records.
*/
void pstore_get_backend_records(struct pstore_info *psi,
struct dentry *root, int quiet)
{
int failed = 0;
unsigned int stop_loop = 65536;
struct z_stream_s zstream = {};
if (!psi || !root)
return;
if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && compress) {
zstream.workspace = kvmalloc(zlib_inflate_workspacesize(),
GFP_KERNEL);
zlib_inflateInit2(&zstream, -DEF_WBITS);
}
mutex_lock(&psi->read_mutex);
if (psi->open && psi->open(psi))
goto out;
/*
* Backend callback read() allocates record.buf. decompress_record()
* may reallocate record.buf. On success, pstore_mkfile() will keep
* the record.buf, so free it only on failure.
*/
for (; stop_loop; stop_loop--) {
struct pstore_record *record;
int rc;
record = kzalloc(sizeof(*record), GFP_KERNEL);
if (!record) {
pr_err("out of memory creating record\n");
break;
}
pstore_record_init(record, psi);
record->size = psi->read(record);
/* No more records left in backend? */
if (record->size <= 0) {
kfree(record);
break;
}
decompress_record(record, &zstream);
rc = pstore_mkfile(root, record);
if (rc) {
/* pstore_mkfile() did not take record, so free it. */
kvfree(record->buf);
kfree(record->priv);
kfree(record);
if (rc != -EEXIST || !quiet)
failed++;
}
}
if (psi->close)
psi->close(psi);
out:
mutex_unlock(&psi->read_mutex);
if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && compress) {
if (zlib_inflateEnd(&zstream) != Z_OK)
pr_warn("zlib_inflateEnd() failed\n");
kvfree(zstream.workspace);
}
if (failed)
pr_warn("failed to create %d record(s) from '%s'\n",
failed, psi->name);
if (!stop_loop)
pr_err("looping? Too many records seen from '%s'\n",
psi->name);
}
static void pstore_dowork(struct work_struct *work)
{
pstore_get_records(1);
}
static void pstore_timefunc(struct timer_list *unused)
{
if (pstore_new_entry) {
pstore_new_entry = 0;
schedule_work(&pstore_work);
}
pstore_timer_kick();
}
static int __init pstore_init(void)
{
int ret;
ret = pstore_init_fs();
if (ret)
free_buf_for_compression();
return ret;
}
late_initcall(pstore_init);
static void __exit pstore_exit(void)
{
pstore_exit_fs();
}
module_exit(pstore_exit)
MODULE_AUTHOR("Tony Luck <[email protected]>");
MODULE_DESCRIPTION("Persistent Storage - platform driver interface");
MODULE_LICENSE("GPL");
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