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zone.c
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// SPDX-License-Identifier: GPL-2.0
/*
* Provide a pstore intermediate backend, organized into kernel memory
* allocated zones that are then mapped and flushed into a single
* contiguous region on a storage backend of some kind (block, mtd, etc).
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/mount.h>
#include <linux/printk.h>
#include <linux/fs.h>
#include <linux/pstore_zone.h>
#include <linux/kdev_t.h>
#include <linux/device.h>
#include <linux/namei.h>
#include <linux/fcntl.h>
#include <linux/uio.h>
#include <linux/writeback.h>
#include "internal.h"
/**
* struct psz_head - header of zone to flush to storage
*
* @sig: signature to indicate header (PSZ_SIG xor PSZONE-type value)
* @datalen: length of data in @data
* @start: offset into @data where the beginning of the stored bytes begin
* @data: zone data.
*/
struct psz_buffer {
#define PSZ_SIG (0x43474244) /* DBGC */
uint32_t sig;
atomic_t datalen;
atomic_t start;
uint8_t data[];
};
/**
* struct psz_kmsg_header - kmsg dump-specific header to flush to storage
*
* @magic: magic num for kmsg dump header
* @time: kmsg dump trigger time
* @compressed: whether conpressed
* @counter: kmsg dump counter
* @reason: the kmsg dump reason (e.g. oops, panic, etc)
* @data: pointer to log data
*
* This is a sub-header for a kmsg dump, trailing after &psz_buffer.
*/
struct psz_kmsg_header {
#define PSTORE_KMSG_HEADER_MAGIC 0x4dfc3ae5 /* Just a random number */
uint32_t magic;
struct timespec64 time;
bool compressed;
uint32_t counter;
enum kmsg_dump_reason reason;
uint8_t data[];
};
/**
* struct pstore_zone - single stored buffer
*
* @off: zone offset of storage
* @type: front-end type for this zone
* @name: front-end name for this zone
* @buffer: pointer to data buffer managed by this zone
* @oldbuf: pointer to old data buffer
* @buffer_size: bytes in @buffer->data
* @should_recover: whether this zone should recover from storage
* @dirty: whether the data in @buffer dirty
*
* zone structure in memory.
*/
struct pstore_zone {
loff_t off;
const char *name;
enum pstore_type_id type;
struct psz_buffer *buffer;
struct psz_buffer *oldbuf;
size_t buffer_size;
bool should_recover;
atomic_t dirty;
};
/**
* struct psz_context - all about running state of pstore/zone
*
* @kpszs: kmsg dump storage zones
* @ppsz: pmsg storage zone
* @cpsz: console storage zone
* @fpszs: ftrace storage zones
* @kmsg_max_cnt: max count of @kpszs
* @kmsg_read_cnt: counter of total read kmsg dumps
* @kmsg_write_cnt: counter of total kmsg dump writes
* @pmsg_read_cnt: counter of total read pmsg zone
* @console_read_cnt: counter of total read console zone
* @ftrace_max_cnt: max count of @fpszs
* @ftrace_read_cnt: counter of max read ftrace zone
* @oops_counter: counter of oops dumps
* @panic_counter: counter of panic dumps
* @recovered: whether finished recovering data from storage
* @on_panic: whether panic is happening
* @pstore_zone_info_lock: lock to @pstore_zone_info
* @pstore_zone_info: information from backend
* @pstore: structure for pstore
*/
struct psz_context {
struct pstore_zone **kpszs;
struct pstore_zone *ppsz;
struct pstore_zone *cpsz;
struct pstore_zone **fpszs;
unsigned int kmsg_max_cnt;
unsigned int kmsg_read_cnt;
unsigned int kmsg_write_cnt;
unsigned int pmsg_read_cnt;
unsigned int console_read_cnt;
unsigned int ftrace_max_cnt;
unsigned int ftrace_read_cnt;
/*
* These counters should be calculated during recovery.
* It records the oops/panic times after crashes rather than boots.
*/
unsigned int oops_counter;
unsigned int panic_counter;
atomic_t recovered;
atomic_t on_panic;
/*
* pstore_zone_info_lock protects this entire structure during calls
* to register_pstore_zone()/unregister_pstore_zone().
*/
struct mutex pstore_zone_info_lock;
struct pstore_zone_info *pstore_zone_info;
struct pstore_info pstore;
};
static struct psz_context pstore_zone_cxt;
static void psz_flush_all_dirty_zones(struct work_struct *);
static DECLARE_DELAYED_WORK(psz_cleaner, psz_flush_all_dirty_zones);
/**
* enum psz_flush_mode - flush mode for psz_zone_write()
*
* @FLUSH_NONE: do not flush to storage but update data on memory
* @FLUSH_PART: just flush part of data including meta data to storage
* @FLUSH_META: just flush meta data of zone to storage
* @FLUSH_ALL: flush all of zone
*/
enum psz_flush_mode {
FLUSH_NONE = 0,
FLUSH_PART,
FLUSH_META,
FLUSH_ALL,
};
static inline int buffer_datalen(struct pstore_zone *zone)
{
return atomic_read(&zone->buffer->datalen);
}
static inline int buffer_start(struct pstore_zone *zone)
{
return atomic_read(&zone->buffer->start);
}
static inline bool is_on_panic(void)
{
return atomic_read(&pstore_zone_cxt.on_panic);
}
static ssize_t psz_zone_read_buffer(struct pstore_zone *zone, char *buf,
size_t len, unsigned long off)
{
if (!buf || !zone || !zone->buffer)
return -EINVAL;
if (off > zone->buffer_size)
return -EINVAL;
len = min_t(size_t, len, zone->buffer_size - off);
memcpy(buf, zone->buffer->data + off, len);
return len;
}
static int psz_zone_read_oldbuf(struct pstore_zone *zone, char *buf,
size_t len, unsigned long off)
{
if (!buf || !zone || !zone->oldbuf)
return -EINVAL;
if (off > zone->buffer_size)
return -EINVAL;
len = min_t(size_t, len, zone->buffer_size - off);
memcpy(buf, zone->oldbuf->data + off, len);
return 0;
}
static int psz_zone_write(struct pstore_zone *zone,
enum psz_flush_mode flush_mode, const char *buf,
size_t len, unsigned long off)
{
struct pstore_zone_info *info = pstore_zone_cxt.pstore_zone_info;
ssize_t wcnt = 0;
ssize_t (*writeop)(const char *buf, size_t bytes, loff_t pos);
size_t wlen;
if (off > zone->buffer_size)
return -EINVAL;
wlen = min_t(size_t, len, zone->buffer_size - off);
if (buf && wlen) {
memcpy(zone->buffer->data + off, buf, wlen);
atomic_set(&zone->buffer->datalen, wlen + off);
}
/* avoid to damage old records */
if (!is_on_panic() && !atomic_read(&pstore_zone_cxt.recovered))
goto dirty;
writeop = is_on_panic() ? info->panic_write : info->write;
if (!writeop)
goto dirty;
switch (flush_mode) {
case FLUSH_NONE:
if (unlikely(buf && wlen))
goto dirty;
return 0;
case FLUSH_PART:
wcnt = writeop((const char *)zone->buffer->data + off, wlen,
zone->off + sizeof(*zone->buffer) + off);
if (wcnt != wlen)
goto dirty;
fallthrough;
case FLUSH_META:
wlen = sizeof(struct psz_buffer);
wcnt = writeop((const char *)zone->buffer, wlen, zone->off);
if (wcnt != wlen)
goto dirty;
break;
case FLUSH_ALL:
wlen = zone->buffer_size + sizeof(*zone->buffer);
wcnt = writeop((const char *)zone->buffer, wlen, zone->off);
if (wcnt != wlen)
goto dirty;
break;
}
return 0;
dirty:
/* no need to mark dirty if going to try next zone */
if (wcnt == -ENOMSG)
return -ENOMSG;
atomic_set(&zone->dirty, true);
/* flush dirty zones nicely */
if (wcnt == -EBUSY && !is_on_panic())
schedule_delayed_work(&psz_cleaner, msecs_to_jiffies(500));
return -EBUSY;
}
static int psz_flush_dirty_zone(struct pstore_zone *zone)
{
int ret;
if (unlikely(!zone))
return -EINVAL;
if (unlikely(!atomic_read(&pstore_zone_cxt.recovered)))
return -EBUSY;
if (!atomic_xchg(&zone->dirty, false))
return 0;
ret = psz_zone_write(zone, FLUSH_ALL, NULL, 0, 0);
if (ret)
atomic_set(&zone->dirty, true);
return ret;
}
static int psz_flush_dirty_zones(struct pstore_zone **zones, unsigned int cnt)
{
int i, ret;
struct pstore_zone *zone;
if (!zones)
return -EINVAL;
for (i = 0; i < cnt; i++) {
zone = zones[i];
if (!zone)
return -EINVAL;
ret = psz_flush_dirty_zone(zone);
if (ret)
return ret;
}
return 0;
}
static int psz_move_zone(struct pstore_zone *old, struct pstore_zone *new)
{
const char *data = (const char *)old->buffer->data;
int ret;
ret = psz_zone_write(new, FLUSH_ALL, data, buffer_datalen(old), 0);
if (ret) {
atomic_set(&new->buffer->datalen, 0);
atomic_set(&new->dirty, false);
return ret;
}
atomic_set(&old->buffer->datalen, 0);
return 0;
}
static void psz_flush_all_dirty_zones(struct work_struct *work)
{
struct psz_context *cxt = &pstore_zone_cxt;
int ret = 0;
if (cxt->ppsz)
ret |= psz_flush_dirty_zone(cxt->ppsz);
if (cxt->cpsz)
ret |= psz_flush_dirty_zone(cxt->cpsz);
if (cxt->kpszs)
ret |= psz_flush_dirty_zones(cxt->kpszs, cxt->kmsg_max_cnt);
if (cxt->fpszs)
ret |= psz_flush_dirty_zones(cxt->fpszs, cxt->ftrace_max_cnt);
if (ret && cxt->pstore_zone_info)
schedule_delayed_work(&psz_cleaner, msecs_to_jiffies(1000));
}
static int psz_kmsg_recover_data(struct psz_context *cxt)
{
struct pstore_zone_info *info = cxt->pstore_zone_info;
struct pstore_zone *zone = NULL;
struct psz_buffer *buf;
unsigned long i;
ssize_t rcnt;
if (!info->read)
return -EINVAL;
for (i = 0; i < cxt->kmsg_max_cnt; i++) {
zone = cxt->kpszs[i];
if (unlikely(!zone))
return -EINVAL;
if (atomic_read(&zone->dirty)) {
unsigned int wcnt = cxt->kmsg_write_cnt;
struct pstore_zone *new = cxt->kpszs[wcnt];
int ret;
ret = psz_move_zone(zone, new);
if (ret) {
pr_err("move zone from %lu to %d failed\n",
i, wcnt);
return ret;
}
cxt->kmsg_write_cnt = (wcnt + 1) % cxt->kmsg_max_cnt;
}
if (!zone->should_recover)
continue;
buf = zone->buffer;
rcnt = info->read((char *)buf, zone->buffer_size + sizeof(*buf),
zone->off);
if (rcnt != zone->buffer_size + sizeof(*buf))
return (int)rcnt < 0 ? (int)rcnt : -EIO;
}
return 0;
}
static int psz_kmsg_recover_meta(struct psz_context *cxt)
{
struct pstore_zone_info *info = cxt->pstore_zone_info;
struct pstore_zone *zone;
size_t rcnt, len;
struct psz_buffer *buf;
struct psz_kmsg_header *hdr;
struct timespec64 time = { };
unsigned long i;
/*
* Recover may on panic, we can't allocate any memory by kmalloc.
* So, we use local array instead.
*/
char buffer_header[sizeof(*buf) + sizeof(*hdr)] = {0};
if (!info->read)
return -EINVAL;
len = sizeof(*buf) + sizeof(*hdr);
buf = (struct psz_buffer *)buffer_header;
for (i = 0; i < cxt->kmsg_max_cnt; i++) {
zone = cxt->kpszs[i];
if (unlikely(!zone))
return -EINVAL;
rcnt = info->read((char *)buf, len, zone->off);
if (rcnt == -ENOMSG) {
pr_debug("%s with id %lu may be broken, skip\n",
zone->name, i);
continue;
} else if (rcnt != len) {
pr_err("read %s with id %lu failed\n", zone->name, i);
return (int)rcnt < 0 ? (int)rcnt : -EIO;
}
if (buf->sig != zone->buffer->sig) {
pr_debug("no valid data in kmsg dump zone %lu\n", i);
continue;
}
if (zone->buffer_size < atomic_read(&buf->datalen)) {
pr_info("found overtop zone: %s: id %lu, off %lld, size %zu\n",
zone->name, i, zone->off,
zone->buffer_size);
continue;
}
hdr = (struct psz_kmsg_header *)buf->data;
if (hdr->magic != PSTORE_KMSG_HEADER_MAGIC) {
pr_info("found invalid zone: %s: id %lu, off %lld, size %zu\n",
zone->name, i, zone->off,
zone->buffer_size);
continue;
}
/*
* we get the newest zone, and the next one must be the oldest
* or unused zone, because we do write one by one like a circle.
*/
if (hdr->time.tv_sec >= time.tv_sec) {
time.tv_sec = hdr->time.tv_sec;
cxt->kmsg_write_cnt = (i + 1) % cxt->kmsg_max_cnt;
}
if (hdr->reason == KMSG_DUMP_OOPS)
cxt->oops_counter =
max(cxt->oops_counter, hdr->counter);
else if (hdr->reason == KMSG_DUMP_PANIC)
cxt->panic_counter =
max(cxt->panic_counter, hdr->counter);
if (!atomic_read(&buf->datalen)) {
pr_debug("found erased zone: %s: id %lu, off %lld, size %zu, datalen %d\n",
zone->name, i, zone->off,
zone->buffer_size,
atomic_read(&buf->datalen));
continue;
}
if (!is_on_panic())
zone->should_recover = true;
pr_debug("found nice zone: %s: id %lu, off %lld, size %zu, datalen %d\n",
zone->name, i, zone->off,
zone->buffer_size, atomic_read(&buf->datalen));
}
return 0;
}
static int psz_kmsg_recover(struct psz_context *cxt)
{
int ret;
if (!cxt->kpszs)
return 0;
ret = psz_kmsg_recover_meta(cxt);
if (ret)
goto recover_fail;
ret = psz_kmsg_recover_data(cxt);
if (ret)
goto recover_fail;
return 0;
recover_fail:
pr_debug("psz_recover_kmsg failed\n");
return ret;
}
static int psz_recover_zone(struct psz_context *cxt, struct pstore_zone *zone)
{
struct pstore_zone_info *info = cxt->pstore_zone_info;
struct psz_buffer *oldbuf, tmpbuf;
int ret = 0;
char *buf;
ssize_t rcnt, len, start, off;
if (!zone || zone->oldbuf)
return 0;
if (is_on_panic()) {
/* save data as much as possible */
psz_flush_dirty_zone(zone);
return 0;
}
if (unlikely(!info->read))
return -EINVAL;
len = sizeof(struct psz_buffer);
rcnt = info->read((char *)&tmpbuf, len, zone->off);
if (rcnt != len) {
pr_debug("read zone %s failed\n", zone->name);
return (int)rcnt < 0 ? (int)rcnt : -EIO;
}
if (tmpbuf.sig != zone->buffer->sig) {
pr_debug("no valid data in zone %s\n", zone->name);
return 0;
}
if (zone->buffer_size < atomic_read(&tmpbuf.datalen) ||
zone->buffer_size < atomic_read(&tmpbuf.start)) {
pr_info("found overtop zone: %s: off %lld, size %zu\n",
zone->name, zone->off, zone->buffer_size);
/* just keep going */
return 0;
}
if (!atomic_read(&tmpbuf.datalen)) {
pr_debug("found erased zone: %s: off %lld, size %zu, datalen %d\n",
zone->name, zone->off, zone->buffer_size,
atomic_read(&tmpbuf.datalen));
return 0;
}
pr_debug("found nice zone: %s: off %lld, size %zu, datalen %d\n",
zone->name, zone->off, zone->buffer_size,
atomic_read(&tmpbuf.datalen));
len = atomic_read(&tmpbuf.datalen) + sizeof(*oldbuf);
oldbuf = kzalloc(len, GFP_KERNEL);
if (!oldbuf)
return -ENOMEM;
memcpy(oldbuf, &tmpbuf, sizeof(*oldbuf));
buf = (char *)oldbuf + sizeof(*oldbuf);
len = atomic_read(&oldbuf->datalen);
start = atomic_read(&oldbuf->start);
off = zone->off + sizeof(*oldbuf);
/* get part of data */
rcnt = info->read(buf, len - start, off + start);
if (rcnt != len - start) {
pr_err("read zone %s failed\n", zone->name);
ret = (int)rcnt < 0 ? (int)rcnt : -EIO;
goto free_oldbuf;
}
/* get the rest of data */
rcnt = info->read(buf + len - start, start, off);
if (rcnt != start) {
pr_err("read zone %s failed\n", zone->name);
ret = (int)rcnt < 0 ? (int)rcnt : -EIO;
goto free_oldbuf;
}
zone->oldbuf = oldbuf;
psz_flush_dirty_zone(zone);
return 0;
free_oldbuf:
kfree(oldbuf);
return ret;
}
static int psz_recover_zones(struct psz_context *cxt,
struct pstore_zone **zones, unsigned int cnt)
{
int ret;
unsigned int i;
struct pstore_zone *zone;
if (!zones)
return 0;
for (i = 0; i < cnt; i++) {
zone = zones[i];
if (unlikely(!zone))
continue;
ret = psz_recover_zone(cxt, zone);
if (ret)
goto recover_fail;
}
return 0;
recover_fail:
pr_debug("recover %s[%u] failed\n", zone->name, i);
return ret;
}
/**
* psz_recovery() - recover data from storage
* @cxt: the context of pstore/zone
*
* recovery means reading data back from storage after rebooting
*
* Return: 0 on success, others on failure.
*/
static inline int psz_recovery(struct psz_context *cxt)
{
int ret;
if (atomic_read(&cxt->recovered))
return 0;
ret = psz_kmsg_recover(cxt);
if (ret)
goto out;
ret = psz_recover_zone(cxt, cxt->ppsz);
if (ret)
goto out;
ret = psz_recover_zone(cxt, cxt->cpsz);
if (ret)
goto out;
ret = psz_recover_zones(cxt, cxt->fpszs, cxt->ftrace_max_cnt);
out:
if (unlikely(ret))
pr_err("recover failed\n");
else {
pr_debug("recover end!\n");
atomic_set(&cxt->recovered, 1);
}
return ret;
}
static int psz_pstore_open(struct pstore_info *psi)
{
struct psz_context *cxt = psi->data;
cxt->kmsg_read_cnt = 0;
cxt->pmsg_read_cnt = 0;
cxt->console_read_cnt = 0;
cxt->ftrace_read_cnt = 0;
return 0;
}
static inline bool psz_old_ok(struct pstore_zone *zone)
{
if (zone && zone->oldbuf && atomic_read(&zone->oldbuf->datalen))
return true;
return false;
}
static inline bool psz_ok(struct pstore_zone *zone)
{
if (zone && zone->buffer && buffer_datalen(zone))
return true;
return false;
}
static inline int psz_kmsg_erase(struct psz_context *cxt,
struct pstore_zone *zone, struct pstore_record *record)
{
struct psz_buffer *buffer = zone->buffer;
struct psz_kmsg_header *hdr =
(struct psz_kmsg_header *)buffer->data;
size_t size;
if (unlikely(!psz_ok(zone)))
return 0;
/* this zone is already updated, no need to erase */
if (record->count != hdr->counter)
return 0;
size = buffer_datalen(zone) + sizeof(*zone->buffer);
atomic_set(&zone->buffer->datalen, 0);
if (cxt->pstore_zone_info->erase)
return cxt->pstore_zone_info->erase(size, zone->off);
else
return psz_zone_write(zone, FLUSH_META, NULL, 0, 0);
}
static inline int psz_record_erase(struct psz_context *cxt,
struct pstore_zone *zone)
{
if (unlikely(!psz_old_ok(zone)))
return 0;
kfree(zone->oldbuf);
zone->oldbuf = NULL;
/*
* if there are new data in zone buffer, that means the old data
* are already invalid. It is no need to flush 0 (erase) to
* block device.
*/
if (!buffer_datalen(zone))
return psz_zone_write(zone, FLUSH_META, NULL, 0, 0);
psz_flush_dirty_zone(zone);
return 0;
}
static int psz_pstore_erase(struct pstore_record *record)
{
struct psz_context *cxt = record->psi->data;
switch (record->type) {
case PSTORE_TYPE_DMESG:
if (record->id >= cxt->kmsg_max_cnt)
return -EINVAL;
return psz_kmsg_erase(cxt, cxt->kpszs[record->id], record);
case PSTORE_TYPE_PMSG:
return psz_record_erase(cxt, cxt->ppsz);
case PSTORE_TYPE_CONSOLE:
return psz_record_erase(cxt, cxt->cpsz);
case PSTORE_TYPE_FTRACE:
if (record->id >= cxt->ftrace_max_cnt)
return -EINVAL;
return psz_record_erase(cxt, cxt->fpszs[record->id]);
default: return -EINVAL;
}
}
static void psz_write_kmsg_hdr(struct pstore_zone *zone,
struct pstore_record *record)
{
struct psz_context *cxt = record->psi->data;
struct psz_buffer *buffer = zone->buffer;
struct psz_kmsg_header *hdr =
(struct psz_kmsg_header *)buffer->data;
hdr->magic = PSTORE_KMSG_HEADER_MAGIC;
hdr->compressed = record->compressed;
hdr->time.tv_sec = record->time.tv_sec;
hdr->time.tv_nsec = record->time.tv_nsec;
hdr->reason = record->reason;
if (hdr->reason == KMSG_DUMP_OOPS)
hdr->counter = ++cxt->oops_counter;
else if (hdr->reason == KMSG_DUMP_PANIC)
hdr->counter = ++cxt->panic_counter;
else
hdr->counter = 0;
}
/*
* In case zone is broken, which may occur to MTD device, we try each zones,
* start at cxt->kmsg_write_cnt.
*/
static inline int notrace psz_kmsg_write_record(struct psz_context *cxt,
struct pstore_record *record)
{
size_t size, hlen;
struct pstore_zone *zone;
unsigned int i;
for (i = 0; i < cxt->kmsg_max_cnt; i++) {
unsigned int zonenum, len;
int ret;
zonenum = (cxt->kmsg_write_cnt + i) % cxt->kmsg_max_cnt;
zone = cxt->kpszs[zonenum];
if (unlikely(!zone))
return -ENOSPC;
/* avoid destroying old data, allocate a new one */
len = zone->buffer_size + sizeof(*zone->buffer);
zone->oldbuf = zone->buffer;
zone->buffer = kzalloc(len, GFP_KERNEL);
if (!zone->buffer) {
zone->buffer = zone->oldbuf;
return -ENOMEM;
}
zone->buffer->sig = zone->oldbuf->sig;
pr_debug("write %s to zone id %d\n", zone->name, zonenum);
psz_write_kmsg_hdr(zone, record);
hlen = sizeof(struct psz_kmsg_header);
size = min_t(size_t, record->size, zone->buffer_size - hlen);
ret = psz_zone_write(zone, FLUSH_ALL, record->buf, size, hlen);
if (likely(!ret || ret != -ENOMSG)) {
cxt->kmsg_write_cnt = zonenum + 1;
cxt->kmsg_write_cnt %= cxt->kmsg_max_cnt;
/* no need to try next zone, free last zone buffer */
kfree(zone->oldbuf);
zone->oldbuf = NULL;
return ret;
}
pr_debug("zone %u may be broken, try next dmesg zone\n",
zonenum);
kfree(zone->buffer);
zone->buffer = zone->oldbuf;
zone->oldbuf = NULL;
}
return -EBUSY;
}
static int notrace psz_kmsg_write(struct psz_context *cxt,
struct pstore_record *record)
{
int ret;
/*
* Explicitly only take the first part of any new crash.
* If our buffer is larger than kmsg_bytes, this can never happen,
* and if our buffer is smaller than kmsg_bytes, we don't want the
* report split across multiple records.
*/
if (record->part != 1)
return -ENOSPC;
if (!cxt->kpszs)
return -ENOSPC;
ret = psz_kmsg_write_record(cxt, record);
if (!ret && is_on_panic()) {
/* ensure all data are flushed to storage when panic */
pr_debug("try to flush other dirty zones\n");
psz_flush_all_dirty_zones(NULL);
}
/* always return 0 as we had handled it on buffer */
return 0;
}
static int notrace psz_record_write(struct pstore_zone *zone,
struct pstore_record *record)
{
size_t start, rem;
bool is_full_data = false;
char *buf;
int cnt;
if (!zone || !record)
return -ENOSPC;
if (atomic_read(&zone->buffer->datalen) >= zone->buffer_size)
is_full_data = true;
cnt = record->size;
buf = record->buf;
if (unlikely(cnt > zone->buffer_size)) {
buf += cnt - zone->buffer_size;
cnt = zone->buffer_size;
}
start = buffer_start(zone);
rem = zone->buffer_size - start;
if (unlikely(rem < cnt)) {
psz_zone_write(zone, FLUSH_PART, buf, rem, start);
buf += rem;
cnt -= rem;
start = 0;
is_full_data = true;
}
atomic_set(&zone->buffer->start, cnt + start);
psz_zone_write(zone, FLUSH_PART, buf, cnt, start);
/**
* psz_zone_write will set datalen as start + cnt.
* It work if actual data length lesser than buffer size.
* If data length greater than buffer size, pmsg will rewrite to
* beginning of zone, which make buffer->datalen wrongly.
* So we should reset datalen as buffer size once actual data length
* greater than buffer size.
*/
if (is_full_data) {
atomic_set(&zone->buffer->datalen, zone->buffer_size);
psz_zone_write(zone, FLUSH_META, NULL, 0, 0);
}
return 0;
}
static int notrace psz_pstore_write(struct pstore_record *record)
{
struct psz_context *cxt = record->psi->data;
if (record->type == PSTORE_TYPE_DMESG &&
record->reason == KMSG_DUMP_PANIC)
atomic_set(&cxt->on_panic, 1);
/*
* if on panic, do not write except panic records
* Fix case that panic_write prints log which wakes up console backend.
*/
if (is_on_panic() && record->type != PSTORE_TYPE_DMESG)
return -EBUSY;
switch (record->type) {
case PSTORE_TYPE_DMESG:
return psz_kmsg_write(cxt, record);
case PSTORE_TYPE_CONSOLE:
return psz_record_write(cxt->cpsz, record);
case PSTORE_TYPE_PMSG:
return psz_record_write(cxt->ppsz, record);
case PSTORE_TYPE_FTRACE: {
int zonenum = smp_processor_id();
if (!cxt->fpszs)
return -ENOSPC;
return psz_record_write(cxt->fpszs[zonenum], record);
}
default:
return -EINVAL;
}
}
static struct pstore_zone *psz_read_next_zone(struct psz_context *cxt)
{
struct pstore_zone *zone = NULL;
while (cxt->kmsg_read_cnt < cxt->kmsg_max_cnt) {
zone = cxt->kpszs[cxt->kmsg_read_cnt++];
if (psz_ok(zone))
return zone;
}
if (cxt->ftrace_read_cnt < cxt->ftrace_max_cnt)
/*
* No need psz_old_ok(). Let psz_ftrace_read() do so for
* combination. psz_ftrace_read() should traverse over
* all zones in case of some zone without data.
*/
return cxt->fpszs[cxt->ftrace_read_cnt++];
if (cxt->pmsg_read_cnt == 0) {
cxt->pmsg_read_cnt++;
zone = cxt->ppsz;
if (psz_old_ok(zone))
return zone;
}
if (cxt->console_read_cnt == 0) {
cxt->console_read_cnt++;
zone = cxt->cpsz;
if (psz_old_ok(zone))
return zone;
}
return NULL;
}
static int psz_kmsg_read_hdr(struct pstore_zone *zone,
struct pstore_record *record)
{
struct psz_buffer *buffer = zone->buffer;
struct psz_kmsg_header *hdr =
(struct psz_kmsg_header *)buffer->data;
if (hdr->magic != PSTORE_KMSG_HEADER_MAGIC)
return -EINVAL;
record->compressed = hdr->compressed;
record->time.tv_sec = hdr->time.tv_sec;
record->time.tv_nsec = hdr->time.tv_nsec;
record->reason = hdr->reason;
record->count = hdr->counter;
return 0;
}
static ssize_t psz_kmsg_read(struct pstore_zone *zone,
struct pstore_record *record)
{
ssize_t size, hlen = 0;
size = buffer_datalen(zone);
/* Clear and skip this kmsg dump record if it has no valid header */
if (psz_kmsg_read_hdr(zone, record)) {
atomic_set(&zone->buffer->datalen, 0);
atomic_set(&zone->dirty, 0);
return -ENOMSG;
}
size -= sizeof(struct psz_kmsg_header);
if (!record->compressed) {
char *buf = kasprintf(GFP_KERNEL, "%s: Total %d times\n",
kmsg_dump_reason_str(record->reason),
record->count);
hlen = strlen(buf);
record->buf = krealloc(buf, hlen + size, GFP_KERNEL);
if (!record->buf) {
kfree(buf);
return -ENOMEM;
}
} else {
record->buf = kmalloc(size, GFP_KERNEL);
if (!record->buf)
return -ENOMEM;
}
size = psz_zone_read_buffer(zone, record->buf + hlen, size,
sizeof(struct psz_kmsg_header));
if (unlikely(size < 0)) {
kfree(record->buf);
return -ENOMSG;
}
return size + hlen;
}
/* try to combine all ftrace zones */
static ssize_t psz_ftrace_read(struct pstore_zone *zone,
struct pstore_record *record)