pstore_blk is similar to pstore_ram, but dump log to block devices
rather than persistent ram.
Why should we need pstore_blk?
1. Most embedded intelligent equipment have no persistent ram, which
increases costs. We perfer to cheaper solutions, like block devices.
In fact, there is already a sample for block device logger in driver
MTD (drivers/mtd/mtdoops.c).
2. Do not any equipment have battery, which means that it lost all data
on general ram if power failure. Pstore has little to do for these
equipments.
pstore_blk can only dump Oops/Panic log to block devices. It only
supports dmesg now. To make pstore_blk work, the block driver should
provide the path of a block partition device (/dev/XXXX) and the
read/write apis when on panic.
pstore_blk begins at 'blkz_register', by witch block device can register
a block partition to pstore_blk. Then pstore_blk divide and manage the
partition as zones, which is similar to pstore_ram.
Recommend that, block driver register pstore_blk after block device is
ready.
pstore_blk works well on allwinner(sunxi) platform.
Signed-off-by: liaoweixiong <liaoweixiong@xxxxxxxxxxxxxxxxx>
---
fs/pstore/Kconfig | 7 +
fs/pstore/Makefile | 3 +
fs/pstore/blkzone.c | 954 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/pstore_blk.h | 61 +++
4 files changed, 1025 insertions(+)
create mode 100644 fs/pstore/blkzone.c
create mode 100644 include/linux/pstore_blk.h
diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
index 8b3ba27..a881c53 100644
--- a/fs/pstore/Kconfig
+++ b/fs/pstore/Kconfig
@@ -152,3 +152,10 @@ config PSTORE_RAM
"ramoops.ko".
For more information, see Documentation/admin-guide/ramoops.rst.
+
+config PSTORE_BLK
+ tristate "Log panic/oops to a block device"
+ depends on PSTORE
+ help
+ This enables panic and oops message to be logged to a block dev
+ where it can be read back at some later point.
diff --git a/fs/pstore/Makefile b/fs/pstore/Makefile
index 967b589..0ee2fc8 100644
--- a/fs/pstore/Makefile
+++ b/fs/pstore/Makefile
@@ -12,3 +12,6 @@ pstore-$(CONFIG_PSTORE_PMSG) += pmsg.o
ramoops-objs += ram.o ram_core.o
obj-$(CONFIG_PSTORE_RAM) += ramoops.o
+
+obj-$(CONFIG_PSTORE_BLK) += pstore_blk.o
+pstore_blk-y += blkzone.o
diff --git a/fs/pstore/blkzone.c b/fs/pstore/blkzone.c
new file mode 100644
index 0000000..aca8c2a
--- /dev/null
+++ b/fs/pstore/blkzone.c
@@ -0,0 +1,954 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *
+ * blkzone.c: Block device Oops/Panic logger
+ *
+ * Copyright (C) 2019 liaoweixiong <liaoweixiong@xxxxxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#define MODNAME "pstore-blk"
+#define pr_fmt(fmt) MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/pstore.h>
+#include <linux/mount.h>
+#include <linux/printk.h>
+#include <linux/fs.h>
+#include <linux/pstore_blk.h>
+
+/**
+ * struct blkz_head - head of zone to flush to storage
+ *
+ * @sig: signature to indicate header (BLK_SIG xor BLKZONE-type value)
+ * @datalen: length of data in @data
+ * @data: zone data.
+ */
+struct blkz_buffer {
+#define BLK_SIG (0x43474244) /* DBGC */
+ uint32_t sig;
+ atomic_t datalen;
+ uint8_t data[];
+};
+
+/**
+ * struct blkz_dmesg_header: dmesg information
+ *
+ * @magic: magic num for dmesg header
+ * @time: trigger time
+ * @compressed: whether conpressed
+ * @count: oops/panic counter
+ * @reason: identify oops or panic
+ */
+struct blkz_dmesg_header {
+#define DMESG_HEADER_MAGIC 0x4dfc3ae5
+ uint32_t magic;
+ struct timespec64 time;
+ bool compressed;
+ uint32_t counter;
+ enum kmsg_dump_reason reason;
+ uint8_t data[0];
+};
+
+/**
+ * struct blkz_zone - zone information
+ * @off:
+ * zone offset of partition
+ * @type:
+ * frontent type for this zone
+ * @name:
+ * frontent name for this zone
+ * @buffer:
+ * pointer to data buffer managed by this zone
+ * @buffer_size:
+ * bytes in @buffer->data
+ * @should_recover:
+ * should recover from storage
+ * @dirty:
+ * mark whether the data in @buffer are dirty (not flush to storage yet)
+ */
+struct blkz_zone {
+ unsigned long off;
+ const char *name;
+ enum pstore_type_id type;
+
+ struct blkz_buffer *buffer;
+ size_t buffer_size;
+ bool should_recover;
+ atomic_t dirty;
+};
+
+struct blkz_context {
+ struct blkz_zone **dbzs; /* dmesg block zones */
+ unsigned int dmesg_max_cnt;
+ unsigned int dmesg_read_cnt;
+ unsigned int dmesg_write_cnt;
+ /**
+ * the counter should be recovered when do recovery
+ * It records the oops/panic times after burning rather than booting.
+ */
+ unsigned int oops_counter;
+ unsigned int panic_counter;
+ atomic_t blkdev_up;
+ atomic_t recovery;
+ atomic_t on_panic;
+
+ /*
+ * bzinfo_lock just protects "bzinfo" during calls to
+ * blkz_register/blkz_unregister
+ */
+ spinlock_t bzinfo_lock;
+ struct blkz_info *bzinfo;
+ struct pstore_info pstore;
+};
+static struct blkz_context blkz_cxt;
+
+enum blkz_flush_mode {
+ FLUSH_NONE = 0,
+ FLUSH_PART,
+ FLUSH_META,
+ FLUSH_ALL,
+};
+
+static inline int buffer_datalen(struct blkz_zone *zone)
+{
+ return atomic_read(&zone->buffer->datalen);
+}
+
+static inline bool is_on_panic(void)
+{
+ struct blkz_context *cxt = &blkz_cxt;
+
+ return atomic_read(&cxt->on_panic);
+}
+
+static inline bool is_blkdev_up(void)
+{
+ struct blkz_context *cxt = &blkz_cxt;
+ const char *devpath = cxt->bzinfo->part_path;
+
+ if (atomic_read(&cxt->blkdev_up))
+ return true;
+ if (is_on_panic())
+ goto set_up;
+ if (devpath && !name_to_dev_t(devpath))
+ return false;
+set_up:
+ atomic_set(&cxt->blkdev_up, 1);
+ return true;
+}
+
+static int blkz_zone_read(struct blkz_zone *zone, char *buf,
+ size_t len, unsigned long off)
+{
+ if (!buf || !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 0;
+}
+
+static int blkz_zone_write(struct blkz_zone *zone,
+ enum blkz_flush_mode flush_mode, const char *buf,
+ size_t len, unsigned long off)
+{
+ struct blkz_info *info = blkz_cxt.bzinfo;
+ ssize_t wcnt;
+ 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 (flush_mode != FLUSH_META && flush_mode != FLUSH_NONE) {
+ if (buf && zone->buffer)
+ memcpy(zone->buffer->data + off, buf, wlen);
+ atomic_set(&zone->buffer->datalen, wlen + off);
+ }
+
+ if (!is_blkdev_up())
+ goto set_dirty;
+
+ writeop = is_on_panic() ? info->panic_write : info->write;
+ if (!writeop)
+ return -EINVAL;
+
+ switch (flush_mode) {
+ case FLUSH_NONE:
+ return 0;
+ case FLUSH_PART:
+ wcnt = writeop((const char *)zone->buffer->data + off, wlen,
+ zone->off + sizeof(*zone->buffer) + off);
+ if (wcnt != wlen)
+ goto set_dirty;
+ case FLUSH_META:
+ wlen = sizeof(struct blkz_buffer);
+ wcnt = writeop((const char *)zone->buffer, wlen, zone->off);
+ if (wcnt != wlen)
+ goto set_dirty;
+ break;
+ case FLUSH_ALL:
+ wlen = buffer_datalen(zone) + sizeof(*zone->buffer);
+ wcnt = writeop((const char *)zone->buffer, wlen, zone->off);
+ if (wcnt != wlen)
+ goto set_dirty;
+ break;
+ }
+
+ return 0;
+set_dirty:
+ atomic_set(&zone->dirty, true);
+ return -EBUSY;
+}
+
+/*
+ * blkz_move_zone: move data from a old zone to a new zone
+ *
+ * @old: the old zone
+ * @new: the new zone
+ *
+ * NOTE:
+ * Call blkz_zone_write to copy and flush data. If it failed, we
+ * should reset new->dirty, because the new zone not really dirty.
+ */
+static int blkz_move_zone(struct blkz_zone *old, struct blkz_zone *new)
+{
+ const char *data = (const char *)old->buffer->data;
+ int ret;
+
+ ret = blkz_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 int blkz_recover_dmesg_data(struct blkz_context *cxt)
+{
+ struct blkz_info *info = cxt->bzinfo;
+ struct blkz_zone *zone = NULL;
+ struct blkz_buffer *buf;
+ unsigned long i;
+ ssize_t (*readop)(char *buf, size_t bytes, loff_t pos);
+ ssize_t rcnt;
+
+ readop = is_on_panic() ? info->panic_read : info->read;
+ if (!readop)
+ return -EINVAL;
+
+ for (i = 0; i < cxt->dmesg_max_cnt; i++) {
+ zone = cxt->dbzs[i];
+ if (unlikely(!zone))
+ return -EINVAL;
+ if (atomic_read(&zone->dirty)) {
+ unsigned int wcnt = cxt->dmesg_write_cnt;
+ struct blkz_zone *new = cxt->dbzs[wcnt];
+ int ret;
+
+ ret = blkz_move_zone(zone, new);
+ if (ret) {
+ pr_err("move zone from %lu to %d failed\n",
+ i, wcnt);
+ return ret;
+ }
+ cxt->dmesg_write_cnt = (wcnt + 1) % cxt->dmesg_max_cnt;
+ }
+ if (!zone->should_recover)
+ continue;
+ buf = zone->buffer;
+ rcnt = readop((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;
+}
+
+/**
+ * blkz_recover_dmesg_meta: recover metadata of dmesg
+ *
+ * Recover metadata as follow:
+ * @cxt->dmesg_write_cnt
+ * @cxt->oops_counter
+ * @cxt->panic_counter
+ */
+static int blkz_recover_dmesg_meta(struct blkz_context *cxt)
+{
+ struct blkz_info *info = cxt->bzinfo;
+ struct blkz_zone *zone;
+ size_t rcnt, len;
+ struct blkz_buffer *buf;
+ struct blkz_dmesg_header *hdr;
+ ssize_t (*readop)(char *buf, size_t bytes, loff_t pos);
+ struct timespec64 time = {0};
+ 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};
+
+ readop = is_on_panic() ? info->panic_read : info->read;
+ if (!readop)
+ return -EINVAL;
+
+ len = sizeof(*buf) + sizeof(*hdr);
+ buf = (struct blkz_buffer *)buffer_header;
+ for (i = 0; i < cxt->dmesg_max_cnt; i++) {
+ zone = cxt->dbzs[i];
+ if (unlikely(!zone))
+ return -EINVAL;
+
+ rcnt = readop((char *)buf, len, zone->off);
+ if (rcnt != len)
+ return (int)rcnt < 0 ? (int)rcnt : -EIO;
+
+ /*
+ * If sig NOT match, it means this zone never used before,
+ * because we write one by one, and we never modify sig even
+ * when erase. So, we do not need to check next one.
+ */
+ if (buf->sig != zone->buffer->sig) {
+ cxt->dmesg_write_cnt = i;
+ pr_debug("no valid data in dmesg zone %lu\n", i);
+ break;
+ }
+
+ if (zone->buffer_size < atomic_read(&buf->datalen)) {
+ pr_info("found overtop zone: %s: id %lu, off %lu, size %zu\n",
+ zone->name, i, zone->off,
+ zone->buffer_size);
+ continue;
+ }
+
+ hdr = (struct blkz_dmesg_header *)buf->data;
+ if (hdr->magic != DMESG_HEADER_MAGIC) {
+ pr_info("found invalid zone: %s: id %lu, off %lu, 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->dmesg_write_cnt = (i + 1) % cxt->dmesg_max_cnt;
+ }
+
+ if (hdr->reason == KMSG_DUMP_OOPS)
+ cxt->oops_counter =
+ max(cxt->oops_counter, hdr->counter);
+ else
+ cxt->panic_counter =
+ max(cxt->panic_counter, hdr->counter);
+
+ if (!atomic_read(&buf->datalen)) {
+ pr_debug("found erased zone: %s: id %ld, off %lu, 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 %ld, off %lu, size %zu, datalen %d\n",
+ zone->name, i, zone->off,
+ zone->buffer_size, atomic_read(&buf->datalen));
+ }
+
+ return 0;
+}
+
+static int blkz_recover_dmesg(struct blkz_context *cxt)
+{
+ int ret;
+
+ if (!cxt->dbzs)
+ return 0;
+
+ ret = blkz_recover_dmesg_meta(cxt);
+ if (ret)
+ goto recover_fail;
+
+ ret = blkz_recover_dmesg_data(cxt);
+ if (ret)
+ goto recover_fail;
+
+ return 0;
+recover_fail:
+ pr_debug("recover dmesg failed\n");
+ return ret;
+}
+
+static inline int blkz_recovery(struct blkz_context *cxt)
+{
+ int ret = -EBUSY;
+
+ if (atomic_read(&cxt->recovery))
+ return 0;
+
+ if (!is_blkdev_up())
+ goto recover_fail;
+
+ ret = blkz_recover_dmesg(cxt);
+ if (ret)
+ goto recover_fail;
+
+ atomic_set(&cxt->recovery, 1);
+ pr_debug("recover end!\n");
+ return 0;
+
+recover_fail:
+ pr_debug("recovery failed, handle buffer\n");
+ return ret;
+}
+
+static int blkz_pstore_open(struct pstore_info *psi)
+{
+ struct blkz_context *cxt = psi->data;
+
+ cxt->dmesg_read_cnt = 0;
+ return 0;
+}
+
+static inline bool blkz_ok(struct blkz_zone *zone)
+{
+ if (!zone || !zone->buffer || !buffer_datalen(zone))
+ return false;
+ return true;
+}
+
+static int blkz_pstore_erase(struct pstore_record *record)
+{
+ struct blkz_context *cxt = record->psi->data;
+ struct blkz_zone *zone = NULL;
+
+ if (record->type == PSTORE_TYPE_DMESG)
+ zone = cxt->dbzs[record->id];
+ if (!blkz_ok(zone))
+ return 0;
+
+ atomic_set(&zone->buffer->datalen, 0);
+ return blkz_zone_write(zone, FLUSH_META, NULL, 0, 0);
+}
+
+static void blkz_write_kmsg_hdr(struct blkz_zone *zone,
+ struct pstore_record *record)
+{
+ struct blkz_context *cxt = record->psi->data;
+ struct blkz_buffer *buffer = zone->buffer;
+ struct blkz_dmesg_header *hdr =
+ (struct blkz_dmesg_header *)buffer->data;
+
+ hdr->magic = DMESG_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
+ hdr->counter = ++cxt->panic_counter;
+}
+
+static int notrace blkz_dmesg_write(struct blkz_context *cxt,
+ struct pstore_record *record)
+{
+ struct blkz_info *info = cxt->bzinfo;
+ struct blkz_zone *zone;
+ size_t size, hlen;
+
+ /*
+ * Out of the various dmesg dump types, pstore/blk is currently designed
+ * to only store crash logs, rather than storing general kernel logs.
+ */
+ if (record->reason != KMSG_DUMP_OOPS &&
+ record->reason != KMSG_DUMP_PANIC)
+ return -EINVAL;
+
+ /* Skip Oopes when configured to do so. */
+ if (record->reason == KMSG_DUMP_OOPS && !info->dump_oops)
+ return -EINVAL;
+
+ /*
+ * 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->dbzs)
+ return -ENOSPC;
+
+ zone = cxt->dbzs[cxt->dmesg_write_cnt];
+ if (!zone)
+ return -ENOSPC;
+
+ blkz_write_kmsg_hdr(zone, record);
+ hlen = sizeof(struct blkz_dmesg_header);
+ size = record->size;
+ if (size + hlen > zone->buffer_size)
+ size = zone->buffer_size - hlen;
+ blkz_zone_write(zone, FLUSH_ALL, record->buf, size, hlen);
+
+ pr_debug("write %s to zone id %d\n", zone->name, cxt->dmesg_write_cnt);
+ cxt->dmesg_write_cnt = (cxt->dmesg_write_cnt + 1) % cxt->dmesg_max_cnt;
+ return 0;
+}
+
+static int notrace blkz_pstore_write(struct pstore_record *record)
+{
+ struct blkz_context *cxt = record->psi->data;
+
+ if (record->type == PSTORE_TYPE_DMESG &&
+ record->reason == KMSG_DUMP_PANIC)
+ atomic_set(&cxt->on_panic, 1);
+
+ /*
+ * before write, we must recover from storage.
+ * if recover failed, handle buffer
+ */
+ blkz_recovery(cxt);
+
+ switch (record->type) {
+ case PSTORE_TYPE_DMESG:
+ return blkz_dmesg_write(cxt, record);
+ default:
+ return -EINVAL;
+ }
+}
+
+#define READ_NEXT_ZONE ((ssize_t)(-1024))
+static struct blkz_zone *blkz_read_next_zone(struct blkz_context *cxt)
+{
+ struct blkz_zone *zone = NULL;
+
+ while (cxt->dmesg_read_cnt < cxt->dmesg_max_cnt) {
+ zone = cxt->dbzs[cxt->dmesg_read_cnt++];
+ if (blkz_ok(zone))
+ return zone;
+ }
+
+ return NULL;
+}
+
+static int blkz_read_dmesg_hdr(struct blkz_zone *zone,
+ struct pstore_record *record)
+{
+ struct blkz_buffer *buffer = zone->buffer;
+ struct blkz_dmesg_header *hdr =
+ (struct blkz_dmesg_header *)buffer->data;
+
+ if (hdr->magic != DMESG_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 blkz_dmesg_read(struct blkz_zone *zone,
+ struct pstore_record *record)
+{
+ size_t size, hlen = 0;
+
+ size = buffer_datalen(zone);
+ /* Clear and skip this DMESG record if it has no valid header */
+ if (blkz_read_dmesg_hdr(zone, record)) {
+ atomic_set(&zone->buffer->datalen, 0);
+ atomic_set(&zone->dirty, 0);
+ return READ_NEXT_ZONE;
+ }
+ size -= sizeof(struct blkz_dmesg_header);
+
+ if (!record->compressed) {
+ char *buf = kasprintf(GFP_KERNEL,
+ "%s: Total %d times\n",
+ record->reason == KMSG_DUMP_OOPS ? "Oops" :
+ "Panic", 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;
+ }
+
+ if (unlikely(blkz_zone_read(zone, record->buf + hlen, size,
+ sizeof(struct blkz_dmesg_header)) < 0)) {
+ kfree(record->buf);
+ return READ_NEXT_ZONE;
+ }
+
+ return size + hlen;
+}
+
+static ssize_t blkz_pstore_read(struct pstore_record *record)
+{
+ struct blkz_context *cxt = record->psi->data;
+ ssize_t (*blkz_read)(struct blkz_zone *zone,
+ struct pstore_record *record);
+ struct blkz_zone *zone;
+ ssize_t ret;
+
+ /*
+ * before read, we must recover from storage.
+ * if recover failed, handle buffer
+ */
+ blkz_recovery(cxt);
+
+next_zone:
+ zone = blkz_read_next_zone(cxt);
+ if (!zone)
+ return 0;
+
+ record->type = zone->type;
+ switch (record->type) {
+ case PSTORE_TYPE_DMESG:
+ blkz_read = blkz_dmesg_read;
+ record->id = cxt->dmesg_read_cnt - 1;
+ break;
+ default:
+ goto next_zone;
+ }
+
+ ret = blkz_read(zone, record);
+ if (ret == READ_NEXT_ZONE)
+ goto next_zone;
+ return ret;
+}
+
+static struct blkz_context blkz_cxt = {
+ .bzinfo_lock = __SPIN_LOCK_UNLOCKED(blkz_cxt.bzinfo_lock),
+ .blkdev_up = ATOMIC_INIT(0),
+ .recovery = ATOMIC_INIT(0),
+ .on_panic = ATOMIC_INIT(0),
+ .pstore = {
+ .owner = THIS_MODULE,
+ .name = MODNAME,
+ .open = blkz_pstore_open,
+ .read = blkz_pstore_read,
+ .write = blkz_pstore_write,
+ .erase = blkz_pstore_erase,
+ },
+};
+
+static ssize_t blkz_default_general_read(char *buf, size_t bytes, loff_t pos)
+{
+ struct blkz_context *cxt = &blkz_cxt;
+ const char *devpath = cxt->bzinfo->part_path;
+ struct file *filp;
+ ssize_t ret;
+
+ if (!devpath)
+ return -EINVAL;
+
+ if (!is_blkdev_up())
+ return -EBUSY;
+
+ filp = filp_open(devpath, O_RDONLY, 0);
+ if (IS_ERR(filp)) {
+ pr_debug("open %s failed, maybe unready\n", devpath);
+ return -EACCES;
+ }
+ ret = kernel_read(filp, buf, bytes, &pos);
+ filp_close(filp, NULL);
+
+ return ret;
+}
+
+static ssize_t blkz_default_general_write(const char *buf, size_t bytes,
+ loff_t pos)
+{
+ struct blkz_context *cxt = &blkz_cxt;
+ const char *devpath = cxt->bzinfo->part_path;
+ struct file *filp;
+ ssize_t ret;
+
+ if (!devpath)
+ return -EINVAL;
+
+ if (!is_blkdev_up())
+ return -EBUSY;
+
+ filp = filp_open(devpath, O_WRONLY, 0);
+ if (IS_ERR(filp)) {
+ pr_debug("open %s failed, maybe unready\n", devpath);
+ return -EACCES;
+ }
+ ret = kernel_write(filp, buf, bytes, &pos);
+ vfs_fsync(filp, 0);
+ filp_close(filp, NULL);
+
+ return ret;
+}
+
+static struct blkz_zone *blkz_init_zone(enum pstore_type_id type,
+ unsigned long *off, size_t size)
+{
+ struct blkz_info *info = blkz_cxt.bzinfo;
+ struct blkz_zone *zone;
+ const char *name = pstore_type_to_name(type);
+
+ if (!size)
+ return NULL;
+
+ if (*off + size > info->part_size) {
+ pr_err("no room for %s (0x%zx@0x%lx over 0x%lx)\n",
+ name, size, *off, info->part_size);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ zone = kzalloc(sizeof(struct blkz_zone), GFP_KERNEL);
+ if (!zone)
+ return ERR_PTR(-ENOMEM);
+
+ /**
+ * NOTE: allocate buffer for blk zones for two reasons:
+ * 1. It can temporarily hold the data before
+ * blkz_default_general_read/write are useable.
+ * 2. It makes pstore usable even if no persistent storage. Most
+ * events of pstore except panic are suitable!!
+ */
+ zone->buffer = kmalloc(size, GFP_KERNEL);
+ if (!zone->buffer) {
+ kfree(zone);
+ return ERR_PTR(-ENOMEM);
+ }
+ memset(zone->buffer, 0xFF, size);
+ zone->off = *off;
+ zone->name = name;
+ zone->type = type;
+ zone->buffer_size = size - sizeof(struct blkz_buffer);
+ zone->buffer->sig = type ^ BLK_SIG;
+ atomic_set(&zone->dirty, 0);
+ atomic_set(&zone->buffer->datalen, 0);
+
+ *off += size;
+
+ pr_debug("blkzone %s: off 0x%lx, %zu header, %zu data\n", zone->name,
+ zone->off, sizeof(*zone->buffer), zone->buffer_size);
+ return zone;
+}
+
+static struct blkz_zone **blkz_init_zones(enum pstore_type_id type,
+ unsigned long *off, size_t total_size, ssize_t record_size,
+ unsigned int *cnt)
+{
+ struct blkz_info *info = blkz_cxt.bzinfo;
+ struct blkz_zone **zones, *zone;
+ const char *name = pstore_type_to_name(type);
+ int c, i;
+
+ if (!total_size || !record_size)
+ return NULL;
+
+ if (*off + total_size > info->part_size) {
+ pr_err("no room for zones %s (0x%zx@0x%lx over 0x%lx)\n",
+ name, total_size, *off, info->part_size);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ c = total_size / record_size;
+ zones = kcalloc(c, sizeof(*zones), GFP_KERNEL);
+ if (!zones) {
+ pr_err("allocate for zones %s failed\n", name);
+ return ERR_PTR(-ENOMEM);
+ }
+ memset(zones, 0, c * sizeof(*zones));
+
+ for (i = 0; i < c; i++) {
+ zone = blkz_init_zone(type, off, record_size);
+ if (!zone || IS_ERR(zone)) {
+ pr_err("initialize zones %s failed\n", name);
+ while (--i >= 0)
+ kfree(zones[i]);
+ kfree(zones);
+ return (void *)zone;
+ }
+ zones[i] = zone;
+ }
+
+ *cnt = c;
+ return zones;
+}
+
+static void blkz_free_zone(struct blkz_zone **blkzone)
+{
+ struct blkz_zone *zone = *blkzone;
+
+ if (!zone)
+ return;
+
+ kfree(zone->buffer);
+ kfree(zone);
+ *blkzone = NULL;
+}
+
+static void blkz_free_zones(struct blkz_zone ***blkzones, unsigned int *cnt)
+{
+ struct blkz_zone **zones = *blkzones;
+
+ while (*cnt > 0) {
+ blkz_free_zone(&zones[*cnt]);
+ (*cnt)--;
+ }
+ kfree(zones);
+ *blkzones = NULL;
+}
+
+static int blkz_cut_zones(struct blkz_context *cxt)
+{
+ struct blkz_info *info = cxt->bzinfo;
+ unsigned long off = 0;
+ int err;
+ size_t size;
+
+ size = info->part_size;
+ cxt->dbzs = blkz_init_zones(PSTORE_TYPE_DMESG, &off, size,
+ info->dmesg_size, &cxt->dmesg_max_cnt);
+ if (IS_ERR(cxt->dbzs)) {
+ err = PTR_ERR(cxt->dbzs);
+ goto fail_out;
+ }
+
+ return 0;
+fail_out:
+ return err;
+}
+
+int blkz_register(struct blkz_info *info)
+{
+ int err = -EINVAL;
+ struct blkz_context *cxt = &blkz_cxt;
+ struct module *owner = info->owner;
+
+ if (!info->part_size || !info->dmesg_size) {
+ pr_warn("The memory size and the dmesg size must be non-zero\n");
+ return -EINVAL;
+ }
+
+ if (info->part_size < 4096) {
+ pr_err("partition size must be over 4096 bytes\n");
+ return -EINVAL;
+ }
+
+#define check_size(name, size) { \
+ if (info->name & (size - 1)) { \
+ pr_err(#name " must be a multiple of %d\n", \
+ (size)); \
+ return -EINVAL; \
+ } \
+ }
+
+ check_size(part_size, 4096);
+ check_size(dmesg_size, SECTOR_SIZE);
+
+#undef check_size
+
+ if (!info->read)
+ info->read = blkz_default_general_read;
+ if (!info->write)
+ info->write = blkz_default_general_write;
+
+ if (owner && !try_module_get(owner))
+ return -EINVAL;
+
+ spin_lock(&cxt->bzinfo_lock);
+ if (cxt->bzinfo) {
+ pr_warn("blk '%s' already loaded: ignoring '%s'\n",
+ cxt->bzinfo->name, info->name);
+ spin_unlock(&cxt->bzinfo_lock);
+ return -EBUSY;
+ }
+ cxt->bzinfo = info;
+ spin_unlock(&cxt->bzinfo_lock);
+
+ if (blkz_cut_zones(cxt)) {
+ pr_err("cut zones fialed\n");
+ goto fail_out;
+ }
+
+ cxt->pstore.bufsize = cxt->dbzs[0]->buffer_size -
+ sizeof(struct blkz_dmesg_header);
+ cxt->pstore.buf = kzalloc(cxt->pstore.bufsize, GFP_KERNEL);
+ if (!cxt->pstore.buf) {
+ pr_err("cannot allocate pstore crash dump buffer\n");
+ err = -ENOMEM;
+ goto fail_out;
+ }
+ cxt->pstore.data = cxt;
+ cxt->pstore.flags = PSTORE_FLAGS_DMESG;
+
+ pr_info("Registered %s as blkzone backend for %s%s\n", info->name,
+ cxt->dbzs && cxt->bzinfo->dump_oops ? "Oops " : "",
+ cxt->dbzs && cxt->bzinfo->panic_write ? "Panic " : "");
+
+ err = pstore_register(&cxt->pstore);
+ if (err) {
+ pr_err("registering with pstore failed\n");
+ goto free_pstore_buf;
+ }
+
+ module_put(owner);
+ return 0;
+
+free_pstore_buf:
+ kfree(cxt->pstore.buf);
+fail_out:
+ spin_lock(&blkz_cxt.bzinfo_lock);
+ blkz_cxt.bzinfo = NULL;
+ spin_unlock(&blkz_cxt.bzinfo_lock);
+ return err;
+}
+EXPORT_SYMBOL_GPL(blkz_register);
+
+void blkz_unregister(struct blkz_info *info)
+{
+ struct blkz_context *cxt = &blkz_cxt;
+
+ pstore_unregister(&cxt->pstore);
+ kfree(cxt->pstore.buf);
+ cxt->pstore.bufsize = 0;
+
+ spin_lock(&cxt->bzinfo_lock);
+ blkz_cxt.bzinfo = NULL;
+ spin_unlock(&cxt->bzinfo_lock);
+
+ blkz_free_zones(&cxt->dbzs, &cxt->dmesg_max_cnt);
+
+}
+EXPORT_SYMBOL_GPL(blkz_unregister);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("liaoweixiong <liaoweixiong@xxxxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Block device Oops/Panic logger");
diff --git a/include/linux/pstore_blk.h b/include/linux/pstore_blk.h
new file mode 100644
index 0000000..27b282d
--- /dev/null
+++ b/include/linux/pstore_blk.h
@@ -0,0 +1,61 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __PSTORE_BLK_H_
+#define __PSTORE_BLK_H_
+
+#include <linux/types.h>
+#include <linux/blkdev.h>
+
+#ifndef SECTOR_SIZE
+#define SECTOR_SIZE 512
+#endif
+
+/**
+ * struct blkz_info - backend blkzone driver structure
+ *
+ * @owner:
+ * module which is responsible for this backend driver
+ * @name:
+ * name of the backend driver
+ * @part_path:
+ * path of a storage partition. It's ok to keep it as NULL
+ * if you passing @read and @write in blkz_info. @part_path
+ * is needed by blkz_default_general_read/write. If both of
+ * @part_path, @read and @write are NULL, it will temporarity
+ * hold the data in buffer allocated by 'kmalloc'.
+ * @part_size:
+ * total size of a storage partition in bytes. The partition
+ * will be used to save data of pstore.
+ * @dmesg_size:
+ * the size of each zones for dmesg (oops & panic).
+ * @dump_oops:
+ * dump oops and panic log or only panic.
+ * @read:
+ * the general (not panic) read operation. If NULL, pstore/blk
+ * replaced as blkz_default_general_read. See also @part_path
+ * @write:
+ * the general (not panic) write operation. If NULL, pstore/blk
+ * replaced as blkz_default_general_write. See also @part_path
+ * @panic_read:
+ * the read operation only used for panic.
+ * @panic_write:
+ * the write operation only used for panic.
+ */
+struct blkz_info {
+ struct module *owner;
+ const char *name;
+
+ const char *part_path;
+ unsigned long part_size;
+ unsigned long dmesg_size;
+ int dump_oops;
+ ssize_t (*read)(char *buf, size_t bytes, loff_t pos);
+ ssize_t (*write)(const char *buf, size_t bytes, loff_t pos);
+ ssize_t (*panic_read)(char *buf, size_t bytes, loff_t pos);
+ ssize_t (*panic_write)(const char *buf, size_t bytes, loff_t pos);
+};
+
+extern int blkz_register(struct blkz_info *info);
+extern void blkz_unregister(struct blkz_info *info);
+
+#endif
--
1.9.1
