// SPDX-License-Identifier: GPL-2.0
#define dev_fmt(fmt) "mtdoops-pstore: " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pstore_blk.h>
#include <linux/mtd/mtd.h>
#include <linux/bitops.h>
#include <linux/slab.h>
static struct mtdpstore_context {
int index;
struct pstore_blk_config info;
struct pstore_device_info dev;
struct mtd_info *mtd;
unsigned long *rmmap; /* removed bit map */
unsigned long *usedmap; /* used bit map */
/*
* used for panic write
* As there are no block_isbad for panic case, we should keep this
* status before panic to ensure panic_write not failed.
*/
unsigned long *badmap; /* bad block bit map */
} oops_cxt;
static int mtdpstore_block_isbad(struct mtdpstore_context *cxt, loff_t off)
{
int ret;
struct mtd_info *mtd = cxt->mtd;
u64 blknum;
off = ALIGN_DOWN(off, mtd->erasesize);
blknum = div_u64(off, mtd->erasesize);
if (test_bit(blknum, cxt->badmap))
return true;
ret = mtd_block_isbad(mtd, off);
if (ret < 0) {
dev_err(&mtd->dev, "mtd_block_isbad failed, aborting\n");
return ret;
} else if (ret > 0) {
set_bit(blknum, cxt->badmap);
return true;
}
return false;
}
static inline int mtdpstore_panic_block_isbad(struct mtdpstore_context *cxt,
loff_t off)
{
struct mtd_info *mtd = cxt->mtd;
u64 blknum;
off = ALIGN_DOWN(off, mtd->erasesize);
blknum = div_u64(off, mtd->erasesize);
return test_bit(blknum, cxt->badmap);
}
static inline void mtdpstore_mark_used(struct mtdpstore_context *cxt,
loff_t off)
{
struct mtd_info *mtd = cxt->mtd;
u64 zonenum = div_u64(off, cxt->info.kmsg_size);
dev_dbg(&mtd->dev, "mark zone %llu used\n", zonenum);
set_bit(zonenum, cxt->usedmap);
}
static inline void mtdpstore_mark_unused(struct mtdpstore_context *cxt,
loff_t off)
{
struct mtd_info *mtd = cxt->mtd;
u64 zonenum = div_u64(off, cxt->info.kmsg_size);
dev_dbg(&mtd->dev, "mark zone %llu unused\n", zonenum);
clear_bit(zonenum, cxt->usedmap);
}
static inline void mtdpstore_block_mark_unused(struct mtdpstore_context *cxt,
loff_t off)
{
struct mtd_info *mtd = cxt->mtd;
u32 zonecnt = mtd->erasesize / cxt->info.kmsg_size;
u64 zonenum;
off = ALIGN_DOWN(off, mtd->erasesize);
zonenum = div_u64(off, cxt->info.kmsg_size);
while (zonecnt > 0) {
dev_dbg(&mtd->dev, "mark zone %llu unused\n", zonenum);
clear_bit(zonenum, cxt->usedmap);
zonenum++;
zonecnt--;
}
}
static inline int mtdpstore_is_used(struct mtdpstore_context *cxt, loff_t off)
{
u64 zonenum = div_u64(off, cxt->info.kmsg_size);
u64 blknum = div_u64(off, cxt->mtd->erasesize);
if (test_bit(blknum, cxt->badmap))
return true;
return test_bit(zonenum, cxt->usedmap);
}
static int mtdpstore_block_is_used(struct mtdpstore_context *cxt,
loff_t off)
{
struct mtd_info *mtd = cxt->mtd;
u32 zonecnt = mtd->erasesize / cxt->info.kmsg_size;
u64 zonenum;
off = ALIGN_DOWN(off, mtd->erasesize);
zonenum = div_u64(off, cxt->info.kmsg_size);
while (zonecnt > 0) {
if (test_bit(zonenum, cxt->usedmap))
return true;
zonenum++;
zonecnt--;
}
return false;
}
static int mtdpstore_is_empty(struct mtdpstore_context *cxt, char *buf,
size_t size)
{
struct mtd_info *mtd = cxt->mtd;
size_t sz;
int i;
sz = min_t(uint32_t, size, mtd->writesize / 4);
for (i = 0; i < sz; i++) {
if (buf[i] != (char)0xFF)
return false;
}
return true;
}
static void mtdpstore_mark_removed(struct mtdpstore_context *cxt, loff_t off)
{
struct mtd_info *mtd = cxt->mtd;
u64 zonenum = div_u64(off, cxt->info.kmsg_size);
dev_dbg(&mtd->dev, "mark zone %llu removed\n", zonenum);
set_bit(zonenum, cxt->rmmap);
}
static void mtdpstore_block_clear_removed(struct mtdpstore_context *cxt,
loff_t off)
{
struct mtd_info *mtd = cxt->mtd;
u32 zonecnt = mtd->erasesize / cxt->info.kmsg_size;
u64 zonenum;
off = ALIGN_DOWN(off, mtd->erasesize);
zonenum = div_u64(off, cxt->info.kmsg_size);
while (zonecnt > 0) {
clear_bit(zonenum, cxt->rmmap);
zonenum++;
zonecnt--;
}
}
static int mtdpstore_block_is_removed(struct mtdpstore_context *cxt,
loff_t off)
{
struct mtd_info *mtd = cxt->mtd;
u32 zonecnt = mtd->erasesize / cxt->info.kmsg_size;
u64 zonenum;
off = ALIGN_DOWN(off, mtd->erasesize);
zonenum = div_u64(off, cxt->info.kmsg_size);
while (zonecnt > 0) {
if (test_bit(zonenum, cxt->rmmap))
return true;
zonenum++;
zonecnt--;
}
return false;
}
static int mtdpstore_erase_do(struct mtdpstore_context *cxt, loff_t off)
{
struct mtd_info *mtd = cxt->mtd;
struct erase_info erase;
int ret;
off = ALIGN_DOWN(off, cxt->mtd->erasesize);
dev_dbg(&mtd->dev, "try to erase off 0x%llx\n", off);
erase.len = cxt->mtd->erasesize;
erase.addr = off;
ret = mtd_erase(cxt->mtd, &erase);
if (!ret)
mtdpstore_block_clear_removed(cxt, off);
else
dev_err(&mtd->dev, "erase of region [0x%llx, 0x%llx] on \"%s\" failed\n",
(unsigned long long)erase.addr,
(unsigned long long)erase.len, cxt->info.device);
return ret;
}
/*
* called while removing file
*
* Avoiding over erasing, do erase block only when the whole block is unused.
* If the block contains valid log, do erase lazily on flush_removed() when
* unregister.
*/
static ssize_t mtdpstore_erase(size_t size, loff_t off)
{
struct mtdpstore_context *cxt = &oops_cxt;
if (mtdpstore_block_isbad(cxt, off))
return -EIO;
mtdpstore_mark_unused(cxt, off);
/* If the block still has valid data, mtdpstore do erase lazily */
if (likely(mtdpstore_block_is_used(cxt, off))) {
mtdpstore_mark_removed(cxt, off);
return 0;
}
/* all zones are unused, erase it */
return mtdpstore_erase_do(cxt, off);
}
/*
* What is security for mtdpstore?
* As there is no erase for panic case, we should ensure at least one zone
* is writable. Otherwise, panic write will fail.
* If zone is used, write operation will return -ENOMSG, which means that
* pstore/blk will try one by one until gets an empty zone. So, it is not
* needed to ensure the next zone is empty, but at least one.
*/
static int mtdpstore_security(struct mtdpstore_context *cxt, loff_t off)
{
int ret = 0, i;
struct mtd_info *mtd = cxt->mtd;
u32 zonenum = (u32)div_u64(off, cxt->info.kmsg_size);
u32 zonecnt = (u32)div_u64(cxt->mtd->size, cxt->info.kmsg_size);
u32 blkcnt = (u32)div_u64(cxt->mtd->size, cxt->mtd->erasesize);
u32 erasesize = cxt->mtd->erasesize;
for (i = 0; i < zonecnt; i++) {
u32 num = (zonenum + i) % zonecnt;
/* found empty zone */
if (!test_bit(num, cxt->usedmap))
return 0;
}
/* If there is no any empty zone, we have no way but to do erase */
while (blkcnt--) {
div64_u64_rem(off + erasesize, cxt->mtd->size, (u64 *)&off);
if (mtdpstore_block_isbad(cxt, off))
continue;
ret = mtdpstore_erase_do(cxt, off);
if (!ret) {
mtdpstore_block_mark_unused(cxt, off);
break;
}
}
if (ret)
dev_err(&mtd->dev, "all blocks bad!\n");
dev_dbg(&mtd->dev, "end security\n");
return ret;
}
static ssize_t mtdpstore_write(const char *buf, size_t size, loff_t off)
{
struct mtdpstore_context *cxt = &oops_cxt;
struct mtd_info *mtd = cxt->mtd;
size_t retlen;
int ret;
if (mtdpstore_block_isbad(cxt, off))
return -ENOMSG;
/* zone is used, please try next one */
if (mtdpstore_is_used(cxt, off))
return -ENOMSG;
dev_dbg(&mtd->dev, "try to write off 0x%llx size %zu\n", off, size);
ret = mtd_write(cxt->mtd, off, size, &retlen, (u_char *)buf);
if (ret < 0 || retlen != size) {
dev_err(&mtd->dev, "write failure at %lld (%zu of %zu written), err %d\n",
off, retlen, size, ret);
return -EIO;
}
mtdpstore_mark_used(cxt, off);
mtdpstore_security(cxt, off);
return retlen;
}
static inline bool mtdpstore_is_io_error(int ret)
{
return ret < 0 && !mtd_is_bitflip(ret) && !mtd_is_eccerr(ret);
}
/*
* All zones will be read as pstore/blk will read zone one by one when do
* recover.
*/
static ssize_t mtdpstore_read(char *buf, size_t size, loff_t off)
{
struct mtdpstore_context *cxt = &oops_cxt;
struct mtd_info *mtd = cxt->mtd;
size_t retlen, done;
int ret;
if (mtdpstore_block_isbad(cxt, off))
return -ENOMSG;
dev_dbg(&mtd->dev, "try to read off 0x%llx size %zu\n", off, size);
for (done = 0, retlen = 0; done < size; done += retlen) {
retlen = 0;
ret = mtd_read(cxt->mtd, off + done, size - done, &retlen,
(u_char *)buf + done);
if (mtdpstore_is_io_error(ret)) {
dev_err(&mtd->dev, "read failure at %lld (%zu of %zu read), err %d\n",
off + done, retlen, size - done, ret);
/* the zone may be broken, try next one */
return -ENOMSG;
}
/*
* ECC error. The impact on log data is so small. Maybe we can
* still read it and try to understand. So mtdpstore just hands
* over what it gets and user can judge whether the data is
* valid or not.
*/
if (mtd_is_eccerr(ret)) {
dev_err(&mtd->dev, "ecc error at %lld (%zu of %zu read), err %d\n",
off + done, retlen, size - done, ret);
/* driver may not set retlen when ecc error */
retlen = retlen == 0 ? size - done : retlen;
}
}
if (mtdpstore_is_empty(cxt, buf, size))
mtdpstore_mark_unused(cxt, off);
else
mtdpstore_mark_used(cxt, off);
mtdpstore_security(cxt, off);
return retlen;
}
static ssize_t mtdpstore_panic_write(const char *buf, size_t size, loff_t off)
{
struct mtdpstore_context *cxt = &oops_cxt;
struct mtd_info *mtd = cxt->mtd;
size_t retlen;
int ret;
if (mtdpstore_panic_block_isbad(cxt, off))
return -ENOMSG;
/* zone is used, please try next one */
if (mtdpstore_is_used(cxt, off))
return -ENOMSG;
ret = mtd_panic_write(cxt->mtd, off, size, &retlen, (u_char *)buf);
if (ret < 0 || size != retlen) {
dev_err(&mtd->dev, "panic write failure at %lld (%zu of %zu read), err %d\n",
off, retlen, size, ret);
return -EIO;
}
mtdpstore_mark_used(cxt, off);
return retlen;
}
static void mtdpstore_notify_add(struct mtd_info *mtd)
{
int ret;
struct mtdpstore_context *cxt = &oops_cxt;
struct pstore_blk_config *info = &cxt->info;
unsigned long longcnt;
if (!strcmp(mtd->name, info->device))
cxt->index = mtd->index;
if (mtd->index != cxt->index || cxt->index < 0)
return;
dev_dbg(&mtd->dev, "found matching MTD device %s\n", mtd->name);
if (mtd->size < info->kmsg_size * 2) {
dev_err(&mtd->dev, "MTD partition %d not big enough\n",
mtd->index);
return;
}
/*
* kmsg_size must be aligned to 4096 Bytes, which is limited by
* psblk. The default value of kmsg_size is 64KB. If kmsg_size
* is larger than erasesize, some errors will occur since mtdpstore
* is designed on it.
*/
if (mtd->erasesize < info->kmsg_size) {
dev_err(&mtd->dev, "eraseblock size of MTD partition %d too small\n",
mtd->index);
return;
}
if (unlikely(info->kmsg_size % mtd->writesize)) {
dev_err(&mtd->dev, "record size %lu KB must align to write size %d KB\n",
info->kmsg_size / 1024,
mtd->writesize / 1024);
return;
}
longcnt = BITS_TO_LONGS(div_u64(mtd->size, info->kmsg_size));
cxt->rmmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL);
cxt->usedmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL);
longcnt = BITS_TO_LONGS(div_u64(mtd->size, mtd->erasesize));
cxt->badmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL);
/* just support dmesg right now */
cxt->dev.flags = PSTORE_FLAGS_DMESG;
cxt->dev.zone.read = mtdpstore_read;
cxt->dev.zone.write = mtdpstore_write;
cxt->dev.zone.erase = mtdpstore_erase;
cxt->dev.zone.panic_write = mtdpstore_panic_write;
cxt->dev.zone.total_size = mtd->size;
ret = register_pstore_device(&cxt->dev);
if (ret) {
dev_err(&mtd->dev, "mtd%d register to psblk failed\n",
mtd->index);
return;
}
cxt->mtd = mtd;
dev_info(&mtd->dev, "Attached to MTD device %d\n", mtd->index);
}
static int mtdpstore_flush_removed_do(struct mtdpstore_context *cxt,
loff_t off, size_t size)
{
struct mtd_info *mtd = cxt->mtd;
u_char *buf;
int ret;
size_t retlen;
struct erase_info erase;
buf = kmalloc(mtd->erasesize, GFP_KERNEL);
if (!buf)
return -ENOMEM;
/* 1st. read to cache */
ret = mtd_read(mtd, off, mtd->erasesize, &retlen, buf);
if (mtdpstore_is_io_error(ret))
goto free;
/* 2nd. erase block */
erase.len = mtd->erasesize;
erase.addr = off;
ret = mtd_erase(mtd, &erase);
if (ret)
goto free;
/* 3rd. write back */
while (size) {
unsigned int zonesize = cxt->info.kmsg_size;
/* there is valid data on block, write back */
if (mtdpstore_is_used(cxt, off)) {
ret = mtd_write(mtd, off, zonesize, &retlen, buf);
if (ret)
dev_err(&mtd->dev, "write failure at %lld (%zu of %u written), err %d\n",
off, retlen, zonesize, ret);
}
off += zonesize;
size -= min_t(unsigned int, zonesize, size);
}
free:
kfree(buf);
return ret;
}
/*
* What does mtdpstore_flush_removed() do?
* When user remove any log file on pstore filesystem, mtdpstore should do
* something to ensure log file removed. If the whole block is no longer used,
* it's nice to erase the block. However if the block still contains valid log,
* what mtdpstore can do is to erase and write the valid log back.
*/
static int mtdpstore_flush_removed(struct mtdpstore_context *cxt)
{
struct mtd_info *mtd = cxt->mtd;
int ret;
loff_t off;
u32 blkcnt = (u32)div_u64(mtd->size, mtd->erasesize);
for (off = 0; blkcnt > 0; blkcnt--, off += mtd->erasesize) {
ret = mtdpstore_block_isbad(cxt, off);
if (ret)
continue;
ret = mtdpstore_block_is_removed(cxt, off);
if (!ret)
continue;
ret = mtdpstore_flush_removed_do(cxt, off, mtd->erasesize);
if (ret)
return ret;
}
return 0;
}
static void mtdpstore_notify_remove(struct mtd_info *mtd)
{
struct mtdpstore_context *cxt = &oops_cxt;
if (mtd->index != cxt->index || cxt->index < 0)
return;
mtdpstore_flush_removed(cxt);
unregister_pstore_device(&cxt->dev);
kfree(cxt->badmap);
kfree(cxt->usedmap);
kfree(cxt->rmmap);
cxt->mtd = NULL;
cxt->index = -1;
}
static struct mtd_notifier mtdpstore_notifier = {
.add = mtdpstore_notify_add,
.remove = mtdpstore_notify_remove,
};
static int __init mtdpstore_init(void)
{
int ret;
struct mtdpstore_context *cxt = &oops_cxt;
struct pstore_blk_config *info = &cxt->info;
ret = pstore_blk_get_config(info);
if (unlikely(ret))
return ret;
if (strlen(info->device) == 0) {
pr_err("mtd device must be supplied (device name is empty)\n");
return -EINVAL;
}
if (!info->kmsg_size) {
pr_err("no backend enabled (kmsg_size is 0)\n");
return -EINVAL;
}
/* Setup the MTD device to use */
ret = kstrtoint((char *)info->device, 0, &cxt->index);
if (ret)
cxt->index = -1;
register_mtd_user(&mtdpstore_notifier);
return 0;
}
module_init(mtdpstore_init);
static void __exit mtdpstore_exit(void)
{
unregister_mtd_user(&mtdpstore_notifier);
}
module_exit(mtdpstore_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("WeiXiong Liao <[email protected]>");
MODULE_DESCRIPTION("MTD backend for pstore/blk");
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