diff options
Diffstat (limited to 'drivers/mtd/mtdpstore.c')
| -rw-r--r-- | drivers/mtd/mtdpstore.c | 579 |
1 files changed, 579 insertions, 0 deletions
diff --git a/drivers/mtd/mtdpstore.c b/drivers/mtd/mtdpstore.c new file mode 100644 index 000000000..a3ae8778f --- /dev/null +++ b/drivers/mtd/mtdpstore.c @@ -0,0 +1,579 @@ +// 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 mtdpsotre + * 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); + + cxt->dev.total_size = mtd->size; + /* just support dmesg right now */ + cxt->dev.flags = PSTORE_FLAGS_DMESG; + cxt->dev.read = mtdpstore_read; + cxt->dev.write = mtdpstore_write; + cxt->dev.erase = mtdpstore_erase; + cxt->dev.panic_write = mtdpstore_panic_write; + + 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 <liaoweixiong@allwinnertech.com>"); +MODULE_DESCRIPTION("MTD backend for pstore/blk"); |