hi Kees Cook, On 2020/5/12 下午1:12, Kees Cook wrote: > [resend to proper CC list...] > > On Tue, May 12, 2020 at 11:12:42AM +0800, WeiXiong Liao wrote: >> hi Kees Cook, >> >> The off parameter on mtdpsore_block*() does not align to block size, >> which makes some bugs. For example, a block contains 4 dmesg zones >> and it's expected to erase this block when user remove all files on >> these zones. However it work failed since it get wrongly zonenum from >> misaligned off. > > Ah, okay. I haven't touched any of this logic. Did something change in > pstore/blk or /zone that I broke? Regardless, can you send a regular > patch for what you have below and I'll fold it into the mtdpstore > commit. > I will send a patch later. Maybe it needs to be reviewed again by MTD maintainers. And everything in pstore/blk and /zone are OK. > Thanks! > > -Kees > >> On 2020/5/12 AM 7:32, Kees Cook wrote: >>> From: WeiXiong Liao <liaoweixiong@xxxxxxxxxxxxxxxxx> >>> >>> This introduces mtdpstore, which is similar to mtdoops but more >>> powerful. It uses pstore/blk, and aims to store panic and oops logs to >>> a flash partition, where pstore can later read back and present as files >>> in the mounted pstore filesystem. >>> >>> To make mtdpstore work, the "blkdev" of pstore/blk should be set >>> as MTD device name or MTD device number. For more details, see >>> Documentation/admin-guide/pstore-blk.rst >>> >>> This solves a number of issues: >>> - Work duplication: both of pstore and mtdoops do the same job storing >>> panic/oops log. They have very similar logic, registering to kmsg >>> dumper and storing logs to several chunks one by one. >>> - Layer violations: drivers should provides methods instead of polices. >>> MTD should provide read/write/erase operations, and allow a higher >>> level drivers to provide the chunk management, kmsg dump >>> configuration, etc. >>> - Missing features: pstore provides many additional features, including >>> presenting the logs as files, logging dump time and count, and >>> supporting other frontends like pmsg, console, etc. >>> >>> Signed-off-by: WeiXiong Liao <liaoweixiong@xxxxxxxxxxxxxxxxx> >>> Link: https://lore.kernel.org/r/1585126506-18635-12-git-send-email-liaoweixiong@xxxxxxxxxxxxxxxxx >>> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> >>> --- >>> Documentation/admin-guide/pstore-blk.rst | 9 +- >>> drivers/mtd/Kconfig | 10 + >>> drivers/mtd/Makefile | 1 + >>> drivers/mtd/mtdpstore.c | 563 +++++++++++++++++++++++ >>> 4 files changed, 581 insertions(+), 2 deletions(-) >>> create mode 100644 drivers/mtd/mtdpstore.c >>> >>> diff --git a/Documentation/admin-guide/pstore-blk.rst b/Documentation/admin-guide/pstore-blk.rst >>> index d45341e55e82..296d5027787a 100644 >>> --- a/Documentation/admin-guide/pstore-blk.rst >>> +++ b/Documentation/admin-guide/pstore-blk.rst >>> @@ -43,9 +43,9 @@ blkdev >>> ~~~~~~ >>> >>> The block device to use. Most of the time, it is a partition of block device. >>> -It's required for pstore/blk. >>> +It's required for pstore/blk. It is also used for MTD device. >>> >>> -It accepts the following variants: >>> +It accepts the following variants for block device: >>> >>> 1. <hex_major><hex_minor> device number in hexadecimal represents itself; no >>> leading 0x, for example b302. >>> @@ -64,6 +64,11 @@ It accepts the following variants: >>> partition with a known unique id. >>> #. <major>:<minor> major and minor number of the device separated by a colon. >>> >>> +It accepts the following variants for MTD device: >>> + >>> +1. <device name> MTD device name. "pstore" is recommended. >>> +#. <device number> MTD device number. >>> + >>> kmsg_size >>> ~~~~~~~~~ >>> >>> diff --git a/drivers/mtd/Kconfig b/drivers/mtd/Kconfig >>> index 42d401ea60ee..6ddab796216d 100644 >>> --- a/drivers/mtd/Kconfig >>> +++ b/drivers/mtd/Kconfig >>> @@ -170,6 +170,16 @@ config MTD_OOPS >>> buffer in a flash partition where it can be read back at some >>> later point. >>> >>> +config MTD_PSTORE >>> + tristate "Log panic/oops to an MTD buffer based on pstore" >>> + depends on PSTORE_BLK >>> + help >>> + This enables panic and oops messages to be logged to a circular >>> + buffer in a flash partition where it can be read back as files after >>> + mounting pstore filesystem. >>> + >>> + If unsure, say N. >>> + >>> config MTD_SWAP >>> tristate "Swap on MTD device support" >>> depends on MTD && SWAP >>> diff --git a/drivers/mtd/Makefile b/drivers/mtd/Makefile >>> index 56cc60ccc477..593d0593a038 100644 >>> --- a/drivers/mtd/Makefile >>> +++ b/drivers/mtd/Makefile >>> @@ -20,6 +20,7 @@ obj-$(CONFIG_RFD_FTL) += rfd_ftl.o >>> obj-$(CONFIG_SSFDC) += ssfdc.o >>> obj-$(CONFIG_SM_FTL) += sm_ftl.o >>> obj-$(CONFIG_MTD_OOPS) += mtdoops.o >>> +obj-$(CONFIG_MTD_PSTORE) += mtdpstore.o >>> obj-$(CONFIG_MTD_SWAP) += mtdswap.o >>> >>> nftl-objs := nftlcore.o nftlmount.o >>> diff --git a/drivers/mtd/mtdpstore.c b/drivers/mtd/mtdpstore.c >>> new file mode 100644 >>> index 000000000000..06084eff1004 >>> --- /dev/null >>> +++ b/drivers/mtd/mtdpstore.c >>> @@ -0,0 +1,563 @@ >>> +// 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> >>> + >>> +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 = div_u64(off, mtd->erasesize); >> >> - u64 blknum = div_u64(off, mtd->erasesize); >> + 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 = div_u64(off, mtd->erasesize); >>> + >> >> - u64 blknum = div_u64(off, mtd->erasesize); >> + 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; >>> + u64 zonenum = div_u64(off, cxt->info.kmsg_size); >>> + u32 zonecnt = cxt->mtd->erasesize / cxt->info.kmsg_size; >>> + >> >> - u64 zonenum = div_u64(off, cxt->info.kmsg_size); >> - u32 zonecnt = cxt->mtd->erasesize / cxt->info.kmsg_size; >> + 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) >>> +{ >>> + u64 zonenum = div_u64(off, cxt->info.kmsg_size); >>> + u32 zonecnt = cxt->mtd->erasesize / cxt->info.kmsg_size; >>> + >> >> - u64 zonenum = div_u64(off, cxt->info.kmsg_size); >> - u32 zonecnt = cxt->mtd->erasesize / cxt->info.kmsg_size; >> + 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) >>> +{ >>> + u64 zonenum = div_u64(off, cxt->info.kmsg_size); >>> + u32 zonecnt = cxt->mtd->erasesize / cxt->info.kmsg_size; >>> + >> >> - u64 zonenum = div_u64(off, cxt->info.kmsg_size); >> - u32 zonecnt = cxt->mtd->erasesize / cxt->info.kmsg_size; >> + 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) >>> +{ >>> + u64 zonenum = div_u64(off, cxt->info.kmsg_size); >>> + u32 zonecnt = cxt->mtd->erasesize / cxt->info.kmsg_size; >>> + >> >> - u64 zonenum = div_u64(off, cxt->info.kmsg_size); >> - u32 zonecnt = cxt->mtd->erasesize / cxt->info.kmsg_size; >> + 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; >>> + >> >> int ret; >> >> + off = ALIGN_DOWN(off, cxt->mtd->erasesize); >> dev_dbg(&mtd->dev, "try to erase off 0x%llx\n", off); >> >>> + 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 */ >>> + off = ALIGN_DOWN(off, cxt->mtd->erasesize); >> >> /* all zones are unused, erase it */ >> - off = ALIGN_DOWN(off, cxt->mtd->erasesize); >> return mtdpstore_erase_do(cxt, off); >> >>> + 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 */ >>> + off = ALIGN_DOWN(off, erasesize); >>> + 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@xxxxxxxxxxxxxxxxx>"); >>> +MODULE_DESCRIPTION("MTD backend for pstore/blk"); >>> >> >> -- >> WeiXiong Liao > -- WeiXiong Liao
