diff options
| author | Miquel Raynal <miquel.raynal@bootlin.com> | 2021-11-18 12:46:59 +0100 |
|---|---|---|
| committer | Miquel Raynal <miquel.raynal@bootlin.com> | 2021-12-09 17:51:59 +0100 |
| commit | 67b967ddd93d0ed57d392a00f6f90060f0910c0e (patch) | |
| tree | 7e14f4a0ffe941e5e1dbf883869ed55f0e608f0c /drivers/mtd | |
| parent | 00596576a05145a1b5672897a82ef87af00becf4 (diff) | |
| download | linux-67b967ddd93d0ed57d392a00f6f90060f0910c0e.tar.bz2 | |
mtd: Introduce an expert mode for forensics and debugging purposes
When developping NAND controller drivers or when debugging filesystem
corruptions, it is quite common to need hacking locally into the
MTD/NAND core in order to get access to the content of the bad
blocks. Instead of having multiple implementations out there let's
provide a simple yet effective specific MTD-wide debugfs entry to fully
disable these checks on purpose.
A warning is added to inform the user when this mode gets enabled.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20211118114659.1282855-1-miquel.raynal@bootlin.com
Diffstat (limited to 'drivers/mtd')
| -rw-r--r-- | drivers/mtd/mtdcore.c | 10 | ||||
| -rw-r--r-- | drivers/mtd/nand/core.c | 3 | ||||
| -rw-r--r-- | drivers/mtd/nand/raw/nand_base.c | 3 | ||||
| -rw-r--r-- | drivers/mtd/nand/raw/nand_bbt.c | 3 |
4 files changed, 19 insertions, 0 deletions
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c index a7723a708ea7..70f492dce158 100644 --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -2370,6 +2370,14 @@ static struct backing_dev_info * __init mtd_bdi_init(const char *name) return ret ? ERR_PTR(ret) : bdi; } +char *mtd_expert_analysis_warning = + "Bad block checks have been entirely disabled.\n" + "This is only reserved for post-mortem forensics and debug purposes.\n" + "Never enable this mode if you do not know what you are doing!\n"; +EXPORT_SYMBOL_GPL(mtd_expert_analysis_warning); +bool mtd_expert_analysis_mode; +EXPORT_SYMBOL_GPL(mtd_expert_analysis_mode); + static struct proc_dir_entry *proc_mtd; static int __init init_mtd(void) @@ -2393,6 +2401,8 @@ static int __init init_mtd(void) goto out_procfs; dfs_dir_mtd = debugfs_create_dir("mtd", NULL); + debugfs_create_bool("expert_analysis_mode", 0600, dfs_dir_mtd, + &mtd_expert_analysis_mode); return 0; diff --git a/drivers/mtd/nand/core.c b/drivers/mtd/nand/core.c index 5e13a03d2b32..416947f28b67 100644 --- a/drivers/mtd/nand/core.c +++ b/drivers/mtd/nand/core.c @@ -21,6 +21,9 @@ */ bool nanddev_isbad(struct nand_device *nand, const struct nand_pos *pos) { + if (WARN_ONCE(mtd_expert_analysis_mode, mtd_expert_analysis_warning)) + return false; + if (nanddev_bbt_is_initialized(nand)) { unsigned int entry; int status; diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c index 3d6c6e880520..b3a9bc08b4bb 100644 --- a/drivers/mtd/nand/raw/nand_base.c +++ b/drivers/mtd/nand/raw/nand_base.c @@ -321,6 +321,9 @@ static int nand_isbad_bbm(struct nand_chip *chip, loff_t ofs) if (nand_region_is_secured(chip, ofs, mtd->erasesize)) return -EIO; + if (WARN_ONCE(mtd_expert_analysis_mode, mtd_expert_analysis_warning)) + return 0; + if (chip->legacy.block_bad) return chip->legacy.block_bad(chip, ofs); diff --git a/drivers/mtd/nand/raw/nand_bbt.c b/drivers/mtd/nand/raw/nand_bbt.c index b7ad030225f8..ab630af3a309 100644 --- a/drivers/mtd/nand/raw/nand_bbt.c +++ b/drivers/mtd/nand/raw/nand_bbt.c @@ -1455,6 +1455,9 @@ int nand_isbad_bbt(struct nand_chip *this, loff_t offs, int allowbbt) pr_debug("nand_isbad_bbt(): bbt info for offs 0x%08x: (block %d) 0x%02x\n", (unsigned int)offs, block, res); + if (WARN_ONCE(mtd_expert_analysis_mode, mtd_expert_analysis_warning)) + return 0; + switch (res) { case BBT_BLOCK_GOOD: return 0; |