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* kernel: mtk_bmt: refactor to avoid deep recursionMichał Kępień2023-04-29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A Linksys E8450 (mt7622) device running current master has recently started crashing: [ 0.562900] mtk-ecc 1100e000.ecc: probed [ 0.570254] spi-nand spi2.0: Fidelix SPI NAND was found. [ 0.575576] spi-nand spi2.0: 128 MiB, block size: 128 KiB, page size: 2048, OOB size: 64 [ 0.583780] mtk-snand 1100d000.spi: ECC strength: 4 bits per 512 bytes [ 0.682930] Insufficient stack space to handle exception! [ 0.682939] ESR: 0x0000000096000047 -- DABT (current EL) [ 0.682946] FAR: 0xffffffc008c47fe0 [ 0.682948] Task stack: [0xffffffc008c48000..0xffffffc008c4c000] [ 0.682951] IRQ stack: [0xffffffc008008000..0xffffffc00800c000] [ 0.682954] Overflow stack: [0xffffff801feb00a0..0xffffff801feb10a0] [ 0.682959] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G S 5.15.107 #0 [ 0.682966] Hardware name: Linksys E8450 (DT) [ 0.682969] pstate: 800000c5 (Nzcv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 0.682975] pc : dequeue_entity+0x0/0x250 [ 0.682988] lr : dequeue_task_fair+0x98/0x290 [ 0.682992] sp : ffffffc008c48030 [ 0.682994] x29: ffffffc008c48030 x28: 0000000000000001 x27: ffffff801feb6380 [ 0.683004] x26: 0000000000000001 x25: ffffff801feb6300 x24: ffffff8000068000 [ 0.683011] x23: 0000000000000001 x22: 0000000000000009 x21: 0000000000000000 [ 0.683017] x20: ffffff801feb6380 x19: ffffff8000068080 x18: 0000000017a740a6 [ 0.683024] x17: ffffffc008bae748 x16: ffffffc008bae6d8 x15: ffffffffffffffff [ 0.683031] x14: ffffffffffffffff x13: 0000000000000000 x12: 0000000f00000101 [ 0.683038] x11: 0000000000000449 x10: 0000000000000127 x9 : 0000000000000000 [ 0.683044] x8 : 0000000000000125 x7 : 0000000000116da1 x6 : 0000000000116da1 [ 0.683051] x5 : 00000000001165a1 x4 : ffffff801feb6e00 x3 : 0000000000000000 [ 0.683058] x2 : 0000000000000009 x1 : ffffff8000068080 x0 : ffffff801feb6380 [ 0.683066] Kernel panic - not syncing: kernel stack overflow [ 0.683069] SMP: stopping secondary CPUs [ 1.648361] SMP: failed to stop secondary CPUs 0-1 [ 1.648366] Kernel Offset: disabled [ 1.648368] CPU features: 0x00003000,00000802 [ 1.648372] Memory Limit: none Several factors contributed to this issue: 1. The mtk_bmt driver recursively calls its scan_bmt() helper function during device initialization, while looking for a valid block mapping table (BMT). 2. Commit fa4dc86e98 ("kernel: backport MEMREAD ioctl"): - increased the size of some stack-allocated structures (like struct mtd_oob_ops, used in bbt_nand_read(), which is indirectly called from scan_bmt()), - increased the stack size for some functions (for example, spinand_mtd_read(), which is indirectly called from scan_bmt(), now uses an extra stack-allocated struct mtd_ecc_stats). 3. OpenWrt currently compiles the kernel with the -fno-optimize-sibling-calls flag, which prevents tail-call optimization. Collectively, all of these factors caused stack usage in the mtk_bmt driver to grow excessively large, triggering stack overflows. Recursion is not really necessary in scan_bmt() as it simply iterates over flash memory blocks in reverse order, looking for a valid BMT. Refactor the logic contained in the scan_bmt() and read_bmt() functions in target/linux/generic/files/drivers/mtd/nand/mtk_bmt_v2.c so that deep recursion is prevented (and therefore also any potential stack overflows it may cause). Link: https://lists.openwrt.org/pipermail/openwrt-devel/2023-April/040872.html Signed-off-by: Michał Kępień <openwrt@kempniu.pl>
* kernel: mtk-bmt: fix usage of _oob_readChuanhong Guo2023-01-21
| | | | | | | | _oob_read returns number of bitflips on success while bbt_nand_read should return 0. Fixes: 2d49e49b18 ("mediatek: bmt: use generic mtd api") Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
* kernel: mtk_bmt: skip bitflip check if threshold isn't setChuanhong Guo2022-04-09
| | | | | | kernel spi-nand driver leaves this field empty and let mtd set it later. Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
* kernel: mtk_bmt: add debugfs file to attempt repair of remapped sectorsFelix Fietkau2022-03-25
| | | | | | This can be used for sectors that are not physically damaged Signed-off-by: Felix Fietkau <nbd@nbd.name>
* kernel: add support for mediatek NMBM flash mapping supportFelix Fietkau2022-03-25
| | | | | | | This NAND flash remapping method is used on newer MediaTek devices with NAND flash. Signed-off-by: Felix Fietkau <nbd@nbd.name>
* kernel: mtk_bmt: on error, do not attempt to remap out-of-range blocksFelix Fietkau2022-03-25
| | | | | | Pass errors to caller instead Signed-off-by: Felix Fietkau <nbd@nbd.name>
* kernel: mtk_bmt: fix block copying on remap with bmt v2Felix Fietkau2022-03-25
| | | | | | Copy from the previously mapped block (in case it was remapped already) Signed-off-by: Felix Fietkau <nbd@nbd.name>
* kernel: mtk_bmt: allow get_mapping_block to return an errorFelix Fietkau2022-03-25
| | | | | | | Used by the mapping implementation to indicate that no backing block is available Signed-off-by: Felix Fietkau <nbd@nbd.name>
* kernel: split up mtk_bmt driver codeFelix Fietkau2022-03-25
| | | | | | Keep a separate source file per variant Signed-off-by: Felix Fietkau <nbd@nbd.name>
* kernel: mtk_bmt: add support for the bbt format used on mt7621Felix Fietkau2022-01-13
| | | | | | | | | This does not have spare blocks for remapping, and it is also not suitable for random write access. It only skips over bad blocks on linear writes of an image to a partition. As such, it is really only suitable for the kernel partition, or other partitions with mostly static data Signed-off-by: Felix Fietkau <nbd@nbd.name>
* kernel: mtk_bmt: add abstraction for supporting other formatsFelix Fietkau2022-01-13
| | | | | | Preparation for supporting remapping on MT7621 Signed-off-by: Felix Fietkau <nbd@nbd.name>
* kernel: mtk_bmt: remap blocks after reaching bitflip thresholdFelix Fietkau2022-01-13
| | | | | | This ensures that blocks are remapped before data becomes corrupt Signed-off-by: Felix Fietkau <nbd@nbd.name>
* kernel: mtk_bmt: pass number of bitflips on read to the callerFelix Fietkau2022-01-13
| | | | Signed-off-by: Felix Fietkau <nbd@nbd.name>
* kernel: mtk_bmt: add support for limiting range of remappingFelix Fietkau2022-01-13
| | | | | | | | This can be used to support ubi on top of mtk_bmt without reflashing the boot loader. The boot loader + factory + kernel area is covered, while the rest is passed through as-is Signed-off-by: Felix Fietkau <nbd@nbd.name>
* kernel: mtk_bmt: extend debug interfaceFelix Fietkau2022-01-13
| | | | | | | Add support for showing remapped blocks and garbage collecting old remapped blocks triggered by using the mark_good/mark_bad files Signed-off-by: Felix Fietkau <nbd@nbd.name>
* kernel: mtk_bmt: fix remapping after read/write failureFelix Fietkau2022-01-13
| | | | | | Copy from the previous block in order to preserve existing data Signed-off-by: Felix Fietkau <nbd@nbd.name>
* kernel: move mediatek BMT support patch to generic patchesFelix Fietkau2022-01-13
Preparation for supporting BMT on MT7621. Move source files to the files/ subdirectory in order to simplify maintenance Signed-off-by: Felix Fietkau <nbd@nbd.name>
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