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https://github.com/AsahiLinux/u-boot
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08898e8b22
SPI flash based MTD devs can be registered/unregistered at any time through the sf probe command or the spi_flash_free() function. This commit does not try to fix the root cause as it would probably require rewriting most of the code and have an mtd_info object instance per spi_flash object (not to mention that the the spi-flash layer is likely to be replaced by a spi-nor layer ported from Linux). Instead, we try to be as safe as can be by checking the code returned by del_mtd_device() and complain loudly when there's nothing we can do about the deregistration failure. When that happens we also reset sf_mtd_info.priv to NULL, and check for NULL pointer in the mtd hooks so that -ENODEV is returned instead of hitting a NULL pointer dereference exception when the MTD instance is later accessed by a user. Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com> Tested-by: Heiko Schocher <hs@denx.de>
147 lines
3 KiB
C
147 lines
3 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright (C) 2012-2014 Daniel Schwierzeck, daniel.schwierzeck@gmail.com
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*/
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#include <common.h>
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#include <malloc.h>
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#include <linux/errno.h>
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#include <linux/mtd/mtd.h>
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#include <spi_flash.h>
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static struct mtd_info sf_mtd_info;
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static bool sf_mtd_registered;
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static char sf_mtd_name[8];
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static int spi_flash_mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
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{
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struct spi_flash *flash = mtd->priv;
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int err;
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if (!flash)
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return -ENODEV;
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instr->state = MTD_ERASING;
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err = spi_flash_erase(flash, instr->addr, instr->len);
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if (err) {
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instr->state = MTD_ERASE_FAILED;
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instr->fail_addr = MTD_FAIL_ADDR_UNKNOWN;
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return -EIO;
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}
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instr->state = MTD_ERASE_DONE;
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mtd_erase_callback(instr);
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return 0;
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}
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static int spi_flash_mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
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size_t *retlen, u_char *buf)
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{
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struct spi_flash *flash = mtd->priv;
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int err;
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if (!flash)
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return -ENODEV;
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err = spi_flash_read(flash, from, len, buf);
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if (!err)
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*retlen = len;
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return err;
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}
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static int spi_flash_mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
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size_t *retlen, const u_char *buf)
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{
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struct spi_flash *flash = mtd->priv;
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int err;
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if (!flash)
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return -ENODEV;
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err = spi_flash_write(flash, to, len, buf);
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if (!err)
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*retlen = len;
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return err;
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}
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static void spi_flash_mtd_sync(struct mtd_info *mtd)
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{
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}
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static int spi_flash_mtd_number(void)
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{
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#ifdef CONFIG_SYS_MAX_FLASH_BANKS
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return CONFIG_SYS_MAX_FLASH_BANKS;
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#else
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return 0;
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#endif
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}
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int spi_flash_mtd_register(struct spi_flash *flash)
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{
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int ret;
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if (sf_mtd_registered) {
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ret = del_mtd_device(&sf_mtd_info);
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if (ret)
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return ret;
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sf_mtd_registered = false;
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}
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sf_mtd_registered = false;
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memset(&sf_mtd_info, 0, sizeof(sf_mtd_info));
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sprintf(sf_mtd_name, "nor%d", spi_flash_mtd_number());
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sf_mtd_info.name = sf_mtd_name;
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sf_mtd_info.type = MTD_NORFLASH;
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sf_mtd_info.flags = MTD_CAP_NORFLASH;
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sf_mtd_info.writesize = 1;
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sf_mtd_info.writebufsize = flash->page_size;
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sf_mtd_info._erase = spi_flash_mtd_erase;
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sf_mtd_info._read = spi_flash_mtd_read;
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sf_mtd_info._write = spi_flash_mtd_write;
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sf_mtd_info._sync = spi_flash_mtd_sync;
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sf_mtd_info.size = flash->size;
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sf_mtd_info.priv = flash;
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/* Only uniform flash devices for now */
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sf_mtd_info.numeraseregions = 0;
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sf_mtd_info.erasesize = flash->sector_size;
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ret = add_mtd_device(&sf_mtd_info);
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if (!ret)
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sf_mtd_registered = true;
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return ret;
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}
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void spi_flash_mtd_unregister(void)
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{
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int ret;
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if (!sf_mtd_registered)
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return;
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ret = del_mtd_device(&sf_mtd_info);
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if (!ret) {
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sf_mtd_registered = false;
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return;
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}
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/*
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* Setting mtd->priv to NULL is the best we can do. Thanks to that,
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* the MTD layer can still call mtd hooks without risking a
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* use-after-free bug. Still, things should be fixed to prevent the
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* spi_flash object from being destroyed when del_mtd_device() fails.
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*/
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sf_mtd_info.priv = NULL;
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printf("Failed to unregister MTD %s and the spi_flash object is going away: you're in deep trouble!",
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sf_mtd_info.name);
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}
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