| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20170517143211.205ff5de@bbrezillon>
Date: Wed, 17 May 2017 14:32:11 +0200
From: Boris Brezillon <boris.brezillon@...e-electrons.com>
To: Pavel Machek <pavel@....cz>
Cc: richard@....at, dwmw2@...radead.org, computersforpeace@...il.com,
marek.vasut@...il.com, cyrille.pitchen@...el.com,
linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
mark.marshall@...cronenergy.com, b44839@...escale.com,
prabhakar@...escale.com
Subject: Re: [PATCH] fsl_ifc_nand: fix handing of bit flips in erased nand
On Wed, 17 May 2017 14:22:24 +0200
Pavel Machek <pavel@....cz> wrote:
> If we see unrecoverable ECC error, we need to count number of bitflips
> from all-ones and report correctable/uncorrectable according to
> that. Otherwise we report ECC failed on erased flash with single bit error.
>
> Signed-off-by: Pavel Machek <pavel@...x.de>
>
> diff --git a/drivers/mtd/nand/fsl_ifc_nand.c b/drivers/mtd/nand/fsl_ifc_nand.c
> index d1570f5..1c66696 100644
> --- a/drivers/mtd/nand/fsl_ifc_nand.c
> +++ b/drivers/mtd/nand/fsl_ifc_nand.c
> @@ -171,34 +171,6 @@ static void set_addr(struct mtd_info *mtd, int column, int page_addr, int oob)
> ifc_nand_ctrl->index += mtd->writesize;
> }
>
> -static int is_blank(struct mtd_info *mtd, unsigned int bufnum)
> -{
> - struct nand_chip *chip = mtd_to_nand(mtd);
> - struct fsl_ifc_mtd *priv = nand_get_controller_data(chip);
> - u8 __iomem *addr = priv->vbase + bufnum * (mtd->writesize * 2);
> - u32 __iomem *mainarea = (u32 __iomem *)addr;
> - u8 __iomem *oob = addr + mtd->writesize;
> - struct mtd_oob_region oobregion = { };
> - int i, section = 0;
> -
> - for (i = 0; i < mtd->writesize / 4; i++) {
> - if (__raw_readl(&mainarea[i]) != 0xffffffff)
> - return 0;
> - }
> -
> - mtd_ooblayout_ecc(mtd, section++, &oobregion);
> - while (oobregion.length) {
> - for (i = 0; i < oobregion.length; i++) {
> - if (__raw_readb(&oob[oobregion.offset + i]) != 0xff)
> - return 0;
> - }
> -
> - mtd_ooblayout_ecc(mtd, section++, &oobregion);
> - }
> -
> - return 1;
> -}
> -
> /* returns nonzero if entire page is blank */
> static int check_read_ecc(struct mtd_info *mtd, struct fsl_ifc_ctrl *ctrl,
> u32 *eccstat, unsigned int bufnum)
> @@ -274,16 +246,13 @@ static void fsl_ifc_run_command(struct mtd_info *mtd)
> if (errors == 15) {
> /*
> * Uncorrectable error.
> - * OK only if the whole page is blank.
> + * We'll check for blank pages later.
> *
> * We disable ECCER reporting due to...
> * erratum IFC-A002770 -- so report it now if we
> * see an uncorrectable error in ECCSTAT.
> */
> - if (!is_blank(mtd, bufnum))
> - ctrl->nand_stat |=
> - IFC_NAND_EVTER_STAT_ECCER;
> - break;
> + ctrl->nand_stat |= IFC_NAND_EVTER_STAT_ECCER;
> }
>
> mtd->ecc_stats.corrected += errors;
> @@ -678,6 +648,41 @@ static int fsl_ifc_wait(struct mtd_info *mtd, struct nand_chip *chip)
> return nand_fsr | NAND_STATUS_WP;
> }
>
> +/*
> + * The controller does not check for bitflips in erased pages,
> + * therefore software must check instead.
> + */
> +static int check_erased_page(struct nand_chip *chip, u8 *buf)
> +{
> + struct mtd_info *mtd = nand_to_mtd(chip);
> + u8 *ecc = chip->oob_poi;
> + const int ecc_size = chip->ecc.bytes;
> + const int pkt_size = chip->ecc.size;
> + int i, res, bitflips = 0;
> + struct mtd_oob_region oobregion = { };
> +
> + mtd_ooblayout_ecc(mtd, 0, &oobregion);
> + ecc += oobregion.offset;
> +
> + for (i = 0; i < chip->ecc.steps; ++i) {
> + res = nand_check_erased_ecc_chunk(buf, pkt_size, ecc, ecc_size,
> + NULL, 0,
> + chip->ecc.strength);
> + if (res < 0)
> + mtd->ecc_stats.failed++;
> + else
> + mtd->ecc_stats.corrected += res;
> +
> + bitflips = max(res, bitflips);
> + buf += pkt_size;
> + ecc += ecc_size;
> + }
> +
> + mtd_ooblayout_ecc(mtd, 1, &oobregion);
Why is this needed?
> +
> + return bitflips;
> +}
> +
> static int fsl_ifc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
> uint8_t *buf, int oob_required, int page)
> {
> @@ -689,11 +695,19 @@ static int fsl_ifc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
> if (oob_required)
> fsl_ifc_read_buf(mtd, chip->oob_poi, mtd->oobsize);
>
> - if (ctrl->nand_stat & IFC_NAND_EVTER_STAT_ECCER)
> - dev_err(priv->dev, "NAND Flash ECC Uncorrectable Error\n");
> -
> if (ctrl->nand_stat != IFC_NAND_EVTER_STAT_OPC)
> mtd->ecc_stats.failed++;
> +
> + if (ctrl->nand_stat & IFC_NAND_EVTER_STAT_ECCER) {
> + int res;
> +
> + if (!oob_required)
> + fsl_ifc_read_buf(mtd, chip->oob_poi, mtd->oobsize);
> +
> + res = check_erased_page(chip, buf);
> + return res;
> + }
> +
>
> return nctrl->max_bitflips;
> }
> @@ -904,6 +922,21 @@ static int fsl_ifc_chip_init(struct fsl_ifc_mtd *priv)
> chip->ecc.algo = NAND_ECC_HAMMING;
> }
>
> + {
> + struct mtd_oob_region oobregion = { };
> +
> + mtd_ooblayout_ecc(mtd, 0, &oobregion);
> + if (!oobregion.length) {
> + dev_err(priv->dev, "No ECC in oobregion?\n");
> + return -EINVAL;
> + }
> + mtd_ooblayout_ecc(mtd, 1, &oobregion);
> + if (oobregion.length) {
> + dev_err(priv->dev, "Extra data in oobregion?\n");
> + return -EINVAL;
> + }
> + }
This clearly doesn't belong in this patch. And if you really want to
check that, please create a separate function instead of defining a
non-conditional code block inside fsl_ifc_chip_init().
> +
> if (ctrl->version == FSL_IFC_VERSION_1_1_0)
> fsl_ifc_sram_init(priv);
>
>
>
>
Powered by blists - more mailing lists