linux-kernel - Re: [PATCH v9 2/5] mtd: nand: vf610_nfc: add hardware BCH-ECC support

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

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 31 Jul 2015 16:47:18 -0700
From:	Brian Norris <computersforpeace@...il.com>
To:	Stefan Agner <stefan@...er.ch>
Cc:	dwmw2@...radead.org, sebastian@...akpoint.cc, robh+dt@...nel.org,
	pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	shawn.guo@...aro.org, kernel@...gutronix.de,
	boris.brezillon@...e-electrons.com, marb@...at.de,
	aaron@...tycactus.com, bpringlemeir@...il.com,
	linux-mtd@...ts.infradead.org, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	albert.aribaud@...ev.fr, Bill Pringlemeir <bpringlemeir@...ps.com>
Subject: Re: [PATCH v9 2/5] mtd: nand: vf610_nfc: add hardware BCH-ECC support

On Sat, Aug 01, 2015 at 01:35:52AM +0200, Stefan Agner wrote:
> On 2015-08-01 01:09, Brian Norris wrote:

> >> +static int vf610_nfc_read_page(struct mtd_info *mtd, struct nand_chip *chip,
> >> +				uint8_t *buf, int oob_required, int page)
> >> +{
> >> +	int eccsize = chip->ecc.size;
> >> +	int stat;
> >> +
> >> +	vf610_nfc_read_buf(mtd, buf, eccsize);
> >> +
> >> +	if (oob_required)
> >> +		vf610_nfc_read_buf(mtd, chip->oob_poi, mtd->oobsize);
> > 
> > To fix the bitflips issue above, you'll just want to unconditionally
> > read the OOB (it's fine to ignore 'oob_required') and...
> > 
> >> +
> >> +	stat = vf610_nfc_correct_data(mtd, buf);
> > 
> > ...pass in chip->oob_poi as a third argument.
> > 
> 
> Hm, this probably will have an effect on performance, since we usually
> omit the OOB if not requested.

You could test :) I don't really like performance claims without tests.
(I say this because I added the oob_required flag myself, but just for
functional purposes, not performance. Many drivers got by just fine by
always copying the OOB data.)

> I could fetch the OOB from the NAND
> controllers SRAM only if necessary (if HW ECC status is not ok...). Does
> this sound reasonable?

That does.

Brian
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/