linux-kernel - Re: [PATCH] mtd: spi-nor: intel-spi: Do not try to make the SPI flash chip writable

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] [day] [month] [year] [list]

Date:   Tue, 4 Aug 2020 17:21:11 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Daniel Gutson <daniel.gutson@...ypsium.com>
Cc:     Tudor Ambarus <tudor.ambarus@...rochip.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        linux-mtd <linux-mtd@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Alex Bazhaniuk <alex@...ypsium.com>,
        Richard Hughes <hughsient@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] mtd: spi-nor: intel-spi: Do not try to make the SPI flash
 chip writable

On Tue, Aug 4, 2020 at 3:58 PM Daniel Gutson
<daniel.gutson@...ypsium.com> wrote:
>
> Context, the intel-spi has a module argument that controls
> whether the driver attempts to turn the SPI flash chip writeable.
> The default value is FALSE (don't try to make it writeable).
> However, this flag applies only for a number of devices, coming from the
> platform driver, whereas the devices detected through the PCI driver
> (intel-spi-pci) are not subject to this check since the configuration
> takes place in intel-spi-pci which doesn't have an argument.

This is still factually incorrect, as explained at least three times
now.

Please either make the same change for both the Bay Trail
platform driver and the PCI driver, or explain why you want them to
be different rather than incorrectly claiming that you change them to
be the same.

If you want the BIOS setting to always take precedence over the
module argument, logical change would be to also include
the corresponding change for bay trail and do:

--- a/drivers/mtd/spi-nor/controllers/intel-spi.c
+++ b/drivers/mtd/spi-nor/controllers/intel-spi.c
@@ -324,19 +324,6 @@ static int intel_spi_init(struct intel_spi *ispi)
                ispi->nregions = BYT_FREG_NUM;
                ispi->pr_num = BYT_PR_NUM;
                ispi->swseq_reg = true;
-
-               if (writeable) {
-                       /* Disable write protection */
-                       val = readl(ispi->base + BYT_BCR);
-                       if (!(val & BYT_BCR_WPD)) {
-                               val |= BYT_BCR_WPD;
-                               writel(val, ispi->base + BYT_BCR);
-                               val = readl(ispi->base + BYT_BCR);
-                       }
-
-                       ispi->writeable = !!(val & BYT_BCR_WPD);
-               }
-
                break;

        case INTEL_SPI_LPT: