[U-Boot] [PATCH v2 2/2] arm: Set TTB XN bit in case DCACHE_OFF for LPAE mode

Tom Rini
2016-10-29T17:47:43Z

On Sat, Oct 29, 2016 at 07:44:34PM +0200, Marek Vasut wrote:
> On 10/29/2016 07:41 PM, Tom Rini wrote:
> > On Sat, Oct 29, 2016 at 03:19:10PM +0530, Keerthy wrote:
> >
> >> While we setup the mmu initially we mark set_section_dcache with
> >> DCACHE_OFF flag. In case of non-LPAE mode the DCACHE_OFF macro
> >> is rightly defined with TTB_SECT_XN_MASK set so as to mark all the
> >> 4GB XN. In case of LPAE mode XN(Execute-never) bit is not set with
> >> DCACHE_OFF. Hence XN bit is not set by default for DCACHE_OFF which
> >> keeps all the regions execute okay and this leads to random speculative
> >> fetches in random memory regions which was eventually caught by kernel
> >> omap-l3-noc driver.
> >>
> >> Fix this to mark the regions as XN by default.
> >>
> >> Signed-off-by: Keerthy <j-keerthy@ti.com>
> >> Reviewed-by: Alexander Graf <agraf@suse.de>
> >
> > Reviewed-by: Tom Rini <trini@konsulko.com>
> >
> Isn't this patch exactly undoing the following one ?
>
> commit 8890c2fbe6ed4c5ca9a61f21e846a55f8f2c38fc
> Author: Marek Vasut <>
> Date: Tue Dec 29 19:44:02 2015 +0100
>
> arm: Remove S bit from MMU section entry
>
> Restore the old behavior of the MMU section entries configuration,
> which is without the S-bit.

Is it? I guess perhaps you and Keerthy need to chat then as there's
some other problem they're addressing.

--
Tom
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