linux-kernel - RE: Domain faults when CONFIG_CPU_SW_DOMAIN

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Date:	Thu, 3 Dec 2015 12:08:11 +0000
From:	Peter Rosin <peda@...ntia.se>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
CC:	"'linux-arm-kernel@...ts.infradead.org'" 
	<linux-arm-kernel@...ts.infradead.org>,
	"'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>
Subject: RE: Domain faults when CONFIG_CPU_SW_DOMAIN_PAN is enabled

Russell King wrote:
> On Thu, Dec 03, 2015 at 11:38:20AM +0000, Peter Rosin wrote:
> > Russell King wrote:
> > > On Thu, Dec 03, 2015 at 08:33:13AM +0000, Peter Rosin wrote:
> > > > I wrote:
> > > > > If I enable CONFIG_CPU_SW_DOMAIN_PAN, I sometimes (but not always) get the
> > > > > following (or very similar) on boot.
> > > > 
> > > > I should have said "if I don't disable", as the option is "default y".
> > > > 
> > > > Also, if it survives on boot, below is an example of later trouble (after
> > > > 30+ minutes on this occasion).
> > > 
> > > Please apply this patch so we (might) get a slightly better oops dump,
> > > and then try to reproduce.
> > 
> > Sure thing, but it's still "DAC: 00000051"...
> 
> Thanks, that confirms that something in the uaccess-with-memcpy code
> is clearing the DACR back to 0x51.
> 
> This has come up several times before, and I really can't spot the
> problem in this code, so I've always said to disable the
> uaccess-with-memcpy code.  Personally, I'd like to see the back
> of that code...

Ok, but it's not me doing crazy things if that's what you are implying
(not saying that you are), because the sama5_defconfig has

	CONFIG_UACCESS_WITH_MEMCPY=y

So, something needs to happen or sama5 remains default-broken.

Cheers,
Peter

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