linux-kernel - Re: ARM64: Regression with commit e3067861ba66 ("arm64: add basic VMAP

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Date:   Mon, 16 Oct 2017 14:48:19 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Leo Yan <leo.yan@...aro.org>
Cc:     Robin Murphy <robin.murphy@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        ard.biesheuvel@...aro.org
Subject: Re: ARM64: Regression with commit e3067861ba66 ("arm64: add basic
 VMAP_STACK support")

Hi Leo,

On Mon, Oct 16, 2017 at 09:17:23AM +0800, Leo Yan wrote:
> On Tue, Oct 10, 2017 at 05:03:44PM +0100, Robin Murphy wrote:
> > On 10/10/17 16:45, Mark Rutland wrote:
> > > On Tue, Oct 10, 2017 at 10:27:25PM +0800, Leo Yan wrote:
> > >> I work mainline kernel on Hikey620 board, I find it's easily to
> > >> introduce the panic and report the log as below. So I bisect the kernel
> > >> and finally narrow down the commit e3067861ba66 ("arm64: add basic
> > >> VMAP_STACK support") which introduce this issue.
> > >>
> > >> I tried to remove 'select HAVE_ARCH_VMAP_STACK' from
> > >> arch/arm64/Kconfig, then I can see the panic issue will dismiss. So
> > >> could you check this and have insight for this issue?
> > > 
> > > Given the stuff in the backtrace, my suspicion is something is trying to
> > > perform DMA to/from the stack, getting junk addresses form the attempted
> > > virt<->phys conversions.
> > > 
> > > Could you try enabling both VMAP_STACK and CONFIG_DEBUG_VIRTUAL?
> > 
> > CONFIG_DMA_API_DEBUG should scream about drivers trying to use stack
> > addresses either way, too.
> 
> Thanks for suggestions, Mark & Robin.
> 
> I enabled these debugging configs but cannot get clue from it; but
> occasionally found this issue is quite likely related with CA53 errata,
> especialy ERRATA_A53_855873 is the relative one. So I changed to use
> ARM-TF mainline code with ERRATA fixing, this issue can be dismissed.

Thanks for the update.

Just to confirm, with the updated firmware you no longer see the issue?

I can't immediately see how that would be related.

Thanks,
Mark.