Re: ARM64: Regression with commit e3067861ba66 ("arm64: add basic VMAP_STACK support")

[Leo Yan]

On Mon, Oct 16, 2017 at 02:48:19PM +0100, Mark Rutland wrote:
> 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?

Yes.

> I can't immediately see how that would be related.
> 
> Thanks,
> Mark.