linux-kernel - Re: [PATCH 7/8 v1.5] arm64: Always keep DAIF.[IF] in sync

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Date:   Mon, 22 Feb 2021 18:43:20 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     Hector Martin <marcan@...can.st>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Catalin Marinas <catalin.marinas@....com>,
        James Morse <james.morse@....com>,
        Marc Zyngier <maz@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will@...nel.org>
Subject: Re: [PATCH 7/8 v1.5] arm64: Always keep DAIF.[IF] in sync

On Tue, Feb 23, 2021 at 02:39:11AM +0900, Hector Martin wrote:
> On 20/02/2021 03.26, Mark Rutland wrote:
> > On Sat, Feb 20, 2021 at 02:25:30AM +0900, Hector Martin wrote:
> > > Apple SoCs (A11 and newer) have some interrupt sources hardwired to the
> > > FIQ line. We implement support for this by simply treating IRQs and FIQs
> > > the same way in the interrupt vectors.
> > > 
> > > To support these systems, the FIQ mask bit needs to be kept in sync with
> > > the IRQ mask bit, so both kinds of exceptions are masked together. No
> > > other platforms should be delivering FIQ exceptions right now, and we
> > > already unmask FIQ in normal process context, so this should not have an
> > > effect on other systems - if spurious FIQs were arriving, they would
> > > already panic the kernel.
> > 
> > This looks good to me; I've picked this up and pushed out my arm64/fiq
> > branch [1,2] incorporating this, tagged as arm64-fiq-20210219.
> > 
> > I'll give this version a few days to gather comments before I post a v2.
> > 
> > [1] git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git arm64/fiq
> > [2] https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=arm64/fiqA
> 
> Thanks! Any chance you can do a rebase on top of torvalds/master? Since
> Marc's nVHE changes went in, we're going to need to add a workaround patch
> for the M1's lack of nVHE mode, which is going to be in the next version of
> my M1 bringup series - but right now that would involve telling people to
> merge two trees to build a base to apply it on, which is sub-optimal.

I generally try to base on a stable tag/commit, so I'd prefer to avoid
rebasing the development branch until rc1 if possible. I've pushed out a
new arm64-fiq-mainline-20210222 tag rebased atop torvalds/master:

git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git arm64-fiq-mainline-20210222
https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/tag/?h=arm64-fiq-mainline-20210222

... leaving the main branch atop v5.11. Is that good enough for now? If
that's painful for development I can shuffle the main branch along too.

Thanks,
Mark.