From: Stephen Boyd <swboyd@chromium.org>
To: Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>
Cc: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
dianders@google.com, kernel-team@android.com,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 1/2] arm64: Move handling of erratum 1418040 into C code
Date: Fri, 31 Jul 2020 11:00:34 -0700 [thread overview]
Message-ID: <159621843473.1360974.5165992650144410881@swboyd.mtv.corp.google.com> (raw)
In-Reply-To: <20200731113228.GB26500@willie-the-truck>
Quoting Will Deacon (2020-07-31 04:32:28)
> On Fri, Jul 31, 2020 at 12:14:40PM +0100, Marc Zyngier wrote:
> > On 2020-07-31 11:41, Will Deacon wrote:
> > > On Fri, Jul 31, 2020 at 09:33:57AM +0100, Marc Zyngier wrote:
> > > > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
> > > > index 6089638c7d43..8bbf066224ab 100644
> > > > --- a/arch/arm64/kernel/process.c
> > > > +++ b/arch/arm64/kernel/process.c
> > > > @@ -515,6 +515,40 @@ static void entry_task_switch(struct
> > > > task_struct *next)
> > > > __this_cpu_write(__entry_task, next);
> > > > }
> > > >
> > > > +/*
> > > > + * ARM erratum 1418040 handling, affecting the 32bit view of CNTVCT.
> > > > + * Assuming the virtual counter is enabled at the beginning of times:
> > > > + *
> > > > + * - disable access when switching from a 64bit task to a 32bit task
> > > > + * - enable access when switching from a 32bit task to a 64bit task
> > > > + */
> > > > +static __always_inline
> > >
> > > Do we need the __always_inline? None of the other calls from
> > > __switch_to()
> > > have it.
> >
> > Suggestion from Stephen. In my experience, it doesn't change much as
> > most things get inlined anyway. Happy to drop it.
>
> Yes, please. We can add it back if it's shown to be a problem.
Just for my own edification, why is __always_inline undesirable? Should
there be an always inline version of the function that has the static
key so that the erratum path is kept out of the switch_to() default
path?
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next prev parent reply other threads:[~2020-07-31 18:02 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-31 8:33 [PATCH v2 0/2] arm64: Allow erratum 1418040 for late CPUs Marc Zyngier
2020-07-31 8:33 ` [PATCH v2 1/2] arm64: Move handling of erratum 1418040 into C code Marc Zyngier
2020-07-31 10:41 ` Will Deacon
2020-07-31 11:14 ` Marc Zyngier
2020-07-31 11:32 ` Will Deacon
2020-07-31 18:00 ` Stephen Boyd [this message]
2020-08-01 11:41 ` Catalin Marinas
2020-07-31 8:33 ` [PATCH v2 2/2] arm64: Allow booting of late CPUs affected by erratum 1418040 Marc Zyngier
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