[PATCH v3 05/25] arm64: context switch POR_EL0 register

[Mark Brown]

On Thu, Dec 07, 2023 at 01:55:31PM +0000, Catalin Marinas wrote:
> On Sat, Nov 25, 2023 at 12:02:49PM +0000, Mark Brown wrote:
> > On Fri, Nov 24, 2023 at 04:34:50PM +0000, Joey Gouly wrote:

> > > +static void flush_poe(void)
> > > +{
> > > +	if (system_supports_poe())
> > > +		write_sysreg_s(POR_EL0_INIT, SYS_POR_EL0);
> > > +}

> > Here we have no isb()...

> My immediate thought was that we'd not care about the ISB here since
> we'll have an ERET before getting to EL0. However, we may have some
> LDTR/STTR populating the new process args page on exec which may, in
> theory, pick up a stale POR_EL0.

Yeah, it was a combination of the inconsistency and the lack of clarity
over there being a path which could potentially use POR_EL0 before ERET.
We at least probably need some comments with regard to the requirements
here.
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