From: Catalin Marinas <catalin.marinas@arm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Will Deacon <will.deacon@arm.com>,
James Morse <james.morse@arm.com>,
Andrey Konovalov <andreyknvl@google.com>
Subject: Re: [PATCH V2 3/4] arm64/mm: Consolidate page fault information capture
Date: Thu, 6 Jun 2019 12:23:13 +0100 [thread overview]
Message-ID: <20190606112313.GA56860@arrakis.emea.arm.com> (raw)
In-Reply-To: <20190606093811.GA37430@lakrids.cambridge.arm.com>
On Thu, Jun 06, 2019 at 10:38:11AM +0100, Mark Rutland wrote:
> On Tue, Jun 04, 2019 at 03:42:09PM +0100, Catalin Marinas wrote:
> > On Mon, Jun 03, 2019 at 12:11:24PM +0530, Anshuman Khandual wrote:
> > > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> > > index da02678..4bb65f3 100644
> > > --- a/arch/arm64/mm/fault.c
> > > +++ b/arch/arm64/mm/fault.c
> > > @@ -435,6 +435,14 @@ static bool is_el0_instruction_abort(unsigned int esr)
> > > return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW;
> > > }
> > >
> > > +/*
> > > + * This is applicable only for EL0 write aborts.
> > > + */
> > > +static bool is_el0_write_abort(unsigned int esr)
> > > +{
> > > + return (esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM);
> > > +}
> >
> > What makes this EL0 only?
>
> It returns false for EL1 faults caused by DC IVAC, where write
> permission is required. EL0 can only issue maintenance that requires
> read permission.
>
> For whatever reason, the architecture says that WnR is always 1b1, even
> if read permission was sufficient.
>
> How about:
>
> /*
> * Note: not valid for EL1 DC IVAC, but we never use that such that it
> * should fault.
> */
For completeness, I'd add "... should fault. EL0 cannot issue DC IVAC
(undef)." or something like that.
Looks fine otherwise.
--
Catalin
next prev parent reply other threads:[~2019-06-06 11:23 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-03 6:41 [PATCH V2 0/4] arm64/mm: Clean ups for do_page_fault() Anshuman Khandual
2019-06-03 6:41 ` [PATCH V2 1/4] arm64/mm: Drop mmap_sem before calling __do_kernel_fault() Anshuman Khandual
2019-06-04 14:44 ` Catalin Marinas
2019-06-03 6:41 ` [PATCH V2 2/4] arm64/mm: Drop task_struct argument from __do_page_fault() Anshuman Khandual
2019-06-04 14:45 ` Catalin Marinas
2019-06-03 6:41 ` [PATCH V2 3/4] arm64/mm: Consolidate page fault information capture Anshuman Khandual
2019-06-04 14:42 ` Catalin Marinas
2019-06-06 9:38 ` Mark Rutland
2019-06-06 11:23 ` Catalin Marinas [this message]
2019-06-03 6:41 ` [PATCH V2 4/4] arm64/mm: Drop local variable vm_fault_t from __do_page_fault() Anshuman Khandual
2019-06-04 14:56 ` Catalin Marinas
2019-06-06 4:54 ` Anshuman Khandual
2019-06-06 11:27 ` Catalin Marinas
2019-06-06 11:31 ` Mark Rutland
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