linux-kernel - Re: [PATCH v7 11/25] arm64: irqflags: Use ICC_PMR

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Date:   Thu, 20 Dec 2018 18:53:51 +0100
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     Julien Thierry <julien.thierry@....com>
Cc:     linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        joel@...lfernandes.org, Marc Zyngier <marc.zyngier@....com>,
        Christoffer Dall <christoffer.dall@....com>,
        James Morse <james.morse@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Mark Rutland <mark.rutland@....com>, oleg@...hat.com
Subject: Re: [PATCH v7 11/25] arm64: irqflags: Use ICC_PMR_EL1 for interrupt masking

On Wed, 19 Dec 2018 at 18:01, Julien Thierry <julien.thierry@....com> wrote:
>
> Hi Ard,
>
> On 14/12/2018 16:40, Julien Thierry wrote:
> >
> >
> > On 14/12/2018 15:49, Ard Biesheuvel wrote:
> >> On Fri, 14 Dec 2018 at 16:23, Julien Thierry <julien.thierry@....com> wrote:
> >>>
> >>> Hi,
> >>>
> >>> On 13/12/2018 15:03, Julien Thierry wrote:
> >>>>
> >>>> Argh, not as simple as I had expected.
> >>>>
> >>>> Turns out include/linux/efi.h does not include asm/efi.h (including it
> >>>> at the beginning of the file breaks the build because asm/efi.h misses
> >>>> the efi type definitions.
> >>>>
> >>>> So a thing like:
> >>>>
> >>>> #ifndef efi_get_irqflags
> >>>> #define efi_get_irqflags(flags) local_save_flags(flags)
> >>>> #endif
> >>>>
> >>>> in include/linux/efi.h cannot be overridden.
> >>>>
> >>>> Either I would need to introduce the definitions arm, arm64 and x86 (I
> >>>> don't think there are other arch supporting EFI right now) or I'll need
> >>>> to come up with another solution.
> >>>>
> >>>
> >>
> >> It might be a bit nasty, but can we put the #ifndef above in
> >> runtime-wrappers.c directly? The only reference in linux/efi.h is a
> >> macro, so that shouldn't matter afaict.
> >>
> >
> > Sadly, in arch/x86/platform/uv/bios_uv.c, uv_bios_call() has a reference
> > to the macro efi_call_virt_pointer() which wouldn't be able to see the
> > definition in runtime-wrappers.c
> >
> > Otherwise, we could've moved efi_call_virt_pointer() and
> > __efi_call_virt_pointer in runtime-wrappers.c and things would not have
> > been as nasty.
> >
> > But no, I don't think we can do that without breaking some x86 build :( .
> >
>
> Since the above does not work, would the solution with the
> HAVE_GENERIC_EFI_FLAGS below be acceptable to you? Or would you rather I
> defined helpers in <asm/efi.h> for all arm/arm64/x86?
>
> Or neither and I shall find another way?
>

Would it be possible to introduce a function

efi_call_virt_save_flags()

[as a counterpart to efi_call_virt_check_flags()], and put the
implementation in runtime-wrappers.c (which already includes
asm/efi.h)?

That should allow you to put arch-specific hooks in asm/efi.h, and use
them in the implementation of efi_call_virt_save_flags(). AFAICT, that
removes the need for Kconfig glue.