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

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Message-ID: <361449d8-aaa6-7780-12bb-4b67625b7f00@arm.com>
Date:   Fri, 21 Dec 2018 10:25:27 +0000
From:   Julien Thierry <julien.thierry@....com>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
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 20/12/2018 17:53, Ard Biesheuvel wrote:
> 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.
> 

Yes, that seems to work and does not break other arch.

I'll go with that in my next version of the patches.

Thanks,

-- 
Julien Thierry