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Re: [PATCHv2 0/6] efi: detect erroneous firmware IRQ manipulation

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On Mon, 25 Apr, at 12:04:55PM, Mark Rutland wrote:
> On Mon, Apr 25, 2016 at 11:51:53AM +0100, Matt Fleming wrote:
> > On Mon, 25 Apr, at 11:40:09AM, Mark Rutland wrote:
> > > 
> > > It looks like irqs_disabled_flags() will do what you expect, and ignore
> > > everything but the interrupt flag.
> > > 
> > > However, for ARM that will ignore the other exceptions we've seen FW
> > > erroneously unmask (e.g. FIQ), which is unfortunate, as fiddling with
> > > those is just as disastrous.
> >  
> > Bah, right.
> > 
> > > Would you be happy with an arch_efi_call_check_flags(before, after),
> > > instead? That way we can make the flags we check arch-specific.
> > 
> > Could we just make the flag mask arch-specific instead of the call
> > since the rest of efi_call_virt_check_flags() is good?
> 
> Yup, I meant that arch_efi_call_check_flags would only do the flag
> comparison, only replacing the bit currently in the WARN_ON_ONCE().
> 
> > Something like this (uncompiled, untested, half-baked),
> > 
> > ---
> > 
> > diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c
> > index c38b1cfc26e2..057d00bee7d6 100644
> > --- a/drivers/firmware/efi/runtime-wrappers.c
> > +++ b/drivers/firmware/efi/runtime-wrappers.c
> > @@ -25,9 +25,12 @@
> >  static void efi_call_virt_check_flags(unsigned long flags, const char *call)
> >  {
> >  	unsigned long cur_flags;
> > +	bool mismatch;
> >  
> >  	local_save_flags(cur_flags);
> > -	if (!WARN_ON_ONCE(cur_flags != flags))
> > +
> > +	mismatch = (cur_flags ^ flags) & ARCH_EFI_IRQ_FLAGS_MASK;
> > +	if (!WARN_ON_ONCE(mismatch))
> >  		return;
> 
> This style also works for me.
 
Cool. One thing that occurred to me after I sent it is that
technically we should either,

  1) make 'mismatch' an int or
  2) do mismatch = !!((cur_flags ^ flags) & ARCH_EFI_IRQ_FLAGS_MASK)

Either is fine with me, I just don't want to leave the implicit
conversion to C's type system.

> Should I respin patch 6 as a series doing the above?
> 
> I assume that the first 5 patches are fine as-is.

Yep, they're fine. Sure, go ahead and respin patch 6.

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[PATCHv2 0/6] efi: detect erroneous firmware IRQ manipulation Mark Rutland <mark.rutland@arm.com> - 2016-04-22 16:00 +0200
  [PATCHv2 3/6] arm/efi: move to generic {__,}efi_call_virt Mark Rutland <mark.rutland@arm.com> - 2016-04-22 16:00 +0200
  [PATCHv2 6/6] efi/runtime-wrappers: detect FW irq flag corruption Mark Rutland <mark.rutland@arm.com> - 2016-04-22 16:00 +0200
    Re: [PATCHv2 6/6] efi/runtime-wrappers: detect FW irq flag corruption Matt Fleming <matt@codeblueprint.co.uk> - 2016-04-24 23:20 +0200
  [PATCHv2 2/6] arm64/efi: move to generic {__,}efi_call_virt Mark Rutland <mark.rutland@arm.com> - 2016-04-22 16:00 +0200
  [PATCHv2 1/6] efi/runtime-wrappers: add {__,}efi_call_virt templates Mark Rutland <mark.rutland@arm.com> - 2016-04-22 16:00 +0200
    Re: [PATCHv2 1/6] efi/runtime-wrappers: add {__,}efi_call_virt  templates Matt Fleming <matt@codeblueprint.co.uk> - 2016-04-24 23:20 +0200
  Re: [PATCHv2 0/6] efi: detect erroneous firmware IRQ manipulation Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-04-22 16:20 +0200
    Re: [PATCHv2 0/6] efi: detect erroneous firmware IRQ manipulation Matt Fleming <matt@codeblueprint.co.uk> - 2016-04-24 23:30 +0200
      Re: [PATCHv2 0/6] efi: detect erroneous firmware IRQ manipulation Matt Fleming <matt@codeblueprint.co.uk> - 2016-04-25 12:20 +0200
        Re: [PATCHv2 0/6] efi: detect erroneous firmware IRQ manipulation Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-04-25 12:30 +0200
          Re: [PATCHv2 0/6] efi: detect erroneous firmware IRQ manipulation Matt Fleming <matt@codeblueprint.co.uk> - 2016-04-25 12:30 +0200
            Re: [PATCHv2 0/6] efi: detect erroneous firmware IRQ manipulation Mark Rutland <mark.rutland@arm.com> - 2016-04-25 12:50 +0200
              Re: [PATCHv2 0/6] efi: detect erroneous firmware IRQ manipulation Matt Fleming <matt@codeblueprint.co.uk> - 2016-04-25 13:00 +0200
                Re: [PATCHv2 0/6] efi: detect erroneous firmware IRQ manipulation Mark Rutland <mark.rutland@arm.com> - 2016-04-25 13:10 +0200
                Re: [PATCHv2 0/6] efi: detect erroneous firmware IRQ manipulation Matt Fleming <matt@codeblueprint.co.uk> - 2016-04-25 13:20 +0200

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