Re: [PATCH 5/8] efi: Get the secure boot status [ver #5]

From	Lukas Wunner <lukas@wunner.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH 5/8] efi: Get the secure boot status [ver #5]
Date	2016-12-09 01:40 +0100
Message-ID	<sMhod-4BC-5@gated-at.bofh.it> (permalink)
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On Thu, Dec 08, 2016 at 05:31:13PM +0000, David Howells wrote:
> Lukas Wunner <lukas@wunner.de> wrote:
> > > +out_efi_err:
> > > +	pr_efi_err(sys_table_arg, "Could not determine UEFI Secure Boot status.\n");
> > > +	if (status == EFI_NOT_FOUND)
> > > +		return efi_secureboot_mode_disabled;
> > > +	return efi_secureboot_mode_unknown;
> > > +}
> > 
> > In the out_efi_err path, the if-statement needs to come before the
> > pr_efi_err() call.  Otherwise it would be a change of behaviour for
> > ARM to what we have now.
> 
> As I understand it, if the BIOS is an EFI BIOS, these variables must exist -
> in which case I would argue that the pr_efi_err-statement should be before
> the if-statement.

The existing efi_get_secureboot() in arm-stub.c returns 0 in the
EFI_NOT_FOUND case and the "Could not determine ..."  error is only
printed if the return value is < 0.  So you're introducing a change
of behaviour.

If you feel the change is justified, fine, I won't argue against it
since I don't have a dog in this fight.

But obviously it's something that a reader of your patch will trip over,
so at least explain it in the commit message.  It would also be good to
explain why you're moving the pr_efi_err() calls in the first place.
ISTR it has to do with the different interpretation of an error,
what I wrote in my previous e-mail: x86 defaults to considering secureboot
disabled on error, ARM to enabled.  I'm not even sure that's correct,
I'd have to go re-read the whole thread, which again shows that there's
too little documentation in the commit message.

Thanks,

Lukas

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[PATCH 5/8] efi: Get the secure boot status [ver #5] David Howells <dhowells@redhat.com> - 2016-12-07 14:20 +0100
  Re: [PATCH 5/8] efi: Get the secure boot status [ver #5] Lukas Wunner <lukas@wunner.de> - 2016-12-08 08:00 +0100
    Re: [PATCH 5/8] efi: Get the secure boot status [ver #5] David Howells <dhowells@redhat.com> - 2016-12-08 09:20 +0100
      Re: [PATCH 5/8] efi: Get the secure boot status [ver #5] Lukas Wunner <lukas@wunner.de> - 2016-12-08 13:50 +0100
        Re: [PATCH 5/8] efi: Get the secure boot status [ver #5] David Howells <dhowells@redhat.com> - 2016-12-08 18:40 +0100
          Re: [PATCH 5/8] efi: Get the secure boot status [ver #5] Lukas Wunner <lukas@wunner.de> - 2016-12-09 01:40 +0100

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