On 17 March 2016 at 16:31, Leif Lindholm <[email protected]> wrote:
> On Thu, Mar 17, 2016 at 02:55:00PM +0100, Ard Biesheuvel wrote:
>> The function ArmClearMemoryRegionReadOnly() was supposed to undo the
>> effect of ArmSetMemoryRegionReadOnly(), but instead, it sets the permissions
>> to EL0-no access, EL1-read-only. Since the EL0 bit should be 1 to align
>> with EL2/3 (where the bit is SBO), use TT_AP_RW_RW instead, which makes the
>> entry read-write for EL0 when executing at EL1, and read-write for all other
>> levels.
>>
>> Contributed-under: TianoCore Contribution Agreement 1.0
>> Signed-off-by: Ard Biesheuvel <[email protected]>
>
> Happy with the RO->RW, confused by the NO->RW.
> I presume this is about consistency?
> Why do we need access for EL0?
>

We don't. But when running on EL2 or EL3, the same bit needs to be
set, so either we have two separate definitions, for EL1 and EL2/3, or
we just set the bit for EL0 as well, which shouldn't matter anyway
since we never return to EL0
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