[PATCH v2 1/6] armv8: Disable pointer authentication traps for EL1

[Michael Walle]

Hi,

Am 2021-08-20 16:44, schrieb Andre Przywara:
> On 8/19/21 4:53 PM, Peter Hoyes wrote:
>> From: Peter Hoyes <Peter.Hoyes at arm.com>
>> 
>> The use of ARMv8.3 pointer authentication (PAuth) is governed by 
>> fields
>> in HCR_EL2, which trigger a 'trap to EL2' if not enabled. The reset
>> value of these fields is 'architecturally unknown' so we must ensure
>> that the fields are enabled (to disable the traps) if we are entering
>> the kernel at EL1.
>> 
>> The APK field disables PAuth instruction traps and the API field
>> disables PAuth register traps
>> 
>> Add code to disable the traps in armv8_switch_to_el1_m. Prior to doing
>> so, it checks fields in the ID_AA64ISAR1_EL1 register to ensure 
>> pointer
>> authentication is supported by the hardware.
>> 
>> The runtime checks require a second temporary register, so add this to
>> the EL1 transition macro signature and update 2 call sites.
> 
>                                                 ^^^^^^^^^^^^
> 
> So can we get rid of the rather fragile macro, and just have one
> normal function, in transition.S, which fsl-layerscape/spintable.S
> calls? The code does not seem to return, and also the FSL call site
> does not seem to be in some special section or so, so not sure why
> this was a macro in the first place?

The spin tables will be marked as reserved memory at
   
https://elixir.bootlin.com/u-boot/v2021.10-rc2/source/arch/arm/cpu/armv8/fsl-layerscape/fdt.c#L147
also the code will be moved around:
   
https://elixir.bootlin.com/u-boot/v2021.10-rc2/source/arch/arm/cpu/armv8/fsl-layerscape/mp.c#L97

-michael