[U-Boot] [PATCH] ARMv8/sec_firmware : Update chosen/kaslr-seed

[Alexander Graf]

On 17.05.17 10:17, Peter Robinson wrote:
>>> -----Original Message-----
>>> From: Peter Robinson [mailto:pbrobinson at gmail.com]
>>> Sent: Monday, May 15, 2017 6:18 PM
>>> To: Ruchika Gupta <ruchika.gupta at nxp.com>
>>> Cc: u-boot at lists.denx.de; sun.york at nxp.com; Prabhakar Kushwaha
>>> <prabhakar.kushwaha at nxp.com>
>>> Subject: Re: [U-Boot] [PATCH] ARMv8/sec_firmware : Update chosen/kaslr-
>>> seed
>>>
>>> On Sat, May 13, 2017 at 1:07 AM, Ruchika Gupta <ruchika.gupta at nxp.com>
>>> wrote:
>>>> kASLR support in kernel requires a random number to be passed via
>>>> chosen/kaslr-seed propert. sec_firmware generates this random seed
>>>> which can then be passed in the device tree node
>>>
>>> Is that functionality generic that it can be consumed by other devices?
>> Sec firmware is proprietary firmware which provides this random seed using HW engine on NXP devices.
>> Other devices would need to generate their own random seed to be passed as this property.
>
> yes, my point was more shouldn't there be a generic framework for this
> as the functionality isn't unique to the HW engine on the NXP devices,
> even if the HW is, and kASLR is a pretty generic requirement.
>
> I know Tom, Alexander, myself and others discussed such a thing at ELC
> in Portland in February and if memory serves providing that seed via
> the uefi boot services (I may have that terminology wrong) for ARMv8.
> Tom/Alexander do you remember the details of that conversation, know
> if anyone was working on it?

I think it's perfectly fine to have a proprietary implementation in 
EL3/EL1s that uses whatever hardware provides to fetch a random number. 
I'm surprised you provide that number to Linux using dt though.

So far, I was under the impression that the preferred path for kASLR is 
to use the EFI_RNG_PROTOCOL protocol from the EFI stub. You are 
obviously more than welcome to back that protocol implementation in an 
NXP proprietary fashion with home-grown smc calls.

Let me CC Ard to clarify.


Alex