Re: [PATCH 5/6] x86/shstk: don't create the shadow stack for PF_USER_WORKERs

[Deepak Gupta <debug@rivosinc.com>]

On Fri, Aug 15, 2025 at 12:44:14PM +0100, Mark Brown wrote:
>On Thu, Aug 14, 2025 at 10:43:45PM +0000, Edgecombe, Rick P wrote:
>> On Thu, 2025-08-14 at 19:33 +0100, Mark Brown wrote:
>
>> > Perhaps we should factor the logic for deciding if we need to allocate a
>> > userspace shadow stack out into the arch independent code and do
>> > something like set a flag in kernel_clone_args that the arches can
>> > check?  I think the logic is the same for all arches at the minute and
>> > don't see a reason why it'd diverge.
>
>> Sounds good. Like a little start to this:
>> https://lore.kernel.org/lkml/20241010-shstk_converge-v1-0-631beca676e7@rivosinc.com/
>
>Yes, exactly.
>
>> >   That'd collide a bit with my
>> > clone3() series, there's some overlap there with that creating another
>> > reason why the decision would change.  Reducing the duplication would be
>> > nice.
>
>> Argh, I need to test the latest of that still.
>
>Yury pointed me at some newer x86 systems I was able to get access to so
>I was finally able to test that one myself before sending it out,
>confirmation would be good but hopefully it's fine.  I've been holding
>back on sending a rebased version out since Deepak was going to help me
>get set up to test it on RISC-V.  Though I see now that the RISC-V code
>has vanished from -next (I guess due to fallout from the issues with the
>merge to Linus, it looks like there's almost nothing in the branch
>currently), not sure what the plan is there?
>
>Perhaps I should just send it out, but given the difficulty getting
>anyone to pay attention I was trying to avoid issues with missing
>updates for newly added RISC-V shadow stacks.

Yes I was trying to get that sorted as well. Because now I'll have to
rebase my changes to 6.17. So I wanted to make sure that it applies
cleanly. I suggest that you send it out because risc-v was left out
anyways. I'll apply your patch series on my risc-v shadow stack changes
(on top of 6.17) and will report back. It might be easier that way.

How does that sound?