[GIT PULL] RISC-V updates for v7.0
Paul Walmsley
pjw at kernel.org
Fri Feb 13 16:23:41 PST 2026
On Thu, 12 Feb 2026, Linus Torvalds wrote:
> On Thu, 12 Feb 2026 at 15:39, Paul Walmsley <pjw at kernel.org> wrote:
> >
> > Deepak Gupta (26):
> > prctl: add arch-agnostic prctl()s for indirect branch tracking
>
> Hmm. In the meantime, I had pulled the RSEQ time slice extensions
> stuff first, so what happened was that these prctl numbers got bumped
> up from 79-81 to 80-82.
>
> I note that it looks like linux-next ended up merging things in a
> different order, and so instead left the indirect branch status prctls
> alone, and instead modified the RSEQ one.
>
> Just letting everybody involved know - maybe this was obvious to
> people, and maybe this came as a surprise.
Thanks for the heads-up; shouldn't be a problem.
> And only very tangentially related: I think the indirect branch
> locking could have been just a separate bit from the enable bit. I
> don't see why it needed separate prctls for "set status" and "set
> lock".
Will think this through and respond back.
> On a similar theme: why is it called "indir_br_lp"? That's a horrible name.
>
> This was supposed to be architecture-neutral, but I get the feeling
> that "lp" does not stand for "Long Play" and has nothing to do with
> 12-inch vinyl records.
>
> I think it probably is shorthand for "lpad", which is RISC-V thing.
> Which is complete nonsense for something that is documented to be
> architecture-neutral.
RISC-V didn't invent that term; here are some earlier CFI-related uses:
* ARM (2019): https://developer.arm.com/-/media/Arm%20Developer%20Community/PDF/Learn%20the%20Architecture/Providing%20protection%20for%20complex%20software.pdf
* LWN (2022): https://lwn.net/Articles/900099/
* FineIBT (2023): https://cs.brown.edu/~vpk/papers/fineibt.raid23.pdf
If you're okay with keeping the term "landing pad," we could get rid of
the "LP" and use something like "branch_landing_pad" instead. Or
perhaps "verified_branch_target" could be another option. It would be
nice to avoid using IBT or BTI, since those are definitely associated with
specific architectures. Any preference?
> In other words: I've pulled this, but I expect this to be fixed asap.
Will do, once we stop bikeshedding on the name :-)
thanks
- Paul
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