riscv: Add support for the Svinval extension

[bnovkov]

Summary

This change adds wrappers for the new fine-grained TLB invalidation
instructions and extends the capability detection logic to include
the Svinval extension, which is mandatory in the RVA23S64 profile.

Event: BSDCan 2026

[mhorne]

Is this implemented on the Spacemit K1 ?

sys/riscv/include/cpufunc.h

151

I don't think you are using this yet. But I would suggest this signature instead.

[markj]

sys/conf/kern.mk

169

Are there compilers which will reject this?

sys/riscv/include/cpufunc.h

151

+1

[bnovkov]

sys/conf/kern.mk

169

Looking at the gcc docs it seems that the syntax is the same.

sys/riscv/include/cpufunc.h

151

thank you for the suggestion, I'll work it into the patch before committing.

[jrtc27]

sys/conf/kern.mk

169

Don't know what version it was added in for GCC, but for LLVM it was LLVM 16 https://github.com/llvm/llvm-project/commit/7d7940fd7761e21b68f915e948389b87835d1304

Probably safe to not gate this on such a version check; even CHERI LLVM is LLVM 17

[bnovkov]

In D57623#1325383, @mhorne wrote:

Is this implemented on the Spacemit K1 ?

Sorry, I managed to miss your question. Yes, this extension is implemented on the K1 and I've tested the patches on a banana PI F3.