riscv/pmap.c: Add an Svinval-aware variant of pmap_invalidate_range

[bnovkov]

Summary

This change introduces a variant of pmap_invalidate_range that uses
the fine-grained TLB invalidation instructions introduced by the
Svinval extension. These instructions allow for more efficient TLB
flushing on certain implementations. Under this new scheme,
pmap_invalidate_range was converted to an ifunc that selects the
appropriate variant during boot.

Event: BSDCan 2026

[mhorne]

sys/riscv/riscv/pmap.c

1114–1115

[mhorne]

sys/riscv/riscv/pmap.c

1101

The relationship between this check and the definition above was a momentary confusion for me.

You might do away with the atop() and PAGE_SIZE division altogether.

[markj]

Why not use this for pmap_invalidate_page() as well?

[bnovkov]

Address @markj 's and @mhorne 's comments:

• add an svinval-aware pmap_invalidate_page variant
• remove awkward atop conversion