Merge patch series "riscv: uaccess: optimisations"

Cyril Bur <cyrilbur@tenstorrent.com> says:

This series tries to optimize riscv uaccess by allowing the use of
user_access_begin() and user_access_end() which permits grouping user accesses
and avoiding the CSR write penalty for each access.

The error path can also be optimised using asm goto which patches 3 and 4
achieve. This will speed up jumping to labels by avoiding the need of an
intermediary error type variable within the uaccess macros

I did read the discussion this series generated. It isn't clear to me
which direction to take the patches, if any.

* b4-shazam-merge:
  riscv: uaccess: use 'asm_goto_output' for get_user()
  riscv: uaccess: use 'asm goto' for put_user()
  riscv: uaccess: use input constraints for ptr of __put_user()
  riscv: implement user_access_begin() and families
  riscv: save the SR_SUM status over switches

Link: https://lore.kernel.org/r/20250410070526.3160847-1-cyrilbur@tenstorrent.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>