[PATCH 0/4] Zbb + fast-unaligned string optimization

[Heiko Stuebner]

From: Heiko Stuebner <heiko.stuebner at vrull.eu>

This is a follow-up to my Zbb-based string optimization series, that
then adds another strcmp variant for systems with Zbb that also can
do unaligned accesses fast in hardware.

For this it uses Palmer's series for hw-feature probing that would read
this property from firmware (devicetree), as the performance of unaligned
accesses is an implementation detail of the relevant cpu core.


Right now we're still in the middle of discussing how more complex
cpufeature-combinations should be handled in general, so this is more
of a concept on one possible way to do it.


Dependencies:
- my Zbb string series
  https://lore.kernel.org/r/20230113212301.3534711-1-heiko@sntech.de
- Palmer's hw-probing series
  https://lore.kernel.org/r/20221013163551.6775-1-palmer@rivosinc.com


Heiko Stuebner (4):
  RISC-V: use bit-values instead of numbers to identify patched
    cpu-features
  RISC-V: add alternative-field for bits to not match against
  RISC-V: add cpufeature probing for fast-unaligned access
  RISC-V: add strcmp variant using zbb and fast-unaligned access

 arch/riscv/include/asm/alternative-macros.h |  64 ++++----
 arch/riscv/include/asm/alternative.h        |   1 +
 arch/riscv/include/asm/errata_list.h        |  27 ++--
 arch/riscv/kernel/cpufeature.c              |  33 +++-
 arch/riscv/lib/strcmp.S                     | 170 +++++++++++++++++++-
 arch/riscv/lib/strlen.S                     |   2 +-
 arch/riscv/lib/strncmp.S                    |   2 +-
 7 files changed, 245 insertions(+), 54 deletions(-)

-- 
2.35.1