riscv: Optimize bitops with Zbb extension

Bitops optimization with specialized instructions is common practice in
popular ISAs, this patch set uses RISC-V Zbb extension to optimize four
bitops: __ffs, __fls, ffs and fls.

The first patch rearranges the content in hwcap.h cpufeature.h, it helps
to avoid a cyclic header including issue for patch 2.

The second patch leverages the alternative mechanism to dynamically apply
this optimization.

The series has following dependency:
https://lore.kernel.org/linux-riscv/20230918131518.56803-...

Thanks,
Xiao

v3:
- Fix riscv32 build issue reported by kernel test robot. V3 changes "hwcap.h" to
  "cpufeature.h" for files where cpu feature detection APIs are used. (Yujie)

v2:
- Remove the "EFI_" prefix from macro name "EFI_NO_ALTERNATIVE" to make it
  generic. (Ard)
- patch-1 is added, it's based on "RISC-V: Enable cbo.zero in usermode". (Andrew)


Xiao Wang (2):
  riscv: Rearrange hwcap.h and cpufeature.h
  riscv: Optimize bitops with Zbb extension

 arch/riscv/include/asm/bitops.h       | 266 +++++++++++++++++++++++++-
 arch/riscv/include/asm/cpufeature.h   |  83 ++++++++
 arch/riscv/include/asm/elf.h          |   2 +-
 arch/riscv/include/asm/hwcap.h        |  91 ---------
 arch/riscv/include/asm/pgtable.h      |   1 +
 arch/riscv/include/asm/switch_to.h    |   2 +-
 arch/riscv/include/asm/vector.h       |   2 +-
 arch/riscv/kvm/aia.c                  |   2 +-
 arch/riscv/kvm/main.c                 |   2 +-
 arch/riscv/kvm/tlb.c                  |   2 +-
 arch/riscv/kvm/vcpu_fp.c              |   2 +-
 arch/riscv/kvm/vcpu_onereg.c          |   2 +-
 arch/riscv/kvm/vcpu_vector.c          |   2 +-
 drivers/clocksource/timer-riscv.c     |   2 +-
 drivers/firmware/efi/libstub/Makefile |   2 +-
 drivers/perf/riscv_pmu_sbi.c          |   2 +-
 16 files changed, 359 insertions(+), 106 deletions(-)

-- 
2.25.1