Motivated by [1]. A couple of things to note: RISC-V needs a default implementation to fall back on. Such implementation is available in include/uapi/linux/swab.h in the form of ___constant_swabXX macros. As include/uapi/linux/swab.h can't be included from arch/riscv/include/asm/swab.h, the default implementation has been moved into asm-generic in the first patch of the series. Tested with crc_kunit as pointed out in [2]. I can't provide performance numbers as I don't have RISC-V hardware yet. [1] https://lore.kernel.org/all/20250302220426.GC2079@quark.localdomain/ [2] https://lore.kernel.org/all/20250216225530.306980-1-ebiggers@xxxxxxxxxx/ Signed-off-by: Ignacio Encinas <ignacio@xxxxxxxxxxxx> --- Changes in v2: - Introduce first patch factoring out the default implementation into asm-generic Patch 2: - Remove blank line to make checkpatch happy - Instead of duplicating the default implementation for swap macros, leverage patch 1 and add an include to asm-generic/swab.h - Link to v1: https://lore.kernel.org/r/20250310-riscv-swab-v1-1-34652ef1ee96@xxxxxxxxxxxx --- Ignacio Encinas (2): include/uapi/linux/swab.h: move default implementation for swab macros into asm-generic riscv: introduce asm/swab.h arch/riscv/include/asm/swab.h | 48 +++++++++++++++++++++++++++++++++++++++++ include/uapi/asm-generic/swab.h | 32 +++++++++++++++++++++++++++ include/uapi/linux/swab.h | 33 +--------------------------- 3 files changed, 81 insertions(+), 32 deletions(-) --- base-commit: a7f2e10ecd8f18b83951b0bab47ddaf48f93bf47 change-id: 20250307-riscv-swab-b81b94a9ac1b Best regards, -- Ignacio Encinas <ignacio@xxxxxxxxxxxx>
