linux-toradex.git/arch/riscv/lib/strnlen.S, branch master Linux kernel for Apalis and Colibri modules riscv: lib: add strnlen() implementation 2026-04-05T00:42:44+00:00 Feng Jiang jiangfeng@kylinos.cn 2026-04-04T01:28:47+00:00 5ba15d419fab848a3813eb56bbcad00e291fbc49 Add an optimized strnlen() implementation for RISC-V. This version includes a generic optimization and a Zbb-powered optimization using the 'orc.b' instruction, derived from the strlen() implementation. Benchmark results (QEMU TCG, rv64): Length | Original (MB/s) | Optimized (MB/s) | Improvement -------|-----------------|------------------|------------ 16 B | 179 | 309 | +72.6% 512 B | 347 | 1562 | +350.1% 4096 B | 356 | 1878 | +427.5% Suggested-by: Qingfang Deng <dqfext@gmail.com> Signed-off-by: Feng Jiang <jiangfeng@kylinos.cn> Link: https://patch.msgid.link/20260130025018.172925-7-jiangfeng@kylinos.cn Signed-off-by: Paul Walmsley <pjw@kernel.org> 
Add an optimized strnlen() implementation for RISC-V. This version
includes a generic optimization and a Zbb-powered optimization using
the 'orc.b' instruction, derived from the strlen() implementation.

Benchmark results (QEMU TCG, rv64):
  Length | Original (MB/s) | Optimized (MB/s) | Improvement
  -------|-----------------|------------------|------------
  16 B   | 179             | 309              | +72.6%
  512 B  | 347             | 1562             | +350.1%
  4096 B | 356             | 1878             | +427.5%

Suggested-by: Qingfang Deng <dqfext@gmail.com>
Signed-off-by: Feng Jiang <jiangfeng@kylinos.cn>
Link: https://patch.msgid.link/20260130025018.172925-7-jiangfeng@kylinos.cn
Signed-off-by: Paul Walmsley <pjw@kernel.org>