On Sun, 19 Sep 2021 12:21:01 PDT (-0700), mcroce@xxxxxxxxxxxxxxxxxxx wrote:
From: Matteo Croce <mcroce@xxxxxxxxxxxxx>
Replace the assembly mem{cpy,move,set} with C equivalent.
Try to access RAM with the largest bit width possible, but without
doing unaligned accesses.
A further improvement could be to use multiple read and writes as the
assembly version was trying to do.
Tested on a BeagleV Starlight with a SiFive U74 core, where the
improvement is noticeable.
v3 -> v4:
- incorporate changes from proposed generic version:
https://lore.kernel.org/lkml/20210617152754.17960-1-mcroce@xxxxxxxxxxxxxxxxxxx/
v2 -> v3:
- alias mem* to __mem* and not viceversa
- use __alias instead of a tail call
v1 -> v2:
- reduce the threshold from 64 to 16 bytes
- fix KASAN build
- optimize memset
Matteo Croce (3):
riscv: optimized memcpy
riscv: optimized memmove
riscv: optimized memset
arch/riscv/include/asm/string.h | 18 ++--
arch/riscv/kernel/Makefile | 1 -
arch/riscv/kernel/riscv_ksyms.c | 17 ----
arch/riscv/lib/Makefile | 4 +-
arch/riscv/lib/memcpy.S | 108 ----------------------
arch/riscv/lib/memmove.S | 64 -------------
arch/riscv/lib/memset.S | 113 -----------------------
arch/riscv/lib/string.c | 154 ++++++++++++++++++++++++++++++++
8 files changed, 164 insertions(+), 315 deletions(-)
delete mode 100644 arch/riscv/kernel/riscv_ksyms.c
delete mode 100644 arch/riscv/lib/memcpy.S
delete mode 100644 arch/riscv/lib/memmove.S
delete mode 100644 arch/riscv/lib/memset.S
create mode 100644 arch/riscv/lib/string.c
Thanks. These generally look good, but they're failing to build for me.
I'm getting errors along the lines of
arch/riscv/lib/string.c:89:7: error: inlining failed in call to ‘always_inline’ ‘memcpy’: function body can be overwritten at link time
89 | void *memcpy(void *dest, const void *src, size_t count) __weak __alias(__memcpy); | ^~~~~~
arch/riscv/lib/string.c:99:10: note: called from here
99 | return memcpy(dest, src, count);
| ^~~~~~~~~~~~~~~~~~~~~~~~
I'm still a bit behind on email so I'm going to keep going through
patches, but if there's no v5 by the time I get back here then I'll take
a look.
