On Fri, Oct 8, 2021 at 3:26 AM Palmer Dabbelt <palmer@xxxxxxxxxxx> wrote:
>
> 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.
I've sent a v5 here:
https://lore.kernel.org/linux-riscv/20210929172234.31620-1-mcroce@xxxxxxxxxxxxxxxxxxx/
Regards,
--
per aspera ad upstream
