Re: [PATCH V3 3/5] riscv: ftrace: Reduce the detour code size to half

Guo Ren
2022-11-24T02:11:35Z

On Thu, Nov 24, 2022 at 4:00 AM Conor Dooley <conor@kernel.org> wrote:
>
> On Wed, Nov 23, 2022 at 10:39:48AM -0500, guoren@kernel.org wrote:
> > From: Guo Ren <guoren@linux.alibaba.com>
> >
> > Use a temporary register to reduce the size of detour code from
> > 16 bytes to 8 bytes. The previous implementation is from
> > afc76b8b8011 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of
> > MCOUNT").
> >
> > Before the patch:
> > <func_prolog>:
> > 0: REG_S ra, -SZREG(sp)
> > 4: auipc ra, ?
> > 8: jalr ?(ra)
> > 12: REG_L ra, -SZREG(sp)
> > (func_boddy)
> >
> > After the patch:
> > <func_prolog>:
> > 0: auipc t0, ?
> > 4: jalr t0, ?(t0)
> > (func_boddy)
> >
> > Link: https://lore.kernel.org/linux-riscv/20221122075440.1165172-1-suagrfillet@gmail.com/
> > Co-developed-by: Song Shuai <suagrfillet@gmail.com>
> > Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> > Signed-off-by: Guo Ren <guoren@kernel.org>
>
> FYI missing a sign-off from Song Shuai. They were happy with you folding
> their patch in during the discussion linked above - so I suppose that is
> an accidental omission?
My fault, I missed that.

>
> Thanks,
> Conor.
>

--
Best Regards
Guo Ren