[PATCH] riscv: bypass malloc when spl fit boots from ram

[Rick Chen]

> On 12/27/22 21:22, Rick Chen wrote:
> > Hi Samuel,
> >
> > Samuel Holland <samuel at sholland.org> 於 2022年12月28日 週三 上午10:47寫道：
> >>
> >> On 12/22/22 01:21, Rick Chen wrote:
> >>> When fit image boots from ram, the payload will
> >>> be prepared in the address of SPL_LOAD_FIT_ADDRESS.
> >>> In spl fit generic flow, it will malloc another
> >>> memory address and copy whole fit image to this
> >>> malloc address.  But it is un-necessary for booting
> >>> from RAM.
> >>
> >> This should mostly be solved by using `mkimage -E` or binman's
> >> `fit,external-offset`. Then only the FIT structure, without any data,
> >> will be copied.
> >>
> >>> This patch improves this flow by declare the
> >>> board_spl_fit_buffer_addr() to replace the original one.
> >>> The larger image size (eq: Kernel Image 10~20MB), it
> >>> can save more booting time.
> >>>
> >>> Also enhance memcpy function by checking source and
> >>> destination address. If they are the same address,
> >>> just return and don't copy data anymore.
> >>>
> >>> Signed-off-by: Rick Chen <rick at andestech.com>
> >>> ---
> >>>  arch/riscv/lib/memcpy.S |  2 ++
> >>>  arch/riscv/lib/spl.c    | 16 ++++++++++++++++
> >>>  2 files changed, 18 insertions(+)
> >>>
> >>> diff --git a/arch/riscv/lib/memcpy.S b/arch/riscv/lib/memcpy.S
> >>> index 00672c19ad..9884077c93 100644
> >>> --- a/arch/riscv/lib/memcpy.S
> >>> +++ b/arch/riscv/lib/memcpy.S
> >>> @@ -9,6 +9,7 @@
> >>>  /* void *memcpy(void *, const void *, size_t) */
> >>>  ENTRY(__memcpy)
> >>>  WEAK(memcpy)
> >>> +     beq     a0, a1, .copy_end
> >>
> >> I see one call to memcpy() in common/spl/spl_ram.c. I think it would
> >> make more sense to do the check there instead of adding a branch to
> >> every memcpy() call.
> >
> > There is not only one memcpy being called in spl_ram.c during spl
> > booting progress, but also in spl_fit.c .
>
> Either your FIT uses external data, and the one in spl_ram.c is trivial,
> or it uses internal data, and the one in spl_fit.c is unavoidable.
> Either way, there is only one place where this change makes a difference.
>
> > Otherwise I prefer not to modify it in generic flow level but arch
> > level, because the src and dest checking
> > may not be necessary for other booting devices.
>
> I see arch/arm/lib/memcpy.S has similar logic, so other code may be
> depending on this optimization, and there is precedent for this change.
>
> >>
> >>>       /* Save for return value */
> >>>       mv      t6, a0
> >>>
> >>> @@ -121,6 +122,7 @@ WEAK(memcpy)
> >>>  2:
> >>>
> >>>       mv      a0, t6
> >>> +.copy_end:
> >>>       ret
> >>>
> >>>  .Lmisaligned_word_copy:
> >>> diff --git a/arch/riscv/lib/spl.c b/arch/riscv/lib/spl.c
> >>> index f4d3b67e5d..18f86ee207 100644
> >>> --- a/arch/riscv/lib/spl.c
> >>> +++ b/arch/riscv/lib/spl.c
> >>> @@ -61,3 +61,19 @@ void __noreturn jump_to_image_no_args(struct spl_image_info *spl_image)
> >>>  #endif
> >>>       image_entry(gd->arch.boot_hart, fdt_blob);
> >>>  }
> >>> +
> >>> +#ifdef CONFIG_SPL_RAM_SUPPORT
> >>> +struct legacy_img_hdr *spl_get_load_buffer(ssize_t offset, size_t size)
> >>> +{
> >>> +     return (void *)(CONFIG_SPL_LOAD_FIT_ADDRESS + offset);
> >>> +}
> >>> +
> >>> +void *board_spl_fit_buffer_addr(ulong fit_size, int sectors, int bl_len)
> >>> +{
> >>> +     void *buf;
> >>> +
> >>> +     buf = spl_get_load_buffer(0, sectors * bl_len);
> >>> +
> >>> +     return buf;
> >>> +}
> >>> +#endif
> >>
> >> You cannot provide strong definitions of these functions at an
> >> architecture level, as this prevents any board from overriding them.
> >
> > Originally I wanted to put it in arch/riscv/cpu/ax25/spl.c .
> > However It is a fundamental improvement for spl_ram flow, but not
> > likely a private change.
> > That's why I put it here, so that all boards of RISC-V can be benefited.
>
> This change isn't in any way specific to RISC-V. If you want to make
> this generic, it would belong in spl_ram.c. But I still think it is
> inappropriate to provide a strong definition of board_* functions
> outside board code.

OK, I will move it to arch/riscv/cpu/ax25/spl.c.

>
> Regards,
> Samuel
>