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

[Rick Chen]

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 .
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.

>
> >       /* 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.

Thanks,
Rick

>
> Regards,
> Samuel
>