On Tue, Apr 16, 2024 at 12:04:56AM +0200, Stefan Kanthak wrote:
> "Eric Biggers" <ebiggers@xxxxxxxxxx> wrote:
>
> > On Mon, Apr 15, 2024 at 10:41:07PM +0200, Stefan Kanthak wrote:
> [...]
> >> At last the final change: write the macro straightforward and SIMPLE,
> >> closely matching NIST.FIPS.180-4.pdf and their order of operations.
> >>
> >> @@ ...
> >> +.macro sha256 m0 :req, m1 :req, m2 :req, m3 :req
> >> +.if \@ < 4
> >> + movdqu \@*16(DATA_PTR), \m0
> >> + pshufb SHUF_MASK, \m0 # \m0 = {w(\@*16), w(\@*16+1), w(\@*16+2), w(\@*16+3)}
> >> +.else
> >> + # \m0 = {w(\@*16-16), w(\@*16-15), w(\@*16-14), w(\@*16-13)}
> >> + # \m1 = {w(\@*16-12), w(\@*16-11), w(\@*16-10), w(\@*16-9)}
> >> + # \m2 = {w(\@*16-8), w(\@*16-7), w(\@*16-6), w(\@*16-5)}
> >> + # \m3 = {w(\@*16-4), w(\@*16-3), w(\@*16-2), w(\@*16-1)}
> >> + sha256msg1 \m1, \m0
> >> + movdqa \m3, TMP
> >> + palignr $4, \m2, TMP
> >> + paddd TMP, \m0
> >> + sha256msg2 \m3, \m0 # \m0 = {w(\@*16), w(\@*16+1), w(\@*16+2), w(\@*16+3)}
> >> +.endif
> >> + movdqa (\@-8)*16(SHA256CONSTANTS), MSG
> >> + paddd \m0, MSG
> >> + sha256rnds2 STATE0, STATE1 # STATE1 = {f', e', b', a'}
> >> + punpckhqdq MSG, MSG
> >> + sha256rnds2 STATE1, STATE0 # STATE0 = {f", e", b", a"},
> >> + # STATE1 = {h", g", d", c"}
> >> +.endm
> >>
> >> JFTR: you may simplify this further using .altmacro and generate \m0 to \m3
> >> as MSG%(4-\@&3), MSG%(5-\@&3), MSG%(6-\@&3) and MSG%(7-\@&3) within
> >> the macro, thus getting rid of its 4 arguments.
> >>
> >> @@ ...
> >> +.rept 4 # 4*4*4 rounds
> >> + sha256 MSG0, MSG1, MSG2, MSG3
> >> + sha256 MSG1, MSG2, MSG3, MSG0
> >> + sha256 MSG2, MSG3, MSG0, MSG1
> >> + sha256 MSG3, MSG0, MSG1, MSG2
> >> +.endr
> >
> > Could you please send a real patch, following
> > Documentation/process/submitting-patches.rst? It's hard to understand what
> > you're proposing here.
>
> 1) I replace your macro (which unfortunately follows Tim Chens twisted code)
> COMPLETELY with a clean and simple implementation: message schedule first,
> update of state variables last.
> You don't need ".if \i >= 12 && \i < 60"/".if \i >= 4 && \i < 52" at all!
It's probably intentional that the code does the message schedule computations a
bit ahead of time. This might improve performance by reducing the time spent
waiting for the message schedule.
It would be worth trying a few different variants on different CPUs and seeing
how they actually perform in practice, though.
>
> 2) I replace the .irp which invokes your macro with a .rept: my macro uses \@
> instead of an argument for the round number.
>
> <https://sourceware.org/binutils/docs/as.html#Macro>
The \@ feature is a bit obscure and maybe is best avoided.
- Eric
