The assembly implementations of ladderstep and mul contain register
save prologues that are unnecessary in Go because there are no callee
save registers in the Go ABI. Remove these prologues, update all SP
offsets, and reduce the frame size accordingly.
The SP offsets were updated with:
python -c 'import sys, re; sys.stdout.write(re.sub(r"(\d+)\(SP\)", lambda m: "%d(SP)" % (int(m.group(1))-YYY), sys.stdin.read()))'
where YYY was 64 for mul_amd64.s and 56 for ladderstep_amd64.s.
Change-Id: I728948809f479b1c061cc65167dadad651efab31
Reviewed-on: https://go-review.googlesource.com/31580
Reviewed-by: Adam Langley <agl@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
The curve25519 assembly routines do very non-Go-ABI SP adjustments.
These would thoroughly confuse traceback if it were to fire in one of
these functions (say, because of a signal). Plus, we're about to make
the assembler track SP balance through more operations (which it
should have done all along), and the SP alignment performed by these
functions is going to make the assembler think the SP is out of
balance.
Fix this by eliminating the SP alignment prologue from all four
assembly functions. They don't do any operations that care about SP
alignment, so this is simply unnecessary. square and freeze don't even
use the stack for anything other that saving what were presumably
"callee save" registers in some other ABI, so for these we can
eliminate the stack frame entirely.
Change-Id: If9dbb2fb6800d9cd733daa91f483eb2937e95f0f
Reviewed-on: https://go-review.googlesource.com/31579
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Adam Langley <agl@golang.org>
This consists of ~2000 lines of amd64 assembly and a, much slower,
generic Go version in curve25519.go. The assembly has been ported from
djb's public domain sources and the only semantic alterations are to
deal with Go's split stacks.
R=rsc
CC=golang-dev
https://golang.org/cl/5786045
Russ Cox
Austin Clements
Marga Manterola
Ian Lance Taylor
Adam Langley