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Fix unrolled montgomery multiplication for POWER9

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In the reference C implementation in bn_asm.c, tp[num + 1] contains the
carry bit for accumulations into tp[num]. tp[num + 1] is only ever
assigned, never itself incremented.

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18883)
This commit is contained in:
Rohan McLure 2022-06-30 16:21:06 +10:00 committed by Tomas Mraz
parent eae70100fa
commit 2f1112b22a
1 changed files with 4 additions and 2 deletions
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6
crypto/bn/asm/ppc64-mont-fixed.pl
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@ -63,6 +63,7 @@ my $SIZE_T= 8;
# Registers are global so the code is remotely readable
# Parameters for Montgomery multiplication
my $ze = "r0";
my $sp = "r1";
my $toc = "r2";
my $rp = "r3";
@ -192,6 +193,7 @@ ___
$self->save_registers();
$self->add_code(<<___);
li $ze,0
ld $n0,0($n0)
ld $bp0,0($bp)
@ -242,7 +244,7 @@ ___
$self->add_code(<<___);
addc $tp[$n],$tp[$n],$c0
addze $tp[$n+1],$tp[$n+1]
addze $tp[$n+1],$ze
___
$self->add_code(<<___);
@ -272,7 +274,7 @@ ___
and. $tp[$n],$tp[$n],$tp[$n]
bne $label->{"sub"}
cmpld $tp[$n-1],$npj
cmpld $tp[$n-1],$npj
blt $label->{"copy"}
$label->{"sub"}: