openssl/crypto/modes/asm/ghash-riscv64.pl
Henry Brausen 999376dcf3 Add clmul-based gmult for riscv64 with Zbb, Zbc
ghash-riscv64.pl implements 128-bit galois field multiplication for
use in the GCM mode using RISC-V carryless multiplication primitives.

The clmul-accelerated routine can be selected by setting the Zbb and
Zbc bits of the OPENSSL_riscvcap environment variable at runtime.

Reviewed-by: Philipp Tomsich <philipp.tomsich@vrull.eu>
Signed-off-by: Henry Brausen <henry.brausen@vrull.eu>

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17640)
2022-05-19 16:32:49 +10:00

299 lines
8.7 KiB
Perl

#! /usr/bin/env perl
# Copyright 2022 The OpenSSL Project Authors. All Rights Reserved.
#
# Licensed under the Apache License 2.0 (the "License"). You may not use
# this file except in compliance with the License. You can obtain a copy
# in the file LICENSE in the source distribution or at
# https://www.openssl.org/source/license.html
# $output is the last argument if it looks like a file (it has an extension)
# $flavour is the first argument if it doesn't look like a file
$output = $#ARGV >= 0 && $ARGV[$#ARGV] =~ m|\.\w+$| ? pop : undef;
$flavour = $#ARGV >= 0 && $ARGV[0] !~ m|\.| ? shift : undef;
$output and open STDOUT,">$output";
my @regs = map("x$_",(0..31));
my @regaliases = ('zero','ra','sp','gp','tp','t0','t1','t2','s0','s1',
map("a$_",(0..7)),
map("s$_",(2..11)),
map("t$_",(3..6))
);
my %reglookup;
@reglookup{@regs} = @regs;
@reglookup{@regaliases} = @regs;
# Takes a register name, possibly an alias, and converts it to a register index
# from 0 to 31
sub read_reg {
my $reg = lc shift;
if (!exists($reglookup{$reg})) {
die("Unknown register ".$reg);
}
my $regstr = $reglookup{$reg};
if (!($regstr =~ /^x([0-9]+)$/)) {
die("Could not process register ".$reg);
}
return $1;
}
sub rv64_rev8 {
# Encoding for rev8 rd, rs instruction on RV64
# XXXXXXXXXXXXX_ rs _XXX_ rd _XXXXXXX
my $template = 0b011010111000_00000_101_00000_0010011;
my $rd = read_reg shift;
my $rs = read_reg shift;
return ".word ".($template | ($rs << 15) | ($rd << 7));
}
sub rv64_clmul {
# Encoding for clmul rd, rs1, rs2 instruction on RV64
# XXXXXXX_ rs2 _ rs1 _XXX_ rd _XXXXXXX
my $template = 0b0000101_00000_00000_001_00000_0110011;
my $rd = read_reg shift;
my $rs1 = read_reg shift;
my $rs2 = read_reg shift;
return ".word ".($template | ($rs2 << 20) | ($rs1 << 15) | ($rd << 7));
}
sub rv64_clmulh {
# Encoding for clmulh rd, rs1, rs2 instruction on RV64
# XXXXXXX_ rs2 _ rs1 _XXX_ rd _XXXXXXX
my $template = 0b0000101_00000_00000_011_00000_0110011;
my $rd = read_reg shift;
my $rs1 = read_reg shift;
my $rs2 = read_reg shift;
return ".word ".($template | ($rs2 << 20) | ($rs1 << 15) | ($rd << 7));
}
################################################################################
# gcm_init_clmul_rv64i_zbb_zbc(u128 Htable[16], const u64 Xi[2])
# Initialization function for clmul-based implementation of GMULT
# This function is used in tandem with gcm_gmult_clmul_rv64i_zbb_zbc
################################################################################
{
my ($Haddr,$Xi,$TEMP) = ("a0","a1","a2");
$code .= <<___;
.text
.balign 16
.globl gcm_init_clmul_rv64i_zbb_zbc
.type gcm_init_clmul_rv64i_zbb_zbc,\@function
# Initialize clmul-based implementation of galois field multiplication routine.
# gcm_init_clmul_rv64i_zbb_zbc(ctx->Htable, ctx->H.u)
gcm_init_clmul_rv64i_zbb_zbc:
# argument 0 = ctx->Htable (store H here)
# argument 1 = H.u[] (2x 64-bit words) [H_high64, H_low64]
# Simply store [H_high64, H_low64] for later
ld $TEMP,0($Xi)
sd $TEMP,0($Haddr)
ld $TEMP,8($Xi)
sd $TEMP,8($Haddr)
ret
___
}
################################################################################
# gcm_gmult_clmul_rv64i_zbb_zbc(u64 Xi[2], const u128 Htable[16])
# Compute GMULT (X*H mod f) using the Zbc (clmul) and Zbb (basic bit manip)
# extensions, and the Modified Barrett Reduction technique
################################################################################
{
my ($Xi,$Haddr,$A1,$A0,$B1,$B0,$C1,$C0,$D1,$D0,$E1,$E0,$TEMP,$TEMP2,$qp_low) =
("a0","a1","a2","a3","a4","a5","a6","a7","t0","t1","t2","t3","t4","t5","t6");
$code .= <<___;
.text
.balign 16
.globl gcm_gmult_clmul_rv64i_zbb_zbc
.type gcm_gmult_clmul_rv64i_zbb_zbc,\@function
# static void gcm_gmult_clmul_rv64i_zbb_zbc(u64 Xi[2], const u128 Htable[16])
# Computes product of X*H mod f
gcm_gmult_clmul_rv64i_zbb_zbc:
# Load X and H (H is saved previously in gcm_init_clmul_rv64i_zbb_zbc)
ld $A1,0($Xi)
ld $A0,8($Xi)
ld $B1,0($Haddr)
ld $B0,8($Haddr)
li $qp_low,0xe100000000000000
# Perform Katratsuba Multiplication to generate a 255-bit intermediate
# A = [A1:A0]
# B = [B1:B0]
# Let:
# [C1:C0] = A1*B1
# [D1:D0] = A0*B0
# [E1:E0] = (A0+A1)*(B0+B1)
# Then:
# A*B = [C1:C0+C1+D1+E1:D1+C0+D0+E0:D0]
@{[rv64_rev8 $A1, $A1]}
@{[rv64_clmul $C0,$A1,$B1]}
@{[rv64_clmulh $C1,$A1,$B1]}
@{[rv64_rev8 $A0,$A0]}
@{[rv64_clmul $D0,$A0,$B0]}
@{[rv64_clmulh $D1,$A0,$B0]}
xor $TEMP,$A0,$A1
xor $TEMP2,$B0,$B1
@{[rv64_clmul $E0,$TEMP,$TEMP2]}
@{[rv64_clmulh $E1,$TEMP,$TEMP2]}
# 0th term is just C1
# Construct term 1 in E1 (E1 only appears in dword 1)
xor $E1,$E1,$D1
xor $E1,$E1,$C1
xor $E1,$E1,$C0
# Term 1 is E1
# Construct term 2 in E0 (E0 only appears in dword 2)
xor $E0,$E0,$D0
xor $E0,$E0,$C0
xor $E0,$E0,$D1
# Term 2 is E0
# final term is just D0
# X*H is now stored in [C1,E1,E0,D0]
# Left-justify
slli $C1,$C1,1
# Or in the high bit of E1
srli $TEMP,$E1,63
or $C1,$C1,$TEMP
slli $E1,$E1,1
# Or in the high bit of E0
srli $TEMP2,$E0,63
or $E1,$E1,$TEMP2
slli $E0,$E0,1
# Or in the high bit of D0
srli $TEMP,$D0,63
or $E0,$E0,$TEMP
slli $D0,$D0,1
# Barrett Reduction
# c = [E0, D0]
# We want the top 128 bits of the result of c*f
# We'll get this by computing the low-half (most significant 128 bits in
# the reflected domain) of clmul(c,fs)<<1 first, then
# xor in c to complete the calculation
# AA = [AA1:AA0] = [E0,D0] = c
# BB = [BB1:BB0] = [qp_low,0]
# [CC1:CC0] = AA1*BB1
# [DD1:DD0] = AA0*BB0
# [EE1:EE0] = (AA0+AA1)*(BB0+BB1)
# Then:
# AA*BB = [CC1:CC0+CC1+DD1+EE1:DD1+CC0+DD0+EE0:DD0]
# We only need CC0,DD1,DD0,EE0 to compute the low 128 bits of c * qp_low
___
my ($CC0,$EE0,$AA1,$AA0,$BB1) = ($A0,$B1,$E0,$D0,$qp_low);
$code .= <<___;
@{[rv64_clmul $CC0,$AA1,$BB1]}
#clmul DD0,AA0,BB0 # BB0 is 0, so DD0 = 0
#clmulh DD1,AA0,BB0 # BB0 is 0, so DD1 = 0
xor $TEMP,$AA0,$AA1
#xor TEMP2,BB0,BB1 # TEMP2 = BB1 = qp_low
@{[rv64_clmul $EE0,$TEMP,$BB1]}
# Result is [N/A:N/A:DD1+CC0+DD0+EE0:DD0]
# Simplifying: [CC0+EE0:0]
xor $TEMP2,$CC0,$EE0
# Shift left by 1 to correct for bit reflection
slli $TEMP2,$TEMP2,1
# xor into c = [E0,D0]
# Note that only E0 is affected
xor $E0,$E0,$TEMP2
# Now, q = [E0,D0]
# The final step is to compute clmul(q,[qp_low:0])<<1
# The leftmost 128 bits are the reduced result.
# Once again, we use Karatsuba multiplication, but many of the terms
# simplify or cancel out.
# AA = [AA1:AA0] = [E0,D0] = c
# BB = [BB1:BB0] = [qp_low,0]
# [CC1:CC0] = AA1*BB1
# [DD1:DD0] = AA0*BB0
# [EE1:EE0] = (AA0+AA1)*(BB0+BB1)
# Then:
# AA*BB = [CC1:CC0+CC1+DD1+EE1:DD1+CC0+DD0+EE0:DD0]
# We need CC1,CC0,DD0,DD1,EE1,EE0 to compute the leftmost 128 bits of AA*BB
___
my ($AA1,$AA0,$BB1,$CC1,$CC0,$EE1,$EE0) = ($E0,$D0,$qp_low,$A0,$A1,$C0,$B0);
$code .= <<___;
@{[rv64_clmul $CC0,$AA1,$BB1]}
@{[rv64_clmulh $CC1,$AA1,$BB1]}
#clmul DD0,AA0,BB0 # BB0 = 0 so DD0 = 0
#clmulh DD1,AA0,BB0 # BB0 = 0 so DD1 = 0
xor $TEMP,$AA0,$AA1
#xor TEMP2,BB0,BB1 # BB0 = 0 to TEMP2 == BB1 == qp_low
@{[rv64_clmul $EE0,$TEMP,$BB1]}
@{[rv64_clmulh $EE1,$TEMP,$BB1]}
# Need the DD1+CC0+DD0+EE0 term to shift its leftmost bit into the
# intermediate result.
# This is just CC0+EE0, store it in TEMP
xor $TEMP,$CC0,$EE0
# Result is [CC1:CC0+CC1+EE1:(a single bit)]<<1
# Combine into [CC1:CC0]
xor $CC0,$CC0,$CC1
xor $CC0,$CC0,$EE1
# Shift 128-bit quantity, xor in [C1,E1] and store
slli $CC1,$CC1,1
srli $TEMP2,$CC0,63
or $CC1,$CC1,$TEMP2
# xor in C1
xor $CC1,$CC1,$C1
@{[rv64_rev8 $CC1,$CC1]}
slli $CC0,$CC0,1
srli $TEMP,$TEMP,63
or $CC0,$CC0,$TEMP
# xor in E1
xor $CC0,$CC0,$E1
@{[rv64_rev8 $CC0,$CC0]}
sd $CC1,0(a0)
sd $CC0,8(a0)
ret
___
}
print $code;
close STDOUT or die "error closing STDOUT: $!";