1 // Copyright 2018 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // +build s390x,go1.11,!gccgo,!appengine 6 7 package poly1305 8 9 import ( 10 "golang.org/x/sys/cpu" 11 ) 12 13 // poly1305vx is an assembly implementation of Poly1305 that uses vector 14 // instructions. It must only be called if the vector facility (vx) is 15 // available. 16 //go:noescape 17 func poly1305vx(out *[16]byte, m *byte, mlen uint64, key *[32]byte) 18 19 // poly1305vmsl is an assembly implementation of Poly1305 that uses vector 20 // instructions, including VMSL. It must only be called if the vector facility (vx) is 21 // available and if VMSL is supported. 22 //go:noescape 23 func poly1305vmsl(out *[16]byte, m *byte, mlen uint64, key *[32]byte) 24 25 // Sum generates an authenticator for m using a one-time key and puts the 26 // 16-byte result into out. Authenticating two different messages with the same 27 // key allows an attacker to forge messages at will. 28 func Sum(out *[16]byte, m []byte, key *[32]byte) { 29 if cpu.S390X.HasVX { 30 var mPtr *byte 31 if len(m) > 0 { 32 mPtr = &m[0] 33 } 34 if cpu.S390X.HasVXE && len(m) > 256 { 35 poly1305vmsl(out, mPtr, uint64(len(m)), key) 36 } else { 37 poly1305vx(out, mPtr, uint64(len(m)), key) 38 } 39 } else { 40 sumGeneric(out, m, key) 41 } 42 } 43