sha3: disable s390x assembly

It was integrated in such a way that it made devirtualization
impossible, leading to allocations on every platform.

It can be reintroduced according to AssemblyPolicy and TargetSpecific.

Updates #64897

Change-Id: I3a4edc91185c2928b2c9b80655a2bc8daa6b44e3
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/544816
Reviewed-by: Roland Shoemaker <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Mauri de Souza Meneguzzo <[email protected]>
Auto-Submit: Filippo Valsorda <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>

Author: FiloSottile

sha3/hashes.go

@@ -16,39 +16,27 @@ import (
 // Its generic security strength is 224 bits against preimage attacks,
 // and 112 bits against collision attacks.
 func New224() hash.Hash {
-	if h := new224Asm(); h != nil {
-		return h
-	}
 	return &state{rate: 144, outputLen: 28, dsbyte: 0x06}
 }
 
 // New256 creates a new SHA3-256 hash.
 // Its generic security strength is 256 bits against preimage attacks,
 // and 128 bits against collision attacks.
 func New256() hash.Hash {
-	if h := new256Asm(); h != nil {
-		return h
-	}
 	return &state{rate: 136, outputLen: 32, dsbyte: 0x06}
 }
 
 // New384 creates a new SHA3-384 hash.
 // Its generic security strength is 384 bits against preimage attacks,
 // and 192 bits against collision attacks.
 func New384() hash.Hash {
-	if h := new384Asm(); h != nil {
-		return h
-	}
 	return &state{rate: 104, outputLen: 48, dsbyte: 0x06}
 }
 
 // New512 creates a new SHA3-512 hash.
 // Its generic security strength is 512 bits against preimage attacks,
 // and 256 bits against collision attacks.
 func New512() hash.Hash {
-	if h := new512Asm(); h != nil {
-		return h
-	}
 	return &state{rate: 72, outputLen: 64, dsbyte: 0x06}
 }
 

sha3/hashes_generic.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build gc && !purego
+//go:build gc && !purego && ignore
 
 package sha3
 

sha3/sha3_s390x.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build gc && !purego
+//go:build gc && !purego && ignore
 
 #include "textflag.h"
 

sha3/sha3_s390x.s

@@ -115,19 +115,13 @@ func (c *state) Clone() ShakeHash {
 // Its generic security strength is 128 bits against all attacks if at
 // least 32 bytes of its output are used.
 func NewShake128() ShakeHash {
-	if h := newShake128Asm(); h != nil {
-		return h
-	}
 	return &state{rate: rate128, outputLen: 32, dsbyte: dsbyteShake}
 }
 
 // NewShake256 creates a new SHAKE256 variable-output-length ShakeHash.
 // Its generic security strength is 256 bits against all attacks if
 // at least 64 bytes of its output are used.
 func NewShake256() ShakeHash {
-	if h := newShake256Asm(); h != nil {
-		return h
-	}
 	return &state{rate: rate256, outputLen: 64, dsbyte: dsbyteShake}
 }