ARMv8 assembly pack: add OPENSSL_cleanse.

Reviewed-by: Richard Levitte <levitte@openssl.org>

Configurations/00-base-templates.conf

@@ -245,7 +245,7 @@
     },
     aarch64_asm => {
 	template	=> 1,
-	cpuid_asm_src   => "armcap.c arm64cpuid.S mem_clr.c",
+	cpuid_asm_src   => "armcap.c arm64cpuid.S",
 	ec_asm_src      => "ecp_nistz256.c ecp_nistz256-armv8.S",
 	bn_asm_src      => "bn_asm.c armv8-mont.S",
 	aes_asm_src     => "aes_core.c aes_cbc.c aesv8-armx.S vpaes-armv8.S",

crypto/arm64cpuid.pl

@@ -69,6 +69,37 @@ _armv8_pmull_probe:
 	pmull	v0.1q, v0.1d, v0.1d
 	ret
 .size	_armv8_pmull_probe,.-_armv8_pmull_probe
+
+.globl	OPENSSL_cleanse
+.type	OPENSSL_cleanse,%function
+.align	5
+OPENSSL_cleanse:
+	cbz	x1,.Lret	// len==0?
+	cmp	x1,#15
+	b.hi	.Lot		// len>15
+	nop
+.Little:
+	strb	wzr,[x0],#1	// store byte-by-byte
+	subs	x1,x1,#1
+	b.ne	.Little
+.Lret:	ret
+
+.align	4
+.Lot:	tst	x0,#7
+	b.eq	.Laligned	// inp is aligned
+	strb	wzr,[x0],#1	// store byte-by-byte
+	sub	x1,x1,#1
+	b	.Lot
+
+.align	4
+.Laligned:
+	str	xzr,[x0],#8	// store word-by-word
+	sub	x1,x1,#8
+	tst	x1,#-8
+	b.ne	.Laligned	// len>=8
+	cbnz	x1,.Little	// len!=0?
+	ret
+.size	OPENSSL_cleanse,.-OPENSSL_cleanse
 ___
 
 print $code;