Commit b62b2454 authored by Andy Polyakov's avatar Andy Polyakov Committed by Matt Caswell
Browse files

ec/asm/ecp_nistz256-x86_64.pl: addition to perform stricter reduction. 



Addition was not preserving inputs' property of being fully reduced.

Thanks to Brian Smith for reporting this.

Reviewed-by: default avatarRich Salz <rsalz@openssl.org>
parent 9e421962

crypto/ec/asm/ecp_nistz256-x86_64.pl

+60 −55
Original line number Diff line number Diff line
@@ -135,6 +135,7 @@ ecp_nistz256_mul_by_2: 
	push	%r13



	mov	8*0($a_ptr), $a0

	xor	$t4,$t4

	mov	8*1($a_ptr), $a1

	add	$a0, $a0		# a0:a3+a0:a3

	mov	8*2($a_ptr), $a2
@@ -145,7 +146,7 @@ ecp_nistz256_mul_by_2: 
	adc	$a2, $a2

	adc	$a3, $a3

	 mov	$a1, $t1

	sbb	$t4, $t4

	adc	\$0, $t4



	sub	8*0($a_ptr), $a0

	 mov	$a2, $t2
@@ -153,14 +154,14 @@ ecp_nistz256_mul_by_2: 
	sbb	8*2($a_ptr), $a2

	 mov	$a3, $t3

	sbb	8*3($a_ptr), $a3

	test	$t4, $t4

	sbb	\$0, $t4



	cmovz	$t0, $a0

	cmovz	$t1, $a1

	cmovb	$t0, $a0

	cmovb	$t1, $a1

	mov	$a0, 8*0($r_ptr)

	cmovz	$t2, $a2

	cmovb	$t2, $a2

	mov	$a1, 8*1($r_ptr)

	cmovz	$t3, $a3

	cmovb	$t3, $a3

	mov	$a2, 8*2($r_ptr)

	mov	$a3, 8*3($r_ptr)
@@ -257,12 +258,12 @@ ecp_nistz256_mul_by_3: 
	sbb	\$0, $a2

	 mov	$a3, $t3

	sbb	.Lpoly+8*3(%rip), $a3

	test	$t4, $t4

	sbb	\$0, $t4



	cmovz	$t0, $a0

	cmovz	$t1, $a1

	cmovz	$t2, $a2

	cmovz	$t3, $a3

	cmovb	$t0, $a0

	cmovb	$t1, $a1

	cmovb	$t2, $a2

	cmovb	$t3, $a3



	xor	$t4, $t4

	add	8*0($a_ptr), $a0	# a0:a3+=a_ptr[0:3]
@@ -279,14 +280,14 @@ ecp_nistz256_mul_by_3: 
	sbb	\$0, $a2

	 mov	$a3, $t3

	sbb	.Lpoly+8*3(%rip), $a3

	test	$t4, $t4

	sbb	\$0, $t4



	cmovz	$t0, $a0

	cmovz	$t1, $a1

	cmovb	$t0, $a0

	cmovb	$t1, $a1

	mov	$a0, 8*0($r_ptr)

	cmovz	$t2, $a2

	cmovb	$t2, $a2

	mov	$a1, 8*1($r_ptr)

	cmovz	$t3, $a3

	cmovb	$t3, $a3

	mov	$a2, 8*2($r_ptr)

	mov	$a3, 8*3($r_ptr)
@@ -325,14 +326,14 @@ ecp_nistz256_add: 
	sbb	8*2($a_ptr), $a2

	 mov	$a3, $t3

	sbb	8*3($a_ptr), $a3

	test	$t4, $t4

	sbb	\$0, $t4



	cmovz	$t0, $a0

	cmovz	$t1, $a1

	cmovb	$t0, $a0

	cmovb	$t1, $a1

	mov	$a0, 8*0($r_ptr)

	cmovz	$t2, $a2

	cmovb	$t2, $a2

	mov	$a1, 8*1($r_ptr)

	cmovz	$t3, $a3

	cmovb	$t3, $a3

	mov	$a2, 8*2($r_ptr)

	mov	$a3, 8*3($r_ptr)
@@ -1890,13 +1891,14 @@ $code.=<<___; 
.type	__ecp_nistz256_add_toq,\@abi-omnipotent

.align	32

__ecp_nistz256_add_toq:

	xor	$t4,$t4

	add	8*0($b_ptr), $a0

	adc	8*1($b_ptr), $a1

	 mov	$a0, $t0

	adc	8*2($b_ptr), $a2

	adc	8*3($b_ptr), $a3

	 mov	$a1, $t1

	sbb	$t4, $t4

	adc	\$0, $t4



	sub	\$-1, $a0

	 mov	$a2, $t2
@@ -1904,14 +1906,14 @@ __ecp_nistz256_add_toq: 
	sbb	\$0, $a2

	 mov	$a3, $t3

	sbb	$poly3, $a3

	test	$t4, $t4

	sbb	\$0, $t4



	cmovz	$t0, $a0

	cmovz	$t1, $a1

	cmovb	$t0, $a0

	cmovb	$t1, $a1

	mov	$a0, 8*0($r_ptr)

	cmovz	$t2, $a2

	cmovb	$t2, $a2

	mov	$a1, 8*1($r_ptr)

	cmovz	$t3, $a3

	cmovb	$t3, $a3

	mov	$a2, 8*2($r_ptr)

	mov	$a3, 8*3($r_ptr)
@@ -1979,13 +1981,14 @@ __ecp_nistz256_subq: 
.type	__ecp_nistz256_mul_by_2q,\@abi-omnipotent

.align	32

__ecp_nistz256_mul_by_2q:

	xor	$t4, $t4

	add	$a0, $a0		# a0:a3+a0:a3

	adc	$a1, $a1

	 mov	$a0, $t0

	adc	$a2, $a2

	adc	$a3, $a3

	 mov	$a1, $t1

	sbb	$t4, $t4

	adc	\$0, $t4



	sub	\$-1, $a0

	 mov	$a2, $t2
@@ -1993,14 +1996,14 @@ __ecp_nistz256_mul_by_2q: 
	sbb	\$0, $a2

	 mov	$a3, $t3

	sbb	$poly3, $a3

	test	$t4, $t4

	sbb	\$0, $t4



	cmovz	$t0, $a0

	cmovz	$t1, $a1

	cmovb	$t0, $a0

	cmovb	$t1, $a1

	mov	$a0, 8*0($r_ptr)

	cmovz	$t2, $a2

	cmovb	$t2, $a2

	mov	$a1, 8*1($r_ptr)

	cmovz	$t3, $a3

	cmovb	$t3, $a3

	mov	$a2, 8*2($r_ptr)

	mov	$a3, 8*3($r_ptr)
@@ -2455,6 +2458,7 @@ $code.=<<___; 
	#lea	$Hsqr(%rsp), $r_ptr	# 2*U1*H^2

	#call	__ecp_nistz256_mul_by_2	# ecp_nistz256_mul_by_2(Hsqr, U2);



	xor	$t4, $t4

	add	$acc0, $acc0		# a0:a3+a0:a3

	lea	$Rsqr(%rsp), $a_ptr

	adc	$acc1, $acc1
@@ -2462,7 +2466,7 @@ $code.=<<___; 
	adc	$acc2, $acc2

	adc	$acc3, $acc3

	 mov	$acc1, $t1

	sbb	$t4, $t4

	adc	\$0, $t4



	sub	\$-1, $acc0

	 mov	$acc2, $t2
@@ -2470,15 +2474,15 @@ $code.=<<___; 
	sbb	\$0, $acc2

	 mov	$acc3, $t3

	sbb	$poly3, $acc3

	test	$t4, $t4

	sbb	\$0, $t4



	cmovz	$t0, $acc0

	cmovb	$t0, $acc0

	mov	8*0($a_ptr), $t0

	cmovz	$t1, $acc1

	cmovb	$t1, $acc1

	mov	8*1($a_ptr), $t1

	cmovz	$t2, $acc2

	cmovb	$t2, $acc2

	mov	8*2($a_ptr), $t2

	cmovz	$t3, $acc3

	cmovb	$t3, $acc3

	mov	8*3($a_ptr), $t3



	call	__ecp_nistz256_sub$x		# p256_sub(res_x, Rsqr, Hsqr);
@@ -2760,6 +2764,7 @@ $code.=<<___; 
	#lea	$Hsqr(%rsp), $r_ptr	# 2*U1*H^2

	#call	__ecp_nistz256_mul_by_2	# ecp_nistz256_mul_by_2(Hsqr, U2);



	xor	$t4, $t4

	add	$acc0, $acc0		# a0:a3+a0:a3

	lea	$Rsqr(%rsp), $a_ptr

	adc	$acc1, $acc1
@@ -2767,7 +2772,7 @@ $code.=<<___; 
	adc	$acc2, $acc2

	adc	$acc3, $acc3

	 mov	$acc1, $t1

	sbb	$t4, $t4

	adc	\$0, $t4



	sub	\$-1, $acc0

	 mov	$acc2, $t2
@@ -2775,15 +2780,15 @@ $code.=<<___; 
	sbb	\$0, $acc2

	 mov	$acc3, $t3

	sbb	$poly3, $acc3

	test	$t4, $t4

	sbb	\$0, $t4



	cmovz	$t0, $acc0

	cmovb	$t0, $acc0

	mov	8*0($a_ptr), $t0

	cmovz	$t1, $acc1

	cmovb	$t1, $acc1

	mov	8*1($a_ptr), $t1

	cmovz	$t2, $acc2

	cmovb	$t2, $acc2

	mov	8*2($a_ptr), $t2

	cmovz	$t3, $acc3

	cmovb	$t3, $acc3

	mov	8*3($a_ptr), $t3



	call	__ecp_nistz256_sub$x		# p256_sub(res_x, Rsqr, Hsqr);
@@ -2935,14 +2940,14 @@ __ecp_nistz256_add_tox: 
	sbb	\$0, $a2

	 mov	$a3, $t3

	sbb	$poly3, $a3

	sbb	\$0, $t4



	bt	\$0, $t4

	cmovnc	$t0, $a0

	cmovnc	$t1, $a1

	cmovb	$t0, $a0

	cmovb	$t1, $a1

	mov	$a0, 8*0($r_ptr)

	cmovnc	$t2, $a2

	cmovb	$t2, $a2

	mov	$a1, 8*1($r_ptr)

	cmovnc	$t3, $a3

	cmovb	$t3, $a3

	mov	$a2, 8*2($r_ptr)

	mov	$a3, 8*3($r_ptr)
@@ -3030,14 +3035,14 @@ __ecp_nistz256_mul_by_2x: 
	sbb	\$0, $a2

	 mov	$a3, $t3

	sbb	$poly3, $a3

	sbb	\$0, $t4



	bt	\$0, $t4

	cmovnc	$t0, $a0

	cmovnc	$t1, $a1

	cmovb	$t0, $a0

	cmovb	$t1, $a1

	mov	$a0, 8*0($r_ptr)

	cmovnc	$t2, $a2

	cmovb	$t2, $a2

	mov	$a1, 8*1($r_ptr)

	cmovnc	$t3, $a3

	cmovb	$t3, $a3

	mov	$a2, 8*2($r_ptr)

	mov	$a3, 8*3($r_ptr)

crypto/ec/ecp_nistz256.c

+24 −7
Original line number Diff line number Diff line
@@ -89,19 +89,36 @@ struct nistz256_pre_comp_st { 
};



/* Functions implemented in assembly */

/*

 * Most of below mentioned functions *preserve* the property of inputs

 * being fully reduced, i.e. being in [0, modulus) range. Simply put if

 * inputs are fully reduced, then output is too. Note that reverse is

 * not true, in sense that given partially reduced inputs output can be

 * either, not unlikely reduced. And "most" in first sentence refers to

 * the fact that given the calculations flow one can tolerate that

 * addition, 1st function below, produces partially reduced result *if*

 * multiplications by 2 and 3, which customarily use addition, fully

 * reduce it. This effectively gives two options: a) addition produces

 * fully reduced result [as long as inputs are, just like remaining

 * functions]; b) addition is allowed to produce partially reduced

 * result, but multiplications by 2 and 3 perform additional reduction

 * step. Choice between the two can be platform-specific, but it was a)

 * in all cases so far...

 */

/* Modular add: res = a+b mod P   */

void ecp_nistz256_add(BN_ULONG res[P256_LIMBS],

                      const BN_ULONG a[P256_LIMBS],

                      const BN_ULONG b[P256_LIMBS]);

/* Modular mul by 2: res = 2*a mod P */

void ecp_nistz256_mul_by_2(BN_ULONG res[P256_LIMBS],

                           const BN_ULONG a[P256_LIMBS]);

/* Modular div by 2: res = a/2 mod P */

void ecp_nistz256_div_by_2(BN_ULONG res[P256_LIMBS],

                           const BN_ULONG a[P256_LIMBS]);

/* Modular mul by 3: res = 3*a mod P */

void ecp_nistz256_mul_by_3(BN_ULONG res[P256_LIMBS],

                           const BN_ULONG a[P256_LIMBS]);

/* Modular add: res = a+b mod P   */

void ecp_nistz256_add(BN_ULONG res[P256_LIMBS],

                      const BN_ULONG a[P256_LIMBS],

                      const BN_ULONG b[P256_LIMBS]);



/* Modular div by 2: res = a/2 mod P */

void ecp_nistz256_div_by_2(BN_ULONG res[P256_LIMBS],

                           const BN_ULONG a[P256_LIMBS]);

/* Modular sub: res = a-b mod P   */

void ecp_nistz256_sub(BN_ULONG res[P256_LIMBS],

                      const BN_ULONG a[P256_LIMBS],