From: Andy Polyakov <appro@openssl.org>
Date: Wed, 3 Feb 2016 10:26:11 +0000 (+0100)
Subject: ec/asm/ecp_nistz256-x86_64.pl: get corner case logic right.
X-Git-Tag: OpenSSL_1_0_2g~21
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=64333004a41a9f4aa587b8e5401420fb70d00687;p=oweals%2Fopenssl.git

ec/asm/ecp_nistz256-x86_64.pl: get corner case logic right.

RT#4284

Reviewed-by: Rich Salz <rsalz@openssl.org>
(cherry picked from commit d93753412b455907b4dc09427ccd2382209d9af2)
---

diff --git a/crypto/ec/asm/ecp_nistz256-x86_64.pl b/crypto/ec/asm/ecp_nistz256-x86_64.pl
index e6acfd59f0..7140860e24 100755
--- a/crypto/ec/asm/ecp_nistz256-x86_64.pl
+++ b/crypto/ec/asm/ecp_nistz256-x86_64.pl
@@ -2001,6 +2001,7 @@ $code.=<<___;
 	push	%r15
 	sub	\$32*5+8, %rsp
 
+.Lpoint_double_shortcut$x:
 	movdqu	0x00($a_ptr), %xmm0		# copy	*(P256_POINT *)$a_ptr.x
 	mov	$a_ptr, $b_ptr			# backup copy
 	movdqu	0x10($a_ptr), %xmm1
@@ -2291,6 +2292,7 @@ $code.=<<___;
 	 mov	0x40+8*1($b_ptr), $acc6
 	 mov	0x40+8*2($b_ptr), $acc7
 	 mov	0x40+8*3($b_ptr), $acc0
+	movq	$b_ptr, %xmm1
 
 	lea	0x40-$bias($b_ptr), $a_ptr
 	lea	$Z1sqr(%rsp), $r_ptr		# Z1^2
@@ -2346,7 +2348,7 @@ $code.=<<___;
 	test	$acc0, $acc0
 	jnz	.Ladd_proceed$x			# (in1infty || in2infty)?
 	test	$acc1, $acc1
-	jz	.Ladd_proceed$x			# is_equal(S1,S2)?
+	jz	.Ladd_double$x			# is_equal(S1,S2)?
 
 	movq	%xmm0, $r_ptr			# restore $r_ptr
 	pxor	%xmm0, %xmm0
@@ -2358,6 +2360,13 @@ $code.=<<___;
 	movdqu	%xmm0, 0x50($r_ptr)
 	jmp	.Ladd_done$x
 
+.align	32
+.Ladd_double$x:
+	movq	%xmm1, $a_ptr			# restore $a_ptr
+	movq	%xmm0, $r_ptr			# restore $r_ptr
+	add	\$`32*(18-5)`, %rsp		# difference in frame sizes
+	jmp	.Lpoint_double_shortcut$x
+
 .align	32
 .Ladd_proceed$x:
 	`&load_for_sqr("$R(%rsp)", "$src0")`