Import gcrypt public-key cryptography and implement signature checking.

grub-core/lib/libgcrypt/mpi/i586/mpih-rshift.S

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+/* i80586   rshift
+ *
+ *      Copyright (C) 1992, 1994, 1998,
+ *                    2001, 2002 Free Software Foundation, Inc.
+ *
+ * This file is part of Libgcrypt.
+ *
+ * Libgcrypt is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * Libgcrypt is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ *
+ * Note: This code is heavily based on the GNU MP Library.
+ *	 Actually it's the same code with only minor changes in the
+ *	 way the data is stored; this is to support the abstraction
+ *	 of an optional secure memory allocation which may be used
+ *	 to avoid revealing of sensitive data due to paging etc.
+ */
+
+
+#include "sysdep.h"
+#include "asm-syntax.h"
+
+
+
+/*******************
+ * mpi_limb_t
+ * _gcry_mpih_rshift( mpi_ptr_t wp,	(sp + 4)
+ *		   mpi_ptr_t up,	(sp + 8)
+ *		   mpi_size_t usize,	(sp + 12)
+ *		   unsigned cnt)	(sp + 16)
+ */
+
+.text
+	ALIGN (3)
+	.globl C_SYMBOL_NAME(_gcry_mpih_rshift)
+C_SYMBOL_NAME(_gcry_mpih_rshift:)
+	pushl	%edi
+	pushl	%esi
+	pushl	%ebx
+	pushl	%ebp
+
+	movl	20(%esp),%edi		/* res_ptr */
+	movl	24(%esp),%esi		/* s_ptr */
+	movl	28(%esp),%ebp		/* size */
+	movl	32(%esp),%ecx		/* cnt */
+
+/* We can use faster code for shift-by-1 under certain conditions.  */
+	cmp	$1,%ecx
+	jne	Rnormal
+	leal	4(%edi),%eax
+	cmpl	%esi,%eax
+	jnc	Rspecial		/* jump if res_ptr + 1 >= s_ptr */
+	leal	(%edi,%ebp,4),%eax
+	cmpl	%eax,%esi
+	jnc	Rspecial		/* jump if s_ptr >= res_ptr + size */
+
+Rnormal:
+	movl	(%esi),%edx
+	addl	$4,%esi
+	xorl	%eax,%eax
+	shrdl	%cl,%edx,%eax		/* compute carry limb */
+	pushl	%eax			/* push carry limb onto stack */
+
+	decl	%ebp
+	pushl	%ebp
+	shrl	$3,%ebp
+	jz	Rend
+
+	movl	(%edi),%eax		/* fetch destination cache line */
+
+	ALIGN	(2)
+Roop:	movl	28(%edi),%eax		/* fetch destination cache line */
+	movl	%edx,%ebx
+
+	movl	(%esi),%eax
+	movl	4(%esi),%edx
+	shrdl	%cl,%eax,%ebx
+	shrdl	%cl,%edx,%eax
+	movl	%ebx,(%edi)
+	movl	%eax,4(%edi)
+
+	movl	8(%esi),%ebx
+	movl	12(%esi),%eax
+	shrdl	%cl,%ebx,%edx
+	shrdl	%cl,%eax,%ebx
+	movl	%edx,8(%edi)
+	movl	%ebx,12(%edi)
+
+	movl	16(%esi),%edx
+	movl	20(%esi),%ebx
+	shrdl	%cl,%edx,%eax
+	shrdl	%cl,%ebx,%edx
+	movl	%eax,16(%edi)
+	movl	%edx,20(%edi)
+
+	movl	24(%esi),%eax
+	movl	28(%esi),%edx
+	shrdl	%cl,%eax,%ebx
+	shrdl	%cl,%edx,%eax
+	movl	%ebx,24(%edi)
+	movl	%eax,28(%edi)
+
+	addl	$32,%esi
+	addl	$32,%edi
+	decl	%ebp
+	jnz	Roop
+
+Rend:	popl	%ebp
+	andl	$7,%ebp
+	jz	Rend2
+Roop2:	movl	(%esi),%eax
+	shrdl	%cl,%eax,%edx		/* compute result limb */
+	movl	%edx,(%edi)
+	movl	%eax,%edx
+	addl	$4,%esi
+	addl	$4,%edi
+	decl	%ebp
+	jnz	Roop2
+
+Rend2:	shrl	%cl,%edx		/* compute most significant limb */
+	movl	%edx,(%edi)		/* store it */
+
+	popl	%eax			/* pop carry limb */
+
+	popl	%ebp
+	popl	%ebx
+	popl	%esi
+	popl	%edi
+	ret
+
+/* We loop from least significant end of the arrays, which is only
+   permissable if the source and destination don't overlap, since the
+   function is documented to work for overlapping source and destination.
+*/
+
+Rspecial:
+	leal	-4(%edi,%ebp,4),%edi
+	leal	-4(%esi,%ebp,4),%esi
+
+	movl	(%esi),%edx
+	subl	$4,%esi
+
+	decl	%ebp
+	pushl	%ebp
+	shrl	$3,%ebp
+
+	shrl	$1,%edx
+	incl	%ebp
+	decl	%ebp
+	jz	RLend
+
+	movl	(%edi),%eax		/* fetch destination cache line */
+
+	ALIGN	(2)
+RLoop:	movl	-28(%edi),%eax		/* fetch destination cache line */
+	movl	%edx,%ebx
+
+	movl	(%esi),%eax
+	movl	-4(%esi),%edx
+	rcrl	$1,%eax
+	movl	%ebx,(%edi)
+	rcrl	$1,%edx
+	movl	%eax,-4(%edi)
+
+	movl	-8(%esi),%ebx
+	movl	-12(%esi),%eax
+	rcrl	$1,%ebx
+	movl	%edx,-8(%edi)
+	rcrl	$1,%eax
+	movl	%ebx,-12(%edi)
+
+	movl	-16(%esi),%edx
+	movl	-20(%esi),%ebx
+	rcrl	$1,%edx
+	movl	%eax,-16(%edi)
+	rcrl	$1,%ebx
+	movl	%edx,-20(%edi)
+
+	movl	-24(%esi),%eax
+	movl	-28(%esi),%edx
+	rcrl	$1,%eax
+	movl	%ebx,-24(%edi)
+	rcrl	$1,%edx
+	movl	%eax,-28(%edi)
+
+	leal	-32(%esi),%esi		/* use leal not to clobber carry */
+	leal	-32(%edi),%edi
+	decl	%ebp
+	jnz	RLoop
+
+RLend:	popl	%ebp
+	sbbl	%eax,%eax		/* save carry in %eax */
+	andl	$7,%ebp
+	jz	RLend2
+	addl	%eax,%eax		/* restore carry from eax */
+RLoop2: movl	%edx,%ebx
+	movl	(%esi),%edx
+	rcrl	$1,%edx
+	movl	%ebx,(%edi)
+
+	leal	-4(%esi),%esi		/* use leal not to clobber carry */
+	leal	-4(%edi),%edi
+	decl	%ebp
+	jnz	RLoop2
+
+	jmp	RL1
+RLend2: addl	%eax,%eax		/* restore carry from eax */
+RL1:	movl	%edx,(%edi)		/* store last limb */
+
+	movl	$0,%eax
+	rcrl	$1,%eax
+
+	popl	%ebp
+	popl	%ebx
+	popl	%esi
+	popl	%edi
+	ret
+