call_with_stack.S

/*
 * arch/arm/lib/call_with_stack.S
 *
 * Copyright (C) 2011 ARM Ltd.
 * Written by Will Deacon <will.deacon@arm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU 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
 */

#include <linux/linkage.h>
#include <asm/assembler.h>

/*
 * void call_with_stack(void (*fn)(void *), void *arg, void *sp)
 *
 * Change the stack to that pointed at by sp, then invoke fn(arg) with
 * the new stack.
 */
ENTRY(call_with_stack)
	str	sp, [r2, #-4]!
	str	lr, [r2, #-4]!

	mov	sp, r2
	mov	r2, r0
	mov	r0, r1

	adr	lr, BSYM(1f)
	mov	pc, r2

1:	ldr	lr, [sp]
	ldr	sp, [sp, #4]
	mov	pc, lr
ENDPROC(call_with_stack)