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setstack.S revision 1.6 
      1 /*	$NetBSD: setstack.S,v 1.6 2013/08/18 06:29:29 matt Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1994 Mark Brinicombe.
      5  * Copyright (c) 1994 Brini.
      6  * All rights reserved.
      7  *
      8  * This code is derived from software written for Brini by Mark Brinicombe
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by Brini.
     21  * 4. The name of the company nor the name of the author may be used to
     22  *    endorse or promote products derived from this software without specific
     23  *    prior written permission.
     24  *
     25  * THIS SOFTWARE IS PROVIDED BY BRINI ``AS IS'' AND ANY EXPRESS OR IMPLIED
     26  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     27  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     28  * IN NO EVENT SHALL BRINI OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
     29  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     30  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
     31  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     35  * SUCH DAMAGE.
     36  *
     37  * RiscBSD kernel project
     38  *
     39  * setstack.S
     40  *
     41  * Miscellaneous routine to play with the stack pointer in different CPU modes
     42  *
     43  * Eventually this routine can be inline assembly.
     44  *
     45  * Created      : 17/09/94
     46  *
     47  * Based of kate/display/setstack.s
     48  */
     49 #include <arm/armreg.h>
     50 #include <machine/asm.h>
     51 
     52 	RCSID("$NetBSD: setstack.S,v 1.6 2013/08/18 06:29:29 matt Exp $")
     53 
     54 /* To set the stack pointer for a particular mode we must switch
     55  * to that mode update the banked r13 and then switch back.
     56  * This routine provides an easy way of doing this for any mode
     57  *
     58  * r0 = CPU mode
     59  * r1 = stackptr
     60  */
     61 
     62 ENTRY(set_stackptr)
     63         mrs	r3, cpsr		/* Switch to the appropriate mode */
     64 	bic	r2, r3, #(PSR_MODE)
     65 	orr	r2, r2, r0
     66         msr	cpsr_c, r2
     67 
     68 	mov	sp, r1			/* Set the stack pointer */
     69 
     70         msr	cpsr_c, r3		/* Restore the old mode */
     71 
     72 	RET				/* Exit */
     73 END(set_stackptr)
     74 
     75 /* To get the stack pointer for a particular mode we must switch
     76  * to that mode copy the banked r13 and then switch back.
     77  * This routine provides an easy way of doing this for any mode
     78  *
     79  * r0 = CPU mode
     80  */
     81 
     82 ENTRY(get_stackptr)
     83         mrs	r3, cpsr		/* Switch to the appropriate mode */
     84 	bic	r2, r3, #(PSR_MODE)
     85 	orr	r2, r2, r0
     86         msr	cpsr_c, r2
     87 
     88 	mov	r0, sp			/* Get the stack pointer */
     89 
     90         msr	cpsr_c, r3		/* Restore the old mode */
     91 
     92 	RET				/* Exit */
     93 END(get_stackptr)
     94 
     95 /* End of setstack.S */
     96