arch/arm/mach-ep93xx/crunch-bits.S - kernel/bruno - Git at Google

 /*
  * arch/arm/kernel/crunch-bits.S
  * Cirrus MaverickCrunch context switching and handling
  *
  * Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
  *
  * Shamelessly stolen from the iWMMXt code by Nicolas Pitre, which is
  * Copyright (c) 2003-2004, MontaVista Software, Inc.
  *
  * 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.
  */

 #include <linux/linkage.h>
 #include <asm/ptrace.h>
 #include <asm/thread_info.h>
 #include <asm/asm-offsets.h>
 #include <asm/assembler.h>
 #include <mach/ep93xx-regs.h>

 /*
  * We can't use hex constants here due to a bug in gas.
  */
 #define CRUNCH_MVDX0		0
 #define CRUNCH_MVDX1		8
 #define CRUNCH_MVDX2		16
 #define CRUNCH_MVDX3		24
 #define CRUNCH_MVDX4		32
 #define CRUNCH_MVDX5		40
 #define CRUNCH_MVDX6		48
 #define CRUNCH_MVDX7		56
 #define CRUNCH_MVDX8		64
 #define CRUNCH_MVDX9		72
 #define CRUNCH_MVDX10		80
 #define CRUNCH_MVDX11		88
 #define CRUNCH_MVDX12		96
 #define CRUNCH_MVDX13		104
 #define CRUNCH_MVDX14		112
 #define CRUNCH_MVDX15		120
 #define CRUNCH_MVAX0L		128
 #define CRUNCH_MVAX0M		132
 #define CRUNCH_MVAX0H		136
 #define CRUNCH_MVAX1L		140
 #define CRUNCH_MVAX1M		144
 #define CRUNCH_MVAX1H		148
 #define CRUNCH_MVAX2L		152
 #define CRUNCH_MVAX2M		156
 #define CRUNCH_MVAX2H		160
 #define CRUNCH_MVAX3L		164
 #define CRUNCH_MVAX3M		168
 #define CRUNCH_MVAX3H		172
 #define CRUNCH_DSPSC		176

 #define CRUNCH_SIZE		184

 	.text

 /*
  * Lazy switching of crunch coprocessor context
  *
  * r10 = struct thread_info pointer
  * r9  = ret_from_exception
  * lr  = undefined instr exit
  *
  * called from prefetch exception handler with interrupts enabled
  */
 ENTRY(crunch_task_enable)
 	inc_preempt_count r10, r3

 	ldr	r8, =(EP93XX_APB_VIRT_BASE + 0x00130000)	@ syscon addr

 	ldr	r1, [r8, #0x80]
 	tst	r1, #0x00800000			@ access to crunch enabled?
 	bne	2f				@ if so no business here
 	mov	r3, #0xaa			@ unlock syscon swlock
 	str	r3, [r8, #0xc0]
 	orr	r1, r1, #0x00800000		@ enable access to crunch
 	str	r1, [r8, #0x80]

 	ldr	r3, =crunch_owner
 	add	r0, r10, #TI_CRUNCH_STATE	@ get task crunch save area
 	ldr	r2, [sp, #60]			@ current task pc value
 	ldr	r1, [r3]			@ get current crunch owner
 	str	r0, [r3]			@ this task now owns crunch
 	sub	r2, r2, #4			@ adjust pc back
 	str	r2, [sp, #60]

 	ldr	r2, [r8, #0x80]
 	mov	r2, r2				@ flush out enable (@@@)

 	teq	r1, #0				@ test for last ownership
 	mov	lr, r9				@ normal exit from exception
 	beq	crunch_load			@ no owner, skip save

 crunch_save:
 	cfstr64		mvdx0, [r1, #CRUNCH_MVDX0]	@ save 64b registers
 	cfstr64		mvdx1, [r1, #CRUNCH_MVDX1]
 	cfstr64		mvdx2, [r1, #CRUNCH_MVDX2]
 	cfstr64		mvdx3, [r1, #CRUNCH_MVDX3]
 	cfstr64		mvdx4, [r1, #CRUNCH_MVDX4]
 	cfstr64		mvdx5, [r1, #CRUNCH_MVDX5]
 	cfstr64		mvdx6, [r1, #CRUNCH_MVDX6]
 	cfstr64		mvdx7, [r1, #CRUNCH_MVDX7]
 	cfstr64		mvdx8, [r1, #CRUNCH_MVDX8]
 	cfstr64		mvdx9, [r1, #CRUNCH_MVDX9]
 	cfstr64		mvdx10, [r1, #CRUNCH_MVDX10]
 	cfstr64		mvdx11, [r1, #CRUNCH_MVDX11]
 	cfstr64		mvdx12, [r1, #CRUNCH_MVDX12]
 	cfstr64		mvdx13, [r1, #CRUNCH_MVDX13]
 	cfstr64		mvdx14, [r1, #CRUNCH_MVDX14]
 	cfstr64		mvdx15, [r1, #CRUNCH_MVDX15]

 #ifdef __ARMEB__
 #error fix me for ARMEB
 #endif

 	cfmv32al	mvfx0, mvax0			@ save 72b accumulators
 	cfstr32		mvfx0, [r1, #CRUNCH_MVAX0L]
 	cfmv32am	mvfx0, mvax0
 	cfstr32		mvfx0, [r1, #CRUNCH_MVAX0M]
 	cfmv32ah	mvfx0, mvax0
 	cfstr32		mvfx0, [r1, #CRUNCH_MVAX0H]
 	cfmv32al	mvfx0, mvax1
 	cfstr32		mvfx0, [r1, #CRUNCH_MVAX1L]
 	cfmv32am	mvfx0, mvax1
 	cfstr32		mvfx0, [r1, #CRUNCH_MVAX1M]
 	cfmv32ah	mvfx0, mvax1
 	cfstr32		mvfx0, [r1, #CRUNCH_MVAX1H]
 	cfmv32al	mvfx0, mvax2
 	cfstr32		mvfx0, [r1, #CRUNCH_MVAX2L]
 	cfmv32am	mvfx0, mvax2
 	cfstr32		mvfx0, [r1, #CRUNCH_MVAX2M]
 	cfmv32ah	mvfx0, mvax2
 	cfstr32		mvfx0, [r1, #CRUNCH_MVAX2H]
 	cfmv32al	mvfx0, mvax3
 	cfstr32		mvfx0, [r1, #CRUNCH_MVAX3L]
 	cfmv32am	mvfx0, mvax3
 	cfstr32		mvfx0, [r1, #CRUNCH_MVAX3M]
 	cfmv32ah	mvfx0, mvax3
 	cfstr32		mvfx0, [r1, #CRUNCH_MVAX3H]

 	cfmv32sc	mvdx0, dspsc			@ save status word
 	cfstr64		mvdx0, [r1, #CRUNCH_DSPSC]

 	teq		r0, #0				@ anything to load?
 	cfldr64eq	mvdx0, [r1, #CRUNCH_MVDX0]	@ mvdx0 was clobbered
 	beq		1f

 crunch_load:
 	cfldr64		mvdx0, [r0, #CRUNCH_DSPSC]	@ load status word
 	cfmvsc32	dspsc, mvdx0

 	cfldr32		mvfx0, [r0, #CRUNCH_MVAX0L]	@ load 72b accumulators
 	cfmval32	mvax0, mvfx0
 	cfldr32		mvfx0, [r0, #CRUNCH_MVAX0M]
 	cfmvam32	mvax0, mvfx0
 	cfldr32		mvfx0, [r0, #CRUNCH_MVAX0H]
 	cfmvah32	mvax0, mvfx0
 	cfldr32		mvfx0, [r0, #CRUNCH_MVAX1L]
 	cfmval32	mvax1, mvfx0
 	cfldr32		mvfx0, [r0, #CRUNCH_MVAX1M]
 	cfmvam32	mvax1, mvfx0
 	cfldr32		mvfx0, [r0, #CRUNCH_MVAX1H]
 	cfmvah32	mvax1, mvfx0
 	cfldr32		mvfx0, [r0, #CRUNCH_MVAX2L]
 	cfmval32	mvax2, mvfx0
 	cfldr32		mvfx0, [r0, #CRUNCH_MVAX2M]
 	cfmvam32	mvax2, mvfx0
 	cfldr32		mvfx0, [r0, #CRUNCH_MVAX2H]
 	cfmvah32	mvax2, mvfx0
 	cfldr32		mvfx0, [r0, #CRUNCH_MVAX3L]
 	cfmval32	mvax3, mvfx0
 	cfldr32		mvfx0, [r0, #CRUNCH_MVAX3M]
 	cfmvam32	mvax3, mvfx0
 	cfldr32		mvfx0, [r0, #CRUNCH_MVAX3H]
 	cfmvah32	mvax3, mvfx0

 	cfldr64		mvdx0, [r0, #CRUNCH_MVDX0]	@ load 64b registers
 	cfldr64		mvdx1, [r0, #CRUNCH_MVDX1]
 	cfldr64		mvdx2, [r0, #CRUNCH_MVDX2]
 	cfldr64		mvdx3, [r0, #CRUNCH_MVDX3]
 	cfldr64		mvdx4, [r0, #CRUNCH_MVDX4]
 	cfldr64		mvdx5, [r0, #CRUNCH_MVDX5]
 	cfldr64		mvdx6, [r0, #CRUNCH_MVDX6]
 	cfldr64		mvdx7, [r0, #CRUNCH_MVDX7]
 	cfldr64		mvdx8, [r0, #CRUNCH_MVDX8]
 	cfldr64		mvdx9, [r0, #CRUNCH_MVDX9]
 	cfldr64		mvdx10, [r0, #CRUNCH_MVDX10]
 	cfldr64		mvdx11, [r0, #CRUNCH_MVDX11]
 	cfldr64		mvdx12, [r0, #CRUNCH_MVDX12]
 	cfldr64		mvdx13, [r0, #CRUNCH_MVDX13]
 	cfldr64		mvdx14, [r0, #CRUNCH_MVDX14]
 	cfldr64		mvdx15, [r0, #CRUNCH_MVDX15]

 1:
 #ifdef CONFIG_PREEMPT_COUNT
 	get_thread_info r10
 #endif
 2:	dec_preempt_count r10, r3
 	ret	lr

 /*
  * Back up crunch regs to save area and disable access to them
  * (mainly for gdb or sleep mode usage)
  *
  * r0 = struct thread_info pointer of target task or NULL for any
  */
 ENTRY(crunch_task_disable)
 	stmfd	sp!, {r4, r5, lr}

 	mrs	ip, cpsr
 	orr	r2, ip, #PSR_I_BIT		@ disable interrupts
 	msr	cpsr_c, r2

 	ldr	r4, =(EP93XX_APB_VIRT_BASE + 0x00130000)	@ syscon addr

 	ldr	r3, =crunch_owner
 	add	r2, r0, #TI_CRUNCH_STATE	@ get task crunch save area
 	ldr	r1, [r3]			@ get current crunch owner
 	teq	r1, #0				@ any current owner?
 	beq	1f				@ no: quit
 	teq	r0, #0				@ any owner?
 	teqne	r1, r2				@ or specified one?
 	bne	1f				@ no: quit

 	ldr	r5, [r4, #0x80]			@ enable access to crunch
 	mov	r2, #0xaa
 	str	r2, [r4, #0xc0]
 	orr	r5, r5, #0x00800000
 	str	r5, [r4, #0x80]

 	mov	r0, #0				@ nothing to load
 	str	r0, [r3]			@ no more current owner
 	ldr	r2, [r4, #0x80]			@ flush out enable (@@@)
 	mov	r2, r2
 	bl	crunch_save

 	mov	r2, #0xaa			@ disable access to crunch
 	str	r2, [r4, #0xc0]
 	bic	r5, r5, #0x00800000
 	str	r5, [r4, #0x80]
 	ldr	r5, [r4, #0x80]			@ flush out enable (@@@)
 	mov	r5, r5

 1:	msr	cpsr_c, ip			@ restore interrupt mode
 	ldmfd	sp!, {r4, r5, pc}

 /*
  * Copy crunch state to given memory address
  *
  * r0 = struct thread_info pointer of target task
  * r1 = memory address where to store crunch state
  *
  * this is called mainly in the creation of signal stack frames
  */
 ENTRY(crunch_task_copy)
 	mrs	ip, cpsr
 	orr	r2, ip, #PSR_I_BIT		@ disable interrupts
 	msr	cpsr_c, r2

 	ldr	r3, =crunch_owner
 	add	r2, r0, #TI_CRUNCH_STATE	@ get task crunch save area
 	ldr	r3, [r3]			@ get current crunch owner
 	teq	r2, r3				@ does this task own it...
 	beq	1f

 	@ current crunch values are in the task save area
 	msr	cpsr_c, ip			@ restore interrupt mode
 	mov	r0, r1
 	mov	r1, r2
 	mov	r2, #CRUNCH_SIZE
 	b	memcpy

 1:	@ this task owns crunch regs -- grab a copy from there
 	mov	r0, #0				@ nothing to load
 	mov	r3, lr				@ preserve return address
 	bl	crunch_save
 	msr	cpsr_c, ip			@ restore interrupt mode
 	ret	r3

 /*
  * Restore crunch state from given memory address
  *
  * r0 = struct thread_info pointer of target task
  * r1 = memory address where to get crunch state from
  *
  * this is used to restore crunch state when unwinding a signal stack frame
  */
 ENTRY(crunch_task_restore)
 	mrs	ip, cpsr
 	orr	r2, ip, #PSR_I_BIT		@ disable interrupts
 	msr	cpsr_c, r2

 	ldr	r3, =crunch_owner
 	add	r2, r0, #TI_CRUNCH_STATE	@ get task crunch save area
 	ldr	r3, [r3]			@ get current crunch owner
 	teq	r2, r3				@ does this task own it...
 	beq	1f

 	@ this task doesn't own crunch regs -- use its save area
 	msr	cpsr_c, ip			@ restore interrupt mode
 	mov	r0, r2
 	mov	r2, #CRUNCH_SIZE
 	b	memcpy

 1:	@ this task owns crunch regs -- load them directly
 	mov	r0, r1
 	mov	r1, #0				@ nothing to save
 	mov	r3, lr				@ preserve return address
 	bl	crunch_load
 	msr	cpsr_c, ip			@ restore interrupt mode
 	ret	r3
	/*
	* arch/arm/kernel/crunch-bits.S
	* Cirrus MaverickCrunch context switching and handling
	*
	* Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
	*
	* Shamelessly stolen from the iWMMXt code by Nicolas Pitre, which is
	* Copyright (c) 2003-2004, MontaVista Software, Inc.
	*
	* 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.
	*/

	#include <linux/linkage.h>
	#include <asm/ptrace.h>
	#include <asm/thread_info.h>
	#include <asm/asm-offsets.h>
	#include <asm/assembler.h>
	#include <mach/ep93xx-regs.h>

	/*
	* We can't use hex constants here due to a bug in gas.
	*/
	#define CRUNCH_MVDX0 0
	#define CRUNCH_MVDX1 8
	#define CRUNCH_MVDX2 16
	#define CRUNCH_MVDX3 24
	#define CRUNCH_MVDX4 32
	#define CRUNCH_MVDX5 40
	#define CRUNCH_MVDX6 48
	#define CRUNCH_MVDX7 56
	#define CRUNCH_MVDX8 64
	#define CRUNCH_MVDX9 72
	#define CRUNCH_MVDX10 80
	#define CRUNCH_MVDX11 88
	#define CRUNCH_MVDX12 96
	#define CRUNCH_MVDX13 104
	#define CRUNCH_MVDX14 112
	#define CRUNCH_MVDX15 120
	#define CRUNCH_MVAX0L 128
	#define CRUNCH_MVAX0M 132
	#define CRUNCH_MVAX0H 136
	#define CRUNCH_MVAX1L 140
	#define CRUNCH_MVAX1M 144
	#define CRUNCH_MVAX1H 148
	#define CRUNCH_MVAX2L 152
	#define CRUNCH_MVAX2M 156
	#define CRUNCH_MVAX2H 160
	#define CRUNCH_MVAX3L 164
	#define CRUNCH_MVAX3M 168
	#define CRUNCH_MVAX3H 172
	#define CRUNCH_DSPSC 176

	#define CRUNCH_SIZE 184

	.text

	/*
	* Lazy switching of crunch coprocessor context
	*
	* r10 = struct thread_info pointer
	* r9 = ret_from_exception
	* lr = undefined instr exit
	*
	* called from prefetch exception handler with interrupts enabled
	*/
	ENTRY(crunch_task_enable)
	inc_preempt_count r10, r3

	ldr r8, =(EP93XX_APB_VIRT_BASE + 0x00130000) @ syscon addr

	ldr r1, [r8, #0x80]
	tst r1, #0x00800000 @ access to crunch enabled?
	bne 2f @ if so no business here
	mov r3, #0xaa @ unlock syscon swlock
	str r3, [r8, #0xc0]
	orr r1, r1, #0x00800000 @ enable access to crunch
	str r1, [r8, #0x80]

	ldr r3, =crunch_owner
	add r0, r10, #TI_CRUNCH_STATE @ get task crunch save area
	ldr r2, [sp, #60] @ current task pc value
	ldr r1, [r3] @ get current crunch owner
	str r0, [r3] @ this task now owns crunch
	sub r2, r2, #4 @ adjust pc back
	str r2, [sp, #60]

	ldr r2, [r8, #0x80]
	mov r2, r2 @ flush out enable (@@@)

	teq r1, #0 @ test for last ownership
	mov lr, r9 @ normal exit from exception
	beq crunch_load @ no owner, skip save

	crunch_save:
	cfstr64 mvdx0, [r1, #CRUNCH_MVDX0] @ save 64b registers
	cfstr64 mvdx1, [r1, #CRUNCH_MVDX1]
	cfstr64 mvdx2, [r1, #CRUNCH_MVDX2]
	cfstr64 mvdx3, [r1, #CRUNCH_MVDX3]
	cfstr64 mvdx4, [r1, #CRUNCH_MVDX4]
	cfstr64 mvdx5, [r1, #CRUNCH_MVDX5]
	cfstr64 mvdx6, [r1, #CRUNCH_MVDX6]
	cfstr64 mvdx7, [r1, #CRUNCH_MVDX7]
	cfstr64 mvdx8, [r1, #CRUNCH_MVDX8]
	cfstr64 mvdx9, [r1, #CRUNCH_MVDX9]
	cfstr64 mvdx10, [r1, #CRUNCH_MVDX10]
	cfstr64 mvdx11, [r1, #CRUNCH_MVDX11]
	cfstr64 mvdx12, [r1, #CRUNCH_MVDX12]
	cfstr64 mvdx13, [r1, #CRUNCH_MVDX13]
	cfstr64 mvdx14, [r1, #CRUNCH_MVDX14]
	cfstr64 mvdx15, [r1, #CRUNCH_MVDX15]

	#ifdef __ARMEB__
	#error fix me for ARMEB
	#endif

	cfmv32al mvfx0, mvax0 @ save 72b accumulators
	cfstr32 mvfx0, [r1, #CRUNCH_MVAX0L]
	cfmv32am mvfx0, mvax0
	cfstr32 mvfx0, [r1, #CRUNCH_MVAX0M]
	cfmv32ah mvfx0, mvax0
	cfstr32 mvfx0, [r1, #CRUNCH_MVAX0H]
	cfmv32al mvfx0, mvax1
	cfstr32 mvfx0, [r1, #CRUNCH_MVAX1L]
	cfmv32am mvfx0, mvax1
	cfstr32 mvfx0, [r1, #CRUNCH_MVAX1M]
	cfmv32ah mvfx0, mvax1
	cfstr32 mvfx0, [r1, #CRUNCH_MVAX1H]
	cfmv32al mvfx0, mvax2
	cfstr32 mvfx0, [r1, #CRUNCH_MVAX2L]
	cfmv32am mvfx0, mvax2
	cfstr32 mvfx0, [r1, #CRUNCH_MVAX2M]
	cfmv32ah mvfx0, mvax2
	cfstr32 mvfx0, [r1, #CRUNCH_MVAX2H]
	cfmv32al mvfx0, mvax3
	cfstr32 mvfx0, [r1, #CRUNCH_MVAX3L]
	cfmv32am mvfx0, mvax3
	cfstr32 mvfx0, [r1, #CRUNCH_MVAX3M]
	cfmv32ah mvfx0, mvax3
	cfstr32 mvfx0, [r1, #CRUNCH_MVAX3H]

	cfmv32sc mvdx0, dspsc @ save status word
	cfstr64 mvdx0, [r1, #CRUNCH_DSPSC]

	teq r0, #0 @ anything to load?
	cfldr64eq mvdx0, [r1, #CRUNCH_MVDX0] @ mvdx0 was clobbered
	beq 1f

	crunch_load:
	cfldr64 mvdx0, [r0, #CRUNCH_DSPSC] @ load status word
	cfmvsc32 dspsc, mvdx0

	cfldr32 mvfx0, [r0, #CRUNCH_MVAX0L] @ load 72b accumulators
	cfmval32 mvax0, mvfx0
	cfldr32 mvfx0, [r0, #CRUNCH_MVAX0M]
	cfmvam32 mvax0, mvfx0
	cfldr32 mvfx0, [r0, #CRUNCH_MVAX0H]
	cfmvah32 mvax0, mvfx0
	cfldr32 mvfx0, [r0, #CRUNCH_MVAX1L]
	cfmval32 mvax1, mvfx0
	cfldr32 mvfx0, [r0, #CRUNCH_MVAX1M]
	cfmvam32 mvax1, mvfx0
	cfldr32 mvfx0, [r0, #CRUNCH_MVAX1H]
	cfmvah32 mvax1, mvfx0
	cfldr32 mvfx0, [r0, #CRUNCH_MVAX2L]
	cfmval32 mvax2, mvfx0
	cfldr32 mvfx0, [r0, #CRUNCH_MVAX2M]
	cfmvam32 mvax2, mvfx0
	cfldr32 mvfx0, [r0, #CRUNCH_MVAX2H]
	cfmvah32 mvax2, mvfx0
	cfldr32 mvfx0, [r0, #CRUNCH_MVAX3L]
	cfmval32 mvax3, mvfx0
	cfldr32 mvfx0, [r0, #CRUNCH_MVAX3M]
	cfmvam32 mvax3, mvfx0
	cfldr32 mvfx0, [r0, #CRUNCH_MVAX3H]
	cfmvah32 mvax3, mvfx0

	cfldr64 mvdx0, [r0, #CRUNCH_MVDX0] @ load 64b registers
	cfldr64 mvdx1, [r0, #CRUNCH_MVDX1]
	cfldr64 mvdx2, [r0, #CRUNCH_MVDX2]
	cfldr64 mvdx3, [r0, #CRUNCH_MVDX3]
	cfldr64 mvdx4, [r0, #CRUNCH_MVDX4]
	cfldr64 mvdx5, [r0, #CRUNCH_MVDX5]
	cfldr64 mvdx6, [r0, #CRUNCH_MVDX6]
	cfldr64 mvdx7, [r0, #CRUNCH_MVDX7]
	cfldr64 mvdx8, [r0, #CRUNCH_MVDX8]
	cfldr64 mvdx9, [r0, #CRUNCH_MVDX9]
	cfldr64 mvdx10, [r0, #CRUNCH_MVDX10]
	cfldr64 mvdx11, [r0, #CRUNCH_MVDX11]
	cfldr64 mvdx12, [r0, #CRUNCH_MVDX12]
	cfldr64 mvdx13, [r0, #CRUNCH_MVDX13]
	cfldr64 mvdx14, [r0, #CRUNCH_MVDX14]
	cfldr64 mvdx15, [r0, #CRUNCH_MVDX15]

	1:
	#ifdef CONFIG_PREEMPT_COUNT
	get_thread_info r10
	#endif
	2: dec_preempt_count r10, r3
	ret lr

	/*
	* Back up crunch regs to save area and disable access to them
	* (mainly for gdb or sleep mode usage)
	*
	* r0 = struct thread_info pointer of target task or NULL for any
	*/
	ENTRY(crunch_task_disable)
	stmfd sp!, {r4, r5, lr}

	mrs ip, cpsr
	orr r2, ip, #PSR_I_BIT @ disable interrupts
	msr cpsr_c, r2

	ldr r4, =(EP93XX_APB_VIRT_BASE + 0x00130000) @ syscon addr

	ldr r3, =crunch_owner
	add r2, r0, #TI_CRUNCH_STATE @ get task crunch save area
	ldr r1, [r3] @ get current crunch owner
	teq r1, #0 @ any current owner?
	beq 1f @ no: quit
	teq r0, #0 @ any owner?
	teqne r1, r2 @ or specified one?
	bne 1f @ no: quit

	ldr r5, [r4, #0x80] @ enable access to crunch
	mov r2, #0xaa
	str r2, [r4, #0xc0]
	orr r5, r5, #0x00800000
	str r5, [r4, #0x80]

	mov r0, #0 @ nothing to load
	str r0, [r3] @ no more current owner
	ldr r2, [r4, #0x80] @ flush out enable (@@@)
	mov r2, r2
	bl crunch_save

	mov r2, #0xaa @ disable access to crunch
	str r2, [r4, #0xc0]
	bic r5, r5, #0x00800000
	str r5, [r4, #0x80]
	ldr r5, [r4, #0x80] @ flush out enable (@@@)
	mov r5, r5

	1: msr cpsr_c, ip @ restore interrupt mode
	ldmfd sp!, {r4, r5, pc}

	/*
	* Copy crunch state to given memory address
	*
	* r0 = struct thread_info pointer of target task
	* r1 = memory address where to store crunch state
	*
	* this is called mainly in the creation of signal stack frames
	*/
	ENTRY(crunch_task_copy)
	mrs ip, cpsr
	orr r2, ip, #PSR_I_BIT @ disable interrupts
	msr cpsr_c, r2

	ldr r3, =crunch_owner
	add r2, r0, #TI_CRUNCH_STATE @ get task crunch save area
	ldr r3, [r3] @ get current crunch owner
	teq r2, r3 @ does this task own it...
	beq 1f

	@ current crunch values are in the task save area
	msr cpsr_c, ip @ restore interrupt mode
	mov r0, r1
	mov r1, r2
	mov r2, #CRUNCH_SIZE
	b memcpy

	1: @ this task owns crunch regs -- grab a copy from there
	mov r0, #0 @ nothing to load
	mov r3, lr @ preserve return address
	bl crunch_save
	msr cpsr_c, ip @ restore interrupt mode
	ret r3

	/*
	* Restore crunch state from given memory address
	*
	* r0 = struct thread_info pointer of target task
	* r1 = memory address where to get crunch state from
	*
	* this is used to restore crunch state when unwinding a signal stack frame
	*/
	ENTRY(crunch_task_restore)
	mrs ip, cpsr
	orr r2, ip, #PSR_I_BIT @ disable interrupts
	msr cpsr_c, r2

	ldr r3, =crunch_owner
	add r2, r0, #TI_CRUNCH_STATE @ get task crunch save area
	ldr r3, [r3] @ get current crunch owner
	teq r2, r3 @ does this task own it...
	beq 1f

	@ this task doesn't own crunch regs -- use its save area
	msr cpsr_c, ip @ restore interrupt mode
	mov r0, r2
	mov r2, #CRUNCH_SIZE
	b memcpy

	1: @ this task owns crunch regs -- load them directly
	mov r0, r1
	mov r1, #0 @ nothing to save
	mov r3, lr @ preserve return address
	bl crunch_load
	msr cpsr_c, ip @ restore interrupt mode
	ret r3