linux/arch/arm/kernel/iwmmxt.S

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 *  linux/arch/arm/kernel/iwmmxt.S
 *
 *  XScale iWMMXt (Concan) context switching and handling
 *
 *  Initial code:
 *  Copyright (c) 2003, Intel Corporation
 *
 *  Full lazy switching support, optimizations and more, by Nicolas Pitre
*   Copyright (c) 2003-2004, MontaVista Software, Inc.
 */

#include <linux/linkage.h>
#include <asm/ptrace.h>
#include <asm/thread_info.h>
#include <asm/asm-offsets.h>
#include <asm/assembler.h>
#include "iwmmxt.h"

#define MMX_WR0		 	(0x00)
#define MMX_WR1		 	(0x08)
#define MMX_WR2		 	(0x10)
#define MMX_WR3			(0x18)
#define MMX_WR4		 	(0x20)
#define MMX_WR5		 	(0x28)
#define MMX_WR6		 	(0x30)
#define MMX_WR7		 	(0x38)
#define MMX_WR8		 	(0x40)
#define MMX_WR9		 	(0x48)
#define MMX_WR10		(0x50)
#define MMX_WR11		(0x58)
#define MMX_WR12		(0x60)
#define MMX_WR13		(0x68)
#define MMX_WR14		(0x70)
#define MMX_WR15		(0x78)
#define MMX_WCSSF		(0x80)
#define MMX_WCASF		(0x84)
#define MMX_WCGR0		(0x88)
#define MMX_WCGR1		(0x8C)
#define MMX_WCGR2		(0x90)
#define MMX_WCGR3		(0x94)

#define MMX_SIZE		(0x98)

	.text
	.arm

ENTRY(iwmmxt_undef_handler)
	push		{r9, r10, lr}
	get_thread_info	r10
	mov		r9, pc
	b		iwmmxt_task_enable
	mov		r0, #0
	pop		{r9, r10, pc}
ENDPROC(iwmmxt_undef_handler)

/*
 * Lazy switching of Concan coprocessor context
 *
 * r0  = struct pt_regs pointer
 * r10 = struct thread_info pointer
 * r9  = ret_from_exception
 * lr  = undefined instr exit
 *
 * called from prefetch exception handler with interrupts enabled
 */

ENTRY(iwmmxt_task_enable)
	inc_preempt_count r10, r3

	mrc	p15, 0, r2, c15, c1, 0
	@ CP0 and CP1 accessible?
	tst	r2, #0x3
	bne	4f				@ if so no business here
	@ enable access to CP0 and CP1
	orr	r2, r2, #0x3
	mcr	p15, 0, r2, c15, c1, 0

	ldr	r3, =concan_owner
	ldr	r2, [r0, #S_PC]			@ current task pc value
	ldr	r1, [r3]			@ get current Concan owner
	sub	r2, r2, #4			@ adjust pc back
	str	r2, [r0, #S_PC]
	add	r0, r10, #TI_IWMMXT_STATE	@ get task Concan save area
	str	r0, [r3]			@ this task now owns Concan regs

	mrc	p15, 0, r2, c2, c0, 0
	mov	r2, r2				@ cpwait
	bl	concan_save

#ifdef CONFIG_PREEMPT_COUNT
	get_thread_info r10
#endif
4:	dec_preempt_count r10, r3
	ret	r9				@ normal exit from exception

concan_save:

	teq	r1, #0				@ test for last ownership
	beq	concan_load			@ no owner, skip save

	tmrc	r2, wCon

	@ CUP? wCx
	tst	r2, #0x1
	beq 	1f

concan_dump:

	wstrw	wCSSF, r1, MMX_WCSSF
	wstrw	wCASF, r1, MMX_WCASF
	wstrw	wCGR0, r1, MMX_WCGR0
	wstrw	wCGR1, r1, MMX_WCGR1
	wstrw	wCGR2, r1, MMX_WCGR2
	wstrw	wCGR3, r1, MMX_WCGR3

1:	@ MUP? wRn
	tst	r2, #0x2
	beq	2f

	wstrd	wR0,  r1, MMX_WR0
	wstrd	wR1,  r1, MMX_WR1
	wstrd	wR2,  r1, MMX_WR2
	wstrd	wR3,  r1, MMX_WR3
	wstrd	wR4,  r1, MMX_WR4
	wstrd	wR5,  r1, MMX_WR5
	wstrd	wR6,  r1, MMX_WR6
	wstrd	wR7,  r1, MMX_WR7
	wstrd	wR8,  r1, MMX_WR8
	wstrd	wR9,  r1, MMX_WR9
	wstrd	wR10, r1, MMX_WR10
	wstrd	wR11, r1, MMX_WR11
	wstrd	wR12, r1, MMX_WR12
	wstrd	wR13, r1, MMX_WR13
	wstrd	wR14, r1, MMX_WR14
	wstrd	wR15, r1, MMX_WR15

2:	teq	r0, #0				@ anything to load?
	reteq	lr				@ if not, return

concan_load:

	@ Load wRn
	wldrd	wR0,  r0, MMX_WR0
	wldrd	wR1,  r0, MMX_WR1
	wldrd	wR2,  r0, MMX_WR2
	wldrd	wR3,  r0, MMX_WR3
	wldrd	wR4,  r0, MMX_WR4
	wldrd	wR5,  r0, MMX_WR5
	wldrd	wR6,  r0, MMX_WR6
	wldrd	wR7,  r0, MMX_WR7
	wldrd	wR8,  r0, MMX_WR8
	wldrd	wR9,  r0, MMX_WR9
	wldrd	wR10, r0, MMX_WR10
	wldrd	wR11, r0, MMX_WR11
	wldrd	wR12, r0, MMX_WR12
	wldrd	wR13, r0, MMX_WR13
	wldrd	wR14, r0, MMX_WR14
	wldrd	wR15, r0, MMX_WR15

	@ Load wCx
	wldrw	wCSSF, r0, MMX_WCSSF
	wldrw	wCASF, r0, MMX_WCASF
	wldrw	wCGR0, r0, MMX_WCGR0
	wldrw	wCGR1, r0, MMX_WCGR1
	wldrw	wCGR2, r0, MMX_WCGR2
	wldrw	wCGR3, r0, MMX_WCGR3

	@ clear CUP/MUP (only if r1 != 0)
	teq	r1, #0
	mov 	r2, #0
	reteq	lr

	tmcr	wCon, r2
	ret	lr

ENDPROC(iwmmxt_task_enable)

/*
 * Back up Concan 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(iwmmxt_task_disable)

	stmfd	sp!, {r4, lr}

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

	ldr	r3, =concan_owner
	add	r2, r0, #TI_IWMMXT_STATE	@ get task Concan save area
	ldr	r1, [r3]			@ get current Concan 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

	@ enable access to CP0 and CP1
	mrc	p15, 0, r4, c15, c1, 0
	orr	r4, r4, #0x3
	mcr	p15, 0, r4, c15, c1, 0

	mov	r0, #0				@ nothing to load
	str	r0, [r3]			@ no more current owner
	mrc	p15, 0, r2, c2, c0, 0
	mov	r2, r2				@ cpwait
	bl	concan_save

	@ disable access to CP0 and CP1
	bic	r4, r4, #0x3
	mcr	p15, 0, r4, c15, c1, 0

	mrc	p15, 0, r2, c2, c0, 0
	mov	r2, r2				@ cpwait

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

ENDPROC(iwmmxt_task_disable)

/*
 * Copy Concan state to given memory address
 *
 * r0 = struct thread_info pointer of target task
 * r1 = memory address where to store Concan state
 *
 * this is called mainly in the creation of signal stack frames
 */

ENTRY(iwmmxt_task_copy)

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

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

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

1:	@ this task owns Concan regs -- grab a copy from there
	mov	r0, #0				@ nothing to load
	mov	r2, #3				@ save all regs
	mov	r3, lr				@ preserve return address
	bl	concan_dump
	msr	cpsr_c, ip			@ restore interrupt mode
	ret	r3

ENDPROC(iwmmxt_task_copy)

/*
 * Restore Concan state from given memory address
 *
 * r0 = struct thread_info pointer of target task
 * r1 = memory address where to get Concan state from
 *
 * this is used to restore Concan state when unwinding a signal stack frame
 */

ENTRY(iwmmxt_task_restore)

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

	ldr	r3, =concan_owner
	add	r2, r0, #TI_IWMMXT_STATE	@ get task Concan save area
	ldr	r3, [r3]			@ get current Concan owner
	bic	r2, r2, #0x7			@ 64-bit alignment
	teq	r2, r3				@ does this task own it...
	beq	1f

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

1:	@ this task owns Concan regs -- load them directly
	mov	r0, r1
	mov	r1, #0				@ don't clear CUP/MUP
	mov	r3, lr				@ preserve return address
	bl	concan_load
	msr	cpsr_c, ip			@ restore interrupt mode
	ret	r3

ENDPROC(iwmmxt_task_restore)

/*
 * Concan handling on task switch
 *
 * r0 = next thread_info pointer
 *
 * Called only from the iwmmxt notifier with task preemption disabled.
 */
ENTRY(iwmmxt_task_switch)

	mrc	p15, 0, r1, c15, c1, 0
	@ CP0 and CP1 accessible?
	tst	r1, #0x3
	bne	1f				@ yes: block them for next task

	ldr	r2, =concan_owner
	add	r3, r0, #TI_IWMMXT_STATE	@ get next task Concan save area
	ldr	r2, [r2]			@ get current Concan owner
	teq	r2, r3				@ next task owns it?
	retne	lr				@ no: leave Concan disabled

1:	@ flip Concan access
	eor	r1, r1, #0x3
	mcr	p15, 0, r1, c15, c1, 0

	mrc	p15, 0, r1, c2, c0, 0
	sub	pc, lr, r1, lsr #32		@ cpwait and return

ENDPROC(iwmmxt_task_switch)

/*
 * Remove Concan ownership of given task
 *
 * r0 = struct thread_info pointer
 */
ENTRY(iwmmxt_task_release)

	mrs	r2, cpsr
	orr	ip, r2, #PSR_I_BIT		@ disable interrupts
	msr	cpsr_c, ip
	ldr	r3, =concan_owner
	add	r0, r0, #TI_IWMMXT_STATE	@ get task Concan save area
	ldr	r1, [r3]			@ get current Concan owner
	eors	r0, r0, r1			@ if equal...
	streq	r0, [r3]			@ then clear ownership
	msr	cpsr_c, r2			@ restore interrupts
	ret	lr

ENDPROC(iwmmxt_task_release)

	.data
	.align	2
concan_owner:
	.word	0