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/* $Id: r2300_switch.S,v 1.8 1999/08/18 23:37:44 ralf Exp $
*
* r2300_switch.S: R2300 specific task switching code.
*
* Copyright (C) 1994, 1995, 1996, 1999 by Ralf Baechle
* Copyright (C) 1994, 1995, 1996 by Andreas Busse
*
* Multi-cpu abstraction and macros for easier reading:
* Copyright (C) 1996 David S. Miller (dm@engr.sgi.com)
*
* Further modifications to make this work:
* Copyright (c) 1998-2000 Harald Koerfgen
*/
#include <asm/asm.h>
#include <asm/bootinfo.h>
#include <asm/cachectl.h>
#include <asm/current.h>
#include <asm/fpregdef.h>
#include <asm/mipsregs.h>
#include <asm/offset.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/regdef.h>
#include <asm/stackframe.h>
#include <asm/asmmacro.h>
.set mips1
.align 5
/*
* task_struct *resume(task_struct *prev,
* task_struct *next)
*/
LEAF(resume)
#ifndef CONFIG_CPU_HAS_LLSC
sw zero, ll_bit
#endif
mfc0 t1, CP0_STATUS
sw t1, THREAD_STATUS(a0)
CPU_SAVE_NONSCRATCH(a0)
sw ra, THREAD_REG31(a0)
/*
* The order of restoring the registers takes care of the race
* updating $28, $29 and kernelsp without disabling ints.
*/
move $28, a1
CPU_RESTORE_NONSCRATCH($28)
addiu t0, $28, KERNEL_STACK_SIZE-32
sw t0, kernelsp
mfc0 t1, CP0_STATUS /* Do we really need this? */
li a3, 0xff00
and t1, a3
lw a2, THREAD_STATUS($28)
nor a3, $0, a3
and a2, a3
or a2, t1
mtc0 a2, CP0_STATUS
.set noreorder
jr ra
move v0, a0
.set reorder
END(resume)
/*
* Do lazy fpu context switch. Saves FPU context to the process in a0
* and loads the new context of the current process.
*/
#define ST_OFF (KERNEL_STACK_SIZE - 32 - PT_SIZE + PT_STATUS)
LEAF(lazy_fpu_switch)
mfc0 t0, CP0_STATUS # enable cp1
li t3, 0x20000000
or t0, t3
mtc0 t0, CP0_STATUS
.set noreorder
beqz a0, 2f # Save floating point state
nor t3, zero, t3
.set reorder
lw t1, ST_OFF(a0) # last thread looses fpu
and t1, t3
sw t1, ST_OFF(a0)
FPU_SAVE_SINGLE(a0, t1) # clobbers t1
2:
FPU_RESTORE_SINGLE($28, t0) # clobbers t0
jr ra
END(lazy_fpu_switch)
/*
* Save a thread's fp context.
*/
LEAF(save_fp)
FPU_SAVE_SINGLE(a0, t1) # clobbers t1
jr ra
END(save_fp)
/*
* Restore a thread's fp context.
*/
LEAF(restore_fp)
FPU_RESTORE_SINGLE(a0, t1) # clobbers t1
jr ra
END(restore_fp)
/*
* Load the FPU with signalling NANS. This bit pattern we're using has
* the property that no matter wether considered as single or as double
* precission represents signaling NANS.
*
* We initialize fcr31 to rounding to nearest, no exceptions.
*/
#define FPU_DEFAULT 0x00000000
LEAF(init_fpu)
mfc0 t0, CP0_STATUS
li t1, 0x20000000
or t0, t1
mtc0 t0, CP0_STATUS
li t1, FPU_DEFAULT
ctc1 t1, fcr31
li t0, -1
mtc1 t0, $f0
mtc1 t0, $f1
mtc1 t0, $f2
mtc1 t0, $f3
mtc1 t0, $f4
mtc1 t0, $f5
mtc1 t0, $f6
mtc1 t0, $f7
mtc1 t0, $f8
mtc1 t0, $f9
mtc1 t0, $f10
mtc1 t0, $f11
mtc1 t0, $f12
mtc1 t0, $f13
mtc1 t0, $f14
mtc1 t0, $f15
mtc1 t0, $f16
mtc1 t0, $f17
mtc1 t0, $f18
mtc1 t0, $f19
mtc1 t0, $f20
mtc1 t0, $f21
mtc1 t0, $f22
mtc1 t0, $f23
mtc1 t0, $f24
mtc1 t0, $f25
mtc1 t0, $f26
mtc1 t0, $f27
mtc1 t0, $f28
mtc1 t0, $f29
mtc1 t0, $f30
.set noreorder
jr ra
mtc1 t0, $f31
.set reorder
END(init_fpu)
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