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/*
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.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.
*
* Vineetg: Aug 2009
* -Moved core context switch macro out of entry.S into this file.
* -This is the more "natural" hand written assembler
*/
#include <asm/entry.h> /* For the SAVE_* macros */
#include <asm/asm-offsets.h>
#include <asm/linkage.h>
#define KSP_WORD_OFF ((TASK_THREAD + THREAD_KSP) / 4)
;################### Low Level Context Switch ##########################
.section .sched.text,"ax",@progbits
.align 4
.global __switch_to
.type __switch_to, @function
__switch_to:
/* Save regs on kernel mode stack of task */
st.a blink, [sp, -4]
st.a fp, [sp, -4]
SAVE_CALLEE_SAVED_KERNEL
/* Save the now KSP in task->thread.ksp */
#if KSP_WORD_OFF <= 255
st.as sp, [r0, KSP_WORD_OFF]
#else
/* Workaround for NR_CPUS=4k as ST.as can only take s9 offset */
add2 r24, r0, KSP_WORD_OFF
st sp, [r24]
#endif
/*
* Return last task in r0 (return reg)
* On ARC, Return reg = First Arg reg = r0.
* Since we already have last task in r0,
* don't need to do anything special to return it
*/
/* hardware memory barrier */
sync
/*
* switch to new task, contained in r1
* Temp reg r3 is required to get the ptr to store val
*/
SET_CURR_TASK_ON_CPU r1, r3
/* reload SP with kernel mode stack pointer in task->thread.ksp */
ld.as sp, [r1, (TASK_THREAD + THREAD_KSP)/4]
/* restore the registers */
RESTORE_CALLEE_SAVED_KERNEL
ld.ab fp, [sp, 4]
ld.ab blink, [sp, 4]
j [blink]
ARC_EXIT __switch_to
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