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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/arc/kernel/ctx_sw_asm.S
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/* SPDX-License-Identifier: GPL-2.0-only */

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/*

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 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)

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 *

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 * Vineetg: Aug 2009

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 *  -Moved core context switch macro out of entry.S into this file.

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 *  -This is the more "natural" hand written assembler

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 */

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#include <linux/linkage.h>

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#include <asm/entry.h>       /* For the SAVE_* macros */

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#include <asm/asm-offsets.h>

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; IN

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;  - r0: prev task (also current)

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;  - r1: next task

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; OUT

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;  - r0: prev task (so r0 not touched)

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	.section .sched.text,"ax",@progbits

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ENTRY_CFI(__switch_to)

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	/* save kernel stack frame regs of @prev task */

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	push	blink

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	CFI_DEF_CFA_OFFSET 4

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	CFI_OFFSET r31, -4

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	push	fp

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	CFI_DEF_CFA_OFFSET 8

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	CFI_OFFSET r27, -8

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	mov	fp, sp

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	CFI_DEF_CFA_REGISTER r27

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	/* kernel mode callee regs of @prev */

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	SAVE_CALLEE_SAVED_KERNEL

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	/*

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	 * save final SP to @prev->thread_info.ksp

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	 * @prev is "current" so thread_info derived from SP

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	 */

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	GET_CURR_THR_INFO_FROM_SP  r10

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	st	sp,  [r10, THREAD_INFO_KSP]

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	/* update @next in _current_task[] and GP register caching it */

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	SET_CURR_TASK_ON_CPU  r1, r10

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	/* load SP from @next->thread_info.ksp */

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	ld	r10, [r1, TASK_THREAD_INFO]

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	ld	sp,  [r10, THREAD_INFO_KSP]

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	/* restore callee regs, stack frame regs of @next */

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	RESTORE_CALLEE_SAVED_KERNEL

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	pop	fp

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	CFI_RESTORE r27

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	CFI_DEF_CFA r28, 4

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	pop	blink

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	CFI_RESTORE r31

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	CFI_DEF_CFA_OFFSET 0

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	j      [blink]

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END_CFI(__switch_to)

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