/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
 *
 * Vineetg: Aug 2009
 *  -Moved core context switch macro out of entry.S into this file.
 *  -This is the more "natural" hand written assembler
 */

#include <linux/linkage.h>
#include <asm/entry.h>       /* For the SAVE_* macros */
#include <asm/asm-offsets.h>

; IN
;  - r0: prev task (also current)
;  - r1: next task
; OUT
;  - r0: prev task (so r0 not touched)

        .section .sched.text,"ax",@progbits
ENTRY_CFI(__switch_to)

        /* save kernel stack frame regs of @prev task */
        push    blink
        CFI_DEF_CFA_OFFSET 4
        CFI_OFFSET r31, -4

        push    fp
        CFI_DEF_CFA_OFFSET 8
        CFI_OFFSET r27, -8

        mov     fp, sp
        CFI_DEF_CFA_REGISTER r27

        /* kernel mode callee regs of @prev */
        SAVE_CALLEE_SAVED_KERNEL

        /*
         * save final SP to @prev->thread_info.ksp
         * @prev is "current" so thread_info derived from SP
         */
        GET_CURR_THR_INFO_FROM_SP  r10
        st      sp,  [r10, THREAD_INFO_KSP]

        /* update @next in _current_task[] and GP register caching it */
        SET_CURR_TASK_ON_CPU  r1, r10

        /* load SP from @next->thread_info.ksp */
        ld      r10, [r1, TASK_THREAD_INFO]
        ld      sp,  [r10, THREAD_INFO_KSP]

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

        pop     fp
        CFI_RESTORE r27
        CFI_DEF_CFA r28, 4

        pop     blink
        CFI_RESTORE r31
        CFI_DEF_CFA_OFFSET 0

        j      [blink]
END_CFI(__switch_to)