LXR linux/arch/arc/kernel/ctx_sw

   1/*
   2 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 *
   8 * Vineetg: Aug 2009
   9 *  -Moved core context switch macro out of entry.S into this file.
  10 *  -This is the more "natural" hand written assembler
  11 */
  12
  13#include <asm/entry.h>       /* For the SAVE_* macros */
  14#include <asm/asm-offsets.h>
  15#include <asm/linkage.h>
  16
  17;################### Low Level Context Switch ##########################
  18
  19        .section .sched.text,"ax",@progbits
  20        .align 4
  21        .global __switch_to
  22        .type   __switch_to, @function
  23__switch_to:
  24
  25        /* Save regs on kernel mode stack of task */
  26        st.a    blink, [sp, -4]
  27        st.a    fp, [sp, -4]
  28        SAVE_CALLEE_SAVED_KERNEL
  29
  30        /* Save the now KSP in task->thread.ksp */
  31        st.as  sp, [r0, (TASK_THREAD + THREAD_KSP)/4]
  32
  33        /*
  34        * Return last task in r0 (return reg)
  35        * On ARC, Return reg = First Arg reg = r0.
  36        * Since we already have last task in r0,
  37        * don't need to do anything special to return it
  38        */
  39
  40        /* hardware memory barrier */
  41        sync
  42
  43        /*
  44         * switch to new task, contained in r1
  45         * Temp reg r3 is required to get the ptr to store val
  46         */
  47        SET_CURR_TASK_ON_CPU  r1, r3
  48
  49        /* reload SP with kernel mode stack pointer in task->thread.ksp */
  50        ld.as  sp, [r1, (TASK_THREAD + THREAD_KSP)/4]
  51
  52        /* restore the registers */
  53        RESTORE_CALLEE_SAVED_KERNEL
  54        ld.ab   fp, [sp, 4]
  55        ld.ab   blink, [sp, 4]
  56        j       [blink]
  57
  58ARC_EXIT __switch_to
  59