switch_to.h

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/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2001  Hiroyuki Kondo, Hirokazu Takata, and Hitoshi Yamamoto
 * Copyright (C) 2004, 2006  Hirokazu Takata <takata at linux-m32r.org>
 */
#ifndef _ASM_M32R_SWITCH_TO_H
#define _ASM_M32R_SWITCH_TO_H

/*
 * switch_to(prev, next) should switch from task `prev' to `next'
 * `prev' will never be the same as `next'.
 *
 * `next' and `prev' should be struct task_struct, but it isn't always defined
 */

#if defined(CONFIG_FRAME_POINTER) || \
    !defined(CONFIG_SCHED_OMIT_FRAME_POINTER)
#define M32R_PUSH_FP "  push fp\n"
#define M32R_POP_FP  "  pop  fp\n"
#else
#define M32R_PUSH_FP ""
#define M32R_POP_FP  ""
#endif

#define switch_to(prev, next, last)  do { \
    __asm__ __volatile__ ( \
        "   seth    lr, #high(1f)               \n" \
        "   or3 lr, lr, #low(1f)            \n" \
        "   st  lr, @%4  ; store old LR         \n" \
        "   ld  lr, @%5  ; load new LR          \n" \
            M32R_PUSH_FP \
        "   st  sp, @%2  ; store old SP         \n" \
        "   ld  sp, @%3  ; load new SP          \n" \
        "   push    %1  ; store `prev' on new stack     \n" \
        "   jmp lr                  \n" \
        "   .fillinsn                   \n" \
        "1:                         \n" \
        "   pop %0  ; restore `__last' from new stack   \n" \
            M32R_POP_FP \
        : "=r" (last) \
        : "0" (prev), \
          "r" (&(prev->thread.sp)), "r" (&(next->thread.sp)), \
          "r" (&(prev->thread.lr)), "r" (&(next->thread.lr)) \
        : "memory", "lr" \
    ); \
} while(0)

#endif /* _ASM_M32R_SWITCH_TO_H */