source: mainline/kernel/arch/sparc64/src/context.S@ e7b7be3f

#
# Copyright (c) 2005 Jakub Jermar
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# - Redistributions of source code must retain the above copyright
#   notice, this list of conditions and the following disclaimer.
# - Redistributions in binary form must reproduce the above copyright
#   notice, this list of conditions and the following disclaimer in the
#   documentation and/or other materials provided with the distribution.
# - The name of the author may not be used to endorse or promote products
#   derived from this software without specific prior written permission.
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# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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#include <arch/context_offset.h>

/**
 * Both context_save_arch() and context_restore_arch() are
 * leaf-optimized procedures. This kind of optimization
 * is very important and prevents any implicit window
 * spill/fill/clean traps in these very core kernel
 * functions.
 */
        
.text   

.global context_save_arch
.global context_restore_arch

.macro CONTEXT_STORE r
        stx %sp, [\r + OFFSET_SP]
        stx %o7, [\r + OFFSET_PC]
        stx %i0, [\r + OFFSET_I0]
        stx %i1, [\r + OFFSET_I1]
        stx %i2, [\r + OFFSET_I2]
        stx %i3, [\r + OFFSET_I3]
        stx %i4, [\r + OFFSET_I4]
        stx %i5, [\r + OFFSET_I5]
        stx %fp, [\r + OFFSET_FP]
        stx %i7, [\r + OFFSET_I7]
        stx %l0, [\r + OFFSET_L0]
        stx %l1, [\r + OFFSET_L1]
        stx %l2, [\r + OFFSET_L2]
        stx %l3, [\r + OFFSET_L3]
        stx %l4, [\r + OFFSET_L4]
        stx %l5, [\r + OFFSET_L5]
        stx %l6, [\r + OFFSET_L6]
        stx %l7, [\r + OFFSET_L7]
.endm

.macro CONTEXT_LOAD r
        ldx [\r + OFFSET_SP], %sp
        ldx [\r + OFFSET_PC], %o7
        ldx [\r + OFFSET_I0], %i0
        ldx [\r + OFFSET_I1], %i1
        ldx [\r + OFFSET_I2], %i2
        ldx [\r + OFFSET_I3], %i3
        ldx [\r + OFFSET_I4], %i4
        ldx [\r + OFFSET_I5], %i5
        ldx [\r + OFFSET_FP], %fp
        ldx [\r + OFFSET_I7], %i7
        ldx [\r + OFFSET_L0], %l0
        ldx [\r + OFFSET_L1], %l1
        ldx [\r + OFFSET_L2], %l2
        ldx [\r + OFFSET_L3], %l3
        ldx [\r + OFFSET_L4], %l4
        ldx [\r + OFFSET_L5], %l5
        ldx [\r + OFFSET_L6], %l6
        ldx [\r + OFFSET_L7], %l7
.endm

context_save_arch:
        CONTEXT_STORE %o0
        retl
        mov 1, %o0              ! context_save_arch returns 1

context_restore_arch:
        #
        # Flush all active windows.
        # This is essential, because CONTEXT_LOAD overwrites
        # %sp of CWP - 1 with the value written to %fp of CWP.
        # Flushing all active windows mitigates this problem
        # as CWP - 1 becomes the overlap window.
        #
        flushw
        
        CONTEXT_LOAD %o0
        retl
        xor %o0, %o0, %o0       ! context_restore_arch returns 0