source: mainline/kernel/arch/sparc32/src/context.S@ 208b5f5

#
# Copyright (c) 2005 Jakub Jermar
# Copyright (c) 2013 Jakub Klama
# 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.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

#include <arch/context_offset.h>
#include <arch/arch.h>

.text

.global context_save_arch
.global context_restore_arch

/*
 * context_save_arch() is required not to create its own stack frame. See the
 * generic context.h for explanation.
 */
context_save_arch:
        #
        # Force all our active register windows to memory so that we can find
        # them there even if e.g. the thread is migrated to another processor.
        #
        
        ## flushw
        mov 7, %g1
        1:
                subcc %g1, 1, %g1
                bg 1b
                save %sp, -64, %sp
        
        mov 7, %g1
        1:
                subcc %g1, 1, %g1
                bg 1b
                restore
        
        CONTEXT_SAVE_ARCH_CORE %o0
        retl
        mov 1, %o0              ! context_save_arch returns 1

context_restore_arch:
        #
        # Forget all previous windows, they are not going to be needed again.
        # Enforce a window fill on the next RESTORE instruction by setting
        # CANRESTORE to zero and other window configuration registers
        # accordingly. Note that the same can be achieved by executing the
        # FLUSHW instruction, but since we don't need to remember the previous
        # windows, we do the former and save thus some unnecessary window
        # spills.
        #
        
        ## rdpr %pstate, %l0
        ## andn %l0, PSTATE_IE_BIT, %l1
        ## wrpr %l1, %pstate
        ## wrpr %g0, 0, %canrestore
        ## wrpr %g0, 0, %otherwin
        ## wrpr %g0, NWINDOWS - 2, %cansave
        ## wrpr %l0, %pstate
        
        mov 7, %g1
        1:
                subcc %g1, 1, %g1
                bg 1b
                save %sp, -64, %sp
        
        mov 7, %g1
        1:
                subcc %g1, 1, %g1
                bg 1b
                restore
        
        CONTEXT_RESTORE_ARCH_CORE %o0
        retl
        xor %o0, %o0, %o0       ! context_restore_arch returns 0