source: mainline/kernel/arch/amd64/src/context.S

#
# Copyright (c) 2001-2004 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.
#
# 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
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#

#include <abi/asmtool.h>
#include <arch/context_struct.h>
#include <arch/vreg.h>

.text

## Save current CPU context
#
# Save CPU context to context_t variable
# pointed by the 1st argument. Returns 1 in EAX.
#
FUNCTION_BEGIN(context_save_arch)
        movq (%rsp), %rdx     # the caller's return %rip

        movq %rdx, CONTEXT_OFFSET_PC(%rdi)
        movq %rsp, CONTEXT_OFFSET_SP(%rdi)

        movq %rbx, CONTEXT_OFFSET_RBX(%rdi)
        movq %rbp, CONTEXT_OFFSET_RBP(%rdi)
        movq %r12, CONTEXT_OFFSET_R12(%rdi)
        movq %r13, CONTEXT_OFFSET_R13(%rdi)
        movq %r14, CONTEXT_OFFSET_R14(%rdi)
        movq %r15, CONTEXT_OFFSET_R15(%rdi)

#ifdef MEMORY_MODEL_large
        movabsq $vreg_ptr, %rsi
        movq (%rsi), %rsi
#else
        movq vreg_ptr, %rsi
#endif
        movq %fs:VREG_TP(%rsi), %rsi
        movq %rsi, CONTEXT_OFFSET_TP(%rdi)

        xorl %eax, %eax       # context_save returns 1
        incl %eax
        ret
FUNCTION_END(context_save_arch)


## Restore current CPU context
#
# Restore CPU context from context_t variable
# pointed by the 1st argument. Returns 0 in EAX.
#
FUNCTION_BEGIN(context_restore_arch)
        movq CONTEXT_OFFSET_R15(%rdi), %r15
        movq CONTEXT_OFFSET_R14(%rdi), %r14
        movq CONTEXT_OFFSET_R13(%rdi), %r13
        movq CONTEXT_OFFSET_R12(%rdi), %r12
        movq CONTEXT_OFFSET_RBP(%rdi), %rbp
        movq CONTEXT_OFFSET_RBX(%rdi), %rbx

        movq CONTEXT_OFFSET_SP(%rdi), %rsp

        movq CONTEXT_OFFSET_PC(%rdi), %rdx
        movq %rdx, (%rsp)

        movq CONTEXT_OFFSET_TP(%rdi), %rcx
#ifdef MEMORY_MODEL_large
        movabsq $vreg_ptr, %rsi
        movq (%rsi), %rsi
#else
        movq vreg_ptr, %rsi
#endif
        movq %rcx, %fs:VREG_TP(%rsi)

        xorl %eax, %eax       # context_restore returns 0
        ret
FUNCTION_END(context_restore_arch)