HelenOS sources

root/uspace/lib/c/arch/ia32/src/fibril.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
# 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 <abi/asmtool.h>
#include <libarch/fibril_context.h>

.text

## Save current CPU context
#
# Save CPU context to the context_t variable
# pointed by the 1st argument. Returns 0 in EAX.
#
FUNCTION_BEGIN(__context_save)
        movl 0(%esp), %eax  # the caller's return %eip
        movl 4(%esp), %edx  # address of the context variable to save context to

        # save registers to the context structure
        movl %esp, __CONTEXT_OFFSET_SP(%edx)    # %esp -> ctx->sp
        movl %eax, __CONTEXT_OFFSET_PC(%edx)    # %eip -> ctx->pc
        movl %ebx, __CONTEXT_OFFSET_EBX(%edx)   # %ebx -> ctx->ebx
        movl %esi, __CONTEXT_OFFSET_ESI(%edx)   # %esi -> ctx->esi
        movl %edi, __CONTEXT_OFFSET_EDI(%edx)   # %edi -> ctx->edi
        movl %ebp, __CONTEXT_OFFSET_EBP(%edx)   # %ebp -> ctx->ebp

        # save TLS
        movl %gs:0, %eax
        movl %eax, __CONTEXT_OFFSET_TLS(%edx)   # tls -> ctx->tls

        xorl %eax, %eax         # __context_save returns 0
        ret
FUNCTION_END(__context_save)

## Restore saved CPU context
#
# Restore CPU context from context_t variable
# pointed by the 1st argument. Returns second argument in EAX.
#
FUNCTION_BEGIN(__context_restore)
        movl 4(%esp), %eax  # address of the context variable to restore context from
        movl 8(%esp), %ecx  # return value

        # restore registers from the context structure
        movl __CONTEXT_OFFSET_SP(%eax),%esp     # ctx->sp -> %esp
        movl __CONTEXT_OFFSET_PC(%eax),%edx     # ctx->pc -> \pc
        movl __CONTEXT_OFFSET_EBX(%eax),%ebx    # ctx->ebx -> %ebx
        movl __CONTEXT_OFFSET_ESI(%eax),%esi    # ctx->esi -> %esi
        movl __CONTEXT_OFFSET_EDI(%eax),%edi    # ctx->edi -> %edi
        movl __CONTEXT_OFFSET_EBP(%eax),%ebp    # ctx->ebp -> %ebp

        movl %edx, 0(%esp)  # ctx->pc -> saver's return %eip

        # set thread local storage
        movl __CONTEXT_OFFSET_TLS(%eax), %edx   # Set arg1 to TLS addr
        movl %edx, %gs:0

        movl %ecx, %eax
        ret
FUNCTION_END(__context_restore)