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#
# 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.
#
.text
.global context_save
.global context_restore
## Save current CPU context
#
# Save CPU context to the context_t variable
# pointed by the 1st argument. Returns 1 in EAX.
#
context_save:
movl 0(%esp),%eax # the caller's return %eip
movl 4(%esp),%edx # address of the context variable to save context to
movl %esp,0(%edx) # %esp -> ctx->sp
movl %eax,4(%edx) # %eip -> ctx->pc
movl %ebx,8(%edx) # %ebx -> ctx->ebx
movl %esi,12(%edx) # %esi -> ctx->esi
movl %edi,16(%edx) # %edi -> ctx->edi
movl %ebp,20(%edx) # %ebp -> ctx->ebp
# Save TLS
movl %gs:0, %eax
movl %eax, 24(%edx) # tls -> ctx->tls
xorl %eax,%eax # context_save returns 1
incl %eax
ret
## Restore saved CPU context
#
# Restore CPU context from context_t variable
# pointed by the 1st argument. Returns 0 in EAX.
#
context_restore:
movl 4(%esp),%eax # address of the context variable to restore context from
movl 0(%eax),%esp # ctx->sp -> %esp
movl 4(%eax),%edx # ctx->pc -> %edx
movl 8(%eax),%ebx # ctx->ebx -> %ebx
movl 12(%eax),%esi # ctx->esi -> %esi
movl 16(%eax),%edi # ctx->edi -> %edi
movl 20(%eax),%ebp # ctx->ebp -> %ebp
movl %edx,0(%esp) # ctx->pc -> saver's return %eip
# Set thread local storage
pushl %edx
movl 24(%eax), %edx # Set arg1 to TLS addr
movl $1, %eax # Syscall SYS_TLS_SET
int $0x30
popl %edx
xorl %eax,%eax # context_restore returns 0
ret
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