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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