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1120 palkovsky 1
#
2071 jermar 2
# Copyright (c) 2001-2004 Jakub Jermar
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions
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# are met:
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#
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# - Redistributions of source code must retain the above copyright
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#   notice, this list of conditions and the following disclaimer.
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# - Redistributions in binary form must reproduce the above copyright
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#   notice, this list of conditions and the following disclaimer in the
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#   documentation and/or other materials provided with the distribution.
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# - The name of the author may not be used to endorse or promote products
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#   derived from this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#
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.text
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.global context_save
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.global context_restore
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## Save current CPU context
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#
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# Save CPU context to the context_t variable
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# pointed by the 1st argument. Returns 1 in EAX.
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#
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context_save:
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	movl 0(%esp),%eax	# the caller's return %eip
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	movl 4(%esp),%edx	# address of the context variable to save context to
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	movl %esp,0(%edx)	# %esp -> ctx->sp
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	movl %eax,4(%edx)	# %eip -> ctx->pc
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	movl %ebx,8(%edx)	# %ebx -> ctx->ebx
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	movl %esi,12(%edx)	# %esi -> ctx->esi
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	movl %edi,16(%edx)	# %edi -> ctx->edi
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	movl %ebp,20(%edx)	# %ebp -> ctx->ebp
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	# Save TLS
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	movl %gs:0, %eax
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	movl %eax, 24(%edx)     # tls -> ctx->tls
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	xorl %eax,%eax		# context_save returns 1
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	incl %eax
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	ret
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## Restore saved CPU context
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#
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# Restore CPU context from context_t variable
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# pointed by the 1st argument. Returns 0 in EAX.
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#
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context_restore:
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	movl 4(%esp),%eax	# address of the context variable to restore context from
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	movl 0(%eax),%esp	# ctx->sp -> %esp
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	movl 4(%eax),%edx	# ctx->pc -> %edx
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	movl 8(%eax),%ebx	# ctx->ebx -> %ebx
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	movl 12(%eax),%esi	# ctx->esi -> %esi
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	movl 16(%eax),%edi	# ctx->edi -> %edi
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	movl 20(%eax),%ebp	# ctx->ebp -> %ebp
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	movl %edx,0(%esp)	# ctx->pc -> saver's return %eip
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	# Set thread local storage
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	pushl %edx
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	movl 24(%eax), %edx   # Set arg1 to TLS addr
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	movl $1, %eax         # Syscall SYS_TLS_SET
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	int $0x30
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	popl %edx
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	xorl %eax,%eax		# context_restore returns 0
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	ret