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2613 jermar 1 
#
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# Copyright (c) 2007 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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3485 jermar 31 
/** Syscall wrapper - INT $0x30 version.
2613 jermar 32 
 *
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 * Mind the order of arguments. First two arguments and the syscall number go to
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 * scratch registers. An optimized version of this wrapper for fewer arguments
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 * could benefit from this and not save unused registers on the stack.
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 */
3485 jermar 37 
.global __syscall_int
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__syscall_int:
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	pushl %ebx
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	pushl %esi
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	pushl %edi
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	pushl %ebp
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	movl 20(%esp), %edx	# First argument.
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	movl 24(%esp), %ecx	# Second argument.
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	movl 28(%esp), %ebx	# Third argument.
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	movl 32(%esp), %esi	# Fourth argument.
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	movl 36(%esp), %edi	# Fifth argument.
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	movl 40(%esp), %ebp	# Sixth argument.
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	movl 44(%esp), %eax	# Syscall number.
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	int $0x30
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	popl %ebp
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	popl %edi
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	popl %esi
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	popl %ebx
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	ret
3485 jermar 56 
 
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/** Syscall wrapper - SYSENTER version.
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 *
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 * This is an optimized version of syscall for four or less arguments.  Note
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 * that EBP and EDI are used to remember user stack address and the return
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 * address. The kernel part doesn't save DS, ES and FS so the handler restores
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 * these to the selector immediately following CS (it must be the flat data
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 * segment, otherwise the SYSENTER wouldn't work in the first place).
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 */
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.global __syscall_sysenter
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__syscall_sysenter:
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	pushl %ebx
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	pushl %esi
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	pushl %edi
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	pushl %ebp
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	mov %esp, %ebp
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	lea ra, %edi
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	movl 20(%esp), %edx	# First argument.
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	movl 24(%esp), %ecx	# Second argument.
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	movl 28(%esp), %ebx	# Third argument.
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	movl 32(%esp), %esi	# Fourth argument.
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	movl 44(%esp), %eax	# Syscall number.
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	sysenter
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ra:
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	movw %cs, %cx
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	addw $8, %cx
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	movw %cx, %ds
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	movw %cx, %es
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	movw %cx, %fs
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	popl %ebp
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	popl %edi
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	popl %esi
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	popl %ebx
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	ret