| 1 | #
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| 2 | # Copyright (c) 2007 Jakub Jermar
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| 3 | # All rights reserved.
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| 4 | #
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| 5 | # Redistribution and use in source and binary forms, with or without
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| 6 | # modification, are permitted provided that the following conditions
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| 7 | # are met:
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| 8 | #
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| 9 | # - Redistributions of source code must retain the above copyright
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| 10 | # notice, this list of conditions and the following disclaimer.
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| 11 | # - Redistributions in binary form must reproduce the above copyright
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| 12 | # notice, this list of conditions and the following disclaimer in the
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| 13 | # documentation and/or other materials provided with the distribution.
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| 14 | # - The name of the author may not be used to endorse or promote products
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| 15 | # derived from this software without specific prior written permission.
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| 16 | #
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| 17 | # THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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| 18 | # IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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| 19 | # OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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| 20 | # IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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| 21 | # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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| 22 | # NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| 23 | # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| 24 | # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 25 | # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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| 26 | # THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 27 | #
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| 28 |
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| 29 | .text
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| 30 |
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| 31 | /** Syscall wrapper - INT $0x30 version.
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| 32 | *
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| 33 | * Mind the order of arguments. First two arguments and the syscall number go to
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| 34 | * scratch registers. An optimized version of this wrapper for fewer arguments
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| 35 | * could benefit from this and not save unused registers on the stack.
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| 36 | */
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| 37 | .global __syscall_int
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| 38 | __syscall_int:
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| 39 | pushl %ebx
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| 40 | pushl %esi
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| 41 | pushl %edi
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| 42 | pushl %ebp
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| 43 | movl 20(%esp), %edx # First argument.
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| 44 | movl 24(%esp), %ecx # Second argument.
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| 45 | movl 28(%esp), %ebx # Third argument.
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| 46 | movl 32(%esp), %esi # Fourth argument.
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| 47 | movl 36(%esp), %edi # Fifth argument.
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| 48 | movl 40(%esp), %ebp # Sixth argument.
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| 49 | movl 44(%esp), %eax # Syscall number.
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| 50 | int $0x30
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| 51 | popl %ebp
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| 52 | popl %edi
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| 53 | popl %esi
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| 54 | popl %ebx
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| 55 | ret
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| 56 |
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| 57 |
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| 58 | /** Syscall wrapper - SYSENTER version.
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| 59 | *
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| 60 | * This is an optimized version of syscall for four or less arguments. Note
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| 61 | * that EBP and EDI are used to remember user stack address and the return
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| 62 | * address. The kernel part doesn't save DS, ES and FS so the handler restores
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| 63 | * these to the selector immediately following CS (it must be the flat data
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| 64 | * segment, otherwise the SYSENTER wouldn't work in the first place).
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| 65 | */
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| 66 | .global __syscall_sysenter
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| 67 | __syscall_sysenter:
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| 68 | pushl %ebx
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| 69 | pushl %esi
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| 70 | pushl %edi
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| 71 | pushl %ebp
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| 72 | mov %esp, %ebp
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| 73 | lea ra, %edi
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| 74 | movl 20(%esp), %edx # First argument.
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| 75 | movl 24(%esp), %ecx # Second argument.
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| 76 | movl 28(%esp), %ebx # Third argument.
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| 77 | movl 32(%esp), %esi # Fourth argument.
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| 78 | movl 44(%esp), %eax # Syscall number.
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| 79 | sysenter
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| 80 | ra:
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| 81 | movw %cs, %cx
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| 82 | addw $8, %cx
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| 83 | movw %cx, %ds
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| 84 | movw %cx, %es
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| 85 | movw %cx, %fs
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| 86 | popl %ebp
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| 87 | popl %edi
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| 88 | popl %esi
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| 89 | popl %ebx
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| 90 | ret
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