| 1 | /* ----------------------------------------------------------------------- |
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| 2 | * |
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| 3 | * Copyright 2003-2008 H. Peter Anvin - All Rights Reserved |
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| 4 | * |
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| 5 | * Permission is hereby granted, free of charge, to any person |
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| 6 | * obtaining a copy of this software and associated documentation |
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| 7 | * files (the "Software"), to deal in the Software without |
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| 8 | * restriction, including without limitation the rights to use, |
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| 9 | * copy, modify, merge, publish, distribute, sublicense, and/or |
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| 10 | * sell copies of the Software, and to permit persons to whom |
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| 11 | * the Software is furnished to do so, subject to the following |
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| 12 | * conditions: |
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| 13 | * |
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| 14 | * The above copyright notice and this permission notice shall |
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| 15 | * be included in all copies or substantial portions of the Software. |
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| 16 | * |
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| 17 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
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| 18 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES |
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| 19 | * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
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| 20 | * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT |
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| 21 | * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, |
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| 22 | * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
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| 23 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR |
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| 24 | * OTHER DEALINGS IN THE SOFTWARE. |
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| 25 | * |
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| 26 | * ----------------------------------------------------------------------- */ |
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| 27 | |
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| 28 | /* |
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| 29 | * COM32 start up code - must be linked first in the binary |
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| 30 | */ |
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| 31 | |
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| 32 | /* Number of arguments in our version of the entry structure */ |
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| 33 | #define COM32_ARGS 9 |
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| 34 | |
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| 35 | .section ".init","ax" |
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| 36 | .globl _start |
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| 37 | .type _start, @function |
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| 38 | _start: |
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| 39 | /* This first instruction acts as COM32R magic number */ |
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| 40 | movl $0x21cd4cfe,%eax |
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| 41 | |
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| 42 | /* Upwards string operations */ |
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| 43 | cld |
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| 44 | |
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| 45 | /* Find our own location */ |
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| 46 | call 1f |
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| 47 | 1: popl %ebx |
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| 48 | addl $_GLOBAL_OFFSET_TABLE_ + (. - 1b), %ebx |
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| 49 | |
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| 50 | /* Process relocations (which overlay the .bss segment) */ |
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| 51 | leal _edata@GOTOFF(%ebx),%esi |
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| 52 | leal _start@GOTOFF(%ebx),%edx |
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| 53 | 2: lodsl |
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| 54 | andl %eax,%eax |
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| 55 | jz 3f |
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| 56 | addl %edx,(%eax,%edx) |
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| 57 | jmp 2b |
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| 58 | 3: |
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| 59 | /* Relocate the GOT (is this right?) */ |
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| 60 | leal __got_start@GOTOFF(%ebx),%esi |
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| 61 | leal __got_end@GOTOFF(%ebx),%edi |
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| 62 | 4: |
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| 63 | addl %edx,(%esi) |
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| 64 | addl $4,%esi |
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| 65 | cmpl %edi,%esi |
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| 66 | jb 4b |
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| 67 | |
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| 68 | /* Zero the .bss segment */ |
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| 69 | xorl %eax,%eax |
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| 70 | leal __bss_start@GOTOFF(%ebx),%edi |
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| 71 | leal _end+3@GOTOFF(%ebx),%ecx |
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| 72 | subl %edi,%ecx |
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| 73 | shrl $2,%ecx |
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| 74 | rep ; stosl |
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| 75 | |
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| 76 | /* Copy COM32 invocation parameters */ |
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| 77 | leal 4(%esp),%esi # Argument list |
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| 78 | leal __com32@GOTOFF(%ebx),%edi |
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| 79 | movl $(COM32_ARGS),%ecx |
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| 80 | movl %esp,-4(%edi) # Save the initial stack ptr |
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| 81 | cmpl (%esi),%ecx |
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| 82 | jbe 5f |
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| 83 | movl (%esi),%ecx |
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| 84 | 5: inc %ecx # Copy the argument count, too |
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| 85 | rep ; movsl |
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| 86 | |
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| 87 | /* Parse the command line (assumes REGPARM) */ |
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| 88 | movl __com32+4@GOTOFF(%ebx),%edx # Command line |
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| 89 | pushl %edx # Make space for argv |
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| 90 | movl %esp,%eax |
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| 91 | call __parse_argv |
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| 92 | pushl %eax # Save argc |
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| 93 | |
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| 94 | /* Look for library initialization functions */ |
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| 95 | leal __ctors_start@GOTOFF(%ebx),%esi |
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| 96 | leal __ctors_end@GOTOFF(%ebx),%edi |
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| 97 | 6: |
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| 98 | cmpl %edi,%esi |
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| 99 | jae 7f |
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| 100 | call *(%esi) |
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| 101 | addl $4,%esi |
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| 102 | jmp 6b |
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| 103 | /* |
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| 104 | * Actually run main. This assumes REGPARM is used!!!! |
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| 105 | */ |
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| 106 | 7: |
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| 107 | popl %eax # argc |
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| 108 | popl %edx # argv |
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| 109 | call main |
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| 110 | call *__exit_handler@GOTOFF(%ebx) |
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| 111 | hlt |
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| 112 | .size _start, .-_start |
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| 113 | |
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| 114 | .bss |
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| 115 | .globl __entry_esp |
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| 116 | __entry_esp: .space 4 |
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| 117 | .globl __com32 |
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| 118 | __com32: .space 4*(COM32_ARGS+1) |
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