| 1 | /* Startup code compliant to the ELF m68k ABI. |
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| 2 | Copyright (C) 1996-2022 Free Software Foundation, Inc. |
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| 3 | This file is part of the GNU C Library. |
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| 4 | |
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| 5 | The GNU C Library is free software; you can redistribute it and/or |
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| 6 | modify it under the terms of the GNU Lesser General Public |
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| 7 | License as published by the Free Software Foundation; either |
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| 8 | version 2.1 of the License, or (at your option) any later version. |
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| 9 | |
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| 10 | In addition to the permissions in the GNU Lesser General Public |
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| 11 | License, the Free Software Foundation gives you unlimited |
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| 12 | permission to link the compiled version of this file with other |
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| 13 | programs, and to distribute those programs without any restriction |
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| 14 | coming from the use of this file. (The GNU Lesser General Public |
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| 15 | License restrictions do apply in other respects; for example, they |
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| 16 | cover modification of the file, and distribution when not linked |
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| 17 | into another program.) |
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| 18 | |
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| 19 | Note that people who make modified versions of this file are not |
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| 20 | obligated to grant this special exception for their modified |
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| 21 | versions; it is their choice whether to do so. The GNU Lesser |
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| 22 | General Public License gives permission to release a modified |
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| 23 | version without this exception; this exception also makes it |
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| 24 | possible to release a modified version which carries forward this |
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| 25 | exception. |
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| 26 | |
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| 27 | The GNU C Library is distributed in the hope that it will be useful, |
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| 28 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 29 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 30 | Lesser General Public License for more details. |
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| 31 | |
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| 32 | You should have received a copy of the GNU Lesser General Public |
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| 33 | License along with the GNU C Library. If not, see |
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| 34 | <https://www.gnu.org/licenses/>. */ |
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| 35 | |
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| 36 | /* This is the canonical entry point, usually the first thing in the text |
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| 37 | segment. The SVR4/m68k ABI says that when the entry point runs, |
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| 38 | most registers' values are unspecified, except for: |
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| 39 | |
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| 40 | %a1 Contains a function pointer to be registered with `atexit'. |
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| 41 | This is how the dynamic linker arranges to have DT_FINI |
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| 42 | functions called for shared libraries that have been loaded |
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| 43 | before this code runs. |
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| 44 | |
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| 45 | %sp The stack contains the arguments and environment: |
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| 46 | 0(%sp) argc |
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| 47 | 4(%sp) argv[0] |
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| 48 | ... |
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| 49 | (4*argc)(%sp) NULL |
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| 50 | (4*(argc+1))(%sp) envp[0] |
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| 51 | ... |
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| 52 | NULL |
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| 53 | */ |
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| 54 | |
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| 55 | #include <sysdep.h> |
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| 56 | |
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| 57 | .text |
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| 58 | .globl _start |
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| 59 | .type _start,@function |
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| 60 | _start: |
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| 61 | /* Clear the frame pointer. The ABI suggests this be done, to mark |
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| 62 | the outermost frame obviously. */ |
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| 63 | sub.l %fp, %fp |
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| 64 | |
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| 65 | /* Extract the arguments as encoded on the stack and set up the |
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| 66 | arguments for `main': argc, argv. envp will be determined |
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| 67 | later in __libc_start_main. */ |
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| 68 | move.l (%sp)+, %d0 /* Pop the argument count. */ |
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| 69 | move.l %sp, %a0 /* The argument vector starts just at the |
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| 70 | current stack top. */ |
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| 71 | |
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| 72 | /* Provide the highest stack address to the user code (for stacks |
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| 73 | which grow downward). */ |
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| 74 | pea (%sp) |
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| 75 | |
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| 76 | pea (%a1) /* Push address of the shared library |
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| 77 | termination function. */ |
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| 78 | |
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| 79 | /* These used to be addresses of the .fini and .init entry points. */ |
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| 80 | clr.l -(%sp) |
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| 81 | clr.l -(%sp) |
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| 82 | |
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| 83 | #ifdef PIC |
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| 84 | /* Load PIC register. */ |
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| 85 | LOAD_GOT (%a5) |
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| 86 | |
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| 87 | pea (%a0) /* Push second argument: argv. */ |
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| 88 | move.l %d0, -(%sp) /* Push first argument: argc. */ |
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| 89 | |
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| 90 | move.l main@GOT(%a5), -(%sp) |
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| 91 | |
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| 92 | /* Call the user's main function, and exit with its value. But |
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| 93 | let the libc call main. */ |
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| 94 | jbsr __libc_start_main@PLTPC |
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| 95 | #else |
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| 96 | |
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| 97 | pea (%a0) /* Push second argument: argv. */ |
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| 98 | move.l %d0, -(%sp) /* Push first argument: argc. */ |
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| 99 | |
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| 100 | pea main |
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| 101 | |
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| 102 | /* Call the user's main function, and exit with its value. But |
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| 103 | let the libc call main. */ |
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| 104 | jbsr __libc_start_main |
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| 105 | #endif |
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| 106 | |
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| 107 | illegal /* Crash if somehow `exit' does return. */ |
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| 108 | |
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| 109 | /* Define a symbol for the first piece of initialized data. */ |
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| 110 | .data |
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| 111 | .globl __data_start |
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| 112 | __data_start: |
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| 113 | .long 0 |
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| 114 | .weak data_start |
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| 115 | data_start = __data_start |
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| 116 | |
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