xf.li | bdd93d5 | 2023-05-12 07:10:14 -0700 | [diff] [blame^] | 1 | /* Startup code compliant to the ELF m68k ABI. |
| 2 | Copyright (C) 1996-2016 Free Software Foundation, Inc. |
| 3 | This file is part of the GNU C Library. |
| 4 | |
| 5 | The GNU C Library is free software; you can redistribute it and/or |
| 6 | modify it under the terms of the GNU Lesser General Public |
| 7 | License as published by the Free Software Foundation; either |
| 8 | version 2.1 of the License, or (at your option) any later version. |
| 9 | |
| 10 | In addition to the permissions in the GNU Lesser General Public |
| 11 | License, the Free Software Foundation gives you unlimited |
| 12 | permission to link the compiled version of this file with other |
| 13 | programs, and to distribute those programs without any restriction |
| 14 | coming from the use of this file. (The GNU Lesser General Public |
| 15 | License restrictions do apply in other respects; for example, they |
| 16 | cover modification of the file, and distribution when not linked |
| 17 | into another program.) |
| 18 | |
| 19 | Note that people who make modified versions of this file are not |
| 20 | obligated to grant this special exception for their modified |
| 21 | versions; it is their choice whether to do so. The GNU Lesser |
| 22 | General Public License gives permission to release a modified |
| 23 | version without this exception; this exception also makes it |
| 24 | possible to release a modified version which carries forward this |
| 25 | exception. |
| 26 | |
| 27 | The GNU C Library is distributed in the hope that it will be useful, |
| 28 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 29 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 30 | Lesser General Public License for more details. |
| 31 | |
| 32 | You should have received a copy of the GNU Lesser General Public |
| 33 | License along with the GNU C Library. If not, see |
| 34 | <http://www.gnu.org/licenses/>. */ |
| 35 | |
| 36 | /* This is the canonical entry point, usually the first thing in the text |
| 37 | segment. The SVR4/m68k ABI says that when the entry point runs, |
| 38 | most registers' values are unspecified, except for: |
| 39 | |
| 40 | %a1 Contains a function pointer to be registered with `atexit'. |
| 41 | This is how the dynamic linker arranges to have DT_FINI |
| 42 | functions called for shared libraries that have been loaded |
| 43 | before this code runs. |
| 44 | |
| 45 | %sp The stack contains the arguments and environment: |
| 46 | 0(%sp) argc |
| 47 | 4(%sp) argv[0] |
| 48 | ... |
| 49 | (4*argc)(%sp) NULL |
| 50 | (4*(argc+1))(%sp) envp[0] |
| 51 | ... |
| 52 | NULL |
| 53 | */ |
| 54 | |
| 55 | #include <sysdep.h> |
| 56 | |
| 57 | .text |
| 58 | .globl _start |
| 59 | .type _start,@function |
| 60 | _start: |
| 61 | /* Clear the frame pointer. The ABI suggests this be done, to mark |
| 62 | the outermost frame obviously. */ |
| 63 | sub.l %fp, %fp |
| 64 | |
| 65 | /* Extract the arguments as encoded on the stack and set up the |
| 66 | arguments for `main': argc, argv. envp will be determined |
| 67 | later in __libc_start_main. */ |
| 68 | move.l (%sp)+, %d0 /* Pop the argument count. */ |
| 69 | move.l %sp, %a0 /* The argument vector starts just at the |
| 70 | current stack top. */ |
| 71 | |
| 72 | /* Provide the highest stack address to the user code (for stacks |
| 73 | which grow downward). */ |
| 74 | pea (%sp) |
| 75 | |
| 76 | pea (%a1) /* Push address of the shared library |
| 77 | termination function. */ |
| 78 | |
| 79 | #ifdef SHARED |
| 80 | /* Load PIC register. */ |
| 81 | LOAD_GOT (%a5) |
| 82 | |
| 83 | /* Push the address of our own entry points to `.fini' and |
| 84 | `.init'. */ |
| 85 | move.l __libc_csu_fini@GOT(%a5), -(%sp) |
| 86 | move.l __libc_csu_init@GOT(%a5), -(%sp) |
| 87 | |
| 88 | pea (%a0) /* Push second argument: argv. */ |
| 89 | move.l %d0, -(%sp) /* Push first argument: argc. */ |
| 90 | |
| 91 | move.l main@GOT(%a5), -(%sp) |
| 92 | |
| 93 | /* Call the user's main function, and exit with its value. But |
| 94 | let the libc call main. */ |
| 95 | jbsr __libc_start_main@PLTPC |
| 96 | #else |
| 97 | /* Push the address of our own entry points to `.fini' and |
| 98 | `.init'. */ |
| 99 | pea __libc_csu_fini |
| 100 | pea __libc_csu_init |
| 101 | |
| 102 | pea (%a0) /* Push second argument: argv. */ |
| 103 | move.l %d0, -(%sp) /* Push first argument: argc. */ |
| 104 | |
| 105 | pea main |
| 106 | |
| 107 | /* Call the user's main function, and exit with its value. But |
| 108 | let the libc call main. */ |
| 109 | jbsr __libc_start_main |
| 110 | #endif |
| 111 | |
| 112 | illegal /* Crash if somehow `exit' does return. */ |
| 113 | |
| 114 | /* Define a symbol for the first piece of initialized data. */ |
| 115 | .data |
| 116 | .globl __data_start |
| 117 | __data_start: |
| 118 | .long 0 |
| 119 | .weak data_start |
| 120 | data_start = __data_start |