1/* Startup code compliant to the ELF m68k ABI. 2 Copyright (C) 1996-2022 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 <https://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 /* These used to be addresses of the .fini and .init entry points. */ 80 clr.l -(%sp) 81 clr.l -(%sp) 82 83#ifdef PIC 84 /* Load PIC register. */ 85 LOAD_GOT (%a5) 86 87 pea (%a0) /* Push second argument: argv. */ 88 move.l %d0, -(%sp) /* Push first argument: argc. */ 89 90 move.l main@GOT(%a5), -(%sp) 91 92 /* Call the user's main function, and exit with its value. But 93 let the libc call main. */ 94 jbsr __libc_start_main@PLTPC 95#else 96 97 pea (%a0) /* Push second argument: argv. */ 98 move.l %d0, -(%sp) /* Push first argument: argc. */ 99 100 pea main 101 102 /* Call the user's main function, and exit with its value. But 103 let the libc call main. */ 104 jbsr __libc_start_main 105#endif 106 107 illegal /* Crash if somehow `exit' does return. */ 108 109/* Define a symbol for the first piece of initialized data. */ 110 .data 111 .globl __data_start 112__data_start: 113 .long 0 114 .weak data_start 115 data_start = __data_start 116