| xf.li | bdd93d5 | 2023-05-12 07:10:14 -0700 | [diff] [blame] | 1 | /* Copyright (C) 1995-2016 Free Software Foundation, Inc. |
| 2 | |
| 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 License as |
| 7 | published by the Free Software Foundation; either version 2.1 of the |
| 8 | License, or (at your option) any later version. |
| 9 | |
| 10 | The GNU C Library is distributed in the hope that it will be useful, |
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 13 | Lesser General Public License for more details. |
| 14 | |
| 15 | You should have received a copy of the GNU Lesser General Public |
| 16 | License along with the GNU C Library. If not, see |
| 17 | <http://www.gnu.org/licenses/>. */ |
| 18 | |
| 19 | /* This is the canonical entry point, usually the first thing in the text |
| 20 | segment. |
| 21 | |
| 22 | Note that the code in the .init section has already been run. |
| 23 | This includes _init and _libc_init |
| 24 | |
| 25 | |
| 26 | At this entry point, most registers' values are unspecified, except: |
| 27 | |
| 28 | x0 Contains a function pointer to be registered with `atexit'. |
| 29 | This is how the dynamic linker arranges to have DT_FINI |
| 30 | functions called for shared libraries that have been loaded |
| 31 | before this code runs. |
| 32 | |
| 33 | sp The stack contains the arguments and environment: |
| 34 | 0(sp) argc |
| 35 | 8(sp) argv[0] |
| 36 | ... |
| 37 | (8*argc)(sp) NULL |
| 38 | (8*(argc+1))(sp) envp[0] |
| 39 | ... |
| 40 | NULL |
| 41 | */ |
| 42 | |
| 43 | .text |
| 44 | .globl _start |
| 45 | .type _start,#function |
| 46 | _start: |
| 47 | /* Create an initial frame with 0 LR and FP */ |
| 48 | mov x29, #0 |
| 49 | mov x30, #0 |
| 50 | |
| 51 | /* Setup rtld_fini in argument register */ |
| 52 | mov x5, x0 |
| 53 | |
| 54 | /* Load argc and a pointer to argv */ |
| 55 | ldr x1, [sp, #0] |
| 56 | add x2, sp, #8 |
| 57 | |
| 58 | /* Setup stack limit in argument register */ |
| 59 | mov x6, sp |
| 60 | |
| 61 | #ifdef SHARED |
| 62 | adrp x0, :got:main |
| 63 | ldr x0, [x0, #:got_lo12:main] |
| 64 | |
| 65 | adrp x3, :got:__libc_csu_init |
| 66 | ldr x3, [x3, #:got_lo12:__libc_csu_init] |
| 67 | |
| 68 | adrp x4, :got:__libc_csu_fini |
| 69 | ldr x4, [x4, #:got_lo12:__libc_csu_fini] |
| 70 | #else |
| 71 | /* Set up the other arguments in registers */ |
| 72 | ldr x0, =main |
| 73 | ldr x3, =__libc_csu_init |
| 74 | ldr x4, =__libc_csu_fini |
| 75 | #endif |
| 76 | |
| 77 | /* __libc_start_main (main, argc, argv, init, fini, rtld_fini, |
| 78 | stack_end) */ |
| 79 | |
| 80 | /* Let the libc call main and exit with its return code. */ |
| 81 | bl __libc_start_main |
| 82 | |
| 83 | /* should never get here....*/ |
| 84 | bl abort |
| 85 | |
| 86 | /* Define a symbol for the first piece of initialized data. */ |
| 87 | .data |
| 88 | .globl __data_start |
| 89 | __data_start: |
| 90 | .long 0 |
| 91 | .weak data_start |
| 92 | data_start = __data_start |