| /* Startup code compliant to the 64 bit S/390 ELF ABI. |
| Copyright (C) 2001-2018 Free Software Foundation, Inc. |
| Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com). |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| In addition to the permissions in the GNU Lesser General Public |
| License, the Free Software Foundation gives you unlimited |
| permission to link the compiled version of this file with other |
| programs, and to distribute those programs without any restriction |
| coming from the use of this file. (The GNU Lesser General Public |
| License restrictions do apply in other respects; for example, they |
| cover modification of the file, and distribution when not linked |
| into another program.) |
| |
| Note that people who make modified versions of this file are not |
| obligated to grant this special exception for their modified |
| versions; it is their choice whether to do so. The GNU Lesser |
| General Public License gives permission to release a modified |
| version without this exception; this exception also makes it |
| possible to release a modified version which carries forward this |
| exception. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <sysdep.h> |
| |
| /* |
| This is the canonical entry point, usually the first thing in the text |
| segment. Most registers' values are unspecified, except for: |
| |
| %r14 Contains a function pointer to be registered with `atexit'. |
| This is how the dynamic linker arranges to have DT_FINI |
| functions called for shared libraries that have been loaded |
| before this code runs. |
| |
| %r15 The stack contains the arguments and environment: |
| 0(%r15) argc |
| 8(%r15) argv[0] |
| ... |
| (8*argc)(%r15) NULL |
| (8*(argc+1))(%r15) envp[0] |
| ... |
| NULL |
| */ |
| |
| .text |
| .globl _start |
| .type _start,@function |
| _start: |
| cfi_startproc |
| /* Mark r14 as undefined in order to stop unwinding here! */ |
| cfi_undefined (r14) |
| /* Load argc and argv from stack. */ |
| la %r4,8(%r15) # get argv |
| lg %r3,0(%r15) # get argc |
| |
| /* Align the stack to a double word boundary. */ |
| lghi %r0,-16 |
| ngr %r15,%r0 |
| |
| /* Setup a stack frame and a parameter area. */ |
| aghi %r15,-176 # make room on stack |
| xc 0(8,%r15),0(%r15) # clear back-chain |
| |
| /* Set up arguments for __libc_start_main: |
| main, argc, argv, envp, _init, _fini, rtld_fini, stack_end |
| Note that envp will be determined later in __libc_start_main. |
| */ |
| stmg %r14,%r15,160(%r15) # store rtld_fini/stack_end to parameter area |
| la %r7,160(%r15) |
| larl %r6,__libc_csu_fini # load pointer to __libc_csu_fini |
| larl %r5,__libc_csu_init # load pointer to __libc_csu_init |
| |
| /* Ok, now branch to the libc main routine. */ |
| #ifdef PIC |
| larl %r2,main@GOTENT # load pointer to main |
| lg %r2,0(%r2) |
| brasl %r14,__libc_start_main@plt |
| #else |
| larl %r2,main # load pointer to main |
| brasl %r14,__libc_start_main |
| #endif |
| |
| /* Crash if __libc_start_main returns. */ |
| .word 0 |
| |
| cfi_endproc |
| |
| /* Define a symbol for the first piece of initialized data. */ |
| .data |
| .globl __data_start |
| __data_start: |
| .long 0 |
| .weak data_start |
| data_start = __data_start |