diff options
Diffstat (limited to 'sysdeps/s390/elf/start.S')
| -rw-r--r-- | sysdeps/s390/elf/start.S | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/sysdeps/s390/elf/start.S b/sysdeps/s390/elf/start.S new file mode 100644 index 0000000000..1455572af8 --- /dev/null +++ b/sysdeps/s390/elf/start.S @@ -0,0 +1,95 @@ +/* Startup code compliant to the ELF s390 ABI. + Copyright (C) 2000 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 Library General Public License as + published by the Free Software Foundation; either version 2 of the + License, or (at your option) any later version. + + 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 + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +/* + 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 + 4(%r15) argv[0] + ... + (4*argc)(%r15) NULL + (4*(argc+1))(%r15) envp[0] + ... + NULL +*/ + + .text + .globl _start +_start: + /* Setup pointer to literal pool of _start */ + basr %r13,0 +.L0: ahi %r13,.Llit-.L0 + + /* load argc and argv from stack */ + la %r4,4(%r15) # get argv + l %r3,0(%r15) # get argc + + /* align the stack to a double word boundary */ + lhi %r0,-8 + nr %r15,%r0 + + /* Setup a stack frame and a parameter area */ + ahi %r15,-104 # make room on stack + xc 0(4,%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 + */ + stm %r14,%r15,96(%r15) # store rtld_fini/stack_end to parameter area + la %r7,96(%r15) + l %r6,.L2-.Llit(%r13) # load pointer to _fini + l %r5,.L1-.Llit(%r13) # load pointer to _init + l %r2,.L3-.Llit(%r13) # load pointer to main + + /* ok, now branch to the libc main routine */ + l %r1,.L4-.Llit(%r13) + basr %r14,%r1 + + /* crash if __libc_start_main returns */ + .word 0 + +.Llit: +.L1: .long _init +.L2: .long _fini +.L3: .long main +.L4: .long __libc_start_main + +/* FIXME: FPU flags or what ?!? */ + + .section .rodata + .globl _fp_hw + .long 3 + .size _fp_hw, 4 + +/* 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 |