97 lines
3.0 KiB
ArmAsm
97 lines
3.0 KiB
ArmAsm
/* Startup code compliant to the ELF Mips ABI.
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Copyright (C) 1995, 1997, 2000 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <entry.h>
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#ifndef ENTRY_POINT
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#error ENTRY_POINT needs to be defined for start.S on MIPS/ELF.
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#endif
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/* This is the canonical entry point, usually the first thing in the text
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segment. The SVR4/Mips ABI (pages 3-31, 3-32) says that when the entry
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point runs, most registers' values are unspecified, except for:
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v0 ($2) Contains a function pointer to be registered with `atexit'.
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This is how the dynamic linker arranges to have DT_FINI
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functions called for shared libraries that have been loaded
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before this code runs.
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sp ($29) The stack contains the arguments and environment:
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0(%esp) argc
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4(%esp) argv[0]
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...
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(4*argc)(%esp) NULL
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(4*(argc+1))(%esp) envp[0]
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...
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NULL
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ra ($31) The return address register is set to zero so that programs
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that search backword through stack frames recognize the last
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stack frame.
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*/
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/* We need to call:
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__libc_start_main (int (*main) (int, char **, char **), int argc,
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char **argv, void (*init) (void), void (*fini) (void),
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void (*rtld_fini) (void), void *stack_end)
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*/
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#ifdef __PIC__
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/* A macro to (re)initialize gp. We can get the run time address of 0f in
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ra ($31) by blezal instruction. In this early phase, we can't save gp
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in stack and .cprestore doesn't work properly. So we set gp by using
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this macro. */
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#define SET_GP \
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.set noreorder; \
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bltzal $0,0f; \
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nop; \
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0: .cpload $31; \
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.set reorder;
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#endif
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.text
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.globl ENTRY_POINT
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ENTRY_POINT:
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#ifdef __PIC__
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SET_GP
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#endif
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move $31, $0
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la $4, main /* main */
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lw $5, 0($29) /* argc */
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addu $6, $29, 4 /* argv */
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/* Allocate space on the stack for seven arguments and make sure
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the stack is aligned to double words (8 bytes). */
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and $29, 0xfffffff8
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subu $29, 32
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la $7, _init /* init */
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la $8, _fini
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sw $8, 16($29) /* fini */
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sw $2, 20($29) /* rtld_fini */
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sw $29, 24($29) /* stack_end */
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jal __libc_start_main
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hlt: b hlt /* Crash if somehow it does return. */
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/* Define a symbol for the first piece of initialized data. */
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.data
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.globl __data_start
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__data_start:
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.long 0
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.weak data_start
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data_start = __data_start
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