mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-30 08:40:07 +00:00
129 lines
4.4 KiB
ArmAsm
129 lines
4.4 KiB
ArmAsm
/* Startup code compliant to the ELF x86-64 ABI.
|
|
Copyright (C) 2001-2012 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by Andreas Jaeger <aj@suse.de>, 2001.
|
|
|
|
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/>. */
|
|
|
|
/* This is the canonical entry point, usually the first thing in the text
|
|
segment. The SVR4/i386 ABI (pages 3-31, 3-32) says that when the entry
|
|
point runs, most registers' values are unspecified, except for:
|
|
|
|
%rdx 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.
|
|
|
|
%rsp The stack contains the arguments and environment:
|
|
0(%rsp) argc
|
|
8(%rsp) argv[0]
|
|
...
|
|
(8*argc)(%rsp) NULL
|
|
(8*(argc+1))(%rsp) envp[0]
|
|
...
|
|
NULL
|
|
*/
|
|
|
|
#include <sysdep.h>
|
|
#include "bp-sym.h"
|
|
|
|
.text
|
|
.globl _start
|
|
.type _start,@function
|
|
_start:
|
|
cfi_startproc
|
|
/* Clearing frame pointer is insufficient, use CFI. */
|
|
cfi_undefined (rip)
|
|
/* Clear the frame pointer. The ABI suggests this be done, to mark
|
|
the outermost frame obviously. */
|
|
xorl %ebp, %ebp
|
|
|
|
/* Extract the arguments as encoded on the stack and set up
|
|
the arguments for __libc_start_main (int (*main) (int, char **, char **),
|
|
int argc, char *argv,
|
|
void (*init) (void), void (*fini) (void),
|
|
void (*rtld_fini) (void), void *stack_end).
|
|
The arguments are passed via registers and on the stack:
|
|
main: %rdi
|
|
argc: %rsi
|
|
argv: %rdx
|
|
init: %rcx
|
|
fini: %r8
|
|
rtld_fini: %r9
|
|
stack_end: stack. */
|
|
|
|
movq %rdx, %r9 /* Address of the shared library termination
|
|
function. */
|
|
popq %rsi /* Pop the argument count. */
|
|
movq %rsp, %rdx /* argv starts just at the current stack top. */
|
|
/* Align the stack to a 16 byte boundary to follow the ABI. */
|
|
andq $~15, %rsp
|
|
|
|
pushq %rax /* Push garbage because we push 8 more bytes. */
|
|
|
|
/* Provide the highest stack address to the user code (for stacks
|
|
which grow downwards). */
|
|
pushq %rsp
|
|
|
|
#ifdef SHARED
|
|
/* Pass address of our own entry points to .fini and .init. */
|
|
movq __libc_csu_fini@GOTPCREL(%rip), %r8
|
|
movq __libc_csu_init@GOTPCREL(%rip), %rcx
|
|
|
|
movq BP_SYM (main)@GOTPCREL(%rip), %rdi
|
|
|
|
/* Call the user's main function, and exit with its value.
|
|
But let the libc call main. */
|
|
call BP_SYM (__libc_start_main)@PLT
|
|
#else
|
|
/* Pass address of our own entry points to .fini and .init. */
|
|
movq $__libc_csu_fini, %r8
|
|
movq $__libc_csu_init, %rcx
|
|
|
|
movq $BP_SYM (main), %rdi
|
|
|
|
/* Call the user's main function, and exit with its value.
|
|
But let the libc call main. */
|
|
call BP_SYM (__libc_start_main)
|
|
#endif
|
|
|
|
hlt /* Crash if somehow `exit' does return. */
|
|
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
|