glibc/sysdeps/loongarch/start.S

93 lines
3.2 KiB
ArmAsm

/* Startup code compliant to the ELF LoongArch ABI.
Copyright (C) 2022-2023 Free Software Foundation, Inc.
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
<https://www.gnu.org/licenses/>. */
#define __ASSEMBLY__ 1
#include <entry.h>
#include <sys/asm.h>
/* The entry point's job is to call __libc_start_main. Per the ABI,
a0 contains the address of a function to be passed to atexit.
__libc_start_main wants this in a5. */
/*
int
__libc_start_main (int (*main) (int, char **, char **),
int argc,
char **argv,
__typeof (main) init,
void (*fini) (void),
void (*rtld_fini) (void),
void *stack_end);
*/
ENTRY (ENTRY_POINT)
/* Terminate call stack by noting ra is undefined. Use a dummy
.cfi_label to force starting the FDE. */
.cfi_label .Ldummy
cfi_undefined (1)
or a5, a0, zero /* rtld_fini */
#if ENABLE_STATIC_PIE
/* For static PIE, the GOT cannot be used in _start because the GOT entries are
offsets instead of real addresses before __libc_start_main.
__libc_start_main and/or main may be not local, so we rely on the linker to
produce PLT entries for them. GNU ld >= 2.40 supports this. */
# define LA la.pcrel
#else
/* Old GNU ld (< 2.40) cannot handle PC relative address against a non-local
function correctly. We deem these old linkers failing to support static PIE
and load the addresses from GOT. */
# define LA la.got
#endif
LA a0, t0, main
REG_L a1, sp, 0
ADDI a2, sp, SZREG
/* Adjust $sp for 16-aligned */
BSTRINS sp, zero, 3, 0
move a3, zero /* used to be init */
move a4, zero /* used to be fini */
or a6, sp, zero /* stack_end */
LA ra, t0, __libc_start_main
jirl ra, ra, 0
LA ra, t0, abort
jirl ra, ra, 0
END (ENTRY_POINT)