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/* Copyright (C) 2011-2017 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
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.
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>
/* Get address of "sym" in "reg" assuming r51 holds ".Llink". */
.macro pic_addr reg, sym
moveli \reg, hw1_last(\sym - .Llink)
shl16insli \reg, \reg, hw0(\sym - .Llink)
ADD_PTR \reg, r51, \reg
.endm
.text
ENTRY (_start)
/* Linux starts us with sp pointing at the conventional Elf layout,
but we need to allow two 'caller' words for our ABI convention. */
{
move r52, sp
andi sp, sp, -8
}
cfi_def_cfa_register (r52)
{
/* Point sp at base of ABI area; point r4 to the caller-sp word. */
ADDI_PTR sp, sp, -(2 * REGSIZE)
ADDI_PTR r4, sp, -REGSIZE
}
{
/* Save zero for caller sp in our 'caller' save area, and make
sure lr has a zero value, to limit backtraces. */
move lr, zero
st r4, zero
}
{
move r0, r52
jal _dl_start
}
/* Save returned start of user program address for later. */
move r50, r0
/* See if we were invoked explicitly with the dynamic loader,
in which case we have to adjust the argument vector. */
lnk r51; .Llink:
pic_addr r4, _dl_skip_args
ld4u r4, r4
beqzt r4, .Lno_skip
/* Load the argc word at the initial sp and adjust it.
We basically jump "sp" up over the first few argv entries
and write "argc" a little higher up in memory, to be the
base of the new kernel-initialized stack area. */
LD_PTR r0, r52
{
sub r0, r0, r4
SHL_PTR_ADD r52, r4, r52
}
{
ST_PTR r52, r0
SHL_PTR_ADD sp, r4, sp
}
andi sp, sp, -8
.Lno_skip:
/* Call_dl_init (_dl_loaded, argc, argv, envp). See elf/start.s
for the layout of memory here; r52 is pointing to "+0". */
pic_addr r0, _rtld_local
{
LD_PTR r1, r52 /* load argc in r1 */
ADDLI_PTR r2, r52, __SIZEOF_POINTER__ /* point r2 at argv */
}
{
LD_PTR r0, r0 /* yields _rtld_global._ns_loaded */
addi r3, r1, 1
move lr, zero
}
{
SHL_PTR_ADD r3, r3, r2 /* point r3 at envp */
jal _dl_init
}
/* Call user program whose address we saved in r50.
We invoke it just like a static binary, but with _dl_fini
in r0 so we can distinguish. */
pic_addr r0, _dl_fini
move lr, zero
{
move sp, r52
jr r50
}
/* Tell backtracer to give up (_start has no caller). */
info 2 /* INFO_OP_CANNOT_BACKTRACE */
END (_start)
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