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115 lines
3.1 KiB
ArmAsm
115 lines
3.1 KiB
ArmAsm
/* Copyright (C) 2011-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
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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 Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the 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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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<http://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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/* Get address of "sym" in "reg" assuming r51 holds ".Llink". */
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.macro pic_addr reg, sym
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#ifdef __tilegx__
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moveli \reg, hw1_last(\sym - .Llink)
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shl16insli \reg, \reg, hw0(\sym - .Llink)
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ADD_PTR \reg, r51, \reg
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#else
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ADDLI_PTR \reg, r51, lo16(\sym - .Llink)
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auli \reg, \reg, ha16(\sym - .Llink)
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#endif
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.endm
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.text
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ENTRY (_start)
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/* Linux starts us with sp pointing at the conventional Elf layout,
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but we need to allow two 'caller' words for our ABI convention. */
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{
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move r52, sp
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andi sp, sp, -8
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}
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cfi_def_cfa_register (r52)
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{
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/* Point sp at base of ABI area; point r4 to the caller-sp word. */
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ADDI_PTR sp, sp, -(2 * REGSIZE)
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ADDI_PTR r4, sp, -REGSIZE
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}
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{
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/* Save zero for caller sp in our 'caller' save area, and make
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sure lr has a zero value, to limit backtraces. */
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move lr, zero
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ST r4, zero
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}
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{
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move r0, r52
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jal _dl_start
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}
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/* Save returned start of user program address for later. */
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move r50, r0
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/* See if we were invoked explicitly with the dynamic loader,
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in which case we have to adjust the argument vector. */
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lnk r51; .Llink:
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pic_addr r4, _dl_skip_args
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LD4U r4, r4
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BEQZT r4, .Lno_skip
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/* Load the argc word at the initial sp and adjust it.
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We basically jump "sp" up over the first few argv entries
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and write "argc" a little higher up in memory, to be the
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base of the new kernel-initialized stack area. */
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LD_PTR r0, r52
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{
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sub r0, r0, r4
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SHL_PTR_ADD r52, r4, r52
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}
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{
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ST_PTR r52, r0
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SHL_PTR_ADD sp, r4, sp
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}
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andi sp, sp, -8
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.Lno_skip:
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/* Call_dl_init (_dl_loaded, argc, argv, envp). See elf/start.s
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for the layout of memory here; r52 is pointing to "+0". */
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pic_addr r0, _rtld_local
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{
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LD_PTR r1, r52 /* load argc in r1 */
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ADDLI_PTR r2, r52, __SIZEOF_POINTER__ /* point r2 at argv */
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}
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{
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LD_PTR r0, r0 /* yields _rtld_global._ns_loaded */
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addi r3, r1, 1
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move lr, zero
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}
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{
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SHL_PTR_ADD r3, r3, r2 /* point r3 at envp */
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jal _dl_init
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}
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/* Call user program whose address we saved in r50.
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We invoke it just like a static binary, but with _dl_fini
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in r0 so we can distinguish. */
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pic_addr r0, _dl_fini
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move lr, zero
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{
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move sp, r52
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jr r50
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}
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/* Tell backtracer to give up (_start has no caller). */
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info 2 /* INFO_OP_CANNOT_BACKTRACE */
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END (_start)
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