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/* $OpenBSD: ldasm.S,v 1.9 2023/03/31 18:45:05 kettenis Exp $ */
/*
* Copyright (c) 2016 Dale Rahn
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
#define DL_DATA_SIZE (16 * 8) /* XXX */
#include <machine/asm.h>
#include <sys/syscall.h>
.section .boot.text,"ax",@progbits
_ALIGN_TEXT
.globl _dl_start
.type _dl_start,#function
_dl_start:
mov x29, sp
// need to worry about alignment, I think not?
mov x19, sp
sub sp, sp, #8+8+DL_DATA_SIZE // dl_data size
add x20, sp, #4 // dl_data
mov x21, lr // save old lr
mov x0, x29 // original stack
mov x1, x20 // dl_data
adrp x2, _DYNAMIC /* &_DYNAMIC */
add x2, x2, #:lo12:_DYNAMIC
bl _dl_boot_bind
add x0, x29, #8 // argv
ldr x1, [x29] // load argc
add x1, x0, x1, lsl #3 // envp = argv + argc * 8
add x1, x1, #8 // + 8
ldr x2, [x20, #7*8] // loff from dl_data
mov x3, x20 // dl_data
bl _dl_boot
mov x17, x0
mov sp, x29 // move stack back
mov x29, xzr // clear frame back pointer
mov lr, xzr
adrp x8, :got:_dl_dtors
ldr x2, [x8, :got_lo12:_dl_dtors]
br x17
END(_dl_start)
ENTRY(_dl_bind_start)
/*
* x16 is pointer to pltgot[2]
* x17 is available as scratch register
* return address and pointer to pltgot entry for this
* relocation are on the stack
*/
bti c
mov x17, sp
// save parameter/result registers
stp x0, x1, [sp, #-16]!
stp x2, x3, [sp, #-16]!
stp x4, x5, [sp, #-16]!
stp x6, x7, [sp, #-16]!
stp x8, xzr, [sp, #-16]!
/*
* no need to save v0-v9 as ld.so is compiled with
* -march=armv8-a+nofp+nosimd and therefore doesn't touch the
* SIMD and Floating-Point registers
*/
ldr x0, [x16, #-8] // object
ldr x2, [x17]
sub x1, x2, x16
sub x1, x1, #8
lsr x1, x1, #3 // relidx
bl _dl_bind
mov x17, x0
// restore parameter/result registers
ldp x8, xzr, [sp], #16
ldp x6, x7, [sp], #16
ldp x4, x5, [sp], #16
ldp x2, x3, [sp], #16
ldp x0, x1, [sp], #16
// restore LR saved by PLT stub
ldp xzr, x30, [sp], #16
br x17
END(_dl_bind_start)
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