/*      $OpenBSD: ldasm.S,v 1.11 2023/07/08 14:09:43 jasper 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
         */
        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)