/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 *      Copyright (c) 1988 AT&T
 *        All Rights Reserved
 *
 *
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Bootstrap routine for run-time linker.
 * We get control from exec which has loaded our text and
 * data into the process' address space and created the process
 * stack.
 *
 * On entry, the process stack looks like this:
 *
 *      #                       # <- %rsp
 *      #_______________________#  high addresses
 *      #       strings         #
 *      #_______________________#
 *      #       0 word          #
 *      #_______________________#
 *      #       Auxiliary       #
 *      #       entries         #
 *      #       ...             #
 *      #       (size varies)   #
 *      #_______________________#
 *      #       0 word          #
 *      #_______________________#
 *      #       Environment     #
 *      #       pointers        #
 *      #       ...             #
 *      #       (one word each) #
 *      #_______________________#
 *      #       0 word          #
 *      #_______________________#
 *      #       Argument        # low addresses
 *      #       pointers        #
 *      #       Argc words      #
 *      #_______________________#
 *      #       argc            #
 *      #_______________________# <- %rbp
 *
 *
 * We must calculate the address at which ld.so was loaded,
 * find the addr of the dynamic section of ld.so, of argv[0], and  of
 * the process' environment pointers - and pass the thing to _setup
 * to handle.  We then call _rtld - on return we jump to the entry
 * point for the executable.
 */

#if     defined(lint)

extern  unsigned long   _setup();
extern  void            atexit_fini();
void
main()
{
        (void) _setup();
        atexit_fini();
}

#else

#include        <link.h>

        .file   "boot.s"
        .text
        .globl  _rt_boot
        .globl  _setup
        .globl  _GLOBAL_OFFSET_TABLE_
        .type   _rt_boot,@function
        .align  4

_rt_alias:
        / in case we were invoked from libc.so
        jmp     .get_got
_rt_boot:
        / save for referencing args
        movq    %rsp,%rbp
        / make room for a max sized boot vector
        subq    $EB_MAX_SIZE64,%rsp
        / use esi as a pointer to &eb[0]
        movq    %rsp,%rsi
        / set up tag for argv
        movq    $EB_ARGV,0(%rsi)
        / get address of argv
        leaq    8(%rbp),%rax
        / put after tag
        movq    %rax,8(%rsi)
        / set up tag for envp
        movq    $EB_ENVP,16(%rsi)
        / get # of args
        movq    (%rbp),%rax
        / one for the zero & one for argc
        addq    $2,%rax
        / now points past args & @ envp
        leaq    (%rbp,%rax,8),%rdi
        / set envp
        movq    %rdi,24(%rsi)
        / next
.L0:    addq    $8,%rdi
        / search for 0 at end of env
        cmpq    $0,-8(%rdi)
        jne     .L0
        / set up tag for auxv
        movq    $EB_AUXV,32(%rsi)
        / point to auxv
        movq    %rdi,40(%rsi)
        / set up NULL tag
        movq    $EB_NULL,48(%rsi)

        / arg1 - address of &eb[0]
        movq    %rsi, %rdi
.get_got:
        leaq    _GLOBAL_OFFSET_TABLE_(%rip), %rbx
        / addq  $_GLOBAL_OFFSET_TABLE_, %rbx
        movq    %rbx,%r9
        // addq $[.L2-.L1], %rbx
        movq    %rbx,%r10

        movq    (%rbx),%rsi

        / _setup(&eb[0], _DYNAMIC)
        call    _setup@PLT
        / release stack frame
        movq    %rbp,%rsp

        movq    atexit_fini@GOTPCREL(%rip), %rdx
        / transfer control to the executable
        jmp     *%rax
        .size   _rt_boot,.-_rt_boot
#endif