/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (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 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Bootstrap routine for ld.so.  Control arrives here directly from
 * exec() upon invocation of a dynamically linked program specifying ld.so
 * as its interpreter.
 *
 * On entry, the stack appears as:
 *
 *      !_______________________!  high addresses
 *      !       0 word          !
 *      !_______________________!
 *      !                       !
 *      !       Information     !
 *      !       Block           !
 *      !       (size varies)   !
 *      !_______________________!
 *      !       Auxiliary       !
 *      !       vector          !
 *      !       2 word entries  !
 *      !                       !
 *      !_______________________!
 *      !       0 word          !
 *      !_______________________!
 *      !       Environment     !
 *      !       pointers        !
 *      !       ...             !
 *      !       (one word each) !
 *      !_______________________!
 *      !       0 word          !
 *      !_______________________!
 *      !       Argument        ! low addresses
 *      !       pointers        !
 *      !       Argc words      !
 *      !_______________________!
 *      !                       !
 *      !       Argc            !
 *      !_______________________! <- %sp + STACK_BIAS + WINDOWSIZE
 *      !                       !
 *      !   Window save area    !
 *      !_______________________! <- %sp + STACK_BIAS
 */

#if     defined(lint)

extern  unsigned long   _setup();
extern  void            atexit_fini();

void
main()
{
        (void) _setup();
        atexit_fini();
}

#else

#include <sys/asm_linkage.h>
#include <sys/param.h>
#include <link.h>

        .file   "boot.s"
        .seg    ".text"
        .global _rt_boot, _setup, atexit_fini
        .type   _rt_boot, #function
        .align  4

! Entry vector
!       +0: normal start
!       +4: normal start
!       +8: alias start (frame exists)          XX64 what's this for?

_rt_boot:
        nop
        ba,a    _elf_start
        ba,a    _alias_start

! Start up routines

_elf_start:

! Create a stack frame, perform PIC set up.  We have
! to determine a bunch of things from our "environment" and
! construct an Elf64_Boot attribute value vector.

        save    %sp, -SA(MINFRAME + (EB_MAX * 16)), %sp

_alias_start:

1:                                      ! PIC prologue
        call    2f
        sethi   %hh(_GLOBAL_OFFSET_TABLE_ + (. - 1b)), %g1
2:      or      %g1, %hm(_GLOBAL_OFFSET_TABLE_ + (. - 1b)), %g1
        sllx    %g1, 32, %g5
        sethi   %lm(_GLOBAL_OFFSET_TABLE_ + (. - 1b)), %l7
        or      %l7, %lo(_GLOBAL_OFFSET_TABLE_ + (. - 1b)), %l7
        or      %g5, %l7, %l7
        add     %l7, %o7, %l7           ! finish PIC prologue

! %fp points to the root of our ELF bootstrap vector, use it to construct
! the vector and send it to _setup.
!
! The resulting Elf64_Boot vector looks like this:
!
!       Offset          Contents
!       +0x0            EB_ARGV
!       +0x8            argv[]
!       +0x10           EB_ENVP
!       +0x18           envp[]
!       +0x20           EB_AUXV
!       +0x28           auxv[]
!       +0x30           EB_NULL

        add     %sp, STACK_BIAS + SA(MINFRAME), %o0
                                        ! &eb[0] == %sp + frame size
        mov     EB_ARGV, %l0            ! code for this entry
        stx     %l0, [%o0]              !   store it
        add     %fp, WINDOWSIZE + 8 + STACK_BIAS, %l0
                                        ! argument vector
        stx     %l0, [%o0 + 0x8]        !   store that
        ldx     [%fp + WINDOWSIZE + STACK_BIAS], %l1
                                        ! get argument count (argc)
        inc     %l1                     ! account for last element of 0
        sllx    %l1, 3, %l1             ! multiply by 8
        add     %l0, %l1, %l0           !   and get address of first env ptr
        stx     %l0, [%o0 + 0x18]       ! store it in the vector
        mov     EB_ENVP, %l1            ! code for environment base
        stx     %l1, [%o0 + 0x10]       !   store it
        mov     EB_AUXV, %l1            ! get code for auxiliary vector
        stx     %l1, [%o0 + 0x20]       !   store it

3:      ldx     [%l0], %l1              ! get an entry
        brnz,pt %l1, 3b                 ! if not at end, go back and look again
        add     %l0, 8, %l0             !       incrementing pointer in delay
        stx     %l0, [%o0 + 0x28]       ! store aux vector pointer

        mov     EB_NULL, %l0            ! set up for the last pointer
        stx     %l0, [%o0 + 0x30]       !   and store it
        mov     %g0, %g2                ! clear globals
        mov     %g0, %g3

! Call _setup.  Two arguments, the ELF bootstrap vector and our (unrelocated)
! _DYNAMIC address.  The _DYNAMIC address is located in entry 0 of the GOT


        call    _setup                  ! call it
        ldx     [%l7], %o1

! On return, give callee the exit function in %g1, and jump to the
! target program, clearing out the reserved globals as we go.

        ldx     [%l7 + atexit_fini], %g1! get function address
        restore %o0, %g0, %l1           ! release frame
        jmpl    %l1, %g0                ! call main program
        mov     %g0, %g4                !   clear one last global in delay

        .size   _rt_boot, . - _rt_boot
#endif