/*
 * 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 either directly from
 * exec() upon invocation of a dynamically linked program specifying ld.so
 * as its interpreter.
 *
 * On entry, the stack appears as:
 *
 *      !_______________________!  high addresses
 *      !                       !
 *      !       Information     !
 *      !       Block           !
 *      !       (size varies)   !
 *      !_______________________!
 *      !       0 word          !
 *      !_______________________!
 *      !       Auxiliary       !
 *      !       vector          !
 *      !       2 word entries  !
 *      !                       !
 *      !_______________________!
 *      !       0 word          !
 *      !_______________________!
 *      !       Environment     !
 *      !       pointers        !
 *      !       ...             !
 *      !       (one word each) !
 *      !_______________________!
 *      !       0 word          !
 *      !_______________________!
 *      !       Argument        ! low addresses
 *      !       pointers        !
 *      !       Argc words      !
 *      !_______________________!
 *      !                       !
 *      !       Argc            !
 *      !_______________________! <- %sp + 64
 *      !                       !
 *      !   Window save area    !
 *      !_______________________! <- %sp
 */

#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: compatibility start, now an error
!       +8: alias start (frame exists)

_rt_boot:
        ba,a    _elf_start
        ba,a    _aout_start
        ba,a    _alias_start

! Start up routines -- the aout_start will have a pointer in %o0 that we'll
! want to save -- the elf can be zeroed.

_elf_start:
        clr     %o0                     ! 0 in %o0 == ELF
_aout_start:                            ! (falls through)

! Create a stack frame, perform PIC set up.  If we're a "normal" start, we have
! to determine a bunch of things from our "environment" and construct an ELF
! boot attribute value vector.  Otherwise, it's already been done and we can
! skip it.

        save    %sp, -SA(MINFRAME + (EB_MAX * 8)), %sp
_alias_start:
1:                                      ! PIC prologue
        call    2f
        sethi   %hi(_GLOBAL_OFFSET_TABLE_ + (. - 1b)), %l7
2:
        or      %l7, %lo(_GLOBAL_OFFSET_TABLE_ + (. - 1b)), %l7

! If %i0 (was %o0) is non-zero, we're in compatibility and we can
! skip construction of the ELF boot attribute vector.

        addcc   %i0, %g0, %o0           ! set condition codes
        bne     1f                      ! if non-zero, skip setup
        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.

        add     %sp, SA(MINFRAME), %o0  ! &eb[0] == %sp + frame size
        set     EB_ARGV, %l0            ! code for this entry
        st      %l0, [%o0]              !   store it
        add     %fp, 68, %l0            ! argument vector is at %fp+68
        st      %l0, [%o0 + 4]          !   store that
        ld      [%fp + 64], %l1         ! get argument count
        inc     %l1                     ! account for last element of 0
        sll     %l1, 2, %l1             ! multiply by 4
        add     %l0, %l1, %l0           !   and get address of first env ptr
        st      %l0, [%o0 + 12]         ! store it in the vector
        set     EB_ENVP, %l1            ! code for environment base
        st      %l1, [%o0 + 8]          !   store it
        set     EB_AUXV, %l1            ! get code for auxiliary vector
        st      %l1, [%o0 + 16]         !   store it
2:
        ld      [%l0], %l1              ! get an entry
        tst     %l1                     ! are we at a "0" entry in environment?
        bne     2b                      !   no, go back and look again
        add     %l0, 4, %l0             !       incrementing pointer in delay
        st      %l0, [%o0 + 20]         ! store aux vector pointer
        set     EB_NULL, %l0            ! set up for the last pointer
        st      %l0, [%o0 + 24]         !   and store it

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

1:
        mov     %g0, %g2                ! clear globals
        mov     %g0, %g3
        call    _setup                  ! call it
        ld      [%l7], %o1              ! 2nd parameter

! On return, give callee the exit function in %g1, and either jump to the
! target program (normal), or if return value of _setup is "0" we have
! to return to the compatibility bootstrap.  In either case, clear out
! reserved globals.

        ld      [%l7 + atexit_fini], %g1! get function address
        restore %o0, %g0, %l1           ! release frame
        tst     %l1                     ! compatibility return?
        be      1f                      ! yes,
        mov     %g0, %g4                !   but clear one last global in delay
        jmpl    %l1, %g0                ! call main program
        nop
1:
        retl                            ! compatibility return
        nop

        .size   _rt_boot, . - _rt_boot
#endif