/*      $NetBSD: execsp.S,v 1.2 2025/04/21 02:31:22 riastradh Exp $     */

/*-
* Copyright (c) 2025 The NetBSD Foundation, Inc.
* All rights reserved.
*
* 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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 FOUNDATION OR CONTRIBUTORS
* 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 _LOCORE

#include <machine/asm.h>

RCSID("$NetBSD: execsp.S,v 1.2 2025/04/21 02:31:22 riastradh Exp $")

       .set noat
       .text

/*
* void execsp_start(void *stackpointer@a0, void (*cleanup@a1)(void),
*     void *obj_main@a2, struct ps_strings *ps_strings@a3)
*
*      ELF entry point.  Saves the stack pointer in startsp and defers
*      to the usual csu __start routine.
*/
LEAF(execsp_start, 4)
       LDGP(pv)
       ldq     at_reg, startsp(gp)     !literal
       stq     sp, 0(at_reg)
       ldq     pv, __start(gp)         !literal
       jmp     (pv), __start
END(execsp_start)

/*
* void execsp_ctor(void)
*
*      ELF constructor.  Saves the stack pointer in ctorsp and
*      returns.
*/
LEAF(execsp_ctor, 0)
       LDGP(pv)
       ldq     at_reg, ctorsp(gp)      !literal
       stq     sp, 0(at_reg)
       RET
END(execsp_ctor)

       /* Make execsp_ctor a constructor. */
       .pushsection .ctors,"aw",@progbits
       .p2align 3
       .quad   execsp_ctor
       .popsection

/*
* int main(int argc@a0, char **argv@a1, ...)
*
*      Main function.  Saves the stack pointer in mainsp and returns
*      zero.  We will call execsp_main in execsp_dtor once dtorsp has
*      been initialized.
*/
LEAF(main, 2)
       LDGP(pv)
       ldq     at_reg, mainsp(gp)      !literal
       stq     sp, 0(at_reg)
       mov     zero, v0
       RET
END(main)

/*
* void execsp_dtor(void)
*
*      ELF destructor.  Saves the stack pointer in dtorsp and defers
*      to the C execsp_main in h_execsp.c to report the stack pointers
*      back to the t_signal_and_sp parent.
*/
LEAF(execsp_dtor, 0)
       LDGP(pv)
       ldq     at_reg, dtorsp(gp)      !literal
       stq     sp, 0(at_reg)
       ldq     pv, execsp_main(gp)     !literal
       jmp     (pv), execsp_main
END(execsp_dtor)

       /* Make execsp_ctor a destructor. */
       .pushsection .dtors,"aw",@progbits
       .p2align 3
       .quad   execsp_dtor
       .popsection