/*      $NetBSD: execsp.S,v 1.1 2025/04/20 22:34:07 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 1.1 2025/04/20 22:34:07 riastradh Exp $")

/*
 * void execsp_start(void (*cleanup@a0)(void),
 *     struct ps_strings *ps_strings@a1)
 *
 *      ELF entry point.  Saves the stack pointer in startsp and defers
 *      to the usual csu __start routine.
 */
ENTRY(execsp_start)
        .option push
        .option norelax         /* Don't optimize this into `mv gp, gp'! */
        lla     gp, __global_pointer$
        .option pop

        PTR_LA  t0, _C_LABEL(startsp)   /* t0 := &startsp */
        PTR_S   sp, 0(t0)               /* startsp := sp */
        tail    _C_LABEL(__start)       /* tail call __start */
END(execsp_start)

/*
 * void execsp_ctor(void)
 *
 *      ELF constructor.  Saves the stack pointer in ctorsp and
 *      returns.
 */
ENTRY(execsp_ctor)
        PTR_LA  t0, _C_LABEL(ctorsp)    /* t0 := &ctorsp */
        PTR_S   sp, 0(t0)               /* ctorsp := sp */
        ret
END(execsp_ctor)

        /* Make execsp_ctor a constructor. */
        .section .init_array,"aw"
        .p2align PTR_SCALESHIFT
        PTR_WORD        _C_LABEL(execsp_ctor)

/*
 * 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.
 */
ENTRY(main)
        PTR_LA  t0, _C_LABEL(mainsp)    /* t0 := &mainsp */
        PTR_S   sp, 0(t0)               /* mainsp := sp */
        li      a0, 0                   /* return 0 */
        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.
 */
ENTRY(execsp_dtor)
        PTR_LA  t0, _C_LABEL(dtorsp)    /* t0 := &dtorsp */
        PTR_S   sp, 0(t0)               /* dtorsp := sp */
        tail    _C_LABEL(execsp_main)   /* tail call execsp_main */
END(execsp_dtor)

        /* Make execsp_ctor a destructor. */
        .section .fini_array,"aw"
        .p2align PTR_SCALESHIFT
        PTR_WORD        _C_LABEL(execsp_dtor)