/*      $NetBSD: h_execregs.S,v 1.1 2025/02/27 00:55:32 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 <sys/syscall.h>

#include <machine/asm.h>

#include "execregs.h"

#define REGSIZE 4
#define BUFSIZE (NEXECREGS * REGSIZE)
#define SLOT(n) (n)*REGSIZE(%sp)

ENTRY(execregs_start, 0)
        /* store registers to a buffer on stack */
        subl2   $BUFSIZE,%sp            /* space for NEXECREGS registers */
        movl    %fp,SLOT(0)             /* order matches execregs.h */
        movl    %ap,SLOT(1)
        /* sp: stack pointer */
        movl    %r0,SLOT(2)
        movl    %r1,SLOT(3)
        movl    %r2,SLOT(4)
        movl    %r3,SLOT(5)
        movl    %r4,SLOT(6)
        movl    %r5,SLOT(7)
        /* r6: initial stack pointer */
        movl    %r7,SLOT(8)
        movl    %r8,SLOT(9)
        /* r9: ps_strings */
        movl    %r10,SLOT(10)
        movl    %r11,SLOT(11)

        /* call write(STDOUT_FILENO, regs, sizeof(regs)) */
        pushl   $BUFSIZE                /* arg2 := sizeof(regs) */
        pushal  4(%sp)                  /* arg1 := regs */
        pushl   $1                      /* arg0 := STDOUT_FILENO */
        pushl   $3                      /* number of arguments */
        movl    %sp,%ap                 /* argument pointer */
        chmk    $SYS_write

        bcs     2f                      /* bail if write failed */
        cmpl    $BUFSIZE,%r0            /* bail if wrote wrong # of bytes */
        bneq    2f

        /* call exit(0) */
        pushl   $0                      /* arg0 := 0 */
1:      pushl   $1                      /* number of arguments */
        movl    %sp,%ap                 /* argument pointer */
        chmk    $SYS_exit
        .word   0xffff                  /* paranoia -- illegal opcode */

2:      /* call exit(127) */
        pushl   $127                    /* arg0 := 127 */
        jmp     1b
END(execregs_start)

/* main stub to simplify linking */
ENTRY(main, 0)
        .word   0xffff                  /* illegal opcode */
END(main)