/*      $NetBSD: h_execregs.S,v 1.2 2025/04/25 12:58:40 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"

ENTRY(execregs_start)
       /* create a stack frame with NEXECREGS*8 bytes, aligned to 16-byte */
       stp     fp, lr, [sp, #-(16 + ((NEXECREGS*8 + 15)/16)*16)]!

       /* store registers to buffer on stack */
       stp     x0, x1, [sp, #16]       /* order matches execregs.h */
       /* x2: ps_strings */
       stp     x3, x4, [sp, #(16 + 1*2*8)]
       stp     x5, x6, [sp, #(16 + 2*2*8)]
       stp     x7, x8, [sp, #(16 + 3*2*8)]
       stp     x9, x10, [sp, #(16 + 4*2*8)]
       stp     x11, x12, [sp, #(16 + 5*2*8)]
       stp     x13, x14, [sp, #(16 + 6*2*8)]
       stp     x15, x16, [sp, #(16 + 7*2*8)]
       stp     x17, x18, [sp, #(16 + 8*2*8)]
       stp     x19, x20, [sp, #(16 + 9*2*8)]
       stp     x21, x22, [sp, #(16 + 10*2*8)]
       stp     x23, x24, [sp, #(16 + 11*2*8)]
       stp     x25, x26, [sp, #(16 + 12*2*8)]
       stp     x27, x28, [sp, #(16 + 13*2*8)]
       stp     x29, x30, [sp, #(16 + 14*2*8)]
       mrs     x0, tpidr_el0
       str     x0, [sp, #(16 + 15*2*8)]

       /* call write(STDOUT_FILENO, regs, sizeof(regs)) */
       mov     x0, #1                  /* arg0 := STDOUT_FILENO */
       add     x1, sp, #16             /* arg1 := regs */
       mov     x2, #(NEXECREGS*8)      /* arg2 := sizeof(regs) */
       svc     #SYS_write

       b.cs    2f                      /* bail if write failed */
       cmp     x0, #(NEXECREGS*8)      /* bail if wrote wrong # of bytes */
       b.ne    2f

       /* call exit(0) */
       mov     x0, #0                  /* arg0 := 0 */
1:      svc     #SYS_exit
       brk     #0xffff                 /* paranoia */

2:      /* call exit(127) */
       mov     x0, #127                /* arg0 := 127 */
       b       1b
END(execregs_start)

/* main stub to simplify linking */
ENTRY(main)
       brk     #0xffff
END(main)