/* $NetBSD: h_execregs.S,v 1.1 2025/02/27 00:55:32 riastradh Exp $ */

/* $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"

ENTRY(execregs_start)
andl $-0x4,%esp /* align stack to 4-byte boundary */

/* store registers to a buffer on stack */
subl $(NEXECREGS*4),%esp /* space for NEXECREGS registers */
movl %edi,0*4(%esp) /* order matches execregs.h */
movl %esi,1*4(%esp)
movl %ebp,2*4(%esp)
movl %edx,3*4(%esp)
movl %ecx,4*4(%esp)
movl %eax,5*4(%esp)

/* call write(STDOUT_FILENO, regs, sizeof(regs)) */
movl %esp,%eax /* eax := regs */
pushl $(NEXECREGS*4) /* arg2 := sizeof(regs) */
pushl %eax /* arg1 := regs */
pushl $0x1 /* arg0 := STDOUT_FILENO */
call execregs_write

jb 2f /* bail if write failed */
cmpl $(NEXECREGS*4),%eax /* bail if wrote wrong # of bytes */
jne 2f

/* call exit(0) */
pushl $0 /* arg0 := 0 */
1: call execregs_exit
hlt /* paranoia */

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

ENTRY(execregs_write)
movl $SYS_write,%eax /* syscall number */
int $0x80
retl
END(execregs_write)

ENTRY(execregs_exit)
movl $SYS_exit,%eax /* syscall number */
int $0x80
hlt
END(execregs_exit)

/* main stub to simplify linking */
ENTRY(main)
hlt
END(main)