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h_execregs.S revision 1.1 
      1 /*	$NetBSD: h_execregs.S,v 1.1 2025/02/27 00:55:32 riastradh Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2025 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     17  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     18  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     19  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     20  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     26  * POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #define	_LOCORE
     30 
     31 #include <sys/syscall.h>
     32 
     33 #include <machine/asm.h>
     34 
     35 #include "execregs.h"
     36 
     37 ENTRY(execregs_start)
     38 	andl	$-0x4,%esp		/* align stack to 4-byte boundary */
     39 
     40 	/* store registers to a buffer on stack */
     41 	subl	$(NEXECREGS*4),%esp	/* space for NEXECREGS registers */
     42 	movl	%edi,0*4(%esp)		/* order matches execregs.h */
     43 	movl	%esi,1*4(%esp)
     44 	movl	%ebp,2*4(%esp)
     45 	movl	%edx,3*4(%esp)
     46 	movl	%ecx,4*4(%esp)
     47 	movl	%eax,5*4(%esp)
     48 
     49 	/* call write(STDOUT_FILENO, regs, sizeof(regs)) */
     50 	movl	%esp,%eax		/* eax := regs */
     51 	pushl	$(NEXECREGS*4)		/* arg2 := sizeof(regs) */
     52 	pushl	%eax			/* arg1 := regs */
     53 	pushl	$0x1			/* arg0 := STDOUT_FILENO */
     54 	call	execregs_write
     55 
     56 	jb	2f			/* bail if write failed */
     57 	cmpl	$(NEXECREGS*4),%eax	/* bail if wrote wrong # of bytes */
     58 	jne	2f
     59 
     60 	/* call exit(0) */
     61 	pushl	$0			/* arg0 := 0 */
     62 1:	call	execregs_exit
     63 	hlt				/* paranoia */
     64 
     65 2:	/* call exit(127) */
     66 	pushl	$127			/* arg0 := 127 */
     67 	jmp	1b
     68 END(execregs_start)
     69 
     70 ENTRY(execregs_write)
     71 	movl	$SYS_write,%eax		/* syscall number */
     72 	int	$0x80
     73 	retl
     74 END(execregs_write)
     75 
     76 ENTRY(execregs_exit)
     77 	movl	$SYS_exit,%eax		/* syscall number */
     78 	int	$0x80
     79 	hlt
     80 END(execregs_exit)
     81 
     82 /* main stub to simplify linking */
     83 ENTRY(main)
     84 	hlt
     85 END(main)
     86