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execsp.S revision 1.3 
      1 /*	$NetBSD: execsp.S,v 1.3 2025/06/04 19:25:45 christos 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 <machine/asm.h>
     32 
     33 RCSID("$NetBSD: execsp.S,v 1.3 2025/06/04 19:25:45 christos Exp $")
     34 
     35 /*
     36  * void execsp_start(void (*cleanup@x0)(void), void *obj_main@x1,
     37  *     struct ps_strings *ps_strings@x2)
     38  *
     39  *	ELF entry point.  Saves the stack pointer in startsp and defers
     40  *	to the usual csu __start routine.
     41  */
     42 ENTRY(execsp_start)
     43 	mov	x16, sp
     44 	adrp	x17, _C_LABEL(startsp)
     45 	str	x16, [x17, :lo12:_C_LABEL(startsp)]
     46 	b	_C_LABEL(__start)
     47 END(execsp_start)
     48 
     49 /*
     50  * void execsp_ctor(void)
     51  *
     52  *	ELF constructor.  Saves the stack pointer in ctorsp and
     53  *	returns.
     54  */
     55 ENTRY(execsp_ctor)
     56 	mov	x16, sp
     57 	adrp	x17, _C_LABEL(ctorsp)
     58 	str	x16, [x17, :lo12:_C_LABEL(ctorsp)]
     59 	ret
     60 END(execsp_ctor)
     61 
     62 	/* Make execsp_ctor a constructor. */
     63 	.section .init_array,"aw",%init_array
     64 	.p2align 3
     65 	.xword	_C_LABEL(execsp_ctor)
     66 
     67 /*
     68  * int main(int argc@x0, char **argv@x1, ...)
     69  *
     70  *	Main function.  Saves the stack pointer in mainsp and returns
     71  *	zero.  We will call execsp_main in execsp_dtor once dtorsp has
     72  *	been initialized.
     73  */
     74 ENTRY(main)
     75 	mov	x16, sp
     76 	adrp	x17, _C_LABEL(mainsp)
     77 	str	x16, [x17, :lo12:_C_LABEL(mainsp)]
     78 	mov	x0, #0
     79 	ret
     80 END(main)
     81 
     82 /*
     83  * void execsp_dtor(void)
     84  *
     85  *	ELF destructor.  Saves the stack pointer in dtorsp and defers
     86  *	to the C execsp_main in h_execsp.c to report the stack pointers
     87  *	back to the t_signal_and_sp parent.
     88  */
     89 ENTRY(execsp_dtor)
     90 	mov	x16, sp
     91 	adrp	x17, _C_LABEL(dtorsp)
     92 	str	x16, [x17, :lo12:_C_LABEL(dtorsp)]
     93 	b	_C_LABEL(execsp_main)
     94 END(execsp_dtor)
     95 
     96 	/* Make execsp_ctor a destructor. */
     97 	.section .fini_array,"aw",%fini_array
     98 	.p2align 3
     99 	.xword	_C_LABEL(execsp_dtor)
    100