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      1 /* $NetBSD: __clone.S,v 1.14 2021/06/30 21:20:30 skrll Exp $ */
      2 
      3 /*
      4  * Copyright (c) 2001 Christopher Gilbert
      5  * All rights reserved.
      6  *
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  * 3. The name of the company nor the name of the author may be used to
     13  *    endorse or promote products derived from this software without specific
     14  *    prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
     17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     19  * IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
     20  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     21  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
     22  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26  * SUCH DAMAGE.
     27  */
     28 
     29 #include "SYS.h"
     30 #include <sys/errno.h>
     31 
     32 #ifdef WEAK_ALIAS
     33 WEAK_ALIAS(clone, __clone)
     34 #endif
     35 
     36 /*
     37  * int __clone(int (*fn)(void *), void *stack, int flags, void *arg);
     38  */
     39 ENTRY(__clone)
     40 
     41 	/* test stack and function are not null */
     42 #if defined(__thumb__) && defined(_ARM_ARCH_T2)
     43 	cbz	r0, .Leinval
     44 	cbz	r1, .Leinval
     45 #elif !defined(__thumb__)
     46 	cmp	r0, #0x00
     47 	cmpne	r1, #0x00
     48 	beq	.Leinval
     49 #else
     50 	cmp	r0, #0x00
     51 	beq	.Leinval
     52 	cmp	r1, #0x00
     53 	beq	.Leinval
     54 #endif
     55 
     56 	/* place the func and its arg onto the child's stack */
     57 #if !defined(__thumb__) || defined(_ARM_ARCH_T2)
     58 	stmfd	r1!, {r0, r3}
     59 #else
     60 	subs	r1, r1, #8
     61 	stmia	r1!, {r0, r3}
     62 #endif
     63 
     64 	/* syscall expects (flags, stack) */
     65 	mov	r0, r2
     66 
     67 	SYSTRAP(__clone)
     68 	_INVOKE_CERROR()
     69 
     70 	/*
     71 	 * r1 and r0 are the same as from fork:
     72 	 * r1 == 0 in parent process, r1 == 1 in child process.
     73 	 * r0 == pid of child in parent, r0 == pid of parent in child.
     74 	 */
     75 	/* if this is the parent then just return the pid */
     76 #if defined(__thumb__)
     77 #if defined(_ARM_ARCH_T2)
     78 	cbz	r1, 1f
     79 #else
     80 	cmp	r1, #0x00
     81 	bne	1f
     82 #endif
     83 	RET
     84 1:
     85 #else
     86 	cmp	r1, #0x00
     87 	RETc(eq)
     88 #endif
     89 
     90 	/*
     91 	 * This is the child
     92 	 * load the function and arg off the stack
     93 	 */
     94 	pop	{r1, r2}
     95 
     96 	/* place arg in r0 */
     97 	mov	r0, r2
     98 
     99 	/* call the function */
    100 #ifdef _ARM_ARCH_5T
    101 	blx	r1
    102 #else
    103 	/* setup return address */
    104 	mov	lr, pc
    105 	RETr(r1)
    106 #endif
    107 	/* call _exit with the returned value */
    108 	bl	PLT_SYM(_C_LABEL(_exit))
    109 
    110 	/* NOTREACHED */
    111 
    112 	/* error handler if func or stack is NULL */
    113 	.align	0
    114 .Leinval:
    115 	movs	r0, #EINVAL
    116 #if !defined(__thumb__) || defined(_ARM_ARCH_T2)
    117 	b	CERROR
    118 #else
    119 .Lcerror:
    120 	push	{r3, lr}
    121 	bl	CERROR
    122 	pop	{r3, pc}
    123 #endif
    124 END(__clone)
    125