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arm_initfini.c revision 1.8 
      1 /*-
      2  * Copyright (c) 2013 The NetBSD Foundation, Inc.
      3  * All rights reserved.
      4  *
      5  * This code is derived from software contributed to The NetBSD Foundation
      6  * by Matt Thomas of 3am Software Foundry.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     18  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     19  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     20  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     21  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     22  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     23  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     24  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     25  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     26  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     27  * POSSIBILITY OF SUCH DAMAGE.
     28  */
     29 
     30 #include <sys/cdefs.h>
     31 
     32 __RCSID("$NetBSD: arm_initfini.c,v 1.8 2025/02/27 02:05:03 christos Exp $");
     33 
     34 #include "namespace.h"
     35 
     36 /*
     37  * To properly implement setjmp/longjmp for the ARM AAPCS ABI, it has to be
     38  * aware of whether there is a FPU is present or not.  Regardless of whether
     39  * the hard-float ABI is being used, setjmp needs to save D8-D15.  But it can
     40  * only do this if those instructions won't cause an exception.
     41  */
     42 
     43 #include <sys/param.h>
     44 #include <sys/sysctl.h>
     45 
     46 #include <stdbool.h>
     47 #include <string.h>
     48 #include <stddef.h>
     49 
     50 __dso_hidden int _libc_arm_fpu_present;
     51 #ifndef __ARM_ARCH_EXT_IDIV__
     52 __dso_hidden int _libc_arm_hwdiv_present;
     53 # define NENTRIES 2
     54 #else
     55 # define NENTRIES 1
     56 #endif
     57 
     58 static bool _libc_aapcs_initialized;
     59 
     60 void	_libc_aapcs_init(void) __attribute__((__constructor__, __used__));
     61 
     62 void __section(".text.startup")
     63 _libc_aapcs_init(void)
     64 {
     65 	if (_libc_aapcs_initialized)
     66 		return;
     67 
     68 	struct sysctlnode query, md[64];
     69 	int mib[2];
     70 	size_t len, mlen = sizeof(_libc_arm_fpu_present), nentries = 0;
     71 
     72 	_libc_aapcs_initialized = true;
     73 	mib[0] = CTL_MACHDEP;
     74 	mib[1] = CTL_QUERY;
     75 	memset(&query, 0, sizeof(query));
     76 	query.sysctl_flags = SYSCTL_VERSION;
     77 	len = sizeof(md);
     78 	if (sysctl(mib, 2, md, &len, &query, sizeof(query)) == -1)
     79 		return;
     80 
     81 	for (size_t i = 0; i < len / sizeof(md[0]); i++) {
     82 		if (strcmp(md[i].sysctl_name, "fpu_present") == 0) {
     83 			mib[1] = md[i].sysctl_num;
     84 			(void)sysctl(mib, 2, &_libc_arm_fpu_present, &mlen,
     85 			    NULL, 0);
     86 			nentries++;
     87 
     88 		}
     89 #ifndef __ARM_ARCH_EXT_IDIV__
     90 		else if (strcmp(md[i].sysctl_name, "hwdiv_present") == 0) {
     91 			mib[1] = md[i].sysctl_num;
     92 			(void)sysctl(mib, 2, &_libc_arm_hwdiv_present, &mlen,
     93 			    NULL, 0);
     94 			nentries++;
     95 		}
     96 #endif
     97 		if (nentries >= NENTRIES)
     98 			return;
     99 	}
    100 }
    101