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      1 /*	$NetBSD: elf_support.h,v 1.1 2018/03/29 13:23:39 joerg Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2018 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 #ifndef _SPARC_ELF_SUPPORT_H
     29 #define _SPARC_ELF_SUPPORT_H
     30 
     31 static inline void
     32 sparc_write_branch(void *where_, void *target)
     33 {
     34 	const unsigned int BAA     = 0x30800000U; /* ba,a  (offset / 4) */
     35 	const unsigned int SETHI   = 0x03000000U; /* sethi %hi(0), %g1 */
     36 	const unsigned int JMP     = 0x81c06000U; /* jmpl  %g1+%lo(0), %g0 */
     37 
     38 	unsigned int *where = (unsigned int *)where_;
     39 	unsigned long value = (unsigned long)target;
     40 	unsigned long offset = value - (unsigned long)where;
     41 
     42 #define	HIVAL(v, s)	(((v) >> (s)) & 0x003fffffU)
     43 #define	LOVAL(v, s)	(((v) >> (s)) & 0x000003ffU)
     44 	if (offset + 0x800000 <= 0x7ffffc) {
     45 		/* Displacement is within 8MB, use a direct branch. */
     46 		where[0] = BAA | ((offset >> 2) & 0x3fffff);
     47 		__asm volatile("iflush %0+0" : : "r" (where));
     48 		return;
     49 	}
     50 
     51 	/*
     52 	 * The absolute address is a 32bit value.
     53 	 * This can be encoded as:
     54 	 *	sethi	%hi(value), %g1
     55 	 *	jmp	%g1+%lo(value)
     56 	 */
     57 	where[1] = JMP   | LOVAL(value, 0);
     58 	__asm volatile("iflush %0+4" : : "r" (where));
     59 	where[0] = SETHI | HIVAL(value, 10);
     60 	__asm volatile("iflush %0+0" : : "r" (where));
     61 #undef	HIVAL
     62 #undef	LOVAL
     63 }
     64 #endif
     65