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
31static inline void
32sparc_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