1/*-
2 * Copyright (c) 2008-2010 Rui Paulo <rpaulo@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD$");
29
30#include <sys/types.h>
31#include <elf.h>
32#include <bootstrap.h>
33
34#if defined(__aarch64__) || defined(__amd64__)
35#define	ElfW_Rel	Elf64_Rela
36#define	ElfW_Dyn	Elf64_Dyn
37#define	ELFW_R_TYPE	ELF64_R_TYPE
38#define	ELF_RELA
39#elif defined(__arm__) || defined(__i386__)
40#define	ElfW_Rel	Elf32_Rel
41#define	ElfW_Dyn	Elf32_Dyn
42#define	ELFW_R_TYPE	ELF32_R_TYPE
43#else
44#error architecture not supported
45#endif
46#if defined(__aarch64__)
47#define	RELOC_TYPE_NONE		R_AARCH64_NONE
48#define	RELOC_TYPE_RELATIVE	R_AARCH64_RELATIVE
49#elif defined(__amd64__)
50#define	RELOC_TYPE_NONE		R_X86_64_NONE
51#define	RELOC_TYPE_RELATIVE	R_X86_64_RELATIVE
52#elif defined(__arm__)
53#define	RELOC_TYPE_NONE		R_ARM_NONE
54#define	RELOC_TYPE_RELATIVE	R_ARM_RELATIVE
55#elif defined(__i386__)
56#define	RELOC_TYPE_NONE		R_386_NONE
57#define	RELOC_TYPE_RELATIVE	R_386_RELATIVE
58#endif
59
60void self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic);
61
62/*
63 * A simple elf relocator.
64 */
65void
66self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic)
67{
68	Elf_Word relsz, relent;
69	Elf_Addr *newaddr;
70	ElfW_Rel *rel;
71	ElfW_Dyn *dynp;
72
73	/*
74	 * Find the relocation address, its size and the relocation entry.
75	 */
76	relsz = 0;
77	relent = 0;
78	for (dynp = dynamic; dynp->d_tag != DT_NULL; dynp++) {
79		switch (dynp->d_tag) {
80		case DT_REL:
81		case DT_RELA:
82			rel = (ElfW_Rel *)(dynp->d_un.d_ptr + baseaddr);
83			break;
84		case DT_RELSZ:
85		case DT_RELASZ:
86			relsz = dynp->d_un.d_val;
87			break;
88		case DT_RELENT:
89		case DT_RELAENT:
90			relent = dynp->d_un.d_val;
91			break;
92		default:
93			break;
94		}
95	}
96
97	/*
98	 * Perform the actual relocation. We rely on the object having been
99	 * linked at 0, so that the difference between the load and link
100	 * address is the same as the load address.
101	 */
102	for (; relsz > 0; relsz -= relent) {
103		switch (ELFW_R_TYPE(rel->r_info)) {
104		case RELOC_TYPE_NONE:
105			/* No relocation needs be performed. */
106			break;
107
108		case RELOC_TYPE_RELATIVE:
109			newaddr = (Elf_Addr *)(rel->r_offset + baseaddr);
110#ifdef ELF_RELA
111			/* Addend relative to the base address. */
112			*newaddr = baseaddr + rel->r_addend;
113#else
114			/* Address relative to the base address. */
115			*newaddr += baseaddr;
116#endif
117			break;
118		default:
119			/* XXX: do we need other relocations ? */
120			break;
121		}
122		rel = (ElfW_Rel *)(void *)((caddr_t) rel + relent);
123	}
124}
125