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
29 #include <sys/types.h>
30 #include <elf.h>
31 #include <bootstrap.h>
32
33 #if defined(__aarch64__) || defined(__amd64__)
34 #define ElfW_Rel Elf64_Rela
35 #define ElfW_Dyn Elf64_Dyn
36 #define ELFW_R_TYPE ELF64_R_TYPE
37 #define ELF_RELA
38 #elif defined(__arm__) || defined(__i386__)
39 #define ElfW_Rel Elf32_Rel
40 #define ElfW_Dyn Elf32_Dyn
41 #define ELFW_R_TYPE ELF32_R_TYPE
42 #else
43 #error architecture not supported
44 #endif
45 #if defined(__aarch64__)
46 #define RELOC_TYPE_NONE R_AARCH64_NONE
47 #define RELOC_TYPE_RELATIVE R_AARCH64_RELATIVE
48 #elif defined(__amd64__)
49 #define RELOC_TYPE_NONE R_X86_64_NONE
50 #define RELOC_TYPE_RELATIVE R_X86_64_RELATIVE
51 #elif defined(__arm__)
52 #define RELOC_TYPE_NONE R_ARM_NONE
53 #define RELOC_TYPE_RELATIVE R_ARM_RELATIVE
54 #elif defined(__i386__)
55 #define RELOC_TYPE_NONE R_386_NONE
56 #define RELOC_TYPE_RELATIVE R_386_RELATIVE
57 #endif
58
59 void self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic);
60
61 /*
62 * A simple elf relocator.
63 */
64 void
self_reloc(Elf_Addr baseaddr,ElfW_Dyn * dynamic)65 self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic)
66 {
67 Elf_Word relsz, relent;
68 Elf_Addr *newaddr;
69 ElfW_Rel *rel = 0;
70 ElfW_Dyn *dynp;
71
72 /*
73 * Find the relocation address, its size and the relocation entry.
74 */
75 relsz = 0;
76 relent = 0;
77 for (dynp = dynamic; dynp->d_tag != DT_NULL; dynp++) {
78 switch (dynp->d_tag) {
79 case DT_REL:
80 case DT_RELA:
81 rel = (ElfW_Rel *)(dynp->d_un.d_ptr + baseaddr);
82 break;
83 case DT_RELSZ:
84 case DT_RELASZ:
85 relsz = dynp->d_un.d_val;
86 break;
87 case DT_RELENT:
88 case DT_RELAENT:
89 relent = dynp->d_un.d_val;
90 break;
91 default:
92 break;
93 }
94 }
95
96 /*
97 * Perform the actual relocation. We rely on the object having been
98 * linked at 0, so that the difference between the load and link
99 * address is the same as the load address.
100 */
101 for (; relsz > 0; relsz -= relent) {
102 switch (ELFW_R_TYPE(rel->r_info)) {
103 case RELOC_TYPE_NONE:
104 /* No relocation needs be performed. */
105 break;
106
107 case RELOC_TYPE_RELATIVE:
108 newaddr = (Elf_Addr *)(rel->r_offset + baseaddr);
109 #ifdef ELF_RELA
110 /* Addend relative to the base address. */
111 *newaddr = baseaddr + rel->r_addend;
112 #else
113 /* Address relative to the base address. */
114 *newaddr += baseaddr;
115 #endif
116 break;
117 default:
118 /* XXX: do we need other relocations ? */
119 break;
120 }
121 rel = (ElfW_Rel *)(void *)((caddr_t) rel + relent);
122 }
123 }
124