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 * $FreeBSD: head/sys/boot/common/self_reloc.c 293724 2016-01-12 02:17:39Z smh $
27 */
28
29 #include <sys/types.h>
30 #include <elf.h>
31 #include <bootstrap.h>
32 #include <stddef.h>
33
34 #if defined(__aarch64__)
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(__x86_64__)
40 #define ElfW_Rel Elf64_Rel
41 #define ElfW_Dyn Elf64_Dyn
42 #define ELFW_R_TYPE ELF64_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(__x86_64__)
50 #define RELOC_TYPE_NONE R_X86_64_NONE
51 #define RELOC_TYPE_RELATIVE R_X86_64_RELATIVE
52 #endif
53
54 void self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic);
55
56 /*
57 * A simple elf relocator.
58 */
59 void
self_reloc(Elf_Addr baseaddr,ElfW_Dyn * dynamic)60 self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic)
61 {
62 Elf_Word relsz, relent;
63 Elf_Addr *newaddr;
64 ElfW_Rel *rel = NULL;
65 ElfW_Dyn *dynp;
66
67 /*
68 * Find the relocation address, its size and the relocation entry.
69 */
70 relsz = 0;
71 relent = 0;
72 for (dynp = dynamic; dynp->d_tag != DT_NULL; dynp++) {
73 switch (dynp->d_tag) {
74 case DT_REL:
75 case DT_RELA:
76 rel = (ElfW_Rel *)(dynp->d_un.d_ptr + baseaddr);
77 break;
78 case DT_RELSZ:
79 case DT_RELASZ:
80 relsz = dynp->d_un.d_val;
81 break;
82 case DT_RELENT:
83 case DT_RELAENT:
84 relent = dynp->d_un.d_val;
85 break;
86 default:
87 break;
88 }
89 }
90
91 /*
92 * Perform the actual relocation.
93 */
94 for (; relsz > 0; relsz -= relent) {
95 switch (ELFW_R_TYPE(rel->r_info)) {
96 case RELOC_TYPE_NONE:
97 /* No relocation needs be performed. */
98 break;
99
100 case RELOC_TYPE_RELATIVE:
101 /* Address relative to the base address. */
102 newaddr = (Elf_Addr *)(rel->r_offset + baseaddr);
103 *newaddr += baseaddr;
104 /* Add the addend when the ABI uses them */
105 #ifdef ELF_RELA
106 *newaddr += rel->r_addend;
107 #endif
108 break;
109 default:
110 /* XXX: do we need other relocations ? */
111 break;
112 }
113 rel = (ElfW_Rel *)(void *)((caddr_t) rel + relent);
114 }
115 }
116