1 /* MN10300 Kernel module helper routines
2 *
3 * Copyright (C) 2007, 2008, 2009 Red Hat, Inc. All Rights Reserved.
4 * Written by Mark Salter (msalter@redhat.com)
5 * - Derived from arch/i386/kernel/module.c
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public Licence as published by
9 * the Free Software Foundation; either version 2 of the Licence, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public Licence for more details.
16 *
17 * You should have received a copy of the GNU General Public Licence
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 */
21 #include <linux/moduleloader.h>
22 #include <linux/elf.h>
23 #include <linux/vmalloc.h>
24 #include <linux/fs.h>
25 #include <linux/string.h>
26 #include <linux/kernel.h>
27 #include <linux/bug.h>
28
29 #if 0
30 #define DEBUGP printk
31 #else
32 #define DEBUGP(fmt, ...)
33 #endif
34
reloc_put16(uint8_t * p,uint32_t val)35 static void reloc_put16(uint8_t *p, uint32_t val)
36 {
37 p[0] = val & 0xff;
38 p[1] = (val >> 8) & 0xff;
39 }
40
reloc_put24(uint8_t * p,uint32_t val)41 static void reloc_put24(uint8_t *p, uint32_t val)
42 {
43 reloc_put16(p, val);
44 p[2] = (val >> 16) & 0xff;
45 }
46
reloc_put32(uint8_t * p,uint32_t val)47 static void reloc_put32(uint8_t *p, uint32_t val)
48 {
49 reloc_put16(p, val);
50 reloc_put16(p+2, val >> 16);
51 }
52
53 /*
54 * apply a RELA relocation
55 */
apply_relocate_add(Elf32_Shdr * sechdrs,const char * strtab,unsigned int symindex,unsigned int relsec,struct module * me)56 int apply_relocate_add(Elf32_Shdr *sechdrs,
57 const char *strtab,
58 unsigned int symindex,
59 unsigned int relsec,
60 struct module *me)
61 {
62 unsigned int i, sym_diff_seen = 0;
63 Elf32_Rela *rel = (void *)sechdrs[relsec].sh_addr;
64 Elf32_Sym *sym;
65 Elf32_Addr relocation, sym_diff_val = 0;
66 uint8_t *location;
67 uint32_t value;
68
69 DEBUGP("Applying relocate section %u to %u\n",
70 relsec, sechdrs[relsec].sh_info);
71
72 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
73 /* this is where to make the change */
74 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
75 + rel[i].r_offset;
76
77 /* this is the symbol the relocation is referring to (note that
78 * all undefined symbols have been resolved by the caller) */
79 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
80 + ELF32_R_SYM(rel[i].r_info);
81
82 /* this is the adjustment to be made */
83 relocation = sym->st_value + rel[i].r_addend;
84
85 if (sym_diff_seen) {
86 switch (ELF32_R_TYPE(rel[i].r_info)) {
87 case R_MN10300_32:
88 case R_MN10300_24:
89 case R_MN10300_16:
90 case R_MN10300_8:
91 relocation -= sym_diff_val;
92 sym_diff_seen = 0;
93 break;
94 default:
95 printk(KERN_ERR "module %s: Unexpected SYM_DIFF relocation: %u\n",
96 me->name, ELF32_R_TYPE(rel[i].r_info));
97 return -ENOEXEC;
98 }
99 }
100
101 switch (ELF32_R_TYPE(rel[i].r_info)) {
102 /* for the first four relocation types, we simply
103 * store the adjustment at the location given */
104 case R_MN10300_32:
105 reloc_put32(location, relocation);
106 break;
107 case R_MN10300_24:
108 reloc_put24(location, relocation);
109 break;
110 case R_MN10300_16:
111 reloc_put16(location, relocation);
112 break;
113 case R_MN10300_8:
114 *location = relocation;
115 break;
116
117 /* for the next three relocation types, we write the
118 * adjustment with the address subtracted over the
119 * value at the location given */
120 case R_MN10300_PCREL32:
121 value = relocation - (uint32_t) location;
122 reloc_put32(location, value);
123 break;
124 case R_MN10300_PCREL16:
125 value = relocation - (uint32_t) location;
126 reloc_put16(location, value);
127 break;
128 case R_MN10300_PCREL8:
129 *location = relocation - (uint32_t) location;
130 break;
131
132 case R_MN10300_SYM_DIFF:
133 /* This is used to adjust the next reloc as required
134 * by relaxation. */
135 sym_diff_seen = 1;
136 sym_diff_val = sym->st_value;
137 break;
138
139 case R_MN10300_ALIGN:
140 /* Just ignore the ALIGN relocs.
141 * Only interesting if kernel performed relaxation. */
142 continue;
143
144 default:
145 printk(KERN_ERR "module %s: Unknown relocation: %u\n",
146 me->name, ELF32_R_TYPE(rel[i].r_info));
147 return -ENOEXEC;
148 }
149 }
150 if (sym_diff_seen) {
151 printk(KERN_ERR "module %s: Nothing follows SYM_DIFF relocation: %u\n",
152 me->name, ELF32_R_TYPE(rel[i].r_info));
153 return -ENOEXEC;
154 }
155 return 0;
156 }
157