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1 /*
2 * This program is free software; you can redistribute it and/or modify
3 * it under the terms of the GNU General Public License as published by
4 * the Free Software Foundation; either version 2 of the License, or
5 * (at your option) any later version.
6 *
7 * This program is distributed in the hope that it will be useful,
8 * but WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10 * GNU General Public License for more details.
11 *
12 * You should have received a copy of the GNU General Public License
13 * along with this program; if not, write to the Free Software
14 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
15 *
16 * Copyright (C) 2001 Rusty Russell.
17 * Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)
18 * Copyright (C) 2005 Thiemo Seufer
19 * Copyright (C) 2015 Imagination Technologies Ltd.
20 */
21
22 #include <linux/elf.h>
23 #include <linux/err.h>
24 #include <linux/errno.h>
25 #include <linux/moduleloader.h>
26
27 extern int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v);
28
29 static int apply_r_mips_32_rela(struct module *me, u32 *location, Elf_Addr v)
30 {
31 *location = v;
32
33 return 0;
34 }
35
36 static int apply_r_mips_26_rela(struct module *me, u32 *location, Elf_Addr v)
37 {
38 if (v % 4) {
39 pr_err("module %s: dangerous R_MIPS_26 RELA relocation\n",
40 me->name);
41 return -ENOEXEC;
42 }
43
44 if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
45 pr_err("module %s: relocation overflow\n", me->name);
46 return -ENOEXEC;
47 }
48
49 *location = (*location & ~0x03ffffff) | ((v >> 2) & 0x03ffffff);
50
51 return 0;
52 }
53
54 static int apply_r_mips_hi16_rela(struct module *me, u32 *location, Elf_Addr v)
55 {
56 *location = (*location & 0xffff0000) |
57 ((((long long) v + 0x8000LL) >> 16) & 0xffff);
58
59 return 0;
60 }
61
62 static int apply_r_mips_lo16_rela(struct module *me, u32 *location, Elf_Addr v)
63 {
64 *location = (*location & 0xffff0000) | (v & 0xffff);
65
66 return 0;
67 }
68
69 static int apply_r_mips_pc_rela(struct module *me, u32 *location, Elf_Addr v,
70 unsigned bits)
71 {
72 unsigned long mask = GENMASK(bits - 1, 0);
73 unsigned long se_bits;
74 long offset;
75
76 if (v % 4) {
77 pr_err("module %s: dangerous R_MIPS_PC%u RELA relocation\n",
78 me->name, bits);
79 return -ENOEXEC;
80 }
81
82 offset = ((long)v - (long)location) >> 2;
83
84 /* check the sign bit onwards are identical - ie. we didn't overflow */
85 se_bits = (offset & BIT(bits - 1)) ? ~0ul : 0;
86 if ((offset & ~mask) != (se_bits & ~mask)) {
87 pr_err("module %s: relocation overflow\n", me->name);
88 return -ENOEXEC;
89 }
90
91 *location = (*location & ~mask) | (offset & mask);
92
93 return 0;
94 }
95
96 static int apply_r_mips_pc16_rela(struct module *me, u32 *location, Elf_Addr v)
97 {
98 return apply_r_mips_pc_rela(me, location, v, 16);
99 }
100
101 static int apply_r_mips_pc21_rela(struct module *me, u32 *location, Elf_Addr v)
102 {
103 return apply_r_mips_pc_rela(me, location, v, 21);
104 }
105
106 static int apply_r_mips_pc26_rela(struct module *me, u32 *location, Elf_Addr v)
107 {
108 return apply_r_mips_pc_rela(me, location, v, 26);
109 }
110
111 static int apply_r_mips_64_rela(struct module *me, u32 *location, Elf_Addr v)
112 {
113 *(Elf_Addr *)location = v;
114
115 return 0;
116 }
117
118 static int apply_r_mips_higher_rela(struct module *me, u32 *location,
119 Elf_Addr v)
120 {
121 *location = (*location & 0xffff0000) |
122 ((((long long) v + 0x80008000LL) >> 32) & 0xffff);
123
124 return 0;
125 }
126
127 static int apply_r_mips_highest_rela(struct module *me, u32 *location,
128 Elf_Addr v)
129 {
130 *location = (*location & 0xffff0000) |
131 ((((long long) v + 0x800080008000LL) >> 48) & 0xffff);
132
133 return 0;
134 }
135
136 static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
137 Elf_Addr v) = {
138 [R_MIPS_NONE] = apply_r_mips_none,
139 [R_MIPS_32] = apply_r_mips_32_rela,
140 [R_MIPS_26] = apply_r_mips_26_rela,
141 [R_MIPS_HI16] = apply_r_mips_hi16_rela,
142 [R_MIPS_LO16] = apply_r_mips_lo16_rela,
143 [R_MIPS_PC16] = apply_r_mips_pc16_rela,
144 [R_MIPS_64] = apply_r_mips_64_rela,
145 [R_MIPS_HIGHER] = apply_r_mips_higher_rela,
146 [R_MIPS_HIGHEST] = apply_r_mips_highest_rela,
147 [R_MIPS_PC21_S2] = apply_r_mips_pc21_rela,
148 [R_MIPS_PC26_S2] = apply_r_mips_pc26_rela,
149 };
150
151 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
152 unsigned int symindex, unsigned int relsec,
153 struct module *me)
154 {
155 Elf_Mips_Rela *rel = (void *) sechdrs[relsec].sh_addr;
156 int (*handler)(struct module *me, u32 *location, Elf_Addr v);
157 Elf_Sym *sym;
158 u32 *location;
159 unsigned int i, type;
160 Elf_Addr v;
161 int res;
162
163 pr_debug("Applying relocate section %u to %u\n", relsec,
164 sechdrs[relsec].sh_info);
165
166 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
167 /* This is where to make the change */
168 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
169 + rel[i].r_offset;
170 /* This is the symbol it is referring to */
171 sym = (Elf_Sym *)sechdrs[symindex].sh_addr
172 + ELF_MIPS_R_SYM(rel[i]);
173 if (sym->st_value >= -MAX_ERRNO) {
174 /* Ignore unresolved weak symbol */
175 if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
176 continue;
177 pr_warn("%s: Unknown symbol %s\n",
178 me->name, strtab + sym->st_name);
179 return -ENOENT;
180 }
181
182 type = ELF_MIPS_R_TYPE(rel[i]);
183
184 if (type < ARRAY_SIZE(reloc_handlers_rela))
185 handler = reloc_handlers_rela[type];
186 else
187 handler = NULL;
188
189 if (!handler) {
190 pr_err("%s: Unknown relocation type %u\n",
191 me->name, type);
192 return -EINVAL;
193 }
194
195 v = sym->st_value + rel[i].r_addend;
196 res = handler(me, location, v);
197 if (res)
198 return res;
199 }
200
201 return 0;
202 }
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