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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 *

20 */

22 #include <linux/elf.h>

23 #include <linux/err.h>

24 #include <linux/errno.h>

25 #include <linux/moduleloader.h>

27 extern int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v);

29 static int apply_r_mips_32_rela(struct module *me, u32 *location, Elf_Addr v)

30 {

31 *location = v;

33 return 0;

34 }

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 }

44 if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {

45 pr_err("module %s: relocation overflow\n", me->name);

46 return -ENOEXEC;

47 }

49 *location = (*location & ~0x03ffffff) | ((v >> 2) & 0x03ffffff);

51 return 0;

52 }

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);

59 return 0;

60 }

62 static int apply_r_mips_lo16_rela(struct module *me, u32 *location, Elf_Addr v)

63 {

64 *location = (*location & 0xffff0000) | (v & 0xffff);

66 return 0;

67 }

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;

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 }

82 offset = ((long)v - (long)location) >> 2;

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 }

91 *location = (*location & ~mask) | (offset & mask);

93 return 0;

94 }

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 }