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1da177e4 LT |
1 | /* Kernel module help for Alpha. |
2 | Copyright (C) 2002 Richard Henderson. | |
3 | ||
4 | This program is free software; you can redistribute it and/or modify | |
5 | it under the terms of the GNU General Public License as published by | |
6 | the Free Software Foundation; either version 2 of the License, or | |
7 | (at your option) any later version. | |
8 | ||
9 | This program is distributed in the hope that it will be useful, | |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | GNU General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU General Public License | |
15 | along with this program; if not, write to the Free Software | |
16 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
17 | */ | |
18 | #include <linux/moduleloader.h> | |
19 | #include <linux/elf.h> | |
20 | #include <linux/vmalloc.h> | |
21 | #include <linux/fs.h> | |
22 | #include <linux/string.h> | |
23 | #include <linux/kernel.h> | |
24 | #include <linux/slab.h> | |
25 | ||
26 | #if 0 | |
27 | #define DEBUGP printk | |
28 | #else | |
29 | #define DEBUGP(fmt...) | |
30 | #endif | |
31 | ||
1da177e4 LT |
32 | /* Allocate the GOT at the end of the core sections. */ |
33 | ||
34 | struct got_entry { | |
35 | struct got_entry *next; | |
69ac5964 | 36 | Elf64_Sxword r_addend; |
1da177e4 LT |
37 | int got_offset; |
38 | }; | |
39 | ||
40 | static inline void | |
41 | process_reloc_for_got(Elf64_Rela *rela, | |
42 | struct got_entry *chains, Elf64_Xword *poffset) | |
43 | { | |
44 | unsigned long r_sym = ELF64_R_SYM (rela->r_info); | |
45 | unsigned long r_type = ELF64_R_TYPE (rela->r_info); | |
69ac5964 | 46 | Elf64_Sxword r_addend = rela->r_addend; |
1da177e4 LT |
47 | struct got_entry *g; |
48 | ||
49 | if (r_type != R_ALPHA_LITERAL) | |
50 | return; | |
51 | ||
52 | for (g = chains + r_sym; g ; g = g->next) | |
69ac5964 | 53 | if (g->r_addend == r_addend) { |
1da177e4 LT |
54 | if (g->got_offset == 0) { |
55 | g->got_offset = *poffset; | |
56 | *poffset += 8; | |
57 | } | |
58 | goto found_entry; | |
59 | } | |
60 | ||
61 | g = kmalloc (sizeof (*g), GFP_KERNEL); | |
62 | g->next = chains[r_sym].next; | |
69ac5964 | 63 | g->r_addend = r_addend; |
1da177e4 LT |
64 | g->got_offset = *poffset; |
65 | *poffset += 8; | |
66 | chains[r_sym].next = g; | |
67 | ||
68 | found_entry: | |
69 | /* Trick: most of the ELF64_R_TYPE field is unused. There are | |
70 | 42 valid relocation types, and a 32-bit field. Co-opt the | |
71 | bits above 256 to store the got offset for this reloc. */ | |
72 | rela->r_info |= g->got_offset << 8; | |
73 | } | |
74 | ||
75 | int | |
76 | module_frob_arch_sections(Elf64_Ehdr *hdr, Elf64_Shdr *sechdrs, | |
77 | char *secstrings, struct module *me) | |
78 | { | |
79 | struct got_entry *chains; | |
80 | Elf64_Rela *rela; | |
81 | Elf64_Shdr *esechdrs, *symtab, *s, *got; | |
82 | unsigned long nsyms, nrela, i; | |
83 | ||
84 | esechdrs = sechdrs + hdr->e_shnum; | |
85 | symtab = got = NULL; | |
86 | ||
87 | /* Find out how large the symbol table is. Allocate one got_entry | |
88 | head per symbol. Normally this will be enough, but not always. | |
89 | We'll chain different offsets for the symbol down each head. */ | |
90 | for (s = sechdrs; s < esechdrs; ++s) | |
91 | if (s->sh_type == SHT_SYMTAB) | |
92 | symtab = s; | |
93 | else if (!strcmp(".got", secstrings + s->sh_name)) { | |
94 | got = s; | |
95 | me->arch.gotsecindex = s - sechdrs; | |
96 | } | |
97 | ||
98 | if (!symtab) { | |
99 | printk(KERN_ERR "module %s: no symbol table\n", me->name); | |
100 | return -ENOEXEC; | |
101 | } | |
102 | if (!got) { | |
103 | printk(KERN_ERR "module %s: no got section\n", me->name); | |
104 | return -ENOEXEC; | |
105 | } | |
106 | ||
107 | nsyms = symtab->sh_size / sizeof(Elf64_Sym); | |
dd00cc48 | 108 | chains = kcalloc(nsyms, sizeof(struct got_entry), GFP_KERNEL); |
b901d40c JM |
109 | if (!chains) { |
110 | printk(KERN_ERR | |
111 | "module %s: no memory for symbol chain buffer\n", | |
112 | me->name); | |
113 | return -ENOMEM; | |
114 | } | |
1da177e4 LT |
115 | |
116 | got->sh_size = 0; | |
117 | got->sh_addralign = 8; | |
118 | got->sh_type = SHT_NOBITS; | |
119 | ||
120 | /* Examine all LITERAL relocations to find out what GOT entries | |
121 | are required. This sizes the GOT section as well. */ | |
122 | for (s = sechdrs; s < esechdrs; ++s) | |
123 | if (s->sh_type == SHT_RELA) { | |
124 | nrela = s->sh_size / sizeof(Elf64_Rela); | |
125 | rela = (void *)hdr + s->sh_offset; | |
126 | for (i = 0; i < nrela; ++i) | |
127 | process_reloc_for_got(rela+i, chains, | |
128 | &got->sh_size); | |
129 | } | |
130 | ||
131 | /* Free the memory we allocated. */ | |
132 | for (i = 0; i < nsyms; ++i) { | |
133 | struct got_entry *g, *n; | |
134 | for (g = chains[i].next; g ; g = n) { | |
135 | n = g->next; | |
136 | kfree(g); | |
137 | } | |
138 | } | |
139 | kfree(chains); | |
140 | ||
141 | return 0; | |
142 | } | |
143 | ||
1da177e4 LT |
144 | int |
145 | apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab, | |
146 | unsigned int symindex, unsigned int relsec, | |
147 | struct module *me) | |
148 | { | |
149 | Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr; | |
150 | unsigned long i, n = sechdrs[relsec].sh_size / sizeof(*rela); | |
151 | Elf64_Sym *symtab, *sym; | |
152 | void *base, *location; | |
153 | unsigned long got, gp; | |
154 | ||
155 | DEBUGP("Applying relocate section %u to %u\n", relsec, | |
156 | sechdrs[relsec].sh_info); | |
157 | ||
158 | base = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr; | |
159 | symtab = (Elf64_Sym *)sechdrs[symindex].sh_addr; | |
160 | ||
161 | /* The small sections were sorted to the end of the segment. | |
162 | The following should definitely cover them. */ | |
7523e4dc | 163 | gp = (u64)me->core_layout.base + me->core_layout.size - 0x8000; |
1da177e4 LT |
164 | got = sechdrs[me->arch.gotsecindex].sh_addr; |
165 | ||
166 | for (i = 0; i < n; i++) { | |
167 | unsigned long r_sym = ELF64_R_SYM (rela[i].r_info); | |
168 | unsigned long r_type = ELF64_R_TYPE (rela[i].r_info); | |
169 | unsigned long r_got_offset = r_type >> 8; | |
170 | unsigned long value, hi, lo; | |
171 | r_type &= 0xff; | |
172 | ||
173 | /* This is where to make the change. */ | |
174 | location = base + rela[i].r_offset; | |
175 | ||
176 | /* This is the symbol it is referring to. Note that all | |
177 | unresolved symbols have been resolved. */ | |
178 | sym = symtab + r_sym; | |
179 | value = sym->st_value + rela[i].r_addend; | |
180 | ||
181 | switch (r_type) { | |
182 | case R_ALPHA_NONE: | |
183 | break; | |
184 | case R_ALPHA_REFQUAD: | |
185 | /* BUG() can produce misaligned relocations. */ | |
186 | ((u32 *)location)[0] = value; | |
187 | ((u32 *)location)[1] = value >> 32; | |
188 | break; | |
189 | case R_ALPHA_GPREL32: | |
190 | value -= gp; | |
191 | if ((int)value != value) | |
192 | goto reloc_overflow; | |
193 | *(u32 *)location = value; | |
194 | break; | |
195 | case R_ALPHA_LITERAL: | |
196 | hi = got + r_got_offset; | |
197 | lo = hi - gp; | |
198 | if ((short)lo != lo) | |
199 | goto reloc_overflow; | |
200 | *(u16 *)location = lo; | |
201 | *(u64 *)hi = value; | |
202 | break; | |
203 | case R_ALPHA_LITUSE: | |
204 | break; | |
205 | case R_ALPHA_GPDISP: | |
206 | value = gp - (u64)location; | |
207 | lo = (short)value; | |
208 | hi = (int)(value - lo); | |
209 | if (hi + lo != value) | |
210 | goto reloc_overflow; | |
211 | *(u16 *)location = hi >> 16; | |
212 | *(u16 *)(location + rela[i].r_addend) = lo; | |
213 | break; | |
214 | case R_ALPHA_BRSGP: | |
215 | /* BRSGP is only allowed to bind to local symbols. | |
216 | If the section is undef, this means that the | |
217 | value was resolved from somewhere else. */ | |
218 | if (sym->st_shndx == SHN_UNDEF) | |
219 | goto reloc_overflow; | |
220 | if ((sym->st_other & STO_ALPHA_STD_GPLOAD) == | |
221 | STO_ALPHA_STD_GPLOAD) | |
222 | /* Omit the prologue. */ | |
223 | value += 8; | |
224 | /* FALLTHRU */ | |
225 | case R_ALPHA_BRADDR: | |
226 | value -= (u64)location + 4; | |
227 | if (value & 3) | |
228 | goto reloc_overflow; | |
229 | value = (long)value >> 2; | |
230 | if (value + (1<<21) >= 1<<22) | |
231 | goto reloc_overflow; | |
232 | value &= 0x1fffff; | |
233 | value |= *(u32 *)location & ~0x1fffff; | |
234 | *(u32 *)location = value; | |
235 | break; | |
236 | case R_ALPHA_HINT: | |
237 | break; | |
238 | case R_ALPHA_SREL32: | |
239 | value -= (u64)location; | |
240 | if ((int)value != value) | |
241 | goto reloc_overflow; | |
242 | *(u32 *)location = value; | |
243 | break; | |
244 | case R_ALPHA_SREL64: | |
245 | value -= (u64)location; | |
246 | *(u64 *)location = value; | |
247 | break; | |
248 | case R_ALPHA_GPRELHIGH: | |
249 | value = (long)(value - gp + 0x8000) >> 16; | |
250 | if ((short) value != value) | |
251 | goto reloc_overflow; | |
252 | *(u16 *)location = value; | |
253 | break; | |
254 | case R_ALPHA_GPRELLOW: | |
255 | value -= gp; | |
256 | *(u16 *)location = value; | |
257 | break; | |
258 | case R_ALPHA_GPREL16: | |
259 | value -= gp; | |
260 | if ((short) value != value) | |
261 | goto reloc_overflow; | |
262 | *(u16 *)location = value; | |
263 | break; | |
264 | default: | |
265 | printk(KERN_ERR "module %s: Unknown relocation: %lu\n", | |
266 | me->name, r_type); | |
267 | return -ENOEXEC; | |
268 | reloc_overflow: | |
269 | if (ELF64_ST_TYPE (sym->st_info) == STT_SECTION) | |
270 | printk(KERN_ERR | |
1b75b05b IK |
271 | "module %s: Relocation (type %lu) overflow vs section %d\n", |
272 | me->name, r_type, sym->st_shndx); | |
1da177e4 LT |
273 | else |
274 | printk(KERN_ERR | |
1b75b05b IK |
275 | "module %s: Relocation (type %lu) overflow vs %s\n", |
276 | me->name, r_type, strtab + sym->st_name); | |
1da177e4 LT |
277 | return -ENOEXEC; |
278 | } | |
279 | } | |
280 | ||
281 | return 0; | |
282 | } |