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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 | ||
32 | void * | |
33 | module_alloc(unsigned long size) | |
34 | { | |
35 | if (size == 0) | |
36 | return NULL; | |
37 | return vmalloc(size); | |
38 | } | |
39 | ||
40 | void | |
41 | module_free(struct module *mod, void *module_region) | |
42 | { | |
43 | vfree(module_region); | |
44 | } | |
45 | ||
46 | /* Allocate the GOT at the end of the core sections. */ | |
47 | ||
48 | struct got_entry { | |
49 | struct got_entry *next; | |
69ac5964 | 50 | Elf64_Sxword r_addend; |
1da177e4 LT |
51 | int got_offset; |
52 | }; | |
53 | ||
54 | static inline void | |
55 | process_reloc_for_got(Elf64_Rela *rela, | |
56 | struct got_entry *chains, Elf64_Xword *poffset) | |
57 | { | |
58 | unsigned long r_sym = ELF64_R_SYM (rela->r_info); | |
59 | unsigned long r_type = ELF64_R_TYPE (rela->r_info); | |
69ac5964 | 60 | Elf64_Sxword r_addend = rela->r_addend; |
1da177e4 LT |
61 | struct got_entry *g; |
62 | ||
63 | if (r_type != R_ALPHA_LITERAL) | |
64 | return; | |
65 | ||
66 | for (g = chains + r_sym; g ; g = g->next) | |
69ac5964 | 67 | if (g->r_addend == r_addend) { |
1da177e4 LT |
68 | if (g->got_offset == 0) { |
69 | g->got_offset = *poffset; | |
70 | *poffset += 8; | |
71 | } | |
72 | goto found_entry; | |
73 | } | |
74 | ||
75 | g = kmalloc (sizeof (*g), GFP_KERNEL); | |
76 | g->next = chains[r_sym].next; | |
69ac5964 | 77 | g->r_addend = r_addend; |
1da177e4 LT |
78 | g->got_offset = *poffset; |
79 | *poffset += 8; | |
80 | chains[r_sym].next = g; | |
81 | ||
82 | found_entry: | |
83 | /* Trick: most of the ELF64_R_TYPE field is unused. There are | |
84 | 42 valid relocation types, and a 32-bit field. Co-opt the | |
85 | bits above 256 to store the got offset for this reloc. */ | |
86 | rela->r_info |= g->got_offset << 8; | |
87 | } | |
88 | ||
89 | int | |
90 | module_frob_arch_sections(Elf64_Ehdr *hdr, Elf64_Shdr *sechdrs, | |
91 | char *secstrings, struct module *me) | |
92 | { | |
93 | struct got_entry *chains; | |
94 | Elf64_Rela *rela; | |
95 | Elf64_Shdr *esechdrs, *symtab, *s, *got; | |
96 | unsigned long nsyms, nrela, i; | |
97 | ||
98 | esechdrs = sechdrs + hdr->e_shnum; | |
99 | symtab = got = NULL; | |
100 | ||
101 | /* Find out how large the symbol table is. Allocate one got_entry | |
102 | head per symbol. Normally this will be enough, but not always. | |
103 | We'll chain different offsets for the symbol down each head. */ | |
104 | for (s = sechdrs; s < esechdrs; ++s) | |
105 | if (s->sh_type == SHT_SYMTAB) | |
106 | symtab = s; | |
107 | else if (!strcmp(".got", secstrings + s->sh_name)) { | |
108 | got = s; | |
109 | me->arch.gotsecindex = s - sechdrs; | |
110 | } | |
111 | ||
112 | if (!symtab) { | |
113 | printk(KERN_ERR "module %s: no symbol table\n", me->name); | |
114 | return -ENOEXEC; | |
115 | } | |
116 | if (!got) { | |
117 | printk(KERN_ERR "module %s: no got section\n", me->name); | |
118 | return -ENOEXEC; | |
119 | } | |
120 | ||
121 | nsyms = symtab->sh_size / sizeof(Elf64_Sym); | |
dd00cc48 | 122 | chains = kcalloc(nsyms, sizeof(struct got_entry), GFP_KERNEL); |
1da177e4 LT |
123 | |
124 | got->sh_size = 0; | |
125 | got->sh_addralign = 8; | |
126 | got->sh_type = SHT_NOBITS; | |
127 | ||
128 | /* Examine all LITERAL relocations to find out what GOT entries | |
129 | are required. This sizes the GOT section as well. */ | |
130 | for (s = sechdrs; s < esechdrs; ++s) | |
131 | if (s->sh_type == SHT_RELA) { | |
132 | nrela = s->sh_size / sizeof(Elf64_Rela); | |
133 | rela = (void *)hdr + s->sh_offset; | |
134 | for (i = 0; i < nrela; ++i) | |
135 | process_reloc_for_got(rela+i, chains, | |
136 | &got->sh_size); | |
137 | } | |
138 | ||
139 | /* Free the memory we allocated. */ | |
140 | for (i = 0; i < nsyms; ++i) { | |
141 | struct got_entry *g, *n; | |
142 | for (g = chains[i].next; g ; g = n) { | |
143 | n = g->next; | |
144 | kfree(g); | |
145 | } | |
146 | } | |
147 | kfree(chains); | |
148 | ||
149 | return 0; | |
150 | } | |
151 | ||
152 | int | |
153 | apply_relocate(Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex, | |
154 | unsigned int relsec, struct module *me) | |
155 | { | |
156 | printk(KERN_ERR "module %s: REL relocation unsupported\n", me->name); | |
157 | return -ENOEXEC; | |
158 | } | |
159 | ||
160 | int | |
161 | apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab, | |
162 | unsigned int symindex, unsigned int relsec, | |
163 | struct module *me) | |
164 | { | |
165 | Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr; | |
166 | unsigned long i, n = sechdrs[relsec].sh_size / sizeof(*rela); | |
167 | Elf64_Sym *symtab, *sym; | |
168 | void *base, *location; | |
169 | unsigned long got, gp; | |
170 | ||
171 | DEBUGP("Applying relocate section %u to %u\n", relsec, | |
172 | sechdrs[relsec].sh_info); | |
173 | ||
174 | base = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr; | |
175 | symtab = (Elf64_Sym *)sechdrs[symindex].sh_addr; | |
176 | ||
177 | /* The small sections were sorted to the end of the segment. | |
178 | The following should definitely cover them. */ | |
179 | gp = (u64)me->module_core + me->core_size - 0x8000; | |
180 | got = sechdrs[me->arch.gotsecindex].sh_addr; | |
181 | ||
182 | for (i = 0; i < n; i++) { | |
183 | unsigned long r_sym = ELF64_R_SYM (rela[i].r_info); | |
184 | unsigned long r_type = ELF64_R_TYPE (rela[i].r_info); | |
185 | unsigned long r_got_offset = r_type >> 8; | |
186 | unsigned long value, hi, lo; | |
187 | r_type &= 0xff; | |
188 | ||
189 | /* This is where to make the change. */ | |
190 | location = base + rela[i].r_offset; | |
191 | ||
192 | /* This is the symbol it is referring to. Note that all | |
193 | unresolved symbols have been resolved. */ | |
194 | sym = symtab + r_sym; | |
195 | value = sym->st_value + rela[i].r_addend; | |
196 | ||
197 | switch (r_type) { | |
198 | case R_ALPHA_NONE: | |
199 | break; | |
200 | case R_ALPHA_REFQUAD: | |
201 | /* BUG() can produce misaligned relocations. */ | |
202 | ((u32 *)location)[0] = value; | |
203 | ((u32 *)location)[1] = value >> 32; | |
204 | break; | |
205 | case R_ALPHA_GPREL32: | |
206 | value -= gp; | |
207 | if ((int)value != value) | |
208 | goto reloc_overflow; | |
209 | *(u32 *)location = value; | |
210 | break; | |
211 | case R_ALPHA_LITERAL: | |
212 | hi = got + r_got_offset; | |
213 | lo = hi - gp; | |
214 | if ((short)lo != lo) | |
215 | goto reloc_overflow; | |
216 | *(u16 *)location = lo; | |
217 | *(u64 *)hi = value; | |
218 | break; | |
219 | case R_ALPHA_LITUSE: | |
220 | break; | |
221 | case R_ALPHA_GPDISP: | |
222 | value = gp - (u64)location; | |
223 | lo = (short)value; | |
224 | hi = (int)(value - lo); | |
225 | if (hi + lo != value) | |
226 | goto reloc_overflow; | |
227 | *(u16 *)location = hi >> 16; | |
228 | *(u16 *)(location + rela[i].r_addend) = lo; | |
229 | break; | |
230 | case R_ALPHA_BRSGP: | |
231 | /* BRSGP is only allowed to bind to local symbols. | |
232 | If the section is undef, this means that the | |
233 | value was resolved from somewhere else. */ | |
234 | if (sym->st_shndx == SHN_UNDEF) | |
235 | goto reloc_overflow; | |
236 | if ((sym->st_other & STO_ALPHA_STD_GPLOAD) == | |
237 | STO_ALPHA_STD_GPLOAD) | |
238 | /* Omit the prologue. */ | |
239 | value += 8; | |
240 | /* FALLTHRU */ | |
241 | case R_ALPHA_BRADDR: | |
242 | value -= (u64)location + 4; | |
243 | if (value & 3) | |
244 | goto reloc_overflow; | |
245 | value = (long)value >> 2; | |
246 | if (value + (1<<21) >= 1<<22) | |
247 | goto reloc_overflow; | |
248 | value &= 0x1fffff; | |
249 | value |= *(u32 *)location & ~0x1fffff; | |
250 | *(u32 *)location = value; | |
251 | break; | |
252 | case R_ALPHA_HINT: | |
253 | break; | |
254 | case R_ALPHA_SREL32: | |
255 | value -= (u64)location; | |
256 | if ((int)value != value) | |
257 | goto reloc_overflow; | |
258 | *(u32 *)location = value; | |
259 | break; | |
260 | case R_ALPHA_SREL64: | |
261 | value -= (u64)location; | |
262 | *(u64 *)location = value; | |
263 | break; | |
264 | case R_ALPHA_GPRELHIGH: | |
265 | value = (long)(value - gp + 0x8000) >> 16; | |
266 | if ((short) value != value) | |
267 | goto reloc_overflow; | |
268 | *(u16 *)location = value; | |
269 | break; | |
270 | case R_ALPHA_GPRELLOW: | |
271 | value -= gp; | |
272 | *(u16 *)location = value; | |
273 | break; | |
274 | case R_ALPHA_GPREL16: | |
275 | value -= gp; | |
276 | if ((short) value != value) | |
277 | goto reloc_overflow; | |
278 | *(u16 *)location = value; | |
279 | break; | |
280 | default: | |
281 | printk(KERN_ERR "module %s: Unknown relocation: %lu\n", | |
282 | me->name, r_type); | |
283 | return -ENOEXEC; | |
284 | reloc_overflow: | |
285 | if (ELF64_ST_TYPE (sym->st_info) == STT_SECTION) | |
286 | printk(KERN_ERR | |
1b75b05b IK |
287 | "module %s: Relocation (type %lu) overflow vs section %d\n", |
288 | me->name, r_type, sym->st_shndx); | |
1da177e4 LT |
289 | else |
290 | printk(KERN_ERR | |
1b75b05b IK |
291 | "module %s: Relocation (type %lu) overflow vs %s\n", |
292 | me->name, r_type, strtab + sym->st_name); | |
1da177e4 LT |
293 | return -ENOEXEC; |
294 | } | |
295 | } | |
296 | ||
297 | return 0; | |
298 | } | |
299 | ||
300 | int | |
301 | module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, | |
302 | struct module *me) | |
303 | { | |
304 | return 0; | |
305 | } | |
306 | ||
307 | void | |
308 | module_arch_cleanup(struct module *mod) | |
309 | { | |
310 | } |