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1da177e4 LT |
1 | /* Kernel module help for PPC. |
2 | Copyright (C) 2001 Rusty Russell. | |
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/module.h> | |
19 | #include <linux/moduleloader.h> | |
20 | #include <linux/elf.h> | |
21 | #include <linux/vmalloc.h> | |
22 | #include <linux/fs.h> | |
23 | #include <linux/string.h> | |
24 | #include <linux/kernel.h> | |
25 | #include <linux/cache.h> | |
26 | ||
21c4ff80 BH |
27 | #include "setup.h" |
28 | ||
1da177e4 LT |
29 | #if 0 |
30 | #define DEBUGP printk | |
31 | #else | |
32 | #define DEBUGP(fmt , ...) | |
33 | #endif | |
34 | ||
35 | LIST_HEAD(module_bug_list); | |
36 | ||
37 | void *module_alloc(unsigned long size) | |
38 | { | |
39 | if (size == 0) | |
40 | return NULL; | |
41 | return vmalloc(size); | |
42 | } | |
43 | ||
44 | /* Free memory returned from module_alloc */ | |
45 | void module_free(struct module *mod, void *module_region) | |
46 | { | |
47 | vfree(module_region); | |
48 | /* FIXME: If module_region == mod->init_region, trim exception | |
49 | table entries. */ | |
50 | } | |
51 | ||
52 | /* Count how many different relocations (different symbol, different | |
53 | addend) */ | |
54 | static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num) | |
55 | { | |
56 | unsigned int i, j, ret = 0; | |
57 | ||
58 | /* Sure, this is order(n^2), but it's usually short, and not | |
59 | time critical */ | |
60 | for (i = 0; i < num; i++) { | |
61 | for (j = 0; j < i; j++) { | |
62 | /* If this addend appeared before, it's | |
63 | already been counted */ | |
64 | if (ELF32_R_SYM(rela[i].r_info) | |
65 | == ELF32_R_SYM(rela[j].r_info) | |
66 | && rela[i].r_addend == rela[j].r_addend) | |
67 | break; | |
68 | } | |
69 | if (j == i) ret++; | |
70 | } | |
71 | return ret; | |
72 | } | |
73 | ||
74 | /* Get the potential trampolines size required of the init and | |
75 | non-init sections */ | |
76 | static unsigned long get_plt_size(const Elf32_Ehdr *hdr, | |
77 | const Elf32_Shdr *sechdrs, | |
78 | const char *secstrings, | |
79 | int is_init) | |
80 | { | |
81 | unsigned long ret = 0; | |
82 | unsigned i; | |
83 | ||
84 | /* Everything marked ALLOC (this includes the exported | |
85 | symbols) */ | |
86 | for (i = 1; i < hdr->e_shnum; i++) { | |
87 | /* If it's called *.init*, and we're not init, we're | |
88 | not interested */ | |
89 | if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != 0) | |
90 | != is_init) | |
91 | continue; | |
92 | ||
93 | /* We don't want to look at debug sections. */ | |
94 | if (strstr(secstrings + sechdrs[i].sh_name, ".debug") != 0) | |
95 | continue; | |
96 | ||
97 | if (sechdrs[i].sh_type == SHT_RELA) { | |
98 | DEBUGP("Found relocations in section %u\n", i); | |
99 | DEBUGP("Ptr: %p. Number: %u\n", | |
100 | (void *)hdr + sechdrs[i].sh_offset, | |
101 | sechdrs[i].sh_size / sizeof(Elf32_Rela)); | |
102 | ret += count_relocs((void *)hdr | |
103 | + sechdrs[i].sh_offset, | |
104 | sechdrs[i].sh_size | |
105 | / sizeof(Elf32_Rela)) | |
106 | * sizeof(struct ppc_plt_entry); | |
107 | } | |
108 | } | |
109 | ||
110 | return ret; | |
111 | } | |
112 | ||
113 | int module_frob_arch_sections(Elf32_Ehdr *hdr, | |
114 | Elf32_Shdr *sechdrs, | |
115 | char *secstrings, | |
116 | struct module *me) | |
117 | { | |
118 | unsigned int i; | |
119 | ||
120 | /* Find .plt and .init.plt sections */ | |
121 | for (i = 0; i < hdr->e_shnum; i++) { | |
122 | if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0) | |
123 | me->arch.init_plt_section = i; | |
124 | else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0) | |
125 | me->arch.core_plt_section = i; | |
126 | } | |
127 | if (!me->arch.core_plt_section || !me->arch.init_plt_section) { | |
128 | printk("Module doesn't contain .plt or .init.plt sections.\n"); | |
129 | return -ENOEXEC; | |
130 | } | |
131 | ||
132 | /* Override their sizes */ | |
133 | sechdrs[me->arch.core_plt_section].sh_size | |
134 | = get_plt_size(hdr, sechdrs, secstrings, 0); | |
135 | sechdrs[me->arch.init_plt_section].sh_size | |
136 | = get_plt_size(hdr, sechdrs, secstrings, 1); | |
137 | return 0; | |
138 | } | |
139 | ||
140 | int apply_relocate(Elf32_Shdr *sechdrs, | |
141 | const char *strtab, | |
142 | unsigned int symindex, | |
143 | unsigned int relsec, | |
144 | struct module *module) | |
145 | { | |
146 | printk(KERN_ERR "%s: Non-ADD RELOCATION unsupported\n", | |
147 | module->name); | |
148 | return -ENOEXEC; | |
149 | } | |
150 | ||
151 | static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val) | |
152 | { | |
153 | if (entry->jump[0] == 0x3d600000 + ((val + 0x8000) >> 16) | |
154 | && entry->jump[1] == 0x396b0000 + (val & 0xffff)) | |
155 | return 1; | |
156 | return 0; | |
157 | } | |
158 | ||
159 | /* Set up a trampoline in the PLT to bounce us to the distant function */ | |
160 | static uint32_t do_plt_call(void *location, | |
161 | Elf32_Addr val, | |
162 | Elf32_Shdr *sechdrs, | |
163 | struct module *mod) | |
164 | { | |
165 | struct ppc_plt_entry *entry; | |
166 | ||
167 | DEBUGP("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location); | |
168 | /* Init, or core PLT? */ | |
169 | if (location >= mod->module_core | |
170 | && location < mod->module_core + mod->core_size) | |
171 | entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr; | |
172 | else | |
173 | entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr; | |
174 | ||
175 | /* Find this entry, or if that fails, the next avail. entry */ | |
176 | while (entry->jump[0]) { | |
177 | if (entry_matches(entry, val)) return (uint32_t)entry; | |
178 | entry++; | |
179 | } | |
180 | ||
181 | /* Stolen from Paul Mackerras as well... */ | |
182 | entry->jump[0] = 0x3d600000+((val+0x8000)>>16); /* lis r11,sym@ha */ | |
183 | entry->jump[1] = 0x396b0000 + (val&0xffff); /* addi r11,r11,sym@l*/ | |
184 | entry->jump[2] = 0x7d6903a6; /* mtctr r11 */ | |
185 | entry->jump[3] = 0x4e800420; /* bctr */ | |
186 | ||
187 | DEBUGP("Initialized plt for 0x%x at %p\n", val, entry); | |
188 | return (uint32_t)entry; | |
189 | } | |
190 | ||
191 | int apply_relocate_add(Elf32_Shdr *sechdrs, | |
192 | const char *strtab, | |
193 | unsigned int symindex, | |
194 | unsigned int relsec, | |
195 | struct module *module) | |
196 | { | |
197 | unsigned int i; | |
198 | Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr; | |
199 | Elf32_Sym *sym; | |
200 | uint32_t *location; | |
201 | uint32_t value; | |
202 | ||
203 | DEBUGP("Applying ADD relocate section %u to %u\n", relsec, | |
204 | sechdrs[relsec].sh_info); | |
205 | for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) { | |
206 | /* This is where to make the change */ | |
207 | location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr | |
208 | + rela[i].r_offset; | |
209 | /* This is the symbol it is referring to. Note that all | |
210 | undefined symbols have been resolved. */ | |
211 | sym = (Elf32_Sym *)sechdrs[symindex].sh_addr | |
212 | + ELF32_R_SYM(rela[i].r_info); | |
213 | /* `Everything is relative'. */ | |
214 | value = sym->st_value + rela[i].r_addend; | |
215 | ||
216 | switch (ELF32_R_TYPE(rela[i].r_info)) { | |
217 | case R_PPC_ADDR32: | |
218 | /* Simply set it */ | |
219 | *(uint32_t *)location = value; | |
220 | break; | |
221 | ||
222 | case R_PPC_ADDR16_LO: | |
223 | /* Low half of the symbol */ | |
224 | *(uint16_t *)location = value; | |
225 | break; | |
226 | ||
227 | case R_PPC_ADDR16_HA: | |
228 | /* Sign-adjusted lower 16 bits: PPC ELF ABI says: | |
229 | (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF. | |
230 | This is the same, only sane. | |
231 | */ | |
232 | *(uint16_t *)location = (value + 0x8000) >> 16; | |
233 | break; | |
234 | ||
235 | case R_PPC_REL24: | |
236 | if ((int)(value - (uint32_t)location) < -0x02000000 | |
237 | || (int)(value - (uint32_t)location) >= 0x02000000) | |
238 | value = do_plt_call(location, value, | |
239 | sechdrs, module); | |
240 | ||
241 | /* Only replace bits 2 through 26 */ | |
242 | DEBUGP("REL24 value = %08X. location = %08X\n", | |
243 | value, (uint32_t)location); | |
244 | DEBUGP("Location before: %08X.\n", | |
245 | *(uint32_t *)location); | |
246 | *(uint32_t *)location | |
247 | = (*(uint32_t *)location & ~0x03fffffc) | |
248 | | ((value - (uint32_t)location) | |
249 | & 0x03fffffc); | |
250 | DEBUGP("Location after: %08X.\n", | |
251 | *(uint32_t *)location); | |
252 | DEBUGP("ie. jump to %08X+%08X = %08X\n", | |
253 | *(uint32_t *)location & 0x03fffffc, | |
254 | (uint32_t)location, | |
255 | (*(uint32_t *)location & 0x03fffffc) | |
256 | + (uint32_t)location); | |
257 | break; | |
258 | ||
259 | case R_PPC_REL32: | |
260 | /* 32-bit relative jump. */ | |
261 | *(uint32_t *)location = value - (uint32_t)location; | |
262 | break; | |
263 | ||
264 | default: | |
265 | printk("%s: unknown ADD relocation: %u\n", | |
266 | module->name, | |
267 | ELF32_R_TYPE(rela[i].r_info)); | |
268 | return -ENOEXEC; | |
269 | } | |
270 | } | |
271 | return 0; | |
272 | } | |
273 | ||
21c4ff80 BH |
274 | static const Elf_Shdr *find_section(const Elf_Ehdr *hdr, |
275 | const Elf_Shdr *sechdrs, | |
276 | const char *name) | |
277 | { | |
278 | char *secstrings; | |
279 | unsigned int i; | |
280 | ||
281 | secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; | |
282 | for (i = 1; i < hdr->e_shnum; i++) | |
283 | if (strcmp(secstrings+sechdrs[i].sh_name, name) == 0) | |
284 | return &sechdrs[i]; | |
285 | return NULL; | |
286 | } | |
287 | ||
1da177e4 LT |
288 | int module_finalize(const Elf_Ehdr *hdr, |
289 | const Elf_Shdr *sechdrs, | |
290 | struct module *me) | |
291 | { | |
21c4ff80 | 292 | const Elf_Shdr *sect; |
1da177e4 LT |
293 | |
294 | me->arch.bug_table = NULL; | |
295 | me->arch.num_bugs = 0; | |
296 | ||
297 | /* Find the __bug_table section, if present */ | |
21c4ff80 BH |
298 | sect = find_section(hdr, sechdrs, "__bug_table"); |
299 | if (sect != NULL) { | |
300 | me->arch.bug_table = (void *) sect->sh_addr; | |
301 | me->arch.num_bugs = sect->sh_size / sizeof(struct bug_entry); | |
1da177e4 LT |
302 | } |
303 | ||
21c4ff80 | 304 | /* |
1da177e4 LT |
305 | * Strictly speaking this should have a spinlock to protect against |
306 | * traversals, but since we only traverse on BUG()s, a spinlock | |
307 | * could potentially lead to deadlock and thus be counter-productive. | |
308 | */ | |
309 | list_add(&me->arch.bug_list, &module_bug_list); | |
310 | ||
21c4ff80 BH |
311 | /* Apply feature fixups */ |
312 | sect = find_section(hdr, sechdrs, "__ftr_fixup"); | |
313 | if (sect != NULL) | |
314 | do_feature_fixups(cur_cpu_spec->cpu_features, | |
315 | (void *)sect->sh_addr, | |
316 | (void *)sect->sh_addr + sect->sh_size); | |
317 | ||
1da177e4 LT |
318 | return 0; |
319 | } | |
320 | ||
321 | void module_arch_cleanup(struct module *mod) | |
322 | { | |
323 | list_del(&mod->arch.bug_list); | |
324 | } | |
325 | ||
326 | struct bug_entry *module_find_bug(unsigned long bugaddr) | |
327 | { | |
328 | struct mod_arch_specific *mod; | |
329 | unsigned int i; | |
330 | struct bug_entry *bug; | |
331 | ||
332 | list_for_each_entry(mod, &module_bug_list, bug_list) { | |
333 | bug = mod->bug_table; | |
334 | for (i = 0; i < mod->num_bugs; ++i, ++bug) | |
335 | if (bugaddr == bug->bug_addr) | |
336 | return bug; | |
337 | } | |
338 | return NULL; | |
339 | } |