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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> | |
73c9ceab | 26 | #include <linux/bug.h> |
1da177e4 | 27 | |
21c4ff80 BH |
28 | #include "setup.h" |
29 | ||
1da177e4 LT |
30 | #if 0 |
31 | #define DEBUGP printk | |
32 | #else | |
33 | #define DEBUGP(fmt , ...) | |
34 | #endif | |
35 | ||
36 | LIST_HEAD(module_bug_list); | |
37 | ||
38 | void *module_alloc(unsigned long size) | |
39 | { | |
40 | if (size == 0) | |
41 | return NULL; | |
42 | return vmalloc(size); | |
43 | } | |
44 | ||
45 | /* Free memory returned from module_alloc */ | |
46 | void module_free(struct module *mod, void *module_region) | |
47 | { | |
48 | vfree(module_region); | |
49 | /* FIXME: If module_region == mod->init_region, trim exception | |
50 | table entries. */ | |
51 | } | |
52 | ||
53 | /* Count how many different relocations (different symbol, different | |
54 | addend) */ | |
55 | static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num) | |
56 | { | |
57 | unsigned int i, j, ret = 0; | |
58 | ||
59 | /* Sure, this is order(n^2), but it's usually short, and not | |
60 | time critical */ | |
61 | for (i = 0; i < num; i++) { | |
62 | for (j = 0; j < i; j++) { | |
63 | /* If this addend appeared before, it's | |
64 | already been counted */ | |
65 | if (ELF32_R_SYM(rela[i].r_info) | |
66 | == ELF32_R_SYM(rela[j].r_info) | |
67 | && rela[i].r_addend == rela[j].r_addend) | |
68 | break; | |
69 | } | |
70 | if (j == i) ret++; | |
71 | } | |
72 | return ret; | |
73 | } | |
74 | ||
75 | /* Get the potential trampolines size required of the init and | |
76 | non-init sections */ | |
77 | static unsigned long get_plt_size(const Elf32_Ehdr *hdr, | |
78 | const Elf32_Shdr *sechdrs, | |
79 | const char *secstrings, | |
80 | int is_init) | |
81 | { | |
82 | unsigned long ret = 0; | |
83 | unsigned i; | |
84 | ||
85 | /* Everything marked ALLOC (this includes the exported | |
86 | symbols) */ | |
87 | for (i = 1; i < hdr->e_shnum; i++) { | |
88 | /* If it's called *.init*, and we're not init, we're | |
89 | not interested */ | |
90 | if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != 0) | |
91 | != is_init) | |
92 | continue; | |
93 | ||
94 | /* We don't want to look at debug sections. */ | |
95 | if (strstr(secstrings + sechdrs[i].sh_name, ".debug") != 0) | |
96 | continue; | |
97 | ||
98 | if (sechdrs[i].sh_type == SHT_RELA) { | |
99 | DEBUGP("Found relocations in section %u\n", i); | |
100 | DEBUGP("Ptr: %p. Number: %u\n", | |
101 | (void *)hdr + sechdrs[i].sh_offset, | |
102 | sechdrs[i].sh_size / sizeof(Elf32_Rela)); | |
103 | ret += count_relocs((void *)hdr | |
104 | + sechdrs[i].sh_offset, | |
105 | sechdrs[i].sh_size | |
106 | / sizeof(Elf32_Rela)) | |
107 | * sizeof(struct ppc_plt_entry); | |
108 | } | |
109 | } | |
110 | ||
111 | return ret; | |
112 | } | |
113 | ||
114 | int module_frob_arch_sections(Elf32_Ehdr *hdr, | |
115 | Elf32_Shdr *sechdrs, | |
116 | char *secstrings, | |
117 | struct module *me) | |
118 | { | |
119 | unsigned int i; | |
120 | ||
121 | /* Find .plt and .init.plt sections */ | |
122 | for (i = 0; i < hdr->e_shnum; i++) { | |
123 | if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0) | |
124 | me->arch.init_plt_section = i; | |
125 | else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0) | |
126 | me->arch.core_plt_section = i; | |
127 | } | |
128 | if (!me->arch.core_plt_section || !me->arch.init_plt_section) { | |
129 | printk("Module doesn't contain .plt or .init.plt sections.\n"); | |
130 | return -ENOEXEC; | |
131 | } | |
132 | ||
133 | /* Override their sizes */ | |
134 | sechdrs[me->arch.core_plt_section].sh_size | |
135 | = get_plt_size(hdr, sechdrs, secstrings, 0); | |
136 | sechdrs[me->arch.init_plt_section].sh_size | |
137 | = get_plt_size(hdr, sechdrs, secstrings, 1); | |
138 | return 0; | |
139 | } | |
140 | ||
141 | int apply_relocate(Elf32_Shdr *sechdrs, | |
142 | const char *strtab, | |
143 | unsigned int symindex, | |
144 | unsigned int relsec, | |
145 | struct module *module) | |
146 | { | |
147 | printk(KERN_ERR "%s: Non-ADD RELOCATION unsupported\n", | |
148 | module->name); | |
149 | return -ENOEXEC; | |
150 | } | |
151 | ||
152 | static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val) | |
153 | { | |
154 | if (entry->jump[0] == 0x3d600000 + ((val + 0x8000) >> 16) | |
155 | && entry->jump[1] == 0x396b0000 + (val & 0xffff)) | |
156 | return 1; | |
157 | return 0; | |
158 | } | |
159 | ||
160 | /* Set up a trampoline in the PLT to bounce us to the distant function */ | |
161 | static uint32_t do_plt_call(void *location, | |
162 | Elf32_Addr val, | |
163 | Elf32_Shdr *sechdrs, | |
164 | struct module *mod) | |
165 | { | |
166 | struct ppc_plt_entry *entry; | |
167 | ||
168 | DEBUGP("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location); | |
169 | /* Init, or core PLT? */ | |
170 | if (location >= mod->module_core | |
171 | && location < mod->module_core + mod->core_size) | |
172 | entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr; | |
173 | else | |
174 | entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr; | |
175 | ||
176 | /* Find this entry, or if that fails, the next avail. entry */ | |
177 | while (entry->jump[0]) { | |
178 | if (entry_matches(entry, val)) return (uint32_t)entry; | |
179 | entry++; | |
180 | } | |
181 | ||
182 | /* Stolen from Paul Mackerras as well... */ | |
183 | entry->jump[0] = 0x3d600000+((val+0x8000)>>16); /* lis r11,sym@ha */ | |
184 | entry->jump[1] = 0x396b0000 + (val&0xffff); /* addi r11,r11,sym@l*/ | |
185 | entry->jump[2] = 0x7d6903a6; /* mtctr r11 */ | |
186 | entry->jump[3] = 0x4e800420; /* bctr */ | |
187 | ||
188 | DEBUGP("Initialized plt for 0x%x at %p\n", val, entry); | |
189 | return (uint32_t)entry; | |
190 | } | |
191 | ||
192 | int apply_relocate_add(Elf32_Shdr *sechdrs, | |
193 | const char *strtab, | |
194 | unsigned int symindex, | |
195 | unsigned int relsec, | |
196 | struct module *module) | |
197 | { | |
198 | unsigned int i; | |
199 | Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr; | |
200 | Elf32_Sym *sym; | |
201 | uint32_t *location; | |
202 | uint32_t value; | |
203 | ||
204 | DEBUGP("Applying ADD relocate section %u to %u\n", relsec, | |
205 | sechdrs[relsec].sh_info); | |
206 | for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) { | |
207 | /* This is where to make the change */ | |
208 | location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr | |
209 | + rela[i].r_offset; | |
210 | /* This is the symbol it is referring to. Note that all | |
211 | undefined symbols have been resolved. */ | |
212 | sym = (Elf32_Sym *)sechdrs[symindex].sh_addr | |
213 | + ELF32_R_SYM(rela[i].r_info); | |
214 | /* `Everything is relative'. */ | |
215 | value = sym->st_value + rela[i].r_addend; | |
216 | ||
217 | switch (ELF32_R_TYPE(rela[i].r_info)) { | |
218 | case R_PPC_ADDR32: | |
219 | /* Simply set it */ | |
220 | *(uint32_t *)location = value; | |
221 | break; | |
222 | ||
223 | case R_PPC_ADDR16_LO: | |
224 | /* Low half of the symbol */ | |
225 | *(uint16_t *)location = value; | |
226 | break; | |
9a3d6458 SV |
227 | |
228 | case R_PPC_ADDR16_HI: | |
229 | /* Higher half of the symbol */ | |
230 | *(uint16_t *)location = (value >> 16); | |
231 | break; | |
232 | ||
1da177e4 LT |
233 | case R_PPC_ADDR16_HA: |
234 | /* Sign-adjusted lower 16 bits: PPC ELF ABI says: | |
235 | (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF. | |
236 | This is the same, only sane. | |
237 | */ | |
238 | *(uint16_t *)location = (value + 0x8000) >> 16; | |
239 | break; | |
240 | ||
241 | case R_PPC_REL24: | |
242 | if ((int)(value - (uint32_t)location) < -0x02000000 | |
243 | || (int)(value - (uint32_t)location) >= 0x02000000) | |
244 | value = do_plt_call(location, value, | |
245 | sechdrs, module); | |
246 | ||
247 | /* Only replace bits 2 through 26 */ | |
248 | DEBUGP("REL24 value = %08X. location = %08X\n", | |
249 | value, (uint32_t)location); | |
250 | DEBUGP("Location before: %08X.\n", | |
251 | *(uint32_t *)location); | |
252 | *(uint32_t *)location | |
253 | = (*(uint32_t *)location & ~0x03fffffc) | |
254 | | ((value - (uint32_t)location) | |
255 | & 0x03fffffc); | |
256 | DEBUGP("Location after: %08X.\n", | |
257 | *(uint32_t *)location); | |
258 | DEBUGP("ie. jump to %08X+%08X = %08X\n", | |
259 | *(uint32_t *)location & 0x03fffffc, | |
260 | (uint32_t)location, | |
261 | (*(uint32_t *)location & 0x03fffffc) | |
262 | + (uint32_t)location); | |
263 | break; | |
264 | ||
265 | case R_PPC_REL32: | |
266 | /* 32-bit relative jump. */ | |
267 | *(uint32_t *)location = value - (uint32_t)location; | |
268 | break; | |
269 | ||
270 | default: | |
271 | printk("%s: unknown ADD relocation: %u\n", | |
272 | module->name, | |
273 | ELF32_R_TYPE(rela[i].r_info)); | |
274 | return -ENOEXEC; | |
275 | } | |
276 | } | |
277 | return 0; | |
278 | } | |
279 | ||
21c4ff80 BH |
280 | static const Elf_Shdr *find_section(const Elf_Ehdr *hdr, |
281 | const Elf_Shdr *sechdrs, | |
282 | const char *name) | |
283 | { | |
284 | char *secstrings; | |
285 | unsigned int i; | |
286 | ||
287 | secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; | |
288 | for (i = 1; i < hdr->e_shnum; i++) | |
289 | if (strcmp(secstrings+sechdrs[i].sh_name, name) == 0) | |
290 | return &sechdrs[i]; | |
291 | return NULL; | |
292 | } | |
293 | ||
1da177e4 LT |
294 | int module_finalize(const Elf_Ehdr *hdr, |
295 | const Elf_Shdr *sechdrs, | |
296 | struct module *me) | |
297 | { | |
21c4ff80 | 298 | const Elf_Shdr *sect; |
73c9ceab | 299 | int err; |
1da177e4 | 300 | |
73c9ceab JF |
301 | err = module_bug_finalize(hdr, sechdrs, me); |
302 | if (err) /* never true, currently */ | |
303 | return err; | |
1da177e4 | 304 | |
21c4ff80 BH |
305 | /* Apply feature fixups */ |
306 | sect = find_section(hdr, sechdrs, "__ftr_fixup"); | |
307 | if (sect != NULL) | |
308 | do_feature_fixups(cur_cpu_spec->cpu_features, | |
309 | (void *)sect->sh_addr, | |
310 | (void *)sect->sh_addr + sect->sh_size); | |
311 | ||
1da177e4 LT |
312 | return 0; |
313 | } | |
314 | ||
315 | void module_arch_cleanup(struct module *mod) | |
316 | { | |
73c9ceab | 317 | module_bug_cleanup(mod); |
1da177e4 LT |
318 | } |
319 | ||
320 | struct bug_entry *module_find_bug(unsigned long bugaddr) | |
321 | { | |
322 | struct mod_arch_specific *mod; | |
323 | unsigned int i; | |
324 | struct bug_entry *bug; | |
325 | ||
326 | list_for_each_entry(mod, &module_bug_list, bug_list) { | |
327 | bug = mod->bug_table; | |
328 | for (i = 0; i < mod->num_bugs; ++i, ++bug) | |
329 | if (bugaddr == bug->bug_addr) | |
330 | return bug; | |
331 | } | |
332 | return NULL; | |
333 | } |