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