Merge master.kernel.org:/pub/scm/linux/kernel/git/dtor/input
[linux-2.6] / arch / ppc / kernel / module.c
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 }