Merge branch 'linux-2.6' into for-linus
[linux-2.6] / arch / powerpc / kernel / module_32.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 #include "setup.h"
28
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
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
288 int module_finalize(const Elf_Ehdr *hdr,
289                     const Elf_Shdr *sechdrs,
290                     struct module *me)
291 {
292         const Elf_Shdr *sect;
293
294         me->arch.bug_table = NULL;
295         me->arch.num_bugs = 0;
296
297         /* Find the __bug_table section, if present */
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);
302         }
303
304         /*
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
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
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 }