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 #include <linux/bug.h>
  27 #include <linux/sort.h>
  28
  29 #include "setup.h"
  30
  31 #if 0
  32 #define DEBUGP printk
  33 #else
  34 #define DEBUGP(fmt , ...)
  35 #endif
  36
  37 LIST_HEAD(module_bug_list);
  38
  39 void *module_alloc(unsigned long size)
  40 {
  41         if (size == 0)
  42                 return NULL;
  43         return vmalloc(size);
  44 }
  45
  46 /* Free memory returned from module_alloc */
  47 void module_free(struct module *mod, void *module_region)
  48 {
  49         vfree(module_region);
  50         /* FIXME: If module_region == mod->init_region, trim exception
  51            table entries. */
  52 }
  53
  54 /* Count how many different relocations (different symbol, different
  55    addend) */
  56 static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num)
  57 {
  58         unsigned int i, r_info, r_addend, _count_relocs;
  59
  60         _count_relocs = 0;
  61         r_info = 0;
  62         r_addend = 0;
  63         for (i = 0; i < num; i++)
  64                 /* Only count 24-bit relocs, others don't need stubs */
  65                 if (ELF32_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&
  66                     (r_info != ELF32_R_SYM(rela[i].r_info) ||
  67                      r_addend != rela[i].r_addend)) {
  68                         _count_relocs++;
  69                         r_info = ELF32_R_SYM(rela[i].r_info);
  70                         r_addend = rela[i].r_addend;
  71                 }
  72
  73         return _count_relocs;
  74 }
  75
  76 static int relacmp(const void *_x, const void *_y)
  77 {
  78         const Elf32_Rela *x, *y;
  79
  80         y = (Elf32_Rela *)_x;
  81         x = (Elf32_Rela *)_y;
  82
  83         /* Compare the entire r_info (as opposed to ELF32_R_SYM(r_info) only) to
  84          * make the comparison cheaper/faster. It won't affect the sorting or
  85          * the counting algorithms' performance
  86          */
  87         if (x->r_info < y->r_info)
  88                 return -1;
  89         else if (x->r_info > y->r_info)
  90                 return 1;
  91         else if (x->r_addend < y->r_addend)
  92                 return -1;
  93         else if (x->r_addend > y->r_addend)
  94                 return 1;
  95         else
  96                 return 0;
  97 }
  98
  99 static void relaswap(void *_x, void *_y, int size)
 100 {
 101         uint32_t *x, *y, tmp;
 102         int i;
 103
 104         y = (uint32_t *)_x;
 105         x = (uint32_t *)_y;
 106
 107         for (i = 0; i < sizeof(Elf32_Rela) / sizeof(uint32_t); i++) {
 108                 tmp = x[i];
 109                 x[i] = y[i];
 110                 y[i] = tmp;
 111         }
 112 }
 113
 114 /* Get the potential trampolines size required of the init and
 115    non-init sections */
 116 static unsigned long get_plt_size(const Elf32_Ehdr *hdr,
 117                                   const Elf32_Shdr *sechdrs,
 118                                   const char *secstrings,
 119                                   int is_init)
 120 {
 121         unsigned long ret = 0;
 122         unsigned i;
 123
 124         /* Everything marked ALLOC (this includes the exported
 125            symbols) */
 126         for (i = 1; i < hdr->e_shnum; i++) {
 127                 /* If it's called *.init*, and we're not init, we're
 128                    not interested */
 129                 if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != 0)
 130                     != is_init)
 131                         continue;
 132
 133                 /* We don't want to look at debug sections. */
 134                 if (strstr(secstrings + sechdrs[i].sh_name, ".debug") != 0)
 135                         continue;
 136
 137                 if (sechdrs[i].sh_type == SHT_RELA) {
 138                         DEBUGP("Found relocations in section %u\n", i);
 139                         DEBUGP("Ptr: %p.  Number: %u\n",
 140                                (void *)hdr + sechdrs[i].sh_offset,
 141                                sechdrs[i].sh_size / sizeof(Elf32_Rela));
 142
 143                         /* Sort the relocation information based on a symbol and
 144                          * addend key. This is a stable O(n*log n) complexity
 145                          * alogrithm but it will reduce the complexity of
 146                          * count_relocs() to linear complexity O(n)
 147                          */
 148                         sort((void *)hdr + sechdrs[i].sh_offset,
 149                              sechdrs[i].sh_size / sizeof(Elf32_Rela),
 150                              sizeof(Elf32_Rela), relacmp, relaswap);
 151
 152                         ret += count_relocs((void *)hdr
 153                                              + sechdrs[i].sh_offset,
 154                                              sechdrs[i].sh_size
 155                                              / sizeof(Elf32_Rela))
 156                                 * sizeof(struct ppc_plt_entry);
 157                 }
 158         }
 159
 160         return ret;
 161 }
 162
 163 int module_frob_arch_sections(Elf32_Ehdr *hdr,
 164                               Elf32_Shdr *sechdrs,
 165                               char *secstrings,
 166                               struct module *me)
 167 {
 168         unsigned int i;
 169
 170         /* Find .plt and .init.plt sections */
 171         for (i = 0; i < hdr->e_shnum; i++) {
 172                 if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0)
 173                         me->arch.init_plt_section = i;
 174                 else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)
 175                         me->arch.core_plt_section = i;
 176         }
 177         if (!me->arch.core_plt_section || !me->arch.init_plt_section) {
 178                 printk("Module doesn't contain .plt or .init.plt sections.\n");
 179                 return -ENOEXEC;
 180         }
 181
 182         /* Override their sizes */
 183         sechdrs[me->arch.core_plt_section].sh_size
 184                 = get_plt_size(hdr, sechdrs, secstrings, 0);
 185         sechdrs[me->arch.init_plt_section].sh_size
 186                 = get_plt_size(hdr, sechdrs, secstrings, 1);
 187         return 0;
 188 }
 189
 190 int apply_relocate(Elf32_Shdr *sechdrs,
 191                    const char *strtab,
 192                    unsigned int symindex,
 193                    unsigned int relsec,
 194                    struct module *module)
 195 {
 196         printk(KERN_ERR "%s: Non-ADD RELOCATION unsupported\n",
 197                module->name);
 198         return -ENOEXEC;
 199 }
 200
 201 static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val)
 202 {
 203         if (entry->jump[0] == 0x3d600000 + ((val + 0x8000) >> 16)
 204             && entry->jump[1] == 0x396b0000 + (val & 0xffff))
 205                 return 1;
 206         return 0;
 207 }
 208
 209 /* Set up a trampoline in the PLT to bounce us to the distant function */
 210 static uint32_t do_plt_call(void *location,
 211                             Elf32_Addr val,
 212                             Elf32_Shdr *sechdrs,
 213                             struct module *mod)
 214 {
 215         struct ppc_plt_entry *entry;
 216
 217         DEBUGP("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location);
 218         /* Init, or core PLT? */
 219         if (location >= mod->module_core
 220             && location < mod->module_core + mod->core_size)
 221                 entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr;
 222         else
 223                 entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr;
 224
 225         /* Find this entry, or if that fails, the next avail. entry */
 226         while (entry->jump[0]) {
 227                 if (entry_matches(entry, val)) return (uint32_t)entry;
 228                 entry++;
 229         }
 230
 231         /* Stolen from Paul Mackerras as well... */
 232         entry->jump[0] = 0x3d600000+((val+0x8000)>>16); /* lis r11,sym@ha */
 233         entry->jump[1] = 0x396b0000 + (val&0xffff);     /* addi r11,r11,sym@l*/
 234         entry->jump[2] = 0x7d6903a6;                    /* mtctr r11 */
 235         entry->jump[3] = 0x4e800420;                    /* bctr */
 236
 237         DEBUGP("Initialized plt for 0x%x at %p\n", val, entry);
 238         return (uint32_t)entry;
 239 }
 240
 241 int apply_relocate_add(Elf32_Shdr *sechdrs,
 242                        const char *strtab,
 243                        unsigned int symindex,
 244                        unsigned int relsec,
 245                        struct module *module)
 246 {
 247         unsigned int i;
 248         Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
 249         Elf32_Sym *sym;
 250         uint32_t *location;
 251         uint32_t value;
 252
 253         DEBUGP("Applying ADD relocate section %u to %u\n", relsec,
 254                sechdrs[relsec].sh_info);
 255         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
 256                 /* This is where to make the change */
 257                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
 258                         + rela[i].r_offset;
 259                 /* This is the symbol it is referring to.  Note that all
 260                    undefined symbols have been resolved.  */
 261                 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
 262                         + ELF32_R_SYM(rela[i].r_info);
 263                 /* `Everything is relative'. */
 264                 value = sym->st_value + rela[i].r_addend;
 265
 266                 switch (ELF32_R_TYPE(rela[i].r_info)) {
 267                 case R_PPC_ADDR32:
 268                         /* Simply set it */
 269                         *(uint32_t *)location = value;
 270                         break;
 271
 272                 case R_PPC_ADDR16_LO:
 273                         /* Low half of the symbol */
 274                         *(uint16_t *)location = value;
 275                         break;
 276
 277                 case R_PPC_ADDR16_HI:
 278                         /* Higher half of the symbol */
 279                         *(uint16_t *)location = (value >> 16);
 280                         break;
 281
 282                 case R_PPC_ADDR16_HA:
 283                         /* Sign-adjusted lower 16 bits: PPC ELF ABI says:
 284                            (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF.
 285                            This is the same, only sane.
 286                          */
 287                         *(uint16_t *)location = (value + 0x8000) >> 16;
 288                         break;
 289
 290                 case R_PPC_REL24:
 291                         if ((int)(value - (uint32_t)location) < -0x02000000
 292                             || (int)(value - (uint32_t)location) >= 0x02000000)
 293                                 value = do_plt_call(location, value,
 294                                                     sechdrs, module);
 295
 296                         /* Only replace bits 2 through 26 */
 297                         DEBUGP("REL24 value = %08X. location = %08X\n",
 298                                value, (uint32_t)location);
 299                         DEBUGP("Location before: %08X.\n",
 300                                *(uint32_t *)location);
 301                         *(uint32_t *)location
 302                                 = (*(uint32_t *)location & ~0x03fffffc)
 303                                 | ((value - (uint32_t)location)
 304                                    & 0x03fffffc);
 305                         DEBUGP("Location after: %08X.\n",
 306                                *(uint32_t *)location);
 307                         DEBUGP("ie. jump to %08X+%08X = %08X\n",
 308                                *(uint32_t *)location & 0x03fffffc,
 309                                (uint32_t)location,
 310                                (*(uint32_t *)location & 0x03fffffc)
 311                                + (uint32_t)location);
 312                         break;
 313
 314                 case R_PPC_REL32:
 315                         /* 32-bit relative jump. */
 316                         *(uint32_t *)location = value - (uint32_t)location;
 317                         break;
 318
 319                 default:
 320                         printk("%s: unknown ADD relocation: %u\n",
 321                                module->name,
 322                                ELF32_R_TYPE(rela[i].r_info));
 323                         return -ENOEXEC;
 324                 }
 325         }
 326         return 0;
 327 }
 328
 329 static const Elf_Shdr *find_section(const Elf_Ehdr *hdr,
 330                                     const Elf_Shdr *sechdrs,
 331                                     const char *name)
 332 {
 333         char *secstrings;
 334         unsigned int i;
 335
 336         secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 337         for (i = 1; i < hdr->e_shnum; i++)
 338                 if (strcmp(secstrings+sechdrs[i].sh_name, name) == 0)
 339                         return &sechdrs[i];
 340         return NULL;
 341 }
 342
 343 int module_finalize(const Elf_Ehdr *hdr,
 344                     const Elf_Shdr *sechdrs,
 345                     struct module *me)
 346 {
 347         const Elf_Shdr *sect;
 348         int err;
 349
 350         err = module_bug_finalize(hdr, sechdrs, me);
 351         if (err)                /* never true, currently */
 352                 return err;
 353
 354         /* Apply feature fixups */
 355         sect = find_section(hdr, sechdrs, "__ftr_fixup");
 356         if (sect != NULL)
 357                 do_feature_fixups(cur_cpu_spec->cpu_features,
 358                                   (void *)sect->sh_addr,
 359                                   (void *)sect->sh_addr + sect->sh_size);
 360
 361         return 0;
 362 }
 363
 364 void module_arch_cleanup(struct module *mod)
 365 {
 366         module_bug_cleanup(mod);
 367 }
 368
 369 struct bug_entry *module_find_bug(unsigned long bugaddr)
 370 {
 371         struct mod_arch_specific *mod;
 372         unsigned int i;
 373         struct bug_entry *bug;
 374
 375         list_for_each_entry(mod, &module_bug_list, bug_list) {
 376                 bug = mod->bug_table;
 377                 for (i = 0; i < mod->num_bugs; ++i, ++bug)
 378                         if (bugaddr == bug->bug_addr)
 379                                 return bug;
 380         }
 381         return NULL;
 382 }