arch/arm/kernel/module.c

   1 /*
   2  *  linux/arch/arm/kernel/module.c
   3  *
   4  *  Copyright (C) 2002 Russell King.
   5  *  Modified for nommu by Hyok S. Choi
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * Module allocation method suggested by Andi Kleen.
  12  */
  13 #include <linux/module.h>
  14 #include <linux/moduleloader.h>
  15 #include <linux/kernel.h>
  16 #include <linux/mm.h>
  17 #include <linux/elf.h>
  18 #include <linux/vmalloc.h>
  19 #include <linux/fs.h>
  20 #include <linux/string.h>
  21 #include <linux/gfp.h>
  22
  23 #include <asm/pgtable.h>
  24 #include <asm/sections.h>
  25 #include <asm/unwind.h>
  26
  27 #ifdef CONFIG_XIP_KERNEL
  28 /*
  29  * The XIP kernel text is mapped in the module area for modules and
  30  * some other stuff to work without any indirect relocations.
  31  * MODULES_VADDR is redefined here and not in asm/memory.h to avoid
  32  * recompiling the whole kernel when CONFIG_XIP_KERNEL is turned on/off.
  33  */
  34 #undef MODULES_VADDR
  35 #define MODULES_VADDR   (((unsigned long)_etext + ~PGDIR_MASK) & PGDIR_MASK)
  36 #endif
  37
  38 #ifdef CONFIG_MMU
  39 void *module_alloc(unsigned long size)
  40 {
  41         struct vm_struct *area;
  42
  43         size = PAGE_ALIGN(size);
  44         if (!size)
  45                 return NULL;
  46
  47         area = __get_vm_area(size, VM_ALLOC, MODULES_VADDR, MODULES_END);
  48         if (!area)
  49                 return NULL;
  50
  51         return __vmalloc_area(area, GFP_KERNEL, PAGE_KERNEL_EXEC);
  52 }
  53 #else /* CONFIG_MMU */
  54 void *module_alloc(unsigned long size)
  55 {
  56         return size == 0 ? NULL : vmalloc(size);
  57 }
  58 #endif /* !CONFIG_MMU */
  59
  60 void module_free(struct module *module, void *region)
  61 {
  62         vfree(region);
  63 }
  64
  65 int module_frob_arch_sections(Elf_Ehdr *hdr,
  66                               Elf_Shdr *sechdrs,
  67                               char *secstrings,
  68                               struct module *mod)
  69 {
  70 #ifdef CONFIG_ARM_UNWIND
  71         Elf_Shdr *s, *sechdrs_end = sechdrs + hdr->e_shnum;
  72         struct arm_unwind_mapping *maps = mod->arch.map;
  73
  74         for (s = sechdrs; s < sechdrs_end; s++) {
  75                 char const *secname = secstrings + s->sh_name;
  76
  77                 if (strcmp(".ARM.exidx.init.text", secname) == 0)
  78                         maps[ARM_SEC_INIT].unw_sec = s;
  79                 else if (strcmp(".ARM.exidx.devinit.text", secname) == 0)
  80                         maps[ARM_SEC_DEVINIT].unw_sec = s;
  81                 else if (strcmp(".ARM.exidx", secname) == 0)
  82                         maps[ARM_SEC_CORE].unw_sec = s;
  83                 else if (strcmp(".init.text", secname) == 0)
  84                         maps[ARM_SEC_INIT].sec_text = s;
  85                 else if (strcmp(".devinit.text", secname) == 0)
  86                         maps[ARM_SEC_DEVINIT].sec_text = s;
  87                 else if (strcmp(".text", secname) == 0)
  88                         maps[ARM_SEC_CORE].sec_text = s;
  89         }
  90 #endif
  91         return 0;
  92 }
  93
  94 int
  95 apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
  96                unsigned int relindex, struct module *module)
  97 {
  98         Elf32_Shdr *symsec = sechdrs + symindex;
  99         Elf32_Shdr *relsec = sechdrs + relindex;
 100         Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
 101         Elf32_Rel *rel = (void *)relsec->sh_addr;
 102         unsigned int i;
 103
 104         for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) {
 105                 unsigned long loc;
 106                 Elf32_Sym *sym;
 107                 s32 offset;
 108 #ifdef CONFIG_THUMB2_KERNEL
 109                 u32 upper, lower, sign, j1, j2;
 110 #endif
 111
 112                 offset = ELF32_R_SYM(rel->r_info);
 113                 if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) {
 114                         printk(KERN_ERR "%s: bad relocation, section %d reloc %d\n",
 115                                 module->name, relindex, i);
 116                         return -ENOEXEC;
 117                 }
 118
 119                 sym = ((Elf32_Sym *)symsec->sh_addr) + offset;
 120
 121                 if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) {
 122                         printk(KERN_ERR "%s: out of bounds relocation, "
 123                                 "section %d reloc %d offset %d size %d\n",
 124                                 module->name, relindex, i, rel->r_offset,
 125                                 dstsec->sh_size);
 126                         return -ENOEXEC;
 127                 }
 128
 129                 loc = dstsec->sh_addr + rel->r_offset;
 130
 131                 switch (ELF32_R_TYPE(rel->r_info)) {
 132                 case R_ARM_NONE:
 133                         /* ignore */
 134                         break;
 135
 136                 case R_ARM_ABS32:
 137                         *(u32 *)loc += sym->st_value;
 138                         break;
 139
 140                 case R_ARM_PC24:
 141                 case R_ARM_CALL:
 142                 case R_ARM_JUMP24:
 143                         offset = (*(u32 *)loc & 0x00ffffff) << 2;
 144                         if (offset & 0x02000000)
 145                                 offset -= 0x04000000;
 146
 147                         offset += sym->st_value - loc;
 148                         if (offset & 3 ||
 149                             offset <= (s32)0xfe000000 ||
 150                             offset >= (s32)0x02000000) {
 151                                 printk(KERN_ERR
 152                                        "%s: relocation out of range, section "
 153                                        "%d reloc %d sym '%s'\n", module->name,
 154                                        relindex, i, strtab + sym->st_name);
 155                                 return -ENOEXEC;
 156                         }
 157
 158                         offset >>= 2;
 159
 160                         *(u32 *)loc &= 0xff000000;
 161                         *(u32 *)loc |= offset & 0x00ffffff;
 162                         break;
 163
 164                case R_ARM_V4BX:
 165                        /* Preserve Rm and the condition code. Alter
 166                         * other bits to re-code instruction as
 167                         * MOV PC,Rm.
 168                         */
 169                        *(u32 *)loc &= 0xf000000f;
 170                        *(u32 *)loc |= 0x01a0f000;
 171                        break;
 172
 173                 case R_ARM_PREL31:
 174                         offset = *(u32 *)loc + sym->st_value - loc;
 175                         *(u32 *)loc = offset & 0x7fffffff;
 176                         break;
 177
 178                 case R_ARM_MOVW_ABS_NC:
 179                 case R_ARM_MOVT_ABS:
 180                         offset = *(u32 *)loc;
 181                         offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
 182                         offset = (offset ^ 0x8000) - 0x8000;
 183
 184                         offset += sym->st_value;
 185                         if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS)
 186                                 offset >>= 16;
 187
 188                         *(u32 *)loc &= 0xfff0f000;
 189                         *(u32 *)loc |= ((offset & 0xf000) << 4) |
 190                                         (offset & 0x0fff);
 191                         break;
 192
 193 #ifdef CONFIG_THUMB2_KERNEL
 194                 case R_ARM_THM_CALL:
 195                 case R_ARM_THM_JUMP24:
 196                         upper = *(u16 *)loc;
 197                         lower = *(u16 *)(loc + 2);
 198
 199                         /*
 200                          * 25 bit signed address range (Thumb-2 BL and B.W
 201                          * instructions):
 202                          *   S:I1:I2:imm10:imm11:0
 203                          * where:
 204                          *   S     = upper[10]   = offset[24]
 205                          *   I1    = ~(J1 ^ S)   = offset[23]
 206                          *   I2    = ~(J2 ^ S)   = offset[22]
 207                          *   imm10 = upper[9:0]  = offset[21:12]
 208                          *   imm11 = lower[10:0] = offset[11:1]
 209                          *   J1    = lower[13]
 210                          *   J2    = lower[11]
 211                          */
 212                         sign = (upper >> 10) & 1;
 213                         j1 = (lower >> 13) & 1;
 214                         j2 = (lower >> 11) & 1;
 215                         offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) |
 216                                 ((~(j2 ^ sign) & 1) << 22) |
 217                                 ((upper & 0x03ff) << 12) |
 218                                 ((lower & 0x07ff) << 1);
 219                         if (offset & 0x01000000)
 220                                 offset -= 0x02000000;
 221                         offset += sym->st_value - loc;
 222
 223                         /* only Thumb addresses allowed (no interworking) */
 224                         if (!(offset & 1) ||
 225                             offset <= (s32)0xff000000 ||
 226                             offset >= (s32)0x01000000) {
 227                                 printk(KERN_ERR
 228                                        "%s: relocation out of range, section "
 229                                        "%d reloc %d sym '%s'\n", module->name,
 230                                        relindex, i, strtab + sym->st_name);
 231                                 return -ENOEXEC;
 232                         }
 233
 234                         sign = (offset >> 24) & 1;
 235                         j1 = sign ^ (~(offset >> 23) & 1);
 236                         j2 = sign ^ (~(offset >> 22) & 1);
 237                         *(u16 *)loc = (u16)((upper & 0xf800) | (sign << 10) |
 238                                             ((offset >> 12) & 0x03ff));
 239                         *(u16 *)(loc + 2) = (u16)((lower & 0xd000) |
 240                                                   (j1 << 13) | (j2 << 11) |
 241                                                   ((offset >> 1) & 0x07ff));
 242                         break;
 243
 244                 case R_ARM_THM_MOVW_ABS_NC:
 245                 case R_ARM_THM_MOVT_ABS:
 246                         upper = *(u16 *)loc;
 247                         lower = *(u16 *)(loc + 2);
 248
 249                         /*
 250                          * MOVT/MOVW instructions encoding in Thumb-2:
 251                          *
 252                          * i    = upper[10]
 253                          * imm4 = upper[3:0]
 254                          * imm3 = lower[14:12]
 255                          * imm8 = lower[7:0]
 256                          *
 257                          * imm16 = imm4:i:imm3:imm8
 258                          */
 259                         offset = ((upper & 0x000f) << 12) |
 260                                 ((upper & 0x0400) << 1) |
 261                                 ((lower & 0x7000) >> 4) | (lower & 0x00ff);
 262                         offset = (offset ^ 0x8000) - 0x8000;
 263                         offset += sym->st_value;
 264
 265                         if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS)
 266                                 offset >>= 16;
 267
 268                         *(u16 *)loc = (u16)((upper & 0xfbf0) |
 269                                             ((offset & 0xf000) >> 12) |
 270                                             ((offset & 0x0800) >> 1));
 271                         *(u16 *)(loc + 2) = (u16)((lower & 0x8f00) |
 272                                                   ((offset & 0x0700) << 4) |
 273                                                   (offset & 0x00ff));
 274                         break;
 275 #endif
 276
 277                 default:
 278                         printk(KERN_ERR "%s: unknown relocation: %u\n",
 279                                module->name, ELF32_R_TYPE(rel->r_info));
 280                         return -ENOEXEC;
 281                 }
 282         }
 283         return 0;
 284 }
 285
 286 int
 287 apply_relocate_add(Elf32_Shdr *sechdrs, const char *strtab,
 288                    unsigned int symindex, unsigned int relsec, struct module *module)
 289 {
 290         printk(KERN_ERR "module %s: ADD RELOCATION unsupported\n",
 291                module->name);
 292         return -ENOEXEC;
 293 }
 294
 295 #ifdef CONFIG_ARM_UNWIND
 296 static void register_unwind_tables(struct module *mod)
 297 {
 298         int i;
 299         for (i = 0; i < ARM_SEC_MAX; ++i) {
 300                 struct arm_unwind_mapping *map = &mod->arch.map[i];
 301                 if (map->unw_sec && map->sec_text)
 302                         map->unwind = unwind_table_add(map->unw_sec->sh_addr,
 303                                                        map->unw_sec->sh_size,
 304                                                        map->sec_text->sh_addr,
 305                                                        map->sec_text->sh_size);
 306         }
 307 }
 308
 309 static void unregister_unwind_tables(struct module *mod)
 310 {
 311         int i = ARM_SEC_MAX;
 312         while (--i >= 0)
 313                 unwind_table_del(mod->arch.map[i].unwind);
 314 }
 315 #else
 316 static inline void register_unwind_tables(struct module *mod) { }
 317 static inline void unregister_unwind_tables(struct module *mod) { }
 318 #endif
 319
 320 int
 321 module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
 322                 struct module *module)
 323 {
 324         register_unwind_tables(module);
 325         return 0;
 326 }
 327
 328 void
 329 module_arch_cleanup(struct module *mod)
 330 {
 331         unregister_unwind_tables(mod);
 332 }