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         return 0;
  71 }
  72
  73 int
  74 apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
  75                unsigned int relindex, struct module *module)
  76 {
  77         Elf32_Shdr *symsec = sechdrs + symindex;
  78         Elf32_Shdr *relsec = sechdrs + relindex;
  79         Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
  80         Elf32_Rel *rel = (void *)relsec->sh_addr;
  81         unsigned int i;
  82
  83         for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) {
  84                 unsigned long loc;
  85                 Elf32_Sym *sym;
  86                 s32 offset;
  87 #ifdef CONFIG_THUMB2_KERNEL
  88                 u32 upper, lower, sign, j1, j2;
  89 #endif
  90
  91                 offset = ELF32_R_SYM(rel->r_info);
  92                 if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) {
  93                         printk(KERN_ERR "%s: bad relocation, section %d reloc %d\n",
  94                                 module->name, relindex, i);
  95                         return -ENOEXEC;
  96                 }
  97
  98                 sym = ((Elf32_Sym *)symsec->sh_addr) + offset;
  99
 100                 if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) {
 101                         printk(KERN_ERR "%s: out of bounds relocation, "
 102                                 "section %d reloc %d offset %d size %d\n",
 103                                 module->name, relindex, i, rel->r_offset,
 104                                 dstsec->sh_size);
 105                         return -ENOEXEC;
 106                 }
 107
 108                 loc = dstsec->sh_addr + rel->r_offset;
 109
 110                 switch (ELF32_R_TYPE(rel->r_info)) {
 111                 case R_ARM_NONE:
 112                         /* ignore */
 113                         break;
 114
 115                 case R_ARM_ABS32:
 116                         *(u32 *)loc += sym->st_value;
 117                         break;
 118
 119                 case R_ARM_PC24:
 120                 case R_ARM_CALL:
 121                 case R_ARM_JUMP24:
 122                         offset = (*(u32 *)loc & 0x00ffffff) << 2;
 123                         if (offset & 0x02000000)
 124                                 offset -= 0x04000000;
 125
 126                         offset += sym->st_value - loc;
 127                         if (offset & 3 ||
 128                             offset <= (s32)0xfe000000 ||
 129                             offset >= (s32)0x02000000) {
 130                                 printk(KERN_ERR
 131                                        "%s: relocation out of range, section "
 132                                        "%d reloc %d sym '%s'\n", module->name,
 133                                        relindex, i, strtab + sym->st_name);
 134                                 return -ENOEXEC;
 135                         }
 136
 137                         offset >>= 2;
 138
 139                         *(u32 *)loc &= 0xff000000;
 140                         *(u32 *)loc |= offset & 0x00ffffff;
 141                         break;
 142
 143                case R_ARM_V4BX:
 144                        /* Preserve Rm and the condition code. Alter
 145                         * other bits to re-code instruction as
 146                         * MOV PC,Rm.
 147                         */
 148                        *(u32 *)loc &= 0xf000000f;
 149                        *(u32 *)loc |= 0x01a0f000;
 150                        break;
 151
 152                 case R_ARM_PREL31:
 153                         offset = *(u32 *)loc + sym->st_value - loc;
 154                         *(u32 *)loc = offset & 0x7fffffff;
 155                         break;
 156
 157                 case R_ARM_MOVW_ABS_NC:
 158                 case R_ARM_MOVT_ABS:
 159                         offset = *(u32 *)loc;
 160                         offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
 161                         offset = (offset ^ 0x8000) - 0x8000;
 162
 163                         offset += sym->st_value;
 164                         if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS)
 165                                 offset >>= 16;
 166
 167                         *(u32 *)loc &= 0xfff0f000;
 168                         *(u32 *)loc |= ((offset & 0xf000) << 4) |
 169                                         (offset & 0x0fff);
 170                         break;
 171
 172 #ifdef CONFIG_THUMB2_KERNEL
 173                 case R_ARM_THM_CALL:
 174                 case R_ARM_THM_JUMP24:
 175                         upper = *(u16 *)loc;
 176                         lower = *(u16 *)(loc + 2);
 177
 178                         /*
 179                          * 25 bit signed address range (Thumb-2 BL and B.W
 180                          * instructions):
 181                          *   S:I1:I2:imm10:imm11:0
 182                          * where:
 183                          *   S     = upper[10]   = offset[24]
 184                          *   I1    = ~(J1 ^ S)   = offset[23]
 185                          *   I2    = ~(J2 ^ S)   = offset[22]
 186                          *   imm10 = upper[9:0]  = offset[21:12]
 187                          *   imm11 = lower[10:0] = offset[11:1]
 188                          *   J1    = lower[13]
 189                          *   J2    = lower[11]
 190                          */
 191                         sign = (upper >> 10) & 1;
 192                         j1 = (lower >> 13) & 1;
 193                         j2 = (lower >> 11) & 1;
 194                         offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) |
 195                                 ((~(j2 ^ sign) & 1) << 22) |
 196                                 ((upper & 0x03ff) << 12) |
 197                                 ((lower & 0x07ff) << 1);
 198                         if (offset & 0x01000000)
 199                                 offset -= 0x02000000;
 200                         offset += sym->st_value - loc;
 201
 202                         /* only Thumb addresses allowed (no interworking) */
 203                         if (!(offset & 1) ||
 204                             offset <= (s32)0xff000000 ||
 205                             offset >= (s32)0x01000000) {
 206                                 printk(KERN_ERR
 207                                        "%s: relocation out of range, section "
 208                                        "%d reloc %d sym '%s'\n", module->name,
 209                                        relindex, i, strtab + sym->st_name);
 210                                 return -ENOEXEC;
 211                         }
 212
 213                         sign = (offset >> 24) & 1;
 214                         j1 = sign ^ (~(offset >> 23) & 1);
 215                         j2 = sign ^ (~(offset >> 22) & 1);
 216                         *(u16 *)loc = (u16)((upper & 0xf800) | (sign << 10) |
 217                                             ((offset >> 12) & 0x03ff));
 218                         *(u16 *)(loc + 2) = (u16)((lower & 0xd000) |
 219                                                   (j1 << 13) | (j2 << 11) |
 220                                                   ((offset >> 1) & 0x07ff));
 221                         break;
 222
 223                 case R_ARM_THM_MOVW_ABS_NC:
 224                 case R_ARM_THM_MOVT_ABS:
 225                         upper = *(u16 *)loc;
 226                         lower = *(u16 *)(loc + 2);
 227
 228                         /*
 229                          * MOVT/MOVW instructions encoding in Thumb-2:
 230                          *
 231                          * i    = upper[10]
 232                          * imm4 = upper[3:0]
 233                          * imm3 = lower[14:12]
 234                          * imm8 = lower[7:0]
 235                          *
 236                          * imm16 = imm4:i:imm3:imm8
 237                          */
 238                         offset = ((upper & 0x000f) << 12) |
 239                                 ((upper & 0x0400) << 1) |
 240                                 ((lower & 0x7000) >> 4) | (lower & 0x00ff);
 241                         offset = (offset ^ 0x8000) - 0x8000;
 242                         offset += sym->st_value;
 243
 244                         if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS)
 245                                 offset >>= 16;
 246
 247                         *(u16 *)loc = (u16)((upper & 0xfbf0) |
 248                                             ((offset & 0xf000) >> 12) |
 249                                             ((offset & 0x0800) >> 1));
 250                         *(u16 *)(loc + 2) = (u16)((lower & 0x8f00) |
 251                                                   ((offset & 0x0700) << 4) |
 252                                                   (offset & 0x00ff));
 253                         break;
 254 #endif
 255
 256                 default:
 257                         printk(KERN_ERR "%s: unknown relocation: %u\n",
 258                                module->name, ELF32_R_TYPE(rel->r_info));
 259                         return -ENOEXEC;
 260                 }
 261         }
 262         return 0;
 263 }
 264
 265 int
 266 apply_relocate_add(Elf32_Shdr *sechdrs, const char *strtab,
 267                    unsigned int symindex, unsigned int relsec, struct module *module)
 268 {
 269         printk(KERN_ERR "module %s: ADD RELOCATION unsupported\n",
 270                module->name);
 271         return -ENOEXEC;
 272 }
 273
 274 struct mod_unwind_map {
 275         const Elf_Shdr *unw_sec;
 276         const Elf_Shdr *txt_sec;
 277 };
 278
 279 int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
 280                     struct module *mod)
 281 {
 282 #ifdef CONFIG_ARM_UNWIND
 283         const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
 284         const Elf_Shdr *s, *sechdrs_end = sechdrs + hdr->e_shnum;
 285         struct mod_unwind_map maps[ARM_SEC_MAX];
 286         int i;
 287
 288         memset(maps, 0, sizeof(maps));
 289
 290         for (s = sechdrs; s < sechdrs_end; s++) {
 291                 const char *secname = secstrs + s->sh_name;
 292
 293                 if (!(s->sh_flags & SHF_ALLOC))
 294                         continue;
 295
 296                 if (strcmp(".ARM.exidx.init.text", secname) == 0)
 297                         maps[ARM_SEC_INIT].unw_sec = s;
 298                 else if (strcmp(".ARM.exidx.devinit.text", secname) == 0)
 299                         maps[ARM_SEC_DEVINIT].unw_sec = s;
 300                 else if (strcmp(".ARM.exidx", secname) == 0)
 301                         maps[ARM_SEC_CORE].unw_sec = s;
 302                 else if (strcmp(".ARM.exidx.exit.text", secname) == 0)
 303                         maps[ARM_SEC_EXIT].unw_sec = s;
 304                 else if (strcmp(".ARM.exidx.devexit.text", secname) == 0)
 305                         maps[ARM_SEC_DEVEXIT].unw_sec = s;
 306                 else if (strcmp(".init.text", secname) == 0)
 307                         maps[ARM_SEC_INIT].txt_sec = s;
 308                 else if (strcmp(".devinit.text", secname) == 0)
 309                         maps[ARM_SEC_DEVINIT].txt_sec = s;
 310                 else if (strcmp(".text", secname) == 0)
 311                         maps[ARM_SEC_CORE].txt_sec = s;
 312                 else if (strcmp(".exit.text", secname) == 0)
 313                         maps[ARM_SEC_EXIT].txt_sec = s;
 314                 else if (strcmp(".devexit.text", secname) == 0)
 315                         maps[ARM_SEC_DEVEXIT].txt_sec = s;
 316         }
 317
 318         for (i = 0; i < ARM_SEC_MAX; i++)
 319                 if (maps[i].unw_sec && maps[i].txt_sec)
 320                         mod->arch.unwind[i] =
 321                                 unwind_table_add(maps[i].unw_sec->sh_addr,
 322                                                  maps[i].unw_sec->sh_size,
 323                                                  maps[i].txt_sec->sh_addr,
 324                                                  maps[i].txt_sec->sh_size);
 325 #endif
 326         return 0;
 327 }
 328
 329 void
 330 module_arch_cleanup(struct module *mod)
 331 {
 332 #ifdef CONFIG_ARM_UNWIND
 333         int i;
 334
 335         for (i = 0; i < ARM_SEC_MAX; i++)
 336                 if (mod->arch.unwind[i])
 337                         unwind_table_del(mod->arch.unwind[i]);
 338 #endif
 339 }