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