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module.c

/*
 *  linux/arch/arm/kernel/module.c
 *
 *  Copyright (C) 2002 Russell King.
 *  Modified for nommu by Hyok S. Choi
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Module allocation method suggested by Andi Kleen.
 */
#include <linux/module.h>
#include <linux/moduleloader.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/gfp.h>

#include <asm/pgtable.h>
#include <asm/sections.h>
#include <asm/unwind.h>

#ifdef CONFIG_XIP_KERNEL
/*
 * The XIP kernel text is mapped in the module area for modules and
 * some other stuff to work without any indirect relocations.
 * MODULES_VADDR is redefined here and not in asm/memory.h to avoid
 * recompiling the whole kernel when CONFIG_XIP_KERNEL is turned on/off.
 */
#undef MODULES_VADDR
#define MODULES_VADDR   (((unsigned long)_etext + ~PGDIR_MASK) & PGDIR_MASK)
#endif

#ifdef CONFIG_MMU
void *module_alloc(unsigned long size)
{
      return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
                        GFP_KERNEL, PAGE_KERNEL_EXEC, -1,
                        __builtin_return_address(0));
}
#else /* CONFIG_MMU */
void *module_alloc(unsigned long size)
{
      return size == 0 ? NULL : vmalloc(size);
}
#endif /* !CONFIG_MMU */

void module_free(struct module *module, void *region)
{
      vfree(region);
}

int module_frob_arch_sections(Elf_Ehdr *hdr,
                        Elf_Shdr *sechdrs,
                        char *secstrings,
                        struct module *mod)
{
      return 0;
}

int
apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
             unsigned int relindex, struct module *module)
{
      Elf32_Shdr *symsec = sechdrs + symindex;
      Elf32_Shdr *relsec = sechdrs + relindex;
      Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
      Elf32_Rel *rel = (void *)relsec->sh_addr;
      unsigned int i;

      for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) {
            unsigned long loc;
            Elf32_Sym *sym;
            s32 offset;
#ifdef CONFIG_THUMB2_KERNEL
            u32 upper, lower, sign, j1, j2;
#endif

            offset = ELF32_R_SYM(rel->r_info);
            if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) {
                  printk(KERN_ERR "%s: bad relocation, section %d reloc %d\n",
                        module->name, relindex, i);
                  return -ENOEXEC;
            }

            sym = ((Elf32_Sym *)symsec->sh_addr) + offset;

            if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) {
                  printk(KERN_ERR "%s: out of bounds relocation, "
                        "section %d reloc %d offset %d size %d\n",
                        module->name, relindex, i, rel->r_offset,
                        dstsec->sh_size);
                  return -ENOEXEC;
            }

            loc = dstsec->sh_addr + rel->r_offset;

            switch (ELF32_R_TYPE(rel->r_info)) {
            case R_ARM_NONE:
                  /* ignore */
                  break;

            case R_ARM_ABS32:
                  *(u32 *)loc += sym->st_value;
                  break;

            case R_ARM_PC24:
            case R_ARM_CALL:
            case R_ARM_JUMP24:
                  offset = (*(u32 *)loc & 0x00ffffff) << 2;
                  if (offset & 0x02000000)
                        offset -= 0x04000000;

                  offset += sym->st_value - loc;
                  if (offset & 3 ||
                      offset <= (s32)0xfe000000 ||
                      offset >= (s32)0x02000000) {
                        printk(KERN_ERR
                               "%s: relocation out of range, section "
                               "%d reloc %d sym '%s'\n", module->name,
                               relindex, i, strtab + sym->st_name);
                        return -ENOEXEC;
                  }

                  offset >>= 2;

                  *(u32 *)loc &= 0xff000000;
                  *(u32 *)loc |= offset & 0x00ffffff;
                  break;

             case R_ARM_V4BX:
                   /* Preserve Rm and the condition code. Alter
                  * other bits to re-code instruction as
                  * MOV PC,Rm.
                  */
                   *(u32 *)loc &= 0xf000000f;
                   *(u32 *)loc |= 0x01a0f000;
                   break;

            case R_ARM_PREL31:
                  offset = *(u32 *)loc + sym->st_value - loc;
                  *(u32 *)loc = offset & 0x7fffffff;
                  break;

            case R_ARM_MOVW_ABS_NC:
            case R_ARM_MOVT_ABS:
                  offset = *(u32 *)loc;
                  offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
                  offset = (offset ^ 0x8000) - 0x8000;

                  offset += sym->st_value;
                  if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS)
                        offset >>= 16;

                  *(u32 *)loc &= 0xfff0f000;
                  *(u32 *)loc |= ((offset & 0xf000) << 4) |
                              (offset & 0x0fff);
                  break;

#ifdef CONFIG_THUMB2_KERNEL
            case R_ARM_THM_CALL:
            case R_ARM_THM_JUMP24:
                  upper = *(u16 *)loc;
                  lower = *(u16 *)(loc + 2);

                  /*
                   * 25 bit signed address range (Thumb-2 BL and B.W
                   * instructions):
                   *   S:I1:I2:imm10:imm11:0
                   * where:
                   *   S     = upper[10]   = offset[24]
                   *   I1    = ~(J1 ^ S)   = offset[23]
                   *   I2    = ~(J2 ^ S)   = offset[22]
                   *   imm10 = upper[9:0]  = offset[21:12]
                   *   imm11 = lower[10:0] = offset[11:1]
                   *   J1    = lower[13]
                   *   J2    = lower[11]
                   */
                  sign = (upper >> 10) & 1;
                  j1 = (lower >> 13) & 1;
                  j2 = (lower >> 11) & 1;
                  offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) |
                        ((~(j2 ^ sign) & 1) << 22) |
                        ((upper & 0x03ff) << 12) |
                        ((lower & 0x07ff) << 1);
                  if (offset & 0x01000000)
                        offset -= 0x02000000;
                  offset += sym->st_value - loc;

                  /* only Thumb addresses allowed (no interworking) */
                  if (!(offset & 1) ||
                      offset <= (s32)0xff000000 ||
                      offset >= (s32)0x01000000) {
                        printk(KERN_ERR
                               "%s: relocation out of range, section "
                               "%d reloc %d sym '%s'\n", module->name,
                               relindex, i, strtab + sym->st_name);
                        return -ENOEXEC;
                  }

                  sign = (offset >> 24) & 1;
                  j1 = sign ^ (~(offset >> 23) & 1);
                  j2 = sign ^ (~(offset >> 22) & 1);
                  *(u16 *)loc = (u16)((upper & 0xf800) | (sign << 10) |
                                  ((offset >> 12) & 0x03ff));
                  *(u16 *)(loc + 2) = (u16)((lower & 0xd000) |
                                      (j1 << 13) | (j2 << 11) |
                                      ((offset >> 1) & 0x07ff));
                  break;

            case R_ARM_THM_MOVW_ABS_NC:
            case R_ARM_THM_MOVT_ABS:
                  upper = *(u16 *)loc;
                  lower = *(u16 *)(loc + 2);

                  /*
                   * MOVT/MOVW instructions encoding in Thumb-2:
                   *
                   * i  = upper[10]
                   * imm4     = upper[3:0]
                   * imm3     = lower[14:12]
                   * imm8     = lower[7:0]
                   *
                   * imm16 = imm4:i:imm3:imm8
                   */
                  offset = ((upper & 0x000f) << 12) |
                        ((upper & 0x0400) << 1) |
                        ((lower & 0x7000) >> 4) | (lower & 0x00ff);
                  offset = (offset ^ 0x8000) - 0x8000;
                  offset += sym->st_value;

                  if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS)
                        offset >>= 16;

                  *(u16 *)loc = (u16)((upper & 0xfbf0) |
                                  ((offset & 0xf000) >> 12) |
                                  ((offset & 0x0800) >> 1));
                  *(u16 *)(loc + 2) = (u16)((lower & 0x8f00) |
                                      ((offset & 0x0700) << 4) |
                                      (offset & 0x00ff));
                  break;
#endif

            default:
                  printk(KERN_ERR "%s: unknown relocation: %u\n",
                         module->name, ELF32_R_TYPE(rel->r_info));
                  return -ENOEXEC;
            }
      }
      return 0;
}

int
apply_relocate_add(Elf32_Shdr *sechdrs, const char *strtab,
               unsigned int symindex, unsigned int relsec, struct module *module)
{
      printk(KERN_ERR "module %s: ADD RELOCATION unsupported\n",
             module->name);
      return -ENOEXEC;
}

00266 struct mod_unwind_map {
      const Elf_Shdr *unw_sec;
      const Elf_Shdr *txt_sec;
};

int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
                struct module *mod)
{
#ifdef CONFIG_ARM_UNWIND
      const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
      const Elf_Shdr *s, *sechdrs_end = sechdrs + hdr->e_shnum;
      struct mod_unwind_map maps[ARM_SEC_MAX];
      int i;

      memset(maps, 0, sizeof(maps));

      for (s = sechdrs; s < sechdrs_end; s++) {
            const char *secname = secstrs + s->sh_name;

            if (!(s->sh_flags & SHF_ALLOC))
                  continue;

            if (strcmp(".ARM.exidx.init.text", secname) == 0)
                  maps[ARM_SEC_INIT].unw_sec = s;
            else if (strcmp(".ARM.exidx.devinit.text", secname) == 0)
                  maps[ARM_SEC_DEVINIT].unw_sec = s;
            else if (strcmp(".ARM.exidx", secname) == 0)
                  maps[ARM_SEC_CORE].unw_sec = s;
            else if (strcmp(".ARM.exidx.exit.text", secname) == 0)
                  maps[ARM_SEC_EXIT].unw_sec = s;
            else if (strcmp(".ARM.exidx.devexit.text", secname) == 0)
                  maps[ARM_SEC_DEVEXIT].unw_sec = s;
            else if (strcmp(".init.text", secname) == 0)
                  maps[ARM_SEC_INIT].txt_sec = s;
            else if (strcmp(".devinit.text", secname) == 0)
                  maps[ARM_SEC_DEVINIT].txt_sec = s;
            else if (strcmp(".text", secname) == 0)
                  maps[ARM_SEC_CORE].txt_sec = s;
            else if (strcmp(".exit.text", secname) == 0)
                  maps[ARM_SEC_EXIT].txt_sec = s;
            else if (strcmp(".devexit.text", secname) == 0)
                  maps[ARM_SEC_DEVEXIT].txt_sec = s;
      }

      for (i = 0; i < ARM_SEC_MAX; i++)
            if (maps[i].unw_sec && maps[i].txt_sec)
                  mod->arch.unwind[i] =
                        unwind_table_add(maps[i].unw_sec->sh_addr,
                                       maps[i].unw_sec->sh_size,
                                       maps[i].txt_sec->sh_addr,
                                       maps[i].txt_sec->sh_size);
#endif
      return 0;
}

void
module_arch_cleanup(struct module *mod)
{
#ifdef CONFIG_ARM_UNWIND
      int i;

      for (i = 0; i < ARM_SEC_MAX; i++)
            if (mod->arch.unwind[i])
                  unwind_table_del(mod->arch.unwind[i]);
#endif
}

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