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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/slab.h>
#include <linux/fs.h>
#include <linux/string.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)
{
      struct vm_struct *area;

      size = PAGE_ALIGN(size);
      if (!size)
            return NULL;

      area = __get_vm_area(size, VM_ALLOC, MODULES_VADDR, MODULES_END);
      if (!area)
            return NULL;

      return __vmalloc_area(area, GFP_KERNEL, PAGE_KERNEL_EXEC);
}
#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)
{
#ifdef CONFIG_ARM_UNWIND
      Elf_Shdr *s, *sechdrs_end = sechdrs + hdr->e_shnum;

      for (s = sechdrs; s < sechdrs_end; s++) {
            if (strcmp(".ARM.exidx.init.text", secstrings + s->sh_name) == 0)
                  mod->arch.unw_sec_init = s;
            else if (strcmp(".ARM.exidx.devinit.text", secstrings + s->sh_name) == 0)
                  mod->arch.unw_sec_devinit = s;
            else if (strcmp(".ARM.exidx", secstrings + s->sh_name) == 0)
                  mod->arch.unw_sec_core = s;
            else if (strcmp(".init.text", secstrings + s->sh_name) == 0)
                  mod->arch.sec_init_text = s;
            else if (strcmp(".devinit.text", secstrings + s->sh_name) == 0)
                  mod->arch.sec_devinit_text = s;
            else if (strcmp(".text", secstrings + s->sh_name) == 0)
                  mod->arch.sec_core_text = s;
      }
#endif
      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;
            u32 upper, lower, sign, j1, j2;

            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;

            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));
                  upper = *(u16 *)loc;
                  lower = *(u16 *)(loc + 2);
                  break;

            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;
}

#ifdef CONFIG_ARM_UNWIND
static void register_unwind_tables(struct module *mod)
{
      if (mod->arch.unw_sec_init && mod->arch.sec_init_text)
            mod->arch.unwind_init =
                  unwind_table_add(mod->arch.unw_sec_init->sh_addr,
                               mod->arch.unw_sec_init->sh_size,
                               mod->arch.sec_init_text->sh_addr,
                               mod->arch.sec_init_text->sh_size);
      if (mod->arch.unw_sec_devinit && mod->arch.sec_devinit_text)
            mod->arch.unwind_devinit =
                  unwind_table_add(mod->arch.unw_sec_devinit->sh_addr,
                               mod->arch.unw_sec_devinit->sh_size,
                               mod->arch.sec_devinit_text->sh_addr,
                               mod->arch.sec_devinit_text->sh_size);
      if (mod->arch.unw_sec_core && mod->arch.sec_core_text)
            mod->arch.unwind_core =
                  unwind_table_add(mod->arch.unw_sec_core->sh_addr,
                               mod->arch.unw_sec_core->sh_size,
                               mod->arch.sec_core_text->sh_addr,
                               mod->arch.sec_core_text->sh_size);
}

static void unregister_unwind_tables(struct module *mod)
{
      unwind_table_del(mod->arch.unwind_init);
      unwind_table_del(mod->arch.unwind_devinit);
      unwind_table_del(mod->arch.unwind_core);
}
#else
static inline void register_unwind_tables(struct module *mod) { }
static inline void unregister_unwind_tables(struct module *mod) { }
#endif

int
module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
            struct module *module)
{
      register_unwind_tables(module);
      return 0;
}

void
module_arch_cleanup(struct module *mod)
{
      unregister_unwind_tables(mod);
}

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