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module.c

/*
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  Copyright (C) 2001 Rusty Russell.
 *  Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)
 *  Copyright (C) 2005 Thiemo Seufer
 */

#undef DEBUG

#include <linux/moduleloader.h>
#include <linux/elf.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <asm/pgtable.h>      /* MODULE_START */

struct mips_hi16 {
      struct mips_hi16 *next;
      Elf_Addr *addr;
      Elf_Addr value;
};

static struct mips_hi16 *mips_hi16_list;

static LIST_HEAD(dbe_list);
static DEFINE_SPINLOCK(dbe_lock);

void *module_alloc(unsigned long size)
{
#ifdef MODULE_START
      struct vm_struct *area;

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

      area = __get_vm_area(size, VM_ALLOC, MODULE_START, MODULE_END);
      if (!area)
            return NULL;

      return __vmalloc_area(area, GFP_KERNEL, PAGE_KERNEL);
#else
      if (size == 0)
            return NULL;
      return vmalloc(size);
#endif
}

/* Free memory returned from module_alloc */
void module_free(struct module *mod, void *module_region)
{
      vfree(module_region);
      /* FIXME: If module_region == mod->init_region, trim exception
           table entries. */
}

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

static int apply_r_mips_none(struct module *me, u32 *location, Elf_Addr v)
{
      return 0;
}

static int apply_r_mips_32_rel(struct module *me, u32 *location, Elf_Addr v)
{
      *location += v;

      return 0;
}

static int apply_r_mips_32_rela(struct module *me, u32 *location, Elf_Addr v)
{
      *location = v;

      return 0;
}

static int apply_r_mips_26_rel(struct module *me, u32 *location, Elf_Addr v)
{
      if (v % 4) {
            printk(KERN_ERR "module %s: dangerous relocation\n", me->name);
            return -ENOEXEC;
      }

      if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
            printk(KERN_ERR
                   "module %s: relocation overflow\n",
                   me->name);
            return -ENOEXEC;
      }

      *location = (*location & ~0x03ffffff) |
                  ((*location + (v >> 2)) & 0x03ffffff);

      return 0;
}

static int apply_r_mips_26_rela(struct module *me, u32 *location, Elf_Addr v)
{
      if (v % 4) {
            printk(KERN_ERR "module %s: dangerous relocation\n", me->name);
            return -ENOEXEC;
      }

      if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
            printk(KERN_ERR
                   "module %s: relocation overflow\n",
                   me->name);
            return -ENOEXEC;
      }

      *location = (*location & ~0x03ffffff) | ((v >> 2) & 0x03ffffff);

      return 0;
}

static int apply_r_mips_hi16_rel(struct module *me, u32 *location, Elf_Addr v)
{
      struct mips_hi16 *n;

      /*
       * We cannot relocate this one now because we don't know the value of
       * the carry we need to add.  Save the information, and let LO16 do the
       * actual relocation.
       */
      n = kmalloc(sizeof *n, GFP_KERNEL);
      if (!n)
            return -ENOMEM;

      n->addr = (Elf_Addr *)location;
      n->value = v;
      n->next = mips_hi16_list;
      mips_hi16_list = n;

      return 0;
}

static int apply_r_mips_hi16_rela(struct module *me, u32 *location, Elf_Addr v)
{
      *location = (*location & 0xffff0000) |
                  ((((long long) v + 0x8000LL) >> 16) & 0xffff);

      return 0;
}

static int apply_r_mips_lo16_rel(struct module *me, u32 *location, Elf_Addr v)
{
      unsigned long insnlo = *location;
      Elf_Addr val, vallo;

      /* Sign extend the addend we extract from the lo insn.  */
      vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000;

      if (mips_hi16_list != NULL) {
            struct mips_hi16 *l;

            l = mips_hi16_list;
            while (l != NULL) {
                  struct mips_hi16 *next;
                  unsigned long insn;

                  /*
                   * The value for the HI16 had best be the same.
                   */
                  if (v != l->value)
                        goto out_danger;

                  /*
                   * Do the HI16 relocation.  Note that we actually don't
                   * need to know anything about the LO16 itself, except
                   * where to find the low 16 bits of the addend needed
                   * by the LO16.
                   */
                  insn = *l->addr;
                  val = ((insn & 0xffff) << 16) + vallo;
                  val += v;

                  /*
                   * Account for the sign extension that will happen in
                   * the low bits.
                   */
                  val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff;

                  insn = (insn & ~0xffff) | val;
                  *l->addr = insn;

                  next = l->next;
                  kfree(l);
                  l = next;
            }

            mips_hi16_list = NULL;
      }

      /*
       * Ok, we're done with the HI16 relocs.  Now deal with the LO16.
       */
      val = v + vallo;
      insnlo = (insnlo & ~0xffff) | (val & 0xffff);
      *location = insnlo;

      return 0;

out_danger:
      printk(KERN_ERR "module %s: dangerous " "relocation\n", me->name);

      return -ENOEXEC;
}

static int apply_r_mips_lo16_rela(struct module *me, u32 *location, Elf_Addr v)
{
      *location = (*location & 0xffff0000) | (v & 0xffff);

      return 0;
}

static int apply_r_mips_64_rela(struct module *me, u32 *location, Elf_Addr v)
{
      *(Elf_Addr *)location = v;

      return 0;
}

static int apply_r_mips_higher_rela(struct module *me, u32 *location,
                            Elf_Addr v)
{
      *location = (*location & 0xffff0000) |
                  ((((long long) v + 0x80008000LL) >> 32) & 0xffff);

      return 0;
}

static int apply_r_mips_highest_rela(struct module *me, u32 *location,
                             Elf_Addr v)
{
      *location = (*location & 0xffff0000) |
                  ((((long long) v + 0x800080008000LL) >> 48) & 0xffff);

      return 0;
}

static int (*reloc_handlers_rel[]) (struct module *me, u32 *location,
                        Elf_Addr v) = {
      [R_MIPS_NONE]           = apply_r_mips_none,
      [R_MIPS_32]       = apply_r_mips_32_rel,
      [R_MIPS_26]       = apply_r_mips_26_rel,
      [R_MIPS_HI16]           = apply_r_mips_hi16_rel,
      [R_MIPS_LO16]           = apply_r_mips_lo16_rel
};

static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
                        Elf_Addr v) = {
      [R_MIPS_NONE]           = apply_r_mips_none,
      [R_MIPS_32]       = apply_r_mips_32_rela,
      [R_MIPS_26]       = apply_r_mips_26_rela,
      [R_MIPS_HI16]           = apply_r_mips_hi16_rela,
      [R_MIPS_LO16]           = apply_r_mips_lo16_rela,
      [R_MIPS_64]       = apply_r_mips_64_rela,
      [R_MIPS_HIGHER]         = apply_r_mips_higher_rela,
      [R_MIPS_HIGHEST]  = apply_r_mips_highest_rela
};

int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
               unsigned int symindex, unsigned int relsec,
               struct module *me)
{
      Elf_Mips_Rel *rel = (void *) sechdrs[relsec].sh_addr;
      Elf_Sym *sym;
      u32 *location;
      unsigned int i;
      Elf_Addr v;
      int res;

      pr_debug("Applying relocate section %u to %u\n", relsec,
             sechdrs[relsec].sh_info);

      for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
            /* This is where to make the change */
            location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
                  + rel[i].r_offset;
            /* This is the symbol it is referring to */
            sym = (Elf_Sym *)sechdrs[symindex].sh_addr
                  + ELF_MIPS_R_SYM(rel[i]);
            if (!sym->st_value) {
                  /* Ignore unresolved weak symbol */
                  if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
                        continue;
                  printk(KERN_WARNING "%s: Unknown symbol %s\n",
                         me->name, strtab + sym->st_name);
                  return -ENOENT;
            }

            v = sym->st_value;

            res = reloc_handlers_rel[ELF_MIPS_R_TYPE(rel[i])](me, location, v);
            if (res)
                  return res;
      }

      return 0;
}

int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
                   unsigned int symindex, unsigned int relsec,
                   struct module *me)
{
      Elf_Mips_Rela *rel = (void *) sechdrs[relsec].sh_addr;
      Elf_Sym *sym;
      u32 *location;
      unsigned int i;
      Elf_Addr v;
      int res;

      pr_debug("Applying relocate section %u to %u\n", relsec,
             sechdrs[relsec].sh_info);

      for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
            /* This is where to make the change */
            location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
                  + rel[i].r_offset;
            /* This is the symbol it is referring to */
            sym = (Elf_Sym *)sechdrs[symindex].sh_addr
                  + ELF_MIPS_R_SYM(rel[i]);
            if (!sym->st_value) {
                  /* Ignore unresolved weak symbol */
                  if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
                        continue;
                  printk(KERN_WARNING "%s: Unknown symbol %s\n",
                         me->name, strtab + sym->st_name);
                  return -ENOENT;
            }

            v = sym->st_value + rel[i].r_addend;

            res = reloc_handlers_rela[ELF_MIPS_R_TYPE(rel[i])](me, location, v);
            if (res)
                  return res;
      }

      return 0;
}

/* Given an address, look for it in the module exception tables. */
const struct exception_table_entry *search_module_dbetables(unsigned long addr)
{
      unsigned long flags;
      const struct exception_table_entry *e = NULL;
      struct mod_arch_specific *dbe;

      spin_lock_irqsave(&dbe_lock, flags);
      list_for_each_entry(dbe, &dbe_list, dbe_list) {
            e = search_extable(dbe->dbe_start, dbe->dbe_end - 1, addr);
            if (e)
                  break;
      }
      spin_unlock_irqrestore(&dbe_lock, flags);

      /* Now, if we found one, we are running inside it now, hence
           we cannot unload the module, hence no refcnt needed. */
      return e;
}

/* Put in dbe list if necessary. */
int module_finalize(const Elf_Ehdr *hdr,
                const Elf_Shdr *sechdrs,
                struct module *me)
{
      const Elf_Shdr *s;
      char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;

      INIT_LIST_HEAD(&me->arch.dbe_list);
      for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
            if (strcmp("__dbe_table", secstrings + s->sh_name) != 0)
                  continue;
            me->arch.dbe_start = (void *)s->sh_addr;
            me->arch.dbe_end = (void *)s->sh_addr + s->sh_size;
            spin_lock_irq(&dbe_lock);
            list_add(&me->arch.dbe_list, &dbe_list);
            spin_unlock_irq(&dbe_lock);
      }
      return 0;
}

void module_arch_cleanup(struct module *mod)
{
      spin_lock_irq(&dbe_lock);
      list_del(&mod->arch.dbe_list);
      spin_unlock_irq(&dbe_lock);
}

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