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module_32.c

/*  Kernel module help for i386.
    Copyright (C) 2001 Rusty Russell.

    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
*/
#include <linux/moduleloader.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/bug.h>

#if 0
#define DEBUGP printk
#else
#define DEBUGP(fmt...)
#endif

void *module_alloc(unsigned long size)
{
      if (size == 0)
            return NULL;
      return vmalloc_exec(size);
}


/* 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. */
}

/* We don't need anything special. */
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 relsec,
               struct module *me)
{
      unsigned int i;
      Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
      Elf32_Sym *sym;
      uint32_t *location;

      DEBUGP("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.  Note that all
               undefined symbols have been resolved.  */
            sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
                  + ELF32_R_SYM(rel[i].r_info);

            switch (ELF32_R_TYPE(rel[i].r_info)) {
            case R_386_32:
                  /* We add the value into the location given */
                  *location += sym->st_value;
                  break;
            case R_386_PC32:
                  /* Add the value, subtract its postition */
                  *location += sym->st_value - (uint32_t)location;
                  break;
            default:
                  printk(KERN_ERR "module %s: Unknown relocation: %u\n",
                         me->name, ELF32_R_TYPE(rel[i].r_info));
                  return -ENOEXEC;
            }
      }
      return 0;
}

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

int module_finalize(const Elf_Ehdr *hdr,
                const Elf_Shdr *sechdrs,
                struct module *me)
{
      const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
            *para = NULL;
      char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;

      for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) { 
            if (!strcmp(".text", secstrings + s->sh_name))
                  text = s;
            if (!strcmp(".altinstructions", secstrings + s->sh_name))
                  alt = s;
            if (!strcmp(".smp_locks", secstrings + s->sh_name))
                  locks= s;
            if (!strcmp(".parainstructions", secstrings + s->sh_name))
                  para = s;
      }

      if (alt) {
            /* patch .altinstructions */
            void *aseg = (void *)alt->sh_addr;
            apply_alternatives(aseg, aseg + alt->sh_size);
      }
      if (locks && text) {
            void *lseg = (void *)locks->sh_addr;
            void *tseg = (void *)text->sh_addr;
            alternatives_smp_module_add(me, me->name,
                                  lseg, lseg + locks->sh_size,
                                  tseg, tseg + text->sh_size);
      }

      if (para) {
            void *pseg = (void *)para->sh_addr;
            apply_paravirt(pseg, pseg + para->sh_size);
      }

      return module_bug_finalize(hdr, sechdrs, me);
}

void module_arch_cleanup(struct module *mod)
{
      alternatives_smp_module_del(mod);
      module_bug_cleanup(mod);
}

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