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module.c

/*
 * arch/v850/kernel/module.c -- Architecture-specific module functions
 *
 *  Copyright (C) 2002,03  NEC Electronics Corporation
 *  Copyright (C) 2002,03  Miles Bader <miles@gnu.org>
 *  Copyright (C) 2001,03  Rusty Russell
 *
 * This file is subject to the terms and conditions of the GNU General
 * Public License.  See the file COPYING in the main directory of this
 * archive for more details.
 *
 * Written by Miles Bader <miles@gnu.org>
 *
 * Derived in part from arch/ppc/kernel/module.c
 */

#include <linux/kernel.h>
#include <linux/vmalloc.h>
#include <linux/moduleloader.h>
#include <linux/elf.h>

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

void *module_alloc (unsigned long size)
{
      return size == 0 ? 0 : vmalloc (size);
}

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_finalize (const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
                 struct module *mod)
{
      return 0;
}

/* Count how many different relocations (different symbol, different
   addend) */
static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num)
{
      unsigned int i, j, ret = 0;

      /* Sure, this is order(n^2), but it's usually short, and not
           time critical */
      for (i = 0; i < num; i++) {
            for (j = 0; j < i; j++) {
                  /* If this addend appeared before, it's
                           already been counted */
                  if (ELF32_R_SYM(rela[i].r_info)
                      == ELF32_R_SYM(rela[j].r_info)
                      && rela[i].r_addend == rela[j].r_addend)
                        break;
            }
            if (j == i) ret++;
      }
      return ret;
}

/* Get the potential trampolines size required of the init and
   non-init sections */
static unsigned long get_plt_size(const Elf32_Ehdr *hdr,
                          const Elf32_Shdr *sechdrs,
                          const char *secstrings,
                          int is_init)
{
      unsigned long ret = 0;
      unsigned i;

      /* Everything marked ALLOC (this includes the exported
           symbols) */
      for (i = 1; i < hdr->e_shnum; i++) {
            /* If it's called *.init*, and we're not init, we're
                   not interested */
            if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != 0)
                != is_init)
                  continue;

            if (sechdrs[i].sh_type == SHT_RELA) {
                  DEBUGP("Found relocations in section %u\n", i);
                  DEBUGP("Ptr: %p.  Number: %u\n",
                         (void *)hdr + sechdrs[i].sh_offset,
                         sechdrs[i].sh_size / sizeof(Elf32_Rela));
                  ret += count_relocs((void *)hdr
                                   + sechdrs[i].sh_offset,
                                   sechdrs[i].sh_size
                                   / sizeof(Elf32_Rela))
                        * sizeof(struct v850_plt_entry);
            }
      }

      return ret;
}

int module_frob_arch_sections(Elf32_Ehdr *hdr,
                        Elf32_Shdr *sechdrs,
                        char *secstrings,
                        struct module *me)
{
      unsigned int i;

      /* Find .plt and .pltinit sections */
      for (i = 0; i < hdr->e_shnum; i++) {
            if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0)
                  me->arch.init_plt_section = i;
            else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)
                  me->arch.core_plt_section = i;
      }
      if (!me->arch.core_plt_section || !me->arch.init_plt_section) {
            printk("Module doesn't contain .plt or .plt.init sections.\n");
            return -ENOEXEC;
      }

      /* Override their sizes */
      sechdrs[me->arch.core_plt_section].sh_size
            = get_plt_size(hdr, sechdrs, secstrings, 0);
      sechdrs[me->arch.init_plt_section].sh_size
            = get_plt_size(hdr, sechdrs, secstrings, 1);
      return 0;
}

int apply_relocate (Elf32_Shdr *sechdrs, const char *strtab,
                unsigned int symindex, unsigned int relsec,
                struct module *mod)
{
      printk ("Barf\n");
      return -ENOEXEC;
}

/* Set up a trampoline in the PLT to bounce us to the distant function */
static uint32_t do_plt_call (void *location, Elf32_Addr val,
                       Elf32_Shdr *sechdrs, struct module *mod)
{
      struct v850_plt_entry *entry;
      /* Instructions used to do the indirect jump.  */
      uint32_t tramp[2];

      /* We have to trash a register, so we assume that any control
         transfer more than 21-bits away must be a function call
         (so we can use a call-clobbered register).  */
      tramp[0] = 0x0621 + ((val & 0xffff) << 16);   /* mov sym, r1 ... */
      tramp[1] = ((val >> 16) & 0xffff) + 0x610000; /* ...; jmp r1 */

      /* Init, or core PLT? */
      if (location >= mod->module_core
          && location < mod->module_core + mod->core_size)
            entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr;
      else
            entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr;

      /* Find this entry, or if that fails, the next avail. entry */
      while (entry->tramp[0])
            if (entry->tramp[0] == tramp[0] && entry->tramp[1] == tramp[1])
                  return (uint32_t)entry;
            else
                  entry++;

      entry->tramp[0] = tramp[0];
      entry->tramp[1] = tramp[1];

      return (uint32_t)entry;
}

int apply_relocate_add (Elf32_Shdr *sechdrs, const char *strtab,
                  unsigned int symindex, unsigned int relsec,
                  struct module *mod)
{
      unsigned int i;
      Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;

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

      for (i = 0; i < sechdrs[relsec].sh_size / sizeof (*rela); i++) {
            /* This is where to make the change */
            uint32_t *loc
                  = ((void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
                     + rela[i].r_offset);
            /* This is the symbol it is referring to.  Note that all
               undefined symbols have been resolved.  */
            Elf32_Sym *sym
                  = ((Elf32_Sym *)sechdrs[symindex].sh_addr
                     + ELF32_R_SYM (rela[i].r_info));
            uint32_t val = sym->st_value + rela[i].r_addend;

            switch (ELF32_R_TYPE (rela[i].r_info)) {
            case R_V850_32:
                  /* We write two shorts instead of a long because even
                     32-bit insns only need half-word alignment, but
                     32-bit data writes need to be long-word aligned.  */
                  val += ((uint16_t *)loc)[0];
                  val += ((uint16_t *)loc)[1] << 16;
                  ((uint16_t *)loc)[0] = val & 0xffff;
                  ((uint16_t *)loc)[1] = (val >> 16) & 0xffff;
                  break;

            case R_V850_22_PCREL:
                  /* Maybe jump indirectly via a PLT table entry.  */
                  if ((int32_t)(val - (uint32_t)loc) > 0x1fffff
                      || (int32_t)(val - (uint32_t)loc) < -0x200000)
                        val = do_plt_call (loc, val, sechdrs, mod);

                  val -= (uint32_t)loc;

                  /* We write two shorts instead of a long because
                     even 32-bit insns only need half-word alignment,
                     but 32-bit data writes need to be long-word
                     aligned.  */
                  ((uint16_t *)loc)[0] =
                        (*(uint16_t *)loc & 0xffc0) /* opcode + reg */
                        | ((val >> 16) & 0xffc03f); /* offs high */
                  ((uint16_t *)loc)[1] =
                        (val & 0xffff);             /* offs low */
                  break;

            default:
                  printk (KERN_ERR "module %s: Unknown reloc: %u\n",
                        mod->name, ELF32_R_TYPE (rela[i].r_info));
                  return -ENOEXEC;
            }
      }

      return 0;
}

void
module_arch_cleanup(struct module *mod)
{
}

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