Logo Search packages:      
Sourcecode: linux-2.6 version File versions  Download package

module.c

/*  Kernel module help for Alpha.
    Copyright (C) 2002 Richard Henderson.

    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/slab.h>

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

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

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

/* Allocate the GOT at the end of the core sections.  */

struct got_entry {
      struct got_entry *next;
      Elf64_Sxword r_addend;
      int got_offset;
};

static inline void
process_reloc_for_got(Elf64_Rela *rela,
                  struct got_entry *chains, Elf64_Xword *poffset)
{
      unsigned long r_sym = ELF64_R_SYM (rela->r_info);
      unsigned long r_type = ELF64_R_TYPE (rela->r_info);
      Elf64_Sxword r_addend = rela->r_addend;
      struct got_entry *g;

      if (r_type != R_ALPHA_LITERAL)
            return;

      for (g = chains + r_sym; g ; g = g->next)
            if (g->r_addend == r_addend) {
                  if (g->got_offset == 0) {
                        g->got_offset = *poffset;
                        *poffset += 8;
                  }
                  goto found_entry;
            }

      g = kmalloc (sizeof (*g), GFP_KERNEL);
      g->next = chains[r_sym].next;
      g->r_addend = r_addend;
      g->got_offset = *poffset;
      *poffset += 8;
      chains[r_sym].next = g;

 found_entry:
      /* Trick: most of the ELF64_R_TYPE field is unused.  There are
         42 valid relocation types, and a 32-bit field.  Co-opt the
         bits above 256 to store the got offset for this reloc.  */
      rela->r_info |= g->got_offset << 8;
}

int
module_frob_arch_sections(Elf64_Ehdr *hdr, Elf64_Shdr *sechdrs,
                    char *secstrings, struct module *me)
{
      struct got_entry *chains;
      Elf64_Rela *rela;
      Elf64_Shdr *esechdrs, *symtab, *s, *got;
      unsigned long nsyms, nrela, i;

      esechdrs = sechdrs + hdr->e_shnum;
      symtab = got = NULL;

      /* Find out how large the symbol table is.  Allocate one got_entry
         head per symbol.  Normally this will be enough, but not always.
         We'll chain different offsets for the symbol down each head.  */
      for (s = sechdrs; s < esechdrs; ++s)
            if (s->sh_type == SHT_SYMTAB)
                  symtab = s;
            else if (!strcmp(".got", secstrings + s->sh_name)) {
                  got = s;
                  me->arch.gotsecindex = s - sechdrs;
            }

      if (!symtab) {
            printk(KERN_ERR "module %s: no symbol table\n", me->name);
            return -ENOEXEC;
      }
      if (!got) {
            printk(KERN_ERR "module %s: no got section\n", me->name);
            return -ENOEXEC;
      }

      nsyms = symtab->sh_size / sizeof(Elf64_Sym);
      chains = kcalloc(nsyms, sizeof(struct got_entry), GFP_KERNEL);
      if (!chains) {
            printk(KERN_ERR
                   "module %s: no memory for symbol chain buffer\n",
                   me->name);
            return -ENOMEM;
      }

      got->sh_size = 0;
      got->sh_addralign = 8;
      got->sh_type = SHT_NOBITS;

      /* Examine all LITERAL relocations to find out what GOT entries
         are required.  This sizes the GOT section as well.  */
      for (s = sechdrs; s < esechdrs; ++s)
            if (s->sh_type == SHT_RELA) {
                  nrela = s->sh_size / sizeof(Elf64_Rela);
                  rela = (void *)hdr + s->sh_offset;
                  for (i = 0; i < nrela; ++i)
                        process_reloc_for_got(rela+i, chains,
                                          &got->sh_size);
            }

      /* Free the memory we allocated.  */
      for (i = 0; i < nsyms; ++i) {
            struct got_entry *g, *n;
            for (g = chains[i].next; g ; g = n) {
                  n = g->next;
                  kfree(g);
            }
      }
      kfree(chains);

      return 0;
}

int
apply_relocate(Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex,
             unsigned int relsec, struct module *me)
{
      printk(KERN_ERR "module %s: REL relocation unsupported\n", me->name);
      return -ENOEXEC;
}

int
apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab,
               unsigned int symindex, unsigned int relsec,
               struct module *me)
{
      Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
      unsigned long i, n = sechdrs[relsec].sh_size / sizeof(*rela);
      Elf64_Sym *symtab, *sym;
      void *base, *location;
      unsigned long got, gp;

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

      base = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr;
      symtab = (Elf64_Sym *)sechdrs[symindex].sh_addr;

      /* The small sections were sorted to the end of the segment.
         The following should definitely cover them.  */
      gp = (u64)me->module_core + me->core_size - 0x8000;
      got = sechdrs[me->arch.gotsecindex].sh_addr;

      for (i = 0; i < n; i++) {
            unsigned long r_sym = ELF64_R_SYM (rela[i].r_info);
            unsigned long r_type = ELF64_R_TYPE (rela[i].r_info);
            unsigned long r_got_offset = r_type >> 8;
            unsigned long value, hi, lo;
            r_type &= 0xff;

            /* This is where to make the change.  */
            location = base + rela[i].r_offset;

            /* This is the symbol it is referring to.  Note that all
               unresolved symbols have been resolved.  */
            sym = symtab + r_sym;
            value = sym->st_value + rela[i].r_addend;

            switch (r_type) {
            case R_ALPHA_NONE:
                  break;
            case R_ALPHA_REFQUAD:
                  /* BUG() can produce misaligned relocations. */
                  ((u32 *)location)[0] = value;
                  ((u32 *)location)[1] = value >> 32;
                  break;
            case R_ALPHA_GPREL32:
                  value -= gp;
                  if ((int)value != value)
                        goto reloc_overflow;
                  *(u32 *)location = value;
                  break;
            case R_ALPHA_LITERAL:
                  hi = got + r_got_offset;
                  lo = hi - gp;
                  if ((short)lo != lo)
                        goto reloc_overflow;
                  *(u16 *)location = lo;
                  *(u64 *)hi = value;
                  break;
            case R_ALPHA_LITUSE:
                  break;
            case R_ALPHA_GPDISP:
                  value = gp - (u64)location;
                  lo = (short)value;
                  hi = (int)(value - lo);
                  if (hi + lo != value)
                        goto reloc_overflow;
                  *(u16 *)location = hi >> 16;
                  *(u16 *)(location + rela[i].r_addend) = lo;
                  break;
            case R_ALPHA_BRSGP:
                  /* BRSGP is only allowed to bind to local symbols.
                     If the section is undef, this means that the
                     value was resolved from somewhere else.  */
                  if (sym->st_shndx == SHN_UNDEF)
                        goto reloc_overflow;
                  if ((sym->st_other & STO_ALPHA_STD_GPLOAD) ==
                      STO_ALPHA_STD_GPLOAD)
                        /* Omit the prologue. */
                        value += 8;
                  /* FALLTHRU */
            case R_ALPHA_BRADDR:
                  value -= (u64)location + 4;
                  if (value & 3)
                        goto reloc_overflow;
                  value = (long)value >> 2;
                  if (value + (1<<21) >= 1<<22)
                        goto reloc_overflow;
                  value &= 0x1fffff;
                  value |= *(u32 *)location & ~0x1fffff;
                  *(u32 *)location = value;
                  break;
            case R_ALPHA_HINT:
                  break;
            case R_ALPHA_SREL32:
                  value -= (u64)location;
                  if ((int)value != value)
                        goto reloc_overflow;
                  *(u32 *)location = value;
                  break;
            case R_ALPHA_SREL64:
                  value -= (u64)location;
                  *(u64 *)location = value;
                  break;
            case R_ALPHA_GPRELHIGH:
                  value = (long)(value - gp + 0x8000) >> 16;
                  if ((short) value != value)
                        goto reloc_overflow;
                  *(u16 *)location = value;
                  break;
            case R_ALPHA_GPRELLOW:
                  value -= gp;
                  *(u16 *)location = value;
                  break;
            case R_ALPHA_GPREL16:
                  value -= gp;
                  if ((short) value != value)
                        goto reloc_overflow;
                  *(u16 *)location = value;
                  break;
            default:
                  printk(KERN_ERR "module %s: Unknown relocation: %lu\n",
                         me->name, r_type);
                  return -ENOEXEC;
            reloc_overflow:
                  if (ELF64_ST_TYPE (sym->st_info) == STT_SECTION)
                    printk(KERN_ERR
                           "module %s: Relocation (type %lu) overflow vs section %d\n",
                           me->name, r_type, sym->st_shndx);
                  else
                    printk(KERN_ERR
                           "module %s: Relocation (type %lu) overflow vs %s\n",
                           me->name, r_type, strtab + sym->st_name);
                  return -ENOEXEC;
            }
      }

      return 0;
}

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

void
module_arch_cleanup(struct module *mod)
{
}

Generated by  Doxygen 1.6.0   Back to index