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module.c

/*
 *  arch/s390/kernel/module.c - Kernel module help for s390.
 *
 *  S390 version
 *    Copyright (C) 2002, 2003 IBM Deutschland Entwicklung GmbH,
 *                       IBM Corporation
 *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
 *           Martin Schwidefsky (schwidefsky@de.ibm.com)
 *
 *  based on i386 version
 *    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/module.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/moduleloader.h>
#include <linux/bug.h>

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

#ifndef CONFIG_64BIT
#define PLT_ENTRY_SIZE 12
#else /* CONFIG_64BIT */
#define PLT_ENTRY_SIZE 20
#endif /* CONFIG_64BIT */

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

static void
check_rela(Elf_Rela *rela, struct module *me)
{
      struct mod_arch_syminfo *info;

      info = me->arch.syminfo + ELF_R_SYM (rela->r_info);
      switch (ELF_R_TYPE (rela->r_info)) {
      case R_390_GOT12: /* 12 bit GOT offset.  */
      case R_390_GOT16: /* 16 bit GOT offset.  */
      case R_390_GOT20: /* 20 bit GOT offset.  */
      case R_390_GOT32: /* 32 bit GOT offset.  */
      case R_390_GOT64: /* 64 bit GOT offset.  */
      case R_390_GOTENT:      /* 32 bit PC rel. to GOT entry shifted by 1. */
      case R_390_GOTPLT12:    /* 12 bit offset to jump slot.      */
      case R_390_GOTPLT16:    /* 16 bit offset to jump slot.  */
      case R_390_GOTPLT20:    /* 20 bit offset to jump slot.  */
      case R_390_GOTPLT32:    /* 32 bit offset to jump slot.  */
      case R_390_GOTPLT64:    /* 64 bit offset to jump slot.      */
      case R_390_GOTPLTENT:   /* 32 bit rel. offset to jump slot >> 1. */
            if (info->got_offset == -1UL) {
                  info->got_offset = me->arch.got_size;
                  me->arch.got_size += sizeof(void*);
            }
            break;
      case R_390_PLT16DBL:    /* 16 bit PC rel. PLT shifted by 1.  */
      case R_390_PLT32DBL:    /* 32 bit PC rel. PLT shifted by 1.  */
      case R_390_PLT32: /* 32 bit PC relative PLT address.  */
      case R_390_PLT64: /* 64 bit PC relative PLT address.  */
      case R_390_PLTOFF16:    /* 16 bit offset from GOT to PLT. */
      case R_390_PLTOFF32:    /* 32 bit offset from GOT to PLT. */
      case R_390_PLTOFF64:    /* 16 bit offset from GOT to PLT. */
            if (info->plt_offset == -1UL) {
                  info->plt_offset = me->arch.plt_size;
                  me->arch.plt_size += PLT_ENTRY_SIZE;
            }
            break;
      case R_390_COPY:
      case R_390_GLOB_DAT:
      case R_390_JMP_SLOT:
      case R_390_RELATIVE:
            /* Only needed if we want to support loading of 
               modules linked with -shared. */
            break;
      }
}

/*
 * Account for GOT and PLT relocations. We can't add sections for
 * got and plt but we can increase the core module size.
 */
int
module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
                    char *secstrings, struct module *me)
{
      Elf_Shdr *symtab;
      Elf_Sym *symbols;
      Elf_Rela *rela;
      char *strings;
      int nrela, i, j;

      /* Find symbol table and string table. */
      symtab = NULL;
      for (i = 0; i < hdr->e_shnum; i++)
            switch (sechdrs[i].sh_type) {
            case SHT_SYMTAB:
                  symtab = sechdrs + i;
                  break;
            }
      if (!symtab) {
            printk(KERN_ERR "module %s: no symbol table\n", me->name);
            return -ENOEXEC;
      }

      /* Allocate one syminfo structure per symbol. */
      me->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
      me->arch.syminfo = vmalloc(me->arch.nsyms *
                           sizeof(struct mod_arch_syminfo));
      if (!me->arch.syminfo)
            return -ENOMEM;
      symbols = (void *) hdr + symtab->sh_offset;
      strings = (void *) hdr + sechdrs[symtab->sh_link].sh_offset;
      for (i = 0; i < me->arch.nsyms; i++) {
            if (symbols[i].st_shndx == SHN_UNDEF &&
                strcmp(strings + symbols[i].st_name,
                     "_GLOBAL_OFFSET_TABLE_") == 0)
                  /* "Define" it as absolute. */
                  symbols[i].st_shndx = SHN_ABS;
            me->arch.syminfo[i].got_offset = -1UL;
            me->arch.syminfo[i].plt_offset = -1UL;
            me->arch.syminfo[i].got_initialized = 0;
            me->arch.syminfo[i].plt_initialized = 0;
      }

      /* Search for got/plt relocations. */
      me->arch.got_size = me->arch.plt_size = 0;
      for (i = 0; i < hdr->e_shnum; i++) {
            if (sechdrs[i].sh_type != SHT_RELA)
                  continue;
            nrela = sechdrs[i].sh_size / sizeof(Elf_Rela);
            rela = (void *) hdr + sechdrs[i].sh_offset;
            for (j = 0; j < nrela; j++)
                  check_rela(rela + j, me);
      }

      /* Increase core size by size of got & plt and set start
         offsets for got and plt. */
      me->core_size = ALIGN(me->core_size, 4);
      me->arch.got_offset = me->core_size;
      me->core_size += me->arch.got_size;
      me->arch.plt_offset = me->core_size;
      me->core_size += me->arch.plt_size;
      return 0;
}

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

static int
apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, 
         struct module *me)
{
      struct mod_arch_syminfo *info;
      Elf_Addr loc, val;
      int r_type, r_sym;

      /* This is where to make the change */
      loc = base + rela->r_offset;
      /* This is the symbol it is referring to.  Note that all
         undefined symbols have been resolved.  */
      r_sym = ELF_R_SYM(rela->r_info);
      r_type = ELF_R_TYPE(rela->r_info);
      info = me->arch.syminfo + r_sym;
      val = symtab[r_sym].st_value;

      switch (r_type) {
      case R_390_8:           /* Direct 8 bit.   */
      case R_390_12:          /* Direct 12 bit.  */
      case R_390_16:          /* Direct 16 bit.  */
      case R_390_20:          /* Direct 20 bit.  */
      case R_390_32:          /* Direct 32 bit.  */
      case R_390_64:          /* Direct 64 bit.  */
            val += rela->r_addend;
            if (r_type == R_390_8)
                  *(unsigned char *) loc = val;
            else if (r_type == R_390_12)
                  *(unsigned short *) loc = (val & 0xfff) |
                        (*(unsigned short *) loc & 0xf000);
            else if (r_type == R_390_16)
                  *(unsigned short *) loc = val;
            else if (r_type == R_390_20)
                  *(unsigned int *) loc =
                        (*(unsigned int *) loc & 0xf00000ff) |
                        (val & 0xfff) << 16 | (val & 0xff000) >> 4;
            else if (r_type == R_390_32)
                  *(unsigned int *) loc = val;
            else if (r_type == R_390_64)
                  *(unsigned long *) loc = val;
            break;
      case R_390_PC16:  /* PC relative 16 bit.  */
      case R_390_PC16DBL:     /* PC relative 16 bit shifted by 1.  */
      case R_390_PC32DBL:     /* PC relative 32 bit shifted by 1.  */
      case R_390_PC32:  /* PC relative 32 bit.  */
      case R_390_PC64:  /* PC relative 64 bit.  */
            val += rela->r_addend - loc;
            if (r_type == R_390_PC16)
                  *(unsigned short *) loc = val;
            else if (r_type == R_390_PC16DBL)
                  *(unsigned short *) loc = val >> 1;
            else if (r_type == R_390_PC32DBL)
                  *(unsigned int *) loc = val >> 1;
            else if (r_type == R_390_PC32)
                  *(unsigned int *) loc = val;
            else if (r_type == R_390_PC64)
                  *(unsigned long *) loc = val;
            break;
      case R_390_GOT12: /* 12 bit GOT offset.  */
      case R_390_GOT16: /* 16 bit GOT offset.  */
      case R_390_GOT20: /* 20 bit GOT offset.  */
      case R_390_GOT32: /* 32 bit GOT offset.  */
      case R_390_GOT64: /* 64 bit GOT offset.  */
      case R_390_GOTENT:      /* 32 bit PC rel. to GOT entry shifted by 1. */
      case R_390_GOTPLT12:    /* 12 bit offset to jump slot.      */
      case R_390_GOTPLT20:    /* 20 bit offset to jump slot.  */
      case R_390_GOTPLT16:    /* 16 bit offset to jump slot.  */
      case R_390_GOTPLT32:    /* 32 bit offset to jump slot.  */
      case R_390_GOTPLT64:    /* 64 bit offset to jump slot.      */
      case R_390_GOTPLTENT:   /* 32 bit rel. offset to jump slot >> 1. */
            if (info->got_initialized == 0) {
                  Elf_Addr *gotent;

                  gotent = me->module_core + me->arch.got_offset +
                        info->got_offset;
                  *gotent = val;
                  info->got_initialized = 1;
            }
            val = info->got_offset + rela->r_addend;
            if (r_type == R_390_GOT12 ||
                r_type == R_390_GOTPLT12)
                  *(unsigned short *) loc = (val & 0xfff) |
                        (*(unsigned short *) loc & 0xf000);
            else if (r_type == R_390_GOT16 ||
                   r_type == R_390_GOTPLT16)
                  *(unsigned short *) loc = val;
            else if (r_type == R_390_GOT20 ||
                   r_type == R_390_GOTPLT20)
                  *(unsigned int *) loc =
                        (*(unsigned int *) loc & 0xf00000ff) |
                        (val & 0xfff) << 16 | (val & 0xff000) >> 4;
            else if (r_type == R_390_GOT32 ||
                   r_type == R_390_GOTPLT32)
                  *(unsigned int *) loc = val;
            else if (r_type == R_390_GOTENT ||
                   r_type == R_390_GOTPLTENT)
                  *(unsigned int *) loc =
                        (val + (Elf_Addr) me->module_core - loc) >> 1;
            else if (r_type == R_390_GOT64 ||
                   r_type == R_390_GOTPLT64)
                  *(unsigned long *) loc = val;
            break;
      case R_390_PLT16DBL:    /* 16 bit PC rel. PLT shifted by 1.  */
      case R_390_PLT32DBL:    /* 32 bit PC rel. PLT shifted by 1.  */
      case R_390_PLT32: /* 32 bit PC relative PLT address.  */
      case R_390_PLT64: /* 64 bit PC relative PLT address.  */
      case R_390_PLTOFF16:    /* 16 bit offset from GOT to PLT. */
      case R_390_PLTOFF32:    /* 32 bit offset from GOT to PLT. */
      case R_390_PLTOFF64:    /* 16 bit offset from GOT to PLT. */
            if (info->plt_initialized == 0) {
                  unsigned int *ip;
                  ip = me->module_core + me->arch.plt_offset +
                        info->plt_offset;
#ifndef CONFIG_64BIT
                  ip[0] = 0x0d105810; /* basr 1,0; l 1,6(1); br 1 */
                  ip[1] = 0x100607f1;
                  ip[2] = val;
#else /* CONFIG_64BIT */
                  ip[0] = 0x0d10e310; /* basr 1,0; lg 1,10(1); br 1 */
                  ip[1] = 0x100a0004;
                  ip[2] = 0x07f10000;
                  ip[3] = (unsigned int) (val >> 32);
                  ip[4] = (unsigned int) val;
#endif /* CONFIG_64BIT */
                  info->plt_initialized = 1;
            }
            if (r_type == R_390_PLTOFF16 ||
                r_type == R_390_PLTOFF32
                || r_type == R_390_PLTOFF64
                  )
                  val = me->arch.plt_offset - me->arch.got_offset +
                        info->plt_offset + rela->r_addend;
            else
                  val =  (Elf_Addr) me->module_core +
                        me->arch.plt_offset + info->plt_offset + 
                        rela->r_addend - loc;
            if (r_type == R_390_PLT16DBL)
                  *(unsigned short *) loc = val >> 1;
            else if (r_type == R_390_PLTOFF16)
                  *(unsigned short *) loc = val;
            else if (r_type == R_390_PLT32DBL)
                  *(unsigned int *) loc = val >> 1;
            else if (r_type == R_390_PLT32 ||
                   r_type == R_390_PLTOFF32)
                  *(unsigned int *) loc = val;
            else if (r_type == R_390_PLT64 ||
                   r_type == R_390_PLTOFF64)
                  *(unsigned long *) loc = val;
            break;
      case R_390_GOTOFF16:    /* 16 bit offset to GOT.  */
      case R_390_GOTOFF32:    /* 32 bit offset to GOT.  */
      case R_390_GOTOFF64:    /* 64 bit offset to GOT. */
            val = val + rela->r_addend -
                  ((Elf_Addr) me->module_core + me->arch.got_offset);
            if (r_type == R_390_GOTOFF16)
                  *(unsigned short *) loc = val;
            else if (r_type == R_390_GOTOFF32)
                  *(unsigned int *) loc = val;
            else if (r_type == R_390_GOTOFF64)
                  *(unsigned long *) loc = val;
            break;
      case R_390_GOTPC: /* 32 bit PC relative offset to GOT. */
      case R_390_GOTPCDBL:    /* 32 bit PC rel. off. to GOT shifted by 1. */
            val = (Elf_Addr) me->module_core + me->arch.got_offset +
                  rela->r_addend - loc;
            if (r_type == R_390_GOTPC)
                  *(unsigned int *) loc = val;
            else if (r_type == R_390_GOTPCDBL)
                  *(unsigned int *) loc = val >> 1;
            break;
      case R_390_COPY:
      case R_390_GLOB_DAT:    /* Create GOT entry.  */
      case R_390_JMP_SLOT:    /* Create PLT entry.  */
      case R_390_RELATIVE:    /* Adjust by program base.  */
            /* Only needed if we want to support loading of 
               modules linked with -shared. */
            break;
      default:
            printk(KERN_ERR "module %s: Unknown relocation: %u\n",
                   me->name, r_type);
            return -ENOEXEC;
      }
      return 0;
}

int
apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
               unsigned int symindex, unsigned int relsec,
               struct module *me)
{
      Elf_Addr base;
      Elf_Sym *symtab;
      Elf_Rela *rela;
      unsigned long i, n;
      int rc;

      DEBUGP("Applying relocate section %u to %u\n",
             relsec, sechdrs[relsec].sh_info);
      base = sechdrs[sechdrs[relsec].sh_info].sh_addr;
      symtab = (Elf_Sym *) sechdrs[symindex].sh_addr;
      rela = (Elf_Rela *) sechdrs[relsec].sh_addr;
      n = sechdrs[relsec].sh_size / sizeof(Elf_Rela);

      for (i = 0; i < n; i++, rela++) {
            rc = apply_rela(rela, base, symtab, me);
            if (rc)
                  return rc;
      }
      return 0;
}

int module_finalize(const Elf_Ehdr *hdr,
                const Elf_Shdr *sechdrs,
                struct module *me)
{
      vfree(me->arch.syminfo);
      return module_bug_finalize(hdr, sechdrs, me);
}

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

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