linux/arch/s390/kernel/module.c
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   1/*
   2 *  arch/s390/kernel/module.c - Kernel module help for s390.
   3 *
   4 *  S390 version
   5 *    Copyright (C) 2002, 2003 IBM Deutschland Entwicklung GmbH,
   6 *                             IBM Corporation
   7 *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
   8 *               Martin Schwidefsky (schwidefsky@de.ibm.com)
   9 *
  10 *  based on i386 version
  11 *    Copyright (C) 2001 Rusty Russell.
  12 *
  13 *  This program is free software; you can redistribute it and/or modify
  14 *  it under the terms of the GNU General Public License as published by
  15 *  the Free Software Foundation; either version 2 of the License, or
  16 *  (at your option) any later version.
  17 *
  18 *  This program is distributed in the hope that it will be useful,
  19 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 *  GNU General Public License for more details.
  22 *
  23 *  You should have received a copy of the GNU General Public License
  24 *  along with this program; if not, write to the Free Software
  25 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  26 */
  27#include <linux/module.h>
  28#include <linux/elf.h>
  29#include <linux/vmalloc.h>
  30#include <linux/fs.h>
  31#include <linux/string.h>
  32#include <linux/kernel.h>
  33#include <linux/moduleloader.h>
  34#include <linux/bug.h>
  35
  36#if 0
  37#define DEBUGP printk
  38#else
  39#define DEBUGP(fmt , ...)
  40#endif
  41
  42#ifndef CONFIG_64BIT
  43#define PLT_ENTRY_SIZE 12
  44#else /* CONFIG_64BIT */
  45#define PLT_ENTRY_SIZE 20
  46#endif /* CONFIG_64BIT */
  47
  48void *module_alloc(unsigned long size)
  49{
  50        if (size == 0)
  51                return NULL;
  52        return vmalloc(size);
  53}
  54
  55/* Free memory returned from module_alloc */
  56void module_free(struct module *mod, void *module_region)
  57{
  58        vfree(module_region);
  59        /* FIXME: If module_region == mod->init_region, trim exception
  60           table entries. */
  61}
  62
  63static void
  64check_rela(Elf_Rela *rela, struct module *me)
  65{
  66        struct mod_arch_syminfo *info;
  67
  68        info = me->arch.syminfo + ELF_R_SYM (rela->r_info);
  69        switch (ELF_R_TYPE (rela->r_info)) {
  70        case R_390_GOT12:       /* 12 bit GOT offset.  */
  71        case R_390_GOT16:       /* 16 bit GOT offset.  */
  72        case R_390_GOT20:       /* 20 bit GOT offset.  */
  73        case R_390_GOT32:       /* 32 bit GOT offset.  */
  74        case R_390_GOT64:       /* 64 bit GOT offset.  */
  75        case R_390_GOTENT:      /* 32 bit PC rel. to GOT entry shifted by 1. */
  76        case R_390_GOTPLT12:    /* 12 bit offset to jump slot.  */
  77        case R_390_GOTPLT16:    /* 16 bit offset to jump slot.  */
  78        case R_390_GOTPLT20:    /* 20 bit offset to jump slot.  */
  79        case R_390_GOTPLT32:    /* 32 bit offset to jump slot.  */
  80        case R_390_GOTPLT64:    /* 64 bit offset to jump slot.  */
  81        case R_390_GOTPLTENT:   /* 32 bit rel. offset to jump slot >> 1. */
  82                if (info->got_offset == -1UL) {
  83                        info->got_offset = me->arch.got_size;
  84                        me->arch.got_size += sizeof(void*);
  85                }
  86                break;
  87        case R_390_PLT16DBL:    /* 16 bit PC rel. PLT shifted by 1.  */
  88        case R_390_PLT32DBL:    /* 32 bit PC rel. PLT shifted by 1.  */
  89        case R_390_PLT32:       /* 32 bit PC relative PLT address.  */
  90        case R_390_PLT64:       /* 64 bit PC relative PLT address.  */
  91        case R_390_PLTOFF16:    /* 16 bit offset from GOT to PLT. */
  92        case R_390_PLTOFF32:    /* 32 bit offset from GOT to PLT. */
  93        case R_390_PLTOFF64:    /* 16 bit offset from GOT to PLT. */
  94                if (info->plt_offset == -1UL) {
  95                        info->plt_offset = me->arch.plt_size;
  96                        me->arch.plt_size += PLT_ENTRY_SIZE;
  97                }
  98                break;
  99        case R_390_COPY:
 100        case R_390_GLOB_DAT:
 101        case R_390_JMP_SLOT:
 102        case R_390_RELATIVE:
 103                /* Only needed if we want to support loading of 
 104                   modules linked with -shared. */
 105                break;
 106        }
 107}
 108
 109/*
 110 * Account for GOT and PLT relocations. We can't add sections for
 111 * got and plt but we can increase the core module size.
 112 */
 113int
 114module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
 115                          char *secstrings, struct module *me)
 116{
 117        Elf_Shdr *symtab;
 118        Elf_Sym *symbols;
 119        Elf_Rela *rela;
 120        char *strings;
 121        int nrela, i, j;
 122
 123        /* Find symbol table and string table. */
 124        symtab = NULL;
 125        for (i = 0; i < hdr->e_shnum; i++)
 126                switch (sechdrs[i].sh_type) {
 127                case SHT_SYMTAB:
 128                        symtab = sechdrs + i;
 129                        break;
 130                }
 131        if (!symtab) {
 132                printk(KERN_ERR "module %s: no symbol table\n", me->name);
 133                return -ENOEXEC;
 134        }
 135
 136        /* Allocate one syminfo structure per symbol. */
 137        me->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
 138        me->arch.syminfo = vmalloc(me->arch.nsyms *
 139                                   sizeof(struct mod_arch_syminfo));
 140        if (!me->arch.syminfo)
 141                return -ENOMEM;
 142        symbols = (void *) hdr + symtab->sh_offset;
 143        strings = (void *) hdr + sechdrs[symtab->sh_link].sh_offset;
 144        for (i = 0; i < me->arch.nsyms; i++) {
 145                if (symbols[i].st_shndx == SHN_UNDEF &&
 146                    strcmp(strings + symbols[i].st_name,
 147                           "_GLOBAL_OFFSET_TABLE_") == 0)
 148                        /* "Define" it as absolute. */
 149                        symbols[i].st_shndx = SHN_ABS;
 150                me->arch.syminfo[i].got_offset = -1UL;
 151                me->arch.syminfo[i].plt_offset = -1UL;
 152                me->arch.syminfo[i].got_initialized = 0;
 153                me->arch.syminfo[i].plt_initialized = 0;
 154        }
 155
 156        /* Search for got/plt relocations. */
 157        me->arch.got_size = me->arch.plt_size = 0;
 158        for (i = 0; i < hdr->e_shnum; i++) {
 159                if (sechdrs[i].sh_type != SHT_RELA)
 160                        continue;
 161                nrela = sechdrs[i].sh_size / sizeof(Elf_Rela);
 162                rela = (void *) hdr + sechdrs[i].sh_offset;
 163                for (j = 0; j < nrela; j++)
 164                        check_rela(rela + j, me);
 165        }
 166
 167        /* Increase core size by size of got & plt and set start
 168           offsets for got and plt. */
 169        me->core_size = ALIGN(me->core_size, 4);
 170        me->arch.got_offset = me->core_size;
 171        me->core_size += me->arch.got_size;
 172        me->arch.plt_offset = me->core_size;
 173        me->core_size += me->arch.plt_size;
 174        return 0;
 175}
 176
 177int
 178apply_relocate(Elf_Shdr *sechdrs, const char *strtab, unsigned int symindex,
 179               unsigned int relsec, struct module *me)
 180{
 181        printk(KERN_ERR "module %s: RELOCATION unsupported\n",
 182               me->name);
 183        return -ENOEXEC;
 184}
 185
 186static int
 187apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab, 
 188           struct module *me)
 189{
 190        struct mod_arch_syminfo *info;
 191        Elf_Addr loc, val;
 192        int r_type, r_sym;
 193
 194        /* This is where to make the change */
 195        loc = base + rela->r_offset;
 196        /* This is the symbol it is referring to.  Note that all
 197           undefined symbols have been resolved.  */
 198        r_sym = ELF_R_SYM(rela->r_info);
 199        r_type = ELF_R_TYPE(rela->r_info);
 200        info = me->arch.syminfo + r_sym;
 201        val = symtab[r_sym].st_value;
 202
 203        switch (r_type) {
 204        case R_390_8:           /* Direct 8 bit.   */
 205        case R_390_12:          /* Direct 12 bit.  */
 206        case R_390_16:          /* Direct 16 bit.  */
 207        case R_390_20:          /* Direct 20 bit.  */
 208        case R_390_32:          /* Direct 32 bit.  */
 209        case R_390_64:          /* Direct 64 bit.  */
 210                val += rela->r_addend;
 211                if (r_type == R_390_8)
 212                        *(unsigned char *) loc = val;
 213                else if (r_type == R_390_12)
 214                        *(unsigned short *) loc = (val & 0xfff) |
 215                                (*(unsigned short *) loc & 0xf000);
 216                else if (r_type == R_390_16)
 217                        *(unsigned short *) loc = val;
 218                else if (r_type == R_390_20)
 219                        *(unsigned int *) loc =
 220                                (*(unsigned int *) loc & 0xf00000ff) |
 221                                (val & 0xfff) << 16 | (val & 0xff000) >> 4;
 222                else if (r_type == R_390_32)
 223                        *(unsigned int *) loc = val;
 224                else if (r_type == R_390_64)
 225                        *(unsigned long *) loc = val;
 226                break;
 227        case R_390_PC16:        /* PC relative 16 bit.  */
 228        case R_390_PC16DBL:     /* PC relative 16 bit shifted by 1.  */
 229        case R_390_PC32DBL:     /* PC relative 32 bit shifted by 1.  */
 230        case R_390_PC32:        /* PC relative 32 bit.  */
 231        case R_390_PC64:        /* PC relative 64 bit.  */
 232                val += rela->r_addend - loc;
 233                if (r_type == R_390_PC16)
 234                        *(unsigned short *) loc = val;
 235                else if (r_type == R_390_PC16DBL)
 236                        *(unsigned short *) loc = val >> 1;
 237                else if (r_type == R_390_PC32DBL)
 238                        *(unsigned int *) loc = val >> 1;
 239                else if (r_type == R_390_PC32)
 240                        *(unsigned int *) loc = val;
 241                else if (r_type == R_390_PC64)
 242                        *(unsigned long *) loc = val;
 243                break;
 244        case R_390_GOT12:       /* 12 bit GOT offset.  */
 245        case R_390_GOT16:       /* 16 bit GOT offset.  */
 246        case R_390_GOT20:       /* 20 bit GOT offset.  */
 247        case R_390_GOT32:       /* 32 bit GOT offset.  */
 248        case R_390_GOT64:       /* 64 bit GOT offset.  */
 249        case R_390_GOTENT:      /* 32 bit PC rel. to GOT entry shifted by 1. */
 250        case R_390_GOTPLT12:    /* 12 bit offset to jump slot.  */
 251        case R_390_GOTPLT20:    /* 20 bit offset to jump slot.  */
 252        case R_390_GOTPLT16:    /* 16 bit offset to jump slot.  */
 253        case R_390_GOTPLT32:    /* 32 bit offset to jump slot.  */
 254        case R_390_GOTPLT64:    /* 64 bit offset to jump slot.  */
 255        case R_390_GOTPLTENT:   /* 32 bit rel. offset to jump slot >> 1. */
 256                if (info->got_initialized == 0) {
 257                        Elf_Addr *gotent;
 258
 259                        gotent = me->module_core + me->arch.got_offset +
 260                                info->got_offset;
 261                        *gotent = val;
 262                        info->got_initialized = 1;
 263                }
 264                val = info->got_offset + rela->r_addend;
 265                if (r_type == R_390_GOT12 ||
 266                    r_type == R_390_GOTPLT12)
 267                        *(unsigned short *) loc = (val & 0xfff) |
 268                                (*(unsigned short *) loc & 0xf000);
 269                else if (r_type == R_390_GOT16 ||
 270                         r_type == R_390_GOTPLT16)
 271                        *(unsigned short *) loc = val;
 272                else if (r_type == R_390_GOT20 ||
 273                         r_type == R_390_GOTPLT20)
 274                        *(unsigned int *) loc =
 275                                (*(unsigned int *) loc & 0xf00000ff) |
 276                                (val & 0xfff) << 16 | (val & 0xff000) >> 4;
 277                else if (r_type == R_390_GOT32 ||
 278                         r_type == R_390_GOTPLT32)
 279                        *(unsigned int *) loc = val;
 280                else if (r_type == R_390_GOTENT ||
 281                         r_type == R_390_GOTPLTENT)
 282                        *(unsigned int *) loc =
 283                                (val + (Elf_Addr) me->module_core - loc) >> 1;
 284                else if (r_type == R_390_GOT64 ||
 285                         r_type == R_390_GOTPLT64)
 286                        *(unsigned long *) loc = val;
 287                break;
 288        case R_390_PLT16DBL:    /* 16 bit PC rel. PLT shifted by 1.  */
 289        case R_390_PLT32DBL:    /* 32 bit PC rel. PLT shifted by 1.  */
 290        case R_390_PLT32:       /* 32 bit PC relative PLT address.  */
 291        case R_390_PLT64:       /* 64 bit PC relative PLT address.  */
 292        case R_390_PLTOFF16:    /* 16 bit offset from GOT to PLT. */
 293        case R_390_PLTOFF32:    /* 32 bit offset from GOT to PLT. */
 294        case R_390_PLTOFF64:    /* 16 bit offset from GOT to PLT. */
 295                if (info->plt_initialized == 0) {
 296                        unsigned int *ip;
 297                        ip = me->module_core + me->arch.plt_offset +
 298                                info->plt_offset;
 299#ifndef CONFIG_64BIT
 300                        ip[0] = 0x0d105810; /* basr 1,0; l 1,6(1); br 1 */
 301                        ip[1] = 0x100607f1;
 302                        ip[2] = val;
 303#else /* CONFIG_64BIT */
 304                        ip[0] = 0x0d10e310; /* basr 1,0; lg 1,10(1); br 1 */
 305                        ip[1] = 0x100a0004;
 306                        ip[2] = 0x07f10000;
 307                        ip[3] = (unsigned int) (val >> 32);
 308                        ip[4] = (unsigned int) val;
 309#endif /* CONFIG_64BIT */
 310                        info->plt_initialized = 1;
 311                }
 312                if (r_type == R_390_PLTOFF16 ||
 313                    r_type == R_390_PLTOFF32
 314                    || r_type == R_390_PLTOFF64
 315                        )
 316                        val = me->arch.plt_offset - me->arch.got_offset +
 317                                info->plt_offset + rela->r_addend;
 318                else
 319                        val =  (Elf_Addr) me->module_core +
 320                                me->arch.plt_offset + info->plt_offset + 
 321                                rela->r_addend - loc;
 322                if (r_type == R_390_PLT16DBL)
 323                        *(unsigned short *) loc = val >> 1;
 324                else if (r_type == R_390_PLTOFF16)
 325                        *(unsigned short *) loc = val;
 326                else if (r_type == R_390_PLT32DBL)
 327                        *(unsigned int *) loc = val >> 1;
 328                else if (r_type == R_390_PLT32 ||
 329                         r_type == R_390_PLTOFF32)
 330                        *(unsigned int *) loc = val;
 331                else if (r_type == R_390_PLT64 ||
 332                         r_type == R_390_PLTOFF64)
 333                        *(unsigned long *) loc = val;
 334                break;
 335        case R_390_GOTOFF16:    /* 16 bit offset to GOT.  */
 336        case R_390_GOTOFF32:    /* 32 bit offset to GOT.  */
 337        case R_390_GOTOFF64:    /* 64 bit offset to GOT. */
 338                val = val + rela->r_addend -
 339                        ((Elf_Addr) me->module_core + me->arch.got_offset);
 340                if (r_type == R_390_GOTOFF16)
 341                        *(unsigned short *) loc = val;
 342                else if (r_type == R_390_GOTOFF32)
 343                        *(unsigned int *) loc = val;
 344                else if (r_type == R_390_GOTOFF64)
 345                        *(unsigned long *) loc = val;
 346                break;
 347        case R_390_GOTPC:       /* 32 bit PC relative offset to GOT. */
 348        case R_390_GOTPCDBL:    /* 32 bit PC rel. off. to GOT shifted by 1. */
 349                val = (Elf_Addr) me->module_core + me->arch.got_offset +
 350                        rela->r_addend - loc;
 351                if (r_type == R_390_GOTPC)
 352                        *(unsigned int *) loc = val;
 353                else if (r_type == R_390_GOTPCDBL)
 354                        *(unsigned int *) loc = val >> 1;
 355                break;
 356        case R_390_COPY:
 357        case R_390_GLOB_DAT:    /* Create GOT entry.  */
 358        case R_390_JMP_SLOT:    /* Create PLT entry.  */
 359        case R_390_RELATIVE:    /* Adjust by program base.  */
 360                /* Only needed if we want to support loading of 
 361                   modules linked with -shared. */
 362                break;
 363        default:
 364                printk(KERN_ERR "module %s: Unknown relocation: %u\n",
 365                       me->name, r_type);
 366                return -ENOEXEC;
 367        }
 368        return 0;
 369}
 370
 371int
 372apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
 373                   unsigned int symindex, unsigned int relsec,
 374                   struct module *me)
 375{
 376        Elf_Addr base;
 377        Elf_Sym *symtab;
 378        Elf_Rela *rela;
 379        unsigned long i, n;
 380        int rc;
 381
 382        DEBUGP("Applying relocate section %u to %u\n",
 383               relsec, sechdrs[relsec].sh_info);
 384        base = sechdrs[sechdrs[relsec].sh_info].sh_addr;
 385        symtab = (Elf_Sym *) sechdrs[symindex].sh_addr;
 386        rela = (Elf_Rela *) sechdrs[relsec].sh_addr;
 387        n = sechdrs[relsec].sh_size / sizeof(Elf_Rela);
 388
 389        for (i = 0; i < n; i++, rela++) {
 390                rc = apply_rela(rela, base, symtab, me);
 391                if (rc)
 392                        return rc;
 393        }
 394        return 0;
 395}
 396
 397int module_finalize(const Elf_Ehdr *hdr,
 398                    const Elf_Shdr *sechdrs,
 399                    struct module *me)
 400{
 401        vfree(me->arch.syminfo);
 402        return module_bug_finalize(hdr, sechdrs, me);
 403}
 404
 405void module_arch_cleanup(struct module *mod)
 406{
 407        module_bug_cleanup(mod);
 408}
 409