libexec/rtld-elf/arm/reloc.c

   1 /*      $NetBSD: mdreloc.c,v 1.23 2003/07/26 15:04:38 mrg Exp $ */
   2
   3 #include <sys/cdefs.h>
   4 __FBSDID("$FreeBSD$");
   5 #include <sys/param.h>
   6 #include <sys/mman.h>
   7
   8 #include <errno.h>
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <unistd.h>
  13 #include "debug.h"
  14 #include "rtld.h"
  15
  16 void
  17 init_pltgot(Obj_Entry *obj)
  18 {
  19         if (obj->pltgot != NULL) {
  20                 obj->pltgot[1] = (Elf_Addr) obj;
  21                 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
  22         }
  23 }
  24
  25 int
  26 do_copy_relocations(Obj_Entry *dstobj)
  27 {
  28         const Elf_Rel *rellim;
  29         const Elf_Rel *rel;
  30
  31         assert(dstobj->mainprog);       /* COPY relocations are invalid elsewhere */
  32
  33         rellim = (const Elf_Rel *) ((caddr_t) dstobj->rel + dstobj->relsize);
  34         for (rel = dstobj->rel;  rel < rellim;  rel++) {
  35                 if (ELF_R_TYPE(rel->r_info) == R_ARM_COPY) {
  36                         void *dstaddr;
  37                         const Elf_Sym *dstsym;
  38                         const char *name;
  39                         unsigned long hash;
  40                         size_t size;
  41                         const void *srcaddr;
  42                         const Elf_Sym *srcsym;
  43                         Obj_Entry *srcobj;
  44
  45                         dstaddr = (void *) (dstobj->relocbase + rel->r_offset);
  46                         dstsym = dstobj->symtab + ELF_R_SYM(rel->r_info);
  47                         name = dstobj->strtab + dstsym->st_name;
  48                         hash = elf_hash(name);
  49                         size = dstsym->st_size;
  50
  51                         for (srcobj = dstobj->next;  srcobj != NULL;  srcobj = srcobj->next)
  52                                 if ((srcsym = symlook_obj(name, hash, srcobj, false)) != NULL)
  53                                         break;
  54
  55                         if (srcobj == NULL) {
  56                                 _rtld_error("Undefined symbol \"%s\" referenced from COPY"
  57                                     " relocation in %s", name, dstobj->path);
  58                                 return -1;
  59                         }
  60
  61                         srcaddr = (const void *) (srcobj->relocbase + srcsym->st_value);
  62                         memcpy(dstaddr, srcaddr, size);
  63                 }
  64         }
  65         return 0;
  66 }
  67
  68 void _rtld_bind_start(void);
  69 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
  70
  71 int open();
  72 int _open();
  73 void
  74 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
  75 {
  76         const Elf_Rel *rel = 0, *rellim;
  77         Elf_Addr relsz = 0;
  78         Elf_Addr *where;
  79         uint32_t size;
  80
  81         for (; dynp->d_tag != DT_NULL; dynp++) {
  82                 switch (dynp->d_tag) {
  83                 case DT_REL:
  84                         rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr);
  85                         break;
  86                 case DT_RELSZ:
  87                         relsz = dynp->d_un.d_val;
  88                         break;
  89                 }
  90         }
  91         rellim = (const Elf_Rel *)((caddr_t)rel + relsz);
  92         size = (rellim - 1)->r_offset - rel->r_offset;
  93         for (; rel < rellim; rel++) {
  94                 where = (Elf_Addr *)(relocbase + rel->r_offset);
  95
  96                 *where += (Elf_Addr)relocbase;
  97         }
  98 }
  99 /*
 100  * It is possible for the compiler to emit relocations for unaligned data.
 101  * We handle this situation with these inlines.
 102  */
 103 #define RELOC_ALIGNED_P(x) \
 104         (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0)
 105
 106 static __inline Elf_Addr
 107 load_ptr(void *where)
 108 {
 109         Elf_Addr res;
 110
 111         memcpy(&res, where, sizeof(res));
 112
 113         return (res);
 114 }
 115
 116 static __inline void
 117 store_ptr(void *where, Elf_Addr val)
 118 {
 119
 120         memcpy(where, &val, sizeof(val));
 121 }
 122
 123 static int
 124 reloc_nonplt_object(Obj_Entry *obj, const Elf_Rel *rel, SymCache *cache)
 125 {
 126         Elf_Addr        *where;
 127         const Elf_Sym   *def;
 128         const Obj_Entry *defobj;
 129         Elf_Addr         tmp;
 130         unsigned long    symnum;
 131
 132         where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
 133         symnum = ELF_R_SYM(rel->r_info);
 134
 135         switch (ELF_R_TYPE(rel->r_info)) {
 136         case R_ARM_NONE:
 137                 break;
 138
 139 #if 1 /* XXX should not occur */
 140         case R_ARM_PC24: {      /* word32 S - P + A */
 141                 Elf32_Sword addend;
 142
 143                 /*
 144                  * Extract addend and sign-extend if needed.
 145                  */
 146                 addend = *where;
 147                 if (addend & 0x00800000)
 148                         addend |= 0xff000000;
 149
 150                 def = find_symdef(symnum, obj, &defobj, false, cache);
 151                 if (def == NULL)
 152                                 return -1;
 153                         tmp = (Elf_Addr)obj->relocbase + def->st_value
 154                             - (Elf_Addr)where + (addend << 2);
 155                         if ((tmp & 0xfe000000) != 0xfe000000 &&
 156                             (tmp & 0xfe000000) != 0) {
 157                                 _rtld_error(
 158                                 "%s: R_ARM_PC24 relocation @ %p to %s failed "
 159                                 "(displacement %ld (%#lx) out of range)",
 160                                     obj->path, where,
 161                                     obj->strtab + obj->symtab[symnum].st_name,
 162                                     (long) tmp, (long) tmp);
 163                                 return -1;
 164                         }
 165                         tmp >>= 2;
 166                         *where = (*where & 0xff000000) | (tmp & 0x00ffffff);
 167                         dbg("PC24 %s in %s --> %p @ %p in %s",
 168                             obj->strtab + obj->symtab[symnum].st_name,
 169                             obj->path, (void *)*where, where, defobj->path);
 170                         break;
 171                 }
 172 #endif
 173
 174                 case R_ARM_ABS32:       /* word32 B + S + A */
 175                 case R_ARM_GLOB_DAT:    /* word32 B + S */
 176                         def = find_symdef(symnum, obj, &defobj, false, cache);
 177                         if (def == NULL)
 178                                 return -1;
 179                         if (__predict_true(RELOC_ALIGNED_P(where))) {
 180                                 tmp =  *where + (Elf_Addr)defobj->relocbase +
 181                                     def->st_value;
 182                                 *where = tmp;
 183                         } else {
 184                                 tmp = load_ptr(where) +
 185                                     (Elf_Addr)defobj->relocbase +
 186                                     def->st_value;
 187                                 store_ptr(where, tmp);
 188                         }
 189                         dbg("ABS32/GLOB_DAT %s in %s --> %p @ %p in %s",
 190                             obj->strtab + obj->symtab[symnum].st_name,
 191                             obj->path, (void *)tmp, where, defobj->path);
 192                         break;
 193
 194                 case R_ARM_RELATIVE:    /* word32 B + A */
 195                         if (__predict_true(RELOC_ALIGNED_P(where))) {
 196                                 tmp = *where + (Elf_Addr)obj->relocbase;
 197                                 *where = tmp;
 198                         } else {
 199                                 tmp = load_ptr(where) +
 200                                     (Elf_Addr)obj->relocbase;
 201                                 store_ptr(where, tmp);
 202                         }
 203                         dbg("RELATIVE in %s --> %p", obj->path,
 204                             (void *)tmp);
 205                         break;
 206
 207                 case R_ARM_COPY:
 208                         /*
 209                          * These are deferred until all other relocations have
 210                          * been done.  All we do here is make sure that the
 211                          * COPY relocation is not in a shared library.  They
 212                          * are allowed only in executable files.
 213                          */
 214                         if (!obj->mainprog) {
 215                                 _rtld_error(
 216                         "%s: Unexpected R_COPY relocation in shared library",
 217                                     obj->path);
 218                                 return -1;
 219                         }
 220                         dbg("COPY (avoid in main)");
 221                         break;
 222
 223                 default:
 224                         dbg("sym = %lu, type = %lu, offset = %p, "
 225                             "contents = %p, symbol = %s",
 226                             symnum, (u_long)ELF_R_TYPE(rel->r_info),
 227                             (void *)rel->r_offset, (void *)load_ptr(where),
 228                             obj->strtab + obj->symtab[symnum].st_name);
 229                         _rtld_error("%s: Unsupported relocation type %ld "
 230                             "in non-PLT relocations\n",
 231                             obj->path, (u_long) ELF_R_TYPE(rel->r_info));
 232                         return -1;
 233         }
 234         return 0;
 235 }
 236
 237 /*
 238  *  * Process non-PLT relocations
 239  *   */
 240 int
 241 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
 242 {
 243         const Elf_Rel *rellim;
 244         const Elf_Rel *rel;
 245         SymCache *cache;
 246         int bytes = obj->nchains * sizeof(SymCache);
 247         int r = -1;
 248
 249         /* The relocation for the dynamic loader has already been done. */
 250         if (obj == obj_rtld)
 251                 return (0);
 252         /*
 253          * The dynamic loader may be called from a thread, we have
 254          * limited amounts of stack available so we cannot use alloca().
 255          */
 256         cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
 257         if (cache == MAP_FAILED)
 258                 cache = NULL;
 259
 260         rellim = (const Elf_Rel *)((caddr_t)obj->rel + obj->relsize);
 261         for (rel = obj->rel; rel < rellim; rel++) {
 262                 if (reloc_nonplt_object(obj, rel, cache) < 0)
 263                         goto done;
 264         }
 265         r = 0;
 266 done:
 267         if (cache) {
 268                 munmap(cache, bytes);
 269         }
 270         return (r);
 271 }
 272
 273 /*
 274  *  * Process the PLT relocations.
 275  *   */
 276 int
 277 reloc_plt(Obj_Entry *obj)
 278 {
 279         const Elf_Rel *rellim;
 280         const Elf_Rel *rel;
 281
 282         rellim = (const Elf_Rel *)((char *)obj->pltrel +
 283             obj->pltrelsize);
 284         for (rel = obj->pltrel;  rel < rellim;  rel++) {
 285                 Elf_Addr *where;
 286
 287                 assert(ELF_R_TYPE(rel->r_info) == R_ARM_JUMP_SLOT);
 288
 289                 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
 290                 *where += (Elf_Addr )obj->relocbase;
 291         }
 292
 293         return (0);
 294 }
 295
 296 /*
 297  *  * LD_BIND_NOW was set - force relocation for all jump slots
 298  *   */
 299 int
 300 reloc_jmpslots(Obj_Entry *obj)
 301 {
 302         const Obj_Entry *defobj;
 303         const Elf_Rel *rellim;
 304         const Elf_Rel *rel;
 305         const Elf_Sym *def;
 306         Elf_Addr *where;
 307         Elf_Addr target;
 308
 309         rellim = (const Elf_Rel *)((char *)obj->pltrel + obj->pltrelsize);
 310         for (rel = obj->pltrel; rel < rellim; rel++) {
 311                 assert(ELF_R_TYPE(rel->r_info) == R_ARM_JUMP_SLOT);
 312                 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
 313                 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
 314                     true, NULL);
 315                 if (def == NULL) {
 316                         dbg("reloc_jmpslots: sym not found");
 317                         return (-1);
 318                 }
 319
 320                 target = (Elf_Addr)(defobj->relocbase + def->st_value);
 321                 reloc_jmpslot(where, target, defobj, obj,
 322                     (const Elf_Rel *) rel);
 323         }
 324
 325         obj->jmpslots_done = true;
 326
 327         return (0);
 328 }
 329
 330 Elf_Addr
 331 reloc_jmpslot(Elf_Addr *where, Elf_Addr target, const Obj_Entry *defobj,
 332                 const Obj_Entry *obj, const Elf_Rel *rel)
 333 {
 334
 335         assert(ELF_R_TYPE(rel->r_info) == R_ARM_JUMP_SLOT);
 336
 337         if (*where != target)
 338                 *where = target;
 339
 340         return target;
 341 }
 342
 343 void
 344 allocate_initial_tls(Obj_Entry *objs)
 345 {
 346
 347 }
 348
 349 void *
 350 __tls_get_addr(tls_index* ti)
 351 {
 352         return (NULL);
 353 }