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                         size_t size;
  40                         const void *srcaddr;
  41                         const Elf_Sym *srcsym;
  42                         const Obj_Entry *srcobj, *defobj;
  43                         SymLook req;
  44                         int res;
  45
  46                         dstaddr = (void *) (dstobj->relocbase + rel->r_offset);
  47                         dstsym = dstobj->symtab + ELF_R_SYM(rel->r_info);
  48                         name = dstobj->strtab + dstsym->st_name;
  49                         size = dstsym->st_size;
  50
  51                         symlook_init(&req, name);
  52                         req.ventry = fetch_ventry(dstobj,
  53                             ELF_R_SYM(rel->r_info));
  54                         for (srcobj = dstobj->next;  srcobj != NULL;
  55                              srcobj = srcobj->next) {
  56                                 res = symlook_obj(&req, srcobj);
  57                                 if (res == 0) {
  58                                         srcsym = req.sym_out;
  59                                         defobj = req.defobj_out;
  60                                         break;
  61                                 }
  62                         }
  63                         if (srcobj == NULL) {
  64                                 _rtld_error(
  65 "Undefined symbol \"%s\" referenced from COPY relocation in %s",
  66                                     name, dstobj->path);
  67                                 return (-1);
  68                         }
  69
  70                         srcaddr = (const void *)(defobj->relocbase +
  71                             srcsym->st_value);
  72                         memcpy(dstaddr, srcaddr, size);
  73                 }
  74         }
  75         return 0;
  76 }
  77
  78 void _rtld_bind_start(void);
  79 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
  80
  81 int open();
  82 int _open();
  83 void
  84 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
  85 {
  86         const Elf_Rel *rel = 0, *rellim;
  87         Elf_Addr relsz = 0;
  88         Elf_Addr *where;
  89         uint32_t size;
  90
  91         for (; dynp->d_tag != DT_NULL; dynp++) {
  92                 switch (dynp->d_tag) {
  93                 case DT_REL:
  94                         rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr);
  95                         break;
  96                 case DT_RELSZ:
  97                         relsz = dynp->d_un.d_val;
  98                         break;
  99                 }
 100         }
 101         rellim = (const Elf_Rel *)((caddr_t)rel + relsz);
 102         size = (rellim - 1)->r_offset - rel->r_offset;
 103         for (; rel < rellim; rel++) {
 104                 where = (Elf_Addr *)(relocbase + rel->r_offset);
 105
 106                 *where += (Elf_Addr)relocbase;
 107         }
 108 }
 109 /*
 110  * It is possible for the compiler to emit relocations for unaligned data.
 111  * We handle this situation with these inlines.
 112  */
 113 #define RELOC_ALIGNED_P(x) \
 114         (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0)
 115
 116 static __inline Elf_Addr
 117 load_ptr(void *where)
 118 {
 119         Elf_Addr res;
 120
 121         memcpy(&res, where, sizeof(res));
 122
 123         return (res);
 124 }
 125
 126 static __inline void
 127 store_ptr(void *where, Elf_Addr val)
 128 {
 129
 130         memcpy(where, &val, sizeof(val));
 131 }
 132
 133 static int
 134 reloc_nonplt_object(Obj_Entry *obj, const Elf_Rel *rel, SymCache *cache,
 135     RtldLockState *lockstate)
 136 {
 137         Elf_Addr        *where;
 138         const Elf_Sym   *def;
 139         const Obj_Entry *defobj;
 140         Elf_Addr         tmp;
 141         unsigned long    symnum;
 142
 143         where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
 144         symnum = ELF_R_SYM(rel->r_info);
 145
 146         switch (ELF_R_TYPE(rel->r_info)) {
 147         case R_ARM_NONE:
 148                 break;
 149
 150 #if 1 /* XXX should not occur */
 151         case R_ARM_PC24: {      /* word32 S - P + A */
 152                 Elf32_Sword addend;
 153
 154                 /*
 155                  * Extract addend and sign-extend if needed.
 156                  */
 157                 addend = *where;
 158                 if (addend & 0x00800000)
 159                         addend |= 0xff000000;
 160
 161                 def = find_symdef(symnum, obj, &defobj, false, cache,
 162                     lockstate);
 163                 if (def == NULL)
 164                                 return -1;
 165                         tmp = (Elf_Addr)obj->relocbase + def->st_value
 166                             - (Elf_Addr)where + (addend << 2);
 167                         if ((tmp & 0xfe000000) != 0xfe000000 &&
 168                             (tmp & 0xfe000000) != 0) {
 169                                 _rtld_error(
 170                                 "%s: R_ARM_PC24 relocation @ %p to %s failed "
 171                                 "(displacement %ld (%#lx) out of range)",
 172                                     obj->path, where,
 173                                     obj->strtab + obj->symtab[symnum].st_name,
 174                                     (long) tmp, (long) tmp);
 175                                 return -1;
 176                         }
 177                         tmp >>= 2;
 178                         *where = (*where & 0xff000000) | (tmp & 0x00ffffff);
 179                         dbg("PC24 %s in %s --> %p @ %p in %s",
 180                             obj->strtab + obj->symtab[symnum].st_name,
 181                             obj->path, (void *)*where, where, defobj->path);
 182                         break;
 183                 }
 184 #endif
 185
 186                 case R_ARM_ABS32:       /* word32 B + S + A */
 187                 case R_ARM_GLOB_DAT:    /* word32 B + S */
 188                         def = find_symdef(symnum, obj, &defobj, false, cache,
 189                             lockstate);
 190                         if (def == NULL)
 191                                 return -1;
 192                         if (__predict_true(RELOC_ALIGNED_P(where))) {
 193                                 tmp =  *where + (Elf_Addr)defobj->relocbase +
 194                                     def->st_value;
 195                                 *where = tmp;
 196                         } else {
 197                                 tmp = load_ptr(where) +
 198                                     (Elf_Addr)defobj->relocbase +
 199                                     def->st_value;
 200                                 store_ptr(where, tmp);
 201                         }
 202                         dbg("ABS32/GLOB_DAT %s in %s --> %p @ %p in %s",
 203                             obj->strtab + obj->symtab[symnum].st_name,
 204                             obj->path, (void *)tmp, where, defobj->path);
 205                         break;
 206
 207                 case R_ARM_RELATIVE:    /* word32 B + A */
 208                         if (__predict_true(RELOC_ALIGNED_P(where))) {
 209                                 tmp = *where + (Elf_Addr)obj->relocbase;
 210                                 *where = tmp;
 211                         } else {
 212                                 tmp = load_ptr(where) +
 213                                     (Elf_Addr)obj->relocbase;
 214                                 store_ptr(where, tmp);
 215                         }
 216                         dbg("RELATIVE in %s --> %p", obj->path,
 217                             (void *)tmp);
 218                         break;
 219
 220                 case R_ARM_COPY:
 221                         /*
 222                          * These are deferred until all other relocations have
 223                          * been done.  All we do here is make sure that the
 224                          * COPY relocation is not in a shared library.  They
 225                          * are allowed only in executable files.
 226                          */
 227                         if (!obj->mainprog) {
 228                                 _rtld_error(
 229                         "%s: Unexpected R_COPY relocation in shared library",
 230                                     obj->path);
 231                                 return -1;
 232                         }
 233                         dbg("COPY (avoid in main)");
 234                         break;
 235
 236                 default:
 237                         dbg("sym = %lu, type = %lu, offset = %p, "
 238                             "contents = %p, symbol = %s",
 239                             symnum, (u_long)ELF_R_TYPE(rel->r_info),
 240                             (void *)rel->r_offset, (void *)load_ptr(where),
 241                             obj->strtab + obj->symtab[symnum].st_name);
 242                         _rtld_error("%s: Unsupported relocation type %ld "
 243                             "in non-PLT relocations\n",
 244                             obj->path, (u_long) ELF_R_TYPE(rel->r_info));
 245                         return -1;
 246         }
 247         return 0;
 248 }
 249
 250 /*
 251  *  * Process non-PLT relocations
 252  *   */
 253 int
 254 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, RtldLockState *lockstate)
 255 {
 256         const Elf_Rel *rellim;
 257         const Elf_Rel *rel;
 258         SymCache *cache;
 259         int r = -1;
 260
 261         /* The relocation for the dynamic loader has already been done. */
 262         if (obj == obj_rtld)
 263                 return (0);
 264         /*
 265          * The dynamic loader may be called from a thread, we have
 266          * limited amounts of stack available so we cannot use alloca().
 267          */
 268         cache = calloc(obj->nchains, sizeof(SymCache));
 269         /* No need to check for NULL here */
 270
 271         rellim = (const Elf_Rel *)((caddr_t)obj->rel + obj->relsize);
 272         for (rel = obj->rel; rel < rellim; rel++) {
 273                 if (reloc_nonplt_object(obj, rel, cache, lockstate) < 0)
 274                         goto done;
 275         }
 276         r = 0;
 277 done:
 278         if (cache != NULL)
 279                 free(cache);
 280         return (r);
 281 }
 282
 283 /*
 284  *  * Process the PLT relocations.
 285  *   */
 286 int
 287 reloc_plt(Obj_Entry *obj)
 288 {
 289         const Elf_Rel *rellim;
 290         const Elf_Rel *rel;
 291
 292         rellim = (const Elf_Rel *)((char *)obj->pltrel +
 293             obj->pltrelsize);
 294         for (rel = obj->pltrel;  rel < rellim;  rel++) {
 295                 Elf_Addr *where;
 296
 297                 assert(ELF_R_TYPE(rel->r_info) == R_ARM_JUMP_SLOT);
 298
 299                 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
 300                 *where += (Elf_Addr )obj->relocbase;
 301         }
 302
 303         return (0);
 304 }
 305
 306 /*
 307  *  * LD_BIND_NOW was set - force relocation for all jump slots
 308  *   */
 309 int
 310 reloc_jmpslots(Obj_Entry *obj, RtldLockState *lockstate)
 311 {
 312         const Obj_Entry *defobj;
 313         const Elf_Rel *rellim;
 314         const Elf_Rel *rel;
 315         const Elf_Sym *def;
 316         Elf_Addr *where;
 317         Elf_Addr target;
 318
 319         rellim = (const Elf_Rel *)((char *)obj->pltrel + obj->pltrelsize);
 320         for (rel = obj->pltrel; rel < rellim; rel++) {
 321                 assert(ELF_R_TYPE(rel->r_info) == R_ARM_JUMP_SLOT);
 322                 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
 323                 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
 324                     true, NULL, lockstate);
 325                 if (def == NULL) {
 326                         dbg("reloc_jmpslots: sym not found");
 327                         return (-1);
 328                 }
 329
 330                 target = (Elf_Addr)(defobj->relocbase + def->st_value);
 331                 reloc_jmpslot(where, target, defobj, obj,
 332                     (const Elf_Rel *) rel);
 333         }
 334
 335         obj->jmpslots_done = true;
 336
 337         return (0);
 338 }
 339
 340 Elf_Addr
 341 reloc_jmpslot(Elf_Addr *where, Elf_Addr target, const Obj_Entry *defobj,
 342                 const Obj_Entry *obj, const Elf_Rel *rel)
 343 {
 344
 345         assert(ELF_R_TYPE(rel->r_info) == R_ARM_JUMP_SLOT);
 346
 347         if (*where != target)
 348                 *where = target;
 349
 350         return target;
 351 }
 352
 353 void
 354 allocate_initial_tls(Obj_Entry *objs)
 355 {
 356
 357 }
 358
 359 void *
 360 __tls_get_addr(tls_index* ti)
 361 {
 362         return (NULL);
 363 }