sysdeps/s390/s390-32/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  S390 Version.
   2    Copyright (C) 2000-2014 Free Software Foundation, Inc.
   3    Contributed by Carl Pederson & Martin Schwidefsky.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef dl_machine_h
  21 #define dl_machine_h
  22
  23 #define ELF_MACHINE_NAME "s390"
  24
  25 #include <sys/param.h>
  26 #include <string.h>
  27 #include <link.h>
  28 #include <sysdeps/s390/dl-procinfo.h>
  29 #include <dl-irel.h>
  30
  31 /* This is an older, now obsolete value.  */
  32 #define EM_S390_OLD     0xA390
  33
  34 /* Return nonzero iff ELF header is compatible with the running host.  */
  35 static inline int
  36 elf_machine_matches_host (const Elf32_Ehdr *ehdr)
  37 {
  38   /* Check if the kernel provides the high gpr facility if needed by
  39      the binary.  */
  40   if ((ehdr->e_flags & EF_S390_HIGH_GPRS)
  41       && !(GLRO (dl_hwcap) & HWCAP_S390_HIGH_GPRS))
  42     return 0;
  43
  44   return (ehdr->e_machine == EM_S390 || ehdr->e_machine == EM_S390_OLD)
  45          && ehdr->e_ident[EI_CLASS] == ELFCLASS32;
  46 }
  47
  48
  49 /* Return the link-time address of _DYNAMIC.  Conveniently, this is the
  50    first element of the GOT.  This must be inlined in a function which
  51    uses global data.  */
  52
  53 static inline Elf32_Addr
  54 elf_machine_dynamic (void)
  55 {
  56   register Elf32_Addr *got;
  57
  58   asm( "        bras   %0,2f\n"
  59        "1:      .long  _GLOBAL_OFFSET_TABLE_-1b\n"
  60        "2:      al     %0,0(%0)"
  61        : "=&a" (got) : : "0" );
  62
  63   return *got;
  64 }
  65
  66
  67 /* Return the run-time load address of the shared object.  */
  68 static inline Elf32_Addr
  69 elf_machine_load_address (void)
  70 {
  71   Elf32_Addr addr;
  72
  73   asm( "   bras  1,2f\n"
  74        "1: .long _GLOBAL_OFFSET_TABLE_ - 1b\n"
  75        "   .long _dl_start - 1b - 0x80000000\n"
  76        "2: l     %0,4(1)\n"
  77        "   ar    %0,1\n"
  78        "   al    1,0(1)\n"
  79        "   sl    %0,_dl_start@GOT12(1)"
  80        : "=&d" (addr) : : "1" );
  81   return addr;
  82 }
  83
  84 /* Set up the loaded object described by L so its unrelocated PLT
  85    entries will jump to the on-demand fixup code in dl-runtime.c.  */
  86
  87 static inline int __attribute__ ((unused))
  88 elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
  89 {
  90   extern void _dl_runtime_resolve (Elf32_Word);
  91   extern void _dl_runtime_profile (Elf32_Word);
  92
  93   if (l->l_info[DT_JMPREL] && lazy)
  94     {
  95       /* The GOT entries for functions in the PLT have not yet been filled
  96          in.  Their initial contents will arrange when called to push an
  97          offset into the .rel.plt section, push _GLOBAL_OFFSET_TABLE_[1],
  98          and then jump to _GLOBAL_OFFSET_TABLE[2].  */
  99       Elf32_Addr *got;
 100       got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
 101       /* If a library is prelinked but we have to relocate anyway,
 102          we have to be able to undo the prelinking of .got.plt.
 103          The prelinker saved us here address of .plt + 0x2c.  */
 104       if (got[1])
 105         {
 106           l->l_mach.plt = got[1] + l->l_addr;
 107           l->l_mach.gotplt = (Elf32_Addr) &got[3];
 108         }
 109       got[1] = (Elf32_Addr) l;  /* Identify this shared object.  */
 110
 111       /* The got[2] entry contains the address of a function which gets
 112          called to get the address of a so far unresolved function and
 113          jump to it.  The profiling extension of the dynamic linker allows
 114          to intercept the calls to collect information.  In this case we
 115          don't store the address in the GOT so that all future calls also
 116          end in this function.  */
 117       if (__glibc_unlikely (profile))
 118         {
 119           got[2] = (Elf32_Addr) &_dl_runtime_profile;
 120
 121           if (GLRO(dl_profile) != NULL
 122               && _dl_name_match_p (GLRO(dl_profile), l))
 123             /* This is the object we are looking for.  Say that we really
 124                want profiling and the timers are started.  */
 125             GL(dl_profile_map) = l;
 126         }
 127       else
 128         /* This function will get called to fix up the GOT entry indicated by
 129            the offset on the stack, and then jump to the resolved address.  */
 130         got[2] = (Elf32_Addr) &_dl_runtime_resolve;
 131     }
 132
 133   return lazy;
 134 }
 135
 136 /* Mask identifying addresses reserved for the user program,
 137    where the dynamic linker should not map anything.  */
 138 #define ELF_MACHINE_USER_ADDRESS_MASK   0xf8000000UL
 139
 140 /* Initial entry point code for the dynamic linker.
 141    The C function `_dl_start' is the real entry point;
 142    its return value is the user program's entry point.  */
 143
 144 #define RTLD_START asm ("\n\
 145 .text\n\
 146 .align 4\n\
 147 .globl _start\n\
 148 .globl _dl_start_user\n\
 149 _start:\n\
 150         basr  %r13,0\n\
 151 .L0:    ahi   %r13,.Llit-.L0\n\
 152         lr    %r2,%r15\n\
 153         # Alloc stack frame\n\
 154         ahi   %r15,-96\n\
 155         # Set the back chain to zero\n\
 156         xc    0(4,%r15),0(%r15)\n\
 157         # Call _dl_start with %r2 pointing to arg on stack\n\
 158         l     %r14,.Ladr1-.Llit(%r13)\n\
 159         bas   %r14,0(%r14,%r13)   # call _dl_start\n\
 160 _dl_start_user:\n\
 161         # Save the user entry point address in %r8.\n\
 162         lr    %r8,%r2\n\
 163         # Point %r12 at the GOT.\n\
 164         l     %r12,.Ladr0-.Llit(%r13)\n\
 165         ar    %r12,%r13\n\
 166         # See if we were run as a command with the executable file\n\
 167         # name as an extra leading argument.\n\
 168         l     %r1,_dl_skip_args@GOT12(0,%r12)\n\
 169         l     %r1,0(%r1)          # load _dl_skip_args\n\
 170         # Get the original argument count.\n\
 171         l     %r0,96(%r15)\n\
 172         # Subtract _dl_skip_args from it.\n\
 173         sr    %r0,%r1\n\
 174         # Adjust the stack pointer to skip _dl_skip_args words.\n\
 175         sll   %r1,2\n\
 176         ar    %r15,%r1\n\
 177         # Set the back chain to zero again\n\
 178         xc    0(4,%r15),0(%r15)\n\
 179         # Store back the modified argument count.\n\
 180         st    %r0,96(%r15)\n\
 181         # The special initializer gets called with the stack just\n\
 182         # as the application's entry point will see it; it can\n\
 183         # switch stacks if it moves these contents over.\n\
 184 " RTLD_START_SPECIAL_INIT "\n\
 185         # Call the function to run the initializers.\n\
 186         # Load the parameters:\n\
 187         # (%r2, %r3, %r4, %r5) = (_dl_loaded, argc, argv, envp)\n\
 188         l     %r2,_rtld_local@GOT(%r12)\n\
 189         l     %r2,0(%r2)\n\
 190         l     %r3,96(%r15)\n\
 191         la    %r4,100(%r15)\n\
 192         lr    %r5,%r3\n\
 193         sll   %r5,2\n\
 194         la    %r5,104(%r5,%r15)\n\
 195         l     %r1,.Ladr4-.Llit(%r13)\n\
 196         bas   %r14,0(%r1,%r13)\n\
 197         # Pass our finalizer function to the user in %r14, as per ELF ABI.\n\
 198         l     %r14,_dl_fini@GOT(%r12)\n\
 199         # Free stack frame\n\
 200         ahi   %r15,96\n\
 201         # Jump to the user's entry point (saved in %r8).\n\
 202         br    %r8\n\
 203 .Llit:\n\
 204 .Ladr0: .long _GLOBAL_OFFSET_TABLE_-.Llit\n\
 205 .Ladr1: .long _dl_start-.Llit\n\
 206 .Ladr4: .long _dl_init_internal@PLT-.Llit\n\
 207 ");
 208
 209 #ifndef RTLD_START_SPECIAL_INIT
 210 #define RTLD_START_SPECIAL_INIT /* nothing */
 211 #endif
 212
 213 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
 214    TLS variable, so undefined references should not be allowed to
 215    define the value.
 216    ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one
 217    of the main executable's symbols, as for a COPY reloc.  */
 218 #define elf_machine_type_class(type) \
 219   ((((type) == R_390_JMP_SLOT || (type) == R_390_TLS_DTPMOD                   \
 220      || (type) == R_390_TLS_DTPOFF || (type) == R_390_TLS_TPOFF)              \
 221     * ELF_RTYPE_CLASS_PLT)                                                    \
 222    | (((type) == R_390_COPY) * ELF_RTYPE_CLASS_COPY))
 223
 224 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 225 #define ELF_MACHINE_JMP_SLOT    R_390_JMP_SLOT
 226
 227 /* The S390 never uses Elf32_Rel relocations.  */
 228 #define ELF_MACHINE_NO_REL 1
 229
 230 /* We define an initialization functions.  This is called very early in
 231    _dl_sysdep_start.  */
 232 #define DL_PLATFORM_INIT dl_platform_init ()
 233
 234 static inline void __attribute__ ((unused))
 235 dl_platform_init (void)
 236 {
 237   if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0')
 238     /* Avoid an empty string which would disturb us.  */
 239     GLRO(dl_platform) = NULL;
 240 }
 241
 242 static inline Elf32_Addr
 243 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 244                        const Elf32_Rela *reloc,
 245                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 246 {
 247   return *reloc_addr = value;
 248 }
 249
 250 /* Return the final value of a plt relocation.  */
 251 static inline Elf32_Addr
 252 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 253                        Elf32_Addr value)
 254 {
 255   return value;
 256 }
 257
 258 /* Names of the architecture-specific auditing callback functions.  */
 259 #define ARCH_LA_PLTENTER s390_32_gnu_pltenter
 260 #define ARCH_LA_PLTEXIT s390_32_gnu_pltexit
 261
 262 #endif /* !dl_machine_h */
 263
 264
 265 #ifdef RESOLVE_MAP
 266
 267 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 268    MAP is the object containing the reloc.  */
 269
 270 auto inline void
 271 __attribute__ ((always_inline))
 272 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 273                   const Elf32_Sym *sym, const struct r_found_version *version,
 274                   void *const reloc_addr_arg, int skip_ifunc)
 275 {
 276   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 277   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 278
 279 #if !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC
 280   if (__glibc_unlikely (r_type == R_390_RELATIVE))
 281     {
 282 # if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC
 283       /* This is defined in rtld.c, but nowhere in the static libc.a;
 284          make the reference weak so static programs can still link.
 285          This declaration cannot be done when compiling rtld.c
 286          (i.e. #ifdef RTLD_BOOTSTRAP) because rtld.c contains the
 287          common defn for _dl_rtld_map, which is incompatible with a
 288          weak decl in the same file.  */
 289 #  ifndef SHARED
 290       weak_extern (GL(dl_rtld_map));
 291 #  endif
 292       if (map != &GL(dl_rtld_map)) /* Already done in rtld itself.  */
 293 # endif
 294         *reloc_addr = map->l_addr + reloc->r_addend;
 295     }
 296   else
 297 #endif
 298   if (__glibc_unlikely (r_type == R_390_NONE))
 299     return;
 300   else
 301     {
 302 #if !defined RTLD_BOOTSTRAP && !defined RESOLVE_CONFLICT_FIND_MAP
 303       /* Only needed for R_390_COPY below.  */
 304       const Elf32_Sym *const refsym = sym;
 305 #endif
 306       struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
 307       Elf32_Addr value = sym == NULL ? 0 : sym_map->l_addr + sym->st_value;
 308
 309       if (sym != NULL
 310           && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0)
 311           && __builtin_expect (sym->st_shndx != SHN_UNDEF, 1)
 312           && __builtin_expect (!skip_ifunc, 1))
 313         value = elf_ifunc_invoke (value);
 314
 315       switch (r_type)
 316         {
 317         case R_390_IRELATIVE:
 318           value = map->l_addr + reloc->r_addend;
 319           if (__glibc_likely (!skip_ifunc))
 320             value = elf_ifunc_invoke (value);
 321           *reloc_addr = value;
 322           break;
 323
 324         case R_390_GLOB_DAT:
 325         case R_390_JMP_SLOT:
 326           *reloc_addr = value + reloc->r_addend;
 327           break;
 328
 329 #ifndef RESOLVE_CONFLICT_FIND_MAP
 330         case R_390_TLS_DTPMOD:
 331 # ifdef RTLD_BOOTSTRAP
 332           /* During startup the dynamic linker is always the module
 333              with index 1.
 334              XXX If this relocation is necessary move before RESOLVE
 335              call.  */
 336           *reloc_addr = 1;
 337 # else
 338           /* Get the information from the link map returned by the
 339              resolv function.  */
 340           if (sym_map != NULL)
 341             *reloc_addr = sym_map->l_tls_modid;
 342 # endif
 343           break;
 344         case R_390_TLS_DTPOFF:
 345 # ifndef RTLD_BOOTSTRAP
 346           /* During relocation all TLS symbols are defined and used.
 347              Therefore the offset is already correct.  */
 348           if (sym != NULL)
 349             *reloc_addr = sym->st_value + reloc->r_addend;
 350 # endif
 351           break;
 352         case R_390_TLS_TPOFF:
 353           /* The offset is negative, forward from the thread pointer.  */
 354 # ifdef RTLD_BOOTSTRAP
 355           *reloc_addr = sym->st_value + reloc->r_addend - map->l_tls_offset;
 356 # else
 357           /* We know the offset of the object the symbol is contained in.
 358              It is a negative value which will be added to the
 359              thread pointer.  */
 360           if (sym != NULL)
 361             {
 362               CHECK_STATIC_TLS (map, sym_map);
 363               *reloc_addr = (sym->st_value + reloc->r_addend
 364                              - sym_map->l_tls_offset);
 365             }
 366 #endif
 367           break;
 368 #endif  /* use TLS */
 369
 370 #ifndef RTLD_BOOTSTRAP
 371 # ifndef RESOLVE_CONFLICT_FIND_MAP
 372         /* Not needed in dl-conflict.c.  */
 373         case R_390_COPY:
 374           if (sym == NULL)
 375             /* This can happen in trace mode if an object could not be
 376                found.  */
 377             break;
 378           if (__builtin_expect (sym->st_size > refsym->st_size, 0)
 379               || (__builtin_expect (sym->st_size < refsym->st_size, 0)
 380                   && __builtin_expect (GLRO(dl_verbose), 0)))
 381             {
 382               const char *strtab;
 383
 384               strtab = (const char *) D_PTR(map,l_info[DT_STRTAB]);
 385               _dl_error_printf ("\
 386 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
 387                                 RTLD_PROGNAME, strtab + refsym->st_name);
 388             }
 389           memcpy (reloc_addr_arg, (void *) value,
 390                   MIN (sym->st_size, refsym->st_size));
 391           break;
 392 # endif
 393         case R_390_32:
 394           *reloc_addr = value + reloc->r_addend;
 395           break;
 396         case R_390_16:
 397           *(unsigned short *) reloc_addr = value + reloc->r_addend;
 398           break;
 399         case R_390_8:
 400           *(char *) reloc_addr = value + reloc->r_addend;
 401           break;
 402 # ifndef RESOLVE_CONFLICT_FIND_MAP
 403         case R_390_PC32:
 404           *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 405           break;
 406         case R_390_PC16DBL:
 407           *(unsigned short *) reloc_addr = (unsigned short)
 408             ((short) (value + reloc->r_addend - (Elf32_Addr) reloc_addr) >> 1);
 409           break;
 410         case R_390_PC32DBL:
 411           *(unsigned int *) reloc_addr = (unsigned int)
 412             ((int) (value + reloc->r_addend - (Elf32_Addr) reloc_addr) >> 1);
 413           break;
 414         case R_390_PC16:
 415           *(unsigned short *) reloc_addr =
 416             value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 417           break;
 418         case R_390_NONE:
 419           break;
 420 # endif
 421 #endif
 422 #if !defined(RTLD_BOOTSTRAP) || defined(_NDEBUG)
 423         default:
 424           /* We add these checks in the version to relocate ld.so only
 425              if we are still debugging.  */
 426           _dl_reloc_bad_type (map, r_type, 0);
 427           break;
 428 #endif
 429         }
 430     }
 431 }
 432
 433 auto inline void
 434 __attribute__ ((always_inline))
 435 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
 436                            void *const reloc_addr_arg)
 437 {
 438   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 439   *reloc_addr = l_addr + reloc->r_addend;
 440 }
 441
 442 auto inline void
 443 __attribute__ ((always_inline))
 444 elf_machine_lazy_rel (struct link_map *map,
 445                       Elf32_Addr l_addr, const Elf32_Rela *reloc,
 446                       int skip_ifunc)
 447 {
 448   Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
 449   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 450   /* Check for unexpected PLT reloc type.  */
 451   if (__glibc_likely (r_type == R_390_JMP_SLOT))
 452     {
 453       if (__builtin_expect (map->l_mach.plt, 0) == 0)
 454         *reloc_addr += l_addr;
 455       else
 456         *reloc_addr =
 457           map->l_mach.plt
 458           + (((Elf32_Addr) reloc_addr) - map->l_mach.gotplt) * 8;
 459     }
 460   else if (__glibc_likely (r_type == R_390_IRELATIVE))
 461     {
 462       Elf32_Addr value = map->l_addr + reloc->r_addend;
 463       if (__glibc_likely (!skip_ifunc))
 464         value = elf_ifunc_invoke (value);
 465       *reloc_addr = value;
 466     }
 467   else
 468     _dl_reloc_bad_type (map, r_type, 1);
 469 }
 470
 471 #endif /* RESOLVE_MAP */