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

   1 /* Machine-dependent ELF dynamic relocation inline functions.  S390 Version.
   2    Copyright (C) 2000-2015 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) & 0x00000000ffffffff\n"
  76        "2: l     %0,4(1)\n"
  77        "   ar    %0,1\n"
  78        "   al    1,0(1)\n"
  79        "   sl    %0,_dl_start@GOT(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 0:      ahi   %r13,.Llit-0b\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@GOT(%r12)\n\
 169         l     %r1,0(%r1)        # load _dl_skip_args\n\
 170         ltr   %r1,%r1\n\
 171         je    4f                # Skip the arg adjustment if there were none.\n\
 172         # Get the original argument count.\n\
 173         l     %r0,96(%r15)\n\
 174         # Subtract _dl_skip_args from it.\n\
 175         sr    %r0,%r1\n\
 176         # Store back the modified argument count.\n\
 177         st    %r0,96(%r15)\n\
 178         # Copy argv and envp forward to account for skipped argv entries.\n\
 179         # We skipped at least one argument or we would not get here.\n\
 180         la    %r6,100(%r15)     # Destination pointer i.e. &argv[0]\n\
 181         lr    %r5,%r6\n\
 182         lr    %r0,%r1\n\
 183         sll   %r0,2\n           # Number of skipped bytes.\n\
 184         ar    %r5,%r0           # Source pointer = Dest + Skipped args.\n\
 185         # argv copy loop:\n\
 186 1:      l     %r7,0(%r5)        # Load a word from the source.\n\
 187         st    %r7,0(%r6)        # Store the word in the destination.\n\
 188         ahi   %r5,4\n\
 189         ahi   %r6,4\n\
 190         ltr   %r7,%r7\n\
 191         jne   1b                # Stop after copying the NULL.\n\
 192         # envp copy loop:\n\
 193 2:      l     %r7,0(%r5)        # Load a word from the source.\n\
 194         st    %r7,0(%r6)        # Store the word in the destination.\n\
 195         ahi   %r5,4\n\
 196         ahi   %r6,4\n\
 197         ltr   %r7,%r7\n\
 198         jne   2b                # Stop after copying the NULL.\n\
 199         # Now we have to zero out the envp entries after NULL to allow\n\
 200         # start.S to properly find auxv by skipping zeroes.\n\
 201         # zero out loop:\n\
 202         lhi   %r7,0\n\
 203 3:      st    %r7,0(%r6)        # Store zero.\n\
 204         ahi   %r6,4             # Advance dest pointer.\n\
 205         ahi   %r1,-1            # Subtract one from the word count.\n\
 206         ltr   %r1,%r1\n\
 207         jne    3b               # Keep copying if the word count is non-zero.\n\
 208         # Adjust _dl_argv\n\
 209         la    %r6,100(%r15)\n\
 210         l     %r1,_dl_argv@GOT(%r12)\n\
 211         st    %r6,0(%r1)\n\
 212         # The special initializer gets called with the stack just\n\
 213         # as the application's entry point will see it; it can\n\
 214         # switch stacks if it moves these contents over.\n\
 215 " RTLD_START_SPECIAL_INIT "\n\
 216         # Call the function to run the initializers.\n\
 217         # Load the parameters:\n\
 218         # (%r2, %r3, %r4, %r5) = (_dl_loaded, argc, argv, envp)\n\
 219 4:      l     %r2,_rtld_local@GOT(%r12)\n\
 220         l     %r2,0(%r2)\n\
 221         l     %r3,96(%r15)\n\
 222         la    %r4,100(%r15)\n\
 223         lr    %r5,%r3\n\
 224         sll   %r5,2\n\
 225         la    %r5,104(%r5,%r15)\n\
 226         l     %r1,.Ladr4-.Llit(%r13)\n\
 227         bas   %r14,0(%r1,%r13)\n\
 228         # Pass our finalizer function to the user in %r14, as per ELF ABI.\n\
 229         l     %r14,_dl_fini@GOT(%r12)\n\
 230         # Free stack frame\n\
 231         ahi   %r15,96\n\
 232         # Jump to the user's entry point (saved in %r8).\n\
 233         br    %r8\n\
 234 .Llit:\n\
 235 .Ladr0: .long _GLOBAL_OFFSET_TABLE_-.Llit\n\
 236 .Ladr1: .long _dl_start-.Llit\n\
 237 .Ladr4: .long _dl_init@PLT-.Llit\n\
 238 ");
 239
 240 #ifndef RTLD_START_SPECIAL_INIT
 241 #define RTLD_START_SPECIAL_INIT /* nothing */
 242 #endif
 243
 244 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
 245    TLS variable, so undefined references should not be allowed to
 246    define the value.
 247    ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one
 248    of the main executable's symbols, as for a COPY reloc.  */
 249 #define elf_machine_type_class(type) \
 250   ((((type) == R_390_JMP_SLOT || (type) == R_390_TLS_DTPMOD                   \
 251      || (type) == R_390_TLS_DTPOFF || (type) == R_390_TLS_TPOFF)              \
 252     * ELF_RTYPE_CLASS_PLT)                                                    \
 253    | (((type) == R_390_COPY) * ELF_RTYPE_CLASS_COPY))
 254
 255 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 256 #define ELF_MACHINE_JMP_SLOT    R_390_JMP_SLOT
 257
 258 /* The S390 never uses Elf32_Rel relocations.  */
 259 #define ELF_MACHINE_NO_REL 1
 260 #define ELF_MACHINE_NO_RELA 0
 261
 262 /* We define an initialization functions.  This is called very early in
 263    _dl_sysdep_start.  */
 264 #define DL_PLATFORM_INIT dl_platform_init ()
 265
 266 static inline void __attribute__ ((unused))
 267 dl_platform_init (void)
 268 {
 269   if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0')
 270     /* Avoid an empty string which would disturb us.  */
 271     GLRO(dl_platform) = NULL;
 272 }
 273
 274 static inline Elf32_Addr
 275 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 276                        const Elf32_Rela *reloc,
 277                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 278 {
 279   return *reloc_addr = value;
 280 }
 281
 282 /* Return the final value of a plt relocation.  */
 283 static inline Elf32_Addr
 284 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 285                        Elf32_Addr value)
 286 {
 287   return value;
 288 }
 289
 290 /* Names of the architecture-specific auditing callback functions.  */
 291 #define ARCH_LA_PLTENTER s390_32_gnu_pltenter
 292 #define ARCH_LA_PLTEXIT s390_32_gnu_pltexit
 293
 294 #endif /* !dl_machine_h */
 295
 296
 297 #ifdef RESOLVE_MAP
 298
 299 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 300    MAP is the object containing the reloc.  */
 301
 302 auto inline void
 303 __attribute__ ((always_inline))
 304 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 305                   const Elf32_Sym *sym, const struct r_found_version *version,
 306                   void *const reloc_addr_arg, int skip_ifunc)
 307 {
 308   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 309   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 310
 311 #if !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC
 312   if (__glibc_unlikely (r_type == R_390_RELATIVE))
 313     {
 314 # if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC
 315       /* This is defined in rtld.c, but nowhere in the static libc.a;
 316          make the reference weak so static programs can still link.
 317          This declaration cannot be done when compiling rtld.c
 318          (i.e. #ifdef RTLD_BOOTSTRAP) because rtld.c contains the
 319          common defn for _dl_rtld_map, which is incompatible with a
 320          weak decl in the same file.  */
 321 #  ifndef SHARED
 322       weak_extern (GL(dl_rtld_map));
 323 #  endif
 324       if (map != &GL(dl_rtld_map)) /* Already done in rtld itself.  */
 325 # endif
 326         *reloc_addr = map->l_addr + reloc->r_addend;
 327     }
 328   else
 329 #endif
 330   if (__glibc_unlikely (r_type == R_390_NONE))
 331     return;
 332   else
 333     {
 334 #if !defined RTLD_BOOTSTRAP && !defined RESOLVE_CONFLICT_FIND_MAP
 335       /* Only needed for R_390_COPY below.  */
 336       const Elf32_Sym *const refsym = sym;
 337 #endif
 338       struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
 339       Elf32_Addr value = sym == NULL ? 0 : sym_map->l_addr + sym->st_value;
 340
 341       if (sym != NULL
 342           && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0)
 343           && __builtin_expect (sym->st_shndx != SHN_UNDEF, 1)
 344           && __builtin_expect (!skip_ifunc, 1))
 345         value = elf_ifunc_invoke (value);
 346
 347       switch (r_type)
 348         {
 349         case R_390_IRELATIVE:
 350           value = map->l_addr + reloc->r_addend;
 351           if (__glibc_likely (!skip_ifunc))
 352             value = elf_ifunc_invoke (value);
 353           *reloc_addr = value;
 354           break;
 355
 356         case R_390_GLOB_DAT:
 357         case R_390_JMP_SLOT:
 358           *reloc_addr = value + reloc->r_addend;
 359           break;
 360
 361 #ifndef RESOLVE_CONFLICT_FIND_MAP
 362         case R_390_TLS_DTPMOD:
 363 # ifdef RTLD_BOOTSTRAP
 364           /* During startup the dynamic linker is always the module
 365              with index 1.
 366              XXX If this relocation is necessary move before RESOLVE
 367              call.  */
 368           *reloc_addr = 1;
 369 # else
 370           /* Get the information from the link map returned by the
 371              resolv function.  */
 372           if (sym_map != NULL)
 373             *reloc_addr = sym_map->l_tls_modid;
 374 # endif
 375           break;
 376         case R_390_TLS_DTPOFF:
 377 # ifndef RTLD_BOOTSTRAP
 378           /* During relocation all TLS symbols are defined and used.
 379              Therefore the offset is already correct.  */
 380           if (sym != NULL)
 381             *reloc_addr = sym->st_value + reloc->r_addend;
 382 # endif
 383           break;
 384         case R_390_TLS_TPOFF:
 385           /* The offset is negative, forward from the thread pointer.  */
 386 # ifdef RTLD_BOOTSTRAP
 387           *reloc_addr = sym->st_value + reloc->r_addend - map->l_tls_offset;
 388 # else
 389           /* We know the offset of the object the symbol is contained in.
 390              It is a negative value which will be added to the
 391              thread pointer.  */
 392           if (sym != NULL)
 393             {
 394               CHECK_STATIC_TLS (map, sym_map);
 395               *reloc_addr = (sym->st_value + reloc->r_addend
 396                              - sym_map->l_tls_offset);
 397             }
 398 #endif
 399           break;
 400 #endif  /* use TLS */
 401
 402 #ifndef RTLD_BOOTSTRAP
 403 # ifndef RESOLVE_CONFLICT_FIND_MAP
 404         /* Not needed in dl-conflict.c.  */
 405         case R_390_COPY:
 406           if (sym == NULL)
 407             /* This can happen in trace mode if an object could not be
 408                found.  */
 409             break;
 410           if (__builtin_expect (sym->st_size > refsym->st_size, 0)
 411               || (__builtin_expect (sym->st_size < refsym->st_size, 0)
 412                   && __builtin_expect (GLRO(dl_verbose), 0)))
 413             {
 414               const char *strtab;
 415
 416               strtab = (const char *) D_PTR(map,l_info[DT_STRTAB]);
 417               _dl_error_printf ("\
 418 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
 419                                 RTLD_PROGNAME, strtab + refsym->st_name);
 420             }
 421           memcpy (reloc_addr_arg, (void *) value,
 422                   MIN (sym->st_size, refsym->st_size));
 423           break;
 424 # endif
 425         case R_390_32:
 426           *reloc_addr = value + reloc->r_addend;
 427           break;
 428         case R_390_16:
 429           *(unsigned short *) reloc_addr = value + reloc->r_addend;
 430           break;
 431         case R_390_8:
 432           *(char *) reloc_addr = value + reloc->r_addend;
 433           break;
 434 # ifndef RESOLVE_CONFLICT_FIND_MAP
 435         case R_390_PC32:
 436           *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 437           break;
 438         case R_390_PC16DBL:
 439           *(unsigned short *) reloc_addr = (unsigned short)
 440             ((short) (value + reloc->r_addend - (Elf32_Addr) reloc_addr) >> 1);
 441           break;
 442         case R_390_PC32DBL:
 443           *(unsigned int *) reloc_addr = (unsigned int)
 444             ((int) (value + reloc->r_addend - (Elf32_Addr) reloc_addr) >> 1);
 445           break;
 446         case R_390_PC16:
 447           *(unsigned short *) reloc_addr =
 448             value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 449           break;
 450         case R_390_NONE:
 451           break;
 452 # endif
 453 #endif
 454 #if !defined(RTLD_BOOTSTRAP) || defined(_NDEBUG)
 455         default:
 456           /* We add these checks in the version to relocate ld.so only
 457              if we are still debugging.  */
 458           _dl_reloc_bad_type (map, r_type, 0);
 459           break;
 460 #endif
 461         }
 462     }
 463 }
 464
 465 auto inline void
 466 __attribute__ ((always_inline))
 467 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
 468                            void *const reloc_addr_arg)
 469 {
 470   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 471   *reloc_addr = l_addr + reloc->r_addend;
 472 }
 473
 474 auto inline void
 475 __attribute__ ((always_inline))
 476 elf_machine_lazy_rel (struct link_map *map,
 477                       Elf32_Addr l_addr, const Elf32_Rela *reloc,
 478                       int skip_ifunc)
 479 {
 480   Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
 481   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 482   /* Check for unexpected PLT reloc type.  */
 483   if (__glibc_likely (r_type == R_390_JMP_SLOT))
 484     {
 485       if (__builtin_expect (map->l_mach.plt, 0) == 0)
 486         *reloc_addr += l_addr;
 487       else
 488         *reloc_addr =
 489           map->l_mach.plt
 490           + (((Elf32_Addr) reloc_addr) - map->l_mach.gotplt) * 8;
 491     }
 492   else if (__glibc_likely (r_type == R_390_IRELATIVE))
 493     {
 494       Elf32_Addr value = map->l_addr + reloc->r_addend;
 495       if (__glibc_likely (!skip_ifunc))
 496         value = elf_ifunc_invoke (value);
 497       *reloc_addr = value;
 498     }
 499   else
 500     _dl_reloc_bad_type (map, r_type, 1);
 501 }
 502
 503 #endif /* RESOLVE_MAP */