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

   1 /* Machine-dependent ELF dynamic relocation inline functions.  S390 Version.
   2    Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006
   3    Free Software Foundation, Inc.
   4    Contributed by Carl Pederson & Martin Schwidefsky.
   5    This file is part of the GNU C Library.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, write to the Free
  19    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  20    02111-1307 USA.  */
  21
  22 #ifndef dl_machine_h
  23 #define dl_machine_h
  24
  25 #define ELF_MACHINE_NAME "s390"
  26
  27 #include <sys/param.h>
  28 #include <string.h>
  29 #include <link.h>
  30 #include <sysdeps/s390/dl-procinfo.h>
  31
  32 /* This is an older, now obsolete value.  */
  33 #define EM_S390_OLD     0xA390
  34
  35 /* Return nonzero iff ELF header is compatible with the running host.  */
  36 static inline int
  37 elf_machine_matches_host (const Elf32_Ehdr *ehdr)
  38 {
  39   /* Check if the kernel provides the high gpr facility if needed by
  40      the binary.  */
  41   if ((ehdr->e_flags & EF_S390_HIGH_GPRS)
  42       && !(GLRO (dl_hwcap) & HWCAP_S390_HIGH_GPRS))
  43     return 0;
  44
  45   return (ehdr->e_machine == EM_S390 || ehdr->e_machine == EM_S390_OLD)
  46          && ehdr->e_ident[EI_CLASS] == ELFCLASS32;
  47 }
  48
  49
  50 /* Return the link-time address of _DYNAMIC.  Conveniently, this is the
  51    first element of the GOT.  This must be inlined in a function which
  52    uses global data.  */
  53
  54 static inline Elf32_Addr
  55 elf_machine_dynamic (void)
  56 {
  57   register Elf32_Addr *got;
  58
  59   asm( "        bras   %0,2f\n"
  60        "1:      .long  _GLOBAL_OFFSET_TABLE_-1b\n"
  61        "2:      al     %0,0(%0)"
  62        : "=&a" (got) : : "0" );
  63
  64   return *got;
  65 }
  66
  67
  68 /* Return the run-time load address of the shared object.  */
  69 static inline Elf32_Addr
  70 elf_machine_load_address (void)
  71 {
  72   Elf32_Addr addr;
  73
  74   asm( "   bras  1,2f\n"
  75        "1: .long _GLOBAL_OFFSET_TABLE_ - 1b\n"
  76        "   .long _dl_start - 1b - 0x80000000\n"
  77        "2: l     %0,4(1)\n"
  78        "   ar    %0,1\n"
  79        "   al    1,0(1)\n"
  80        "   sl    %0,_dl_start@GOT12(1)"
  81        : "=&d" (addr) : : "1" );
  82   return addr;
  83 }
  84
  85 /* Set up the loaded object described by L so its unrelocated PLT
  86    entries will jump to the on-demand fixup code in dl-runtime.c.  */
  87
  88 static inline int __attribute__ ((unused))
  89 elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
  90 {
  91   extern void _dl_runtime_resolve (Elf32_Word);
  92   extern void _dl_runtime_profile (Elf32_Word);
  93
  94   if (l->l_info[DT_JMPREL] && lazy)
  95     {
  96       /* The GOT entries for functions in the PLT have not yet been filled
  97          in.  Their initial contents will arrange when called to push an
  98          offset into the .rel.plt section, push _GLOBAL_OFFSET_TABLE_[1],
  99          and then jump to _GLOBAL_OFFSET_TABLE[2].  */
 100       Elf32_Addr *got;
 101       got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
 102       /* If a library is prelinked but we have to relocate anyway,
 103          we have to be able to undo the prelinking of .got.plt.
 104          The prelinker saved us here address of .plt + 0x2c.  */
 105       if (got[1])
 106         {
 107           l->l_mach.plt = got[1] + l->l_addr;
 108           l->l_mach.gotplt = (Elf32_Addr) &got[3];
 109         }
 110       got[1] = (Elf32_Addr) l;  /* Identify this shared object.  */
 111
 112       /* The got[2] entry contains the address of a function which gets
 113          called to get the address of a so far unresolved function and
 114          jump to it.  The profiling extension of the dynamic linker allows
 115          to intercept the calls to collect information.  In this case we
 116          don't store the address in the GOT so that all future calls also
 117          end in this function.  */
 118       if (__builtin_expect (profile, 0))
 119         {
 120           got[2] = (Elf32_Addr) &_dl_runtime_profile;
 121
 122           if (GLRO(dl_profile) != NULL
 123               && _dl_name_match_p (GLRO(dl_profile), l))
 124             /* This is the object we are looking for.  Say that we really
 125                want profiling and the timers are started.  */
 126             GL(dl_profile_map) = l;
 127         }
 128       else
 129         /* This function will get called to fix up the GOT entry indicated by
 130            the offset on the stack, and then jump to the resolved address.  */
 131         got[2] = (Elf32_Addr) &_dl_runtime_resolve;
 132     }
 133
 134   return lazy;
 135 }
 136
 137 /* Mask identifying addresses reserved for the user program,
 138    where the dynamic linker should not map anything.  */
 139 #define ELF_MACHINE_USER_ADDRESS_MASK   0xf8000000UL
 140
 141 /* Initial entry point code for the dynamic linker.
 142    The C function `_dl_start' is the real entry point;
 143    its return value is the user program's entry point.  */
 144
 145 #define RTLD_START asm ("\n\
 146 .text\n\
 147 .align 4\n\
 148 .globl _start\n\
 149 .globl _dl_start_user\n\
 150 _start:\n\
 151         basr  %r13,0\n\
 152 .L0:    ahi   %r13,.Llit-.L0\n\
 153         lr    %r2,%r15\n\
 154         # Alloc stack frame\n\
 155         ahi   %r15,-96\n\
 156         # Set the back chain to zero\n\
 157         xc    0(4,%r15),0(%r15)\n\
 158         # Call _dl_start with %r2 pointing to arg on stack\n\
 159         l     %r14,.Ladr1-.Llit(%r13)\n\
 160         bas   %r14,0(%r14,%r13)   # call _dl_start\n\
 161 _dl_start_user:\n\
 162         # Save the user entry point address in %r8.\n\
 163         lr    %r8,%r2\n\
 164         # Point %r12 at the GOT.\n\
 165         l     %r12,.Ladr0-.Llit(%r13)\n\
 166         ar    %r12,%r13\n\
 167         # See if we were run as a command with the executable file\n\
 168         # name as an extra leading argument.\n\
 169         l     %r1,_dl_skip_args@GOT12(0,%r12)\n\
 170         l     %r1,0(%r1)          # load _dl_skip_args\n\
 171         # Get the original argument count.\n\
 172         l     %r0,96(%r15)\n\
 173         # Subtract _dl_skip_args from it.\n\
 174         sr    %r0,%r1\n\
 175         # Adjust the stack pointer to skip _dl_skip_args words.\n\
 176         sll   %r1,2\n\
 177         ar    %r15,%r1\n\
 178         # Set the back chain to zero again\n\
 179         xc    0(4,%r15),0(%r15)\n\
 180         # Store back the modified argument count.\n\
 181         st    %r0,96(%r15)\n\
 182         # The special initializer gets called with the stack just\n\
 183         # as the application's entry point will see it; it can\n\
 184         # switch stacks if it moves these contents over.\n\
 185 " RTLD_START_SPECIAL_INIT "\n\
 186         # Call the function to run the initializers.\n\
 187         # Load the parameters:\n\
 188         # (%r2, %r3, %r4, %r5) = (_dl_loaded, argc, argv, envp)\n\
 189         l     %r2,_rtld_local@GOT(%r12)\n\
 190         l     %r2,0(%r2)\n\
 191         l     %r3,96(%r15)\n\
 192         la    %r4,100(%r15)\n\
 193         lr    %r5,%r3\n\
 194         sll   %r5,2\n\
 195         la    %r5,104(%r5,%r15)\n\
 196         l     %r1,.Ladr4-.Llit(%r13)\n\
 197         bas   %r14,0(%r1,%r13)\n\
 198         # Pass our finalizer function to the user in %r14, as per ELF ABI.\n\
 199         l     %r14,_dl_fini@GOT(%r12)\n\
 200         # Free stack frame\n\
 201         ahi   %r15,96\n\
 202         # Jump to the user's entry point (saved in %r8).\n\
 203         br    %r8\n\
 204 .Llit:\n\
 205 .Ladr0: .long _GLOBAL_OFFSET_TABLE_-.Llit\n\
 206 .Ladr1: .long _dl_start-.Llit\n\
 207 .Ladr4: .long _dl_init_internal@PLT-.Llit\n\
 208 ");
 209
 210 #ifndef RTLD_START_SPECIAL_INIT
 211 #define RTLD_START_SPECIAL_INIT /* nothing */
 212 #endif
 213
 214 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
 215    TLS variable, so undefined references should not be allowed to
 216    define the value.
 217    ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one
 218    of the main executable's symbols, as for a COPY reloc.  */
 219 #define elf_machine_type_class(type) \
 220   ((((type) == R_390_JMP_SLOT || (type) == R_390_TLS_DTPMOD                   \
 221      || (type) == R_390_TLS_DTPOFF || (type) == R_390_TLS_TPOFF)              \
 222     * ELF_RTYPE_CLASS_PLT)                                                    \
 223    | (((type) == R_390_COPY) * ELF_RTYPE_CLASS_COPY))
 224
 225 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 226 #define ELF_MACHINE_JMP_SLOT    R_390_JMP_SLOT
 227
 228 /* The S390 never uses Elf32_Rel relocations.  */
 229 #define ELF_MACHINE_NO_REL 1
 230
 231 /* The S390 overlaps DT_RELA and DT_PLTREL.  */
 232 #define ELF_MACHINE_PLTREL_OVERLAP 1
 233
 234 /* We define an initialization functions.  This is called very early in
 235    _dl_sysdep_start.  */
 236 #define DL_PLATFORM_INIT dl_platform_init ()
 237
 238 static inline void __attribute__ ((unused))
 239 dl_platform_init (void)
 240 {
 241   if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0')
 242     /* Avoid an empty string which would disturb us.  */
 243     GLRO(dl_platform) = NULL;
 244 }
 245
 246 static inline Elf32_Addr
 247 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 248                        const Elf32_Rela *reloc,
 249                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 250 {
 251   return *reloc_addr = value;
 252 }
 253
 254 /* Return the final value of a plt relocation.  */
 255 static inline Elf32_Addr
 256 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 257                        Elf32_Addr value)
 258 {
 259   return value;
 260 }
 261
 262 /* Names of the architecture-specific auditing callback functions.  */
 263 #define ARCH_LA_PLTENTER s390_32_gnu_pltenter
 264 #define ARCH_LA_PLTEXIT s390_32_gnu_pltexit
 265
 266 #endif /* !dl_machine_h */
 267
 268
 269 #ifdef RESOLVE_MAP
 270
 271 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 272    MAP is the object containing the reloc.  */
 273
 274 auto inline void
 275 __attribute__ ((always_inline))
 276 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 277                   const Elf32_Sym *sym, const struct r_found_version *version,
 278                   void *const reloc_addr_arg)
 279 {
 280   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 281   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 282
 283 #if !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC
 284   if (__builtin_expect (r_type == R_390_RELATIVE, 0))
 285     {
 286 # if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC
 287       /* This is defined in rtld.c, but nowhere in the static libc.a;
 288          make the reference weak so static programs can still link.
 289          This declaration cannot be done when compiling rtld.c
 290          (i.e. #ifdef RTLD_BOOTSTRAP) because rtld.c contains the
 291          common defn for _dl_rtld_map, which is incompatible with a
 292          weak decl in the same file.  */
 293 #  ifndef SHARED
 294       weak_extern (GL(dl_rtld_map));
 295 #  endif
 296       if (map != &GL(dl_rtld_map)) /* Already done in rtld itself.  */
 297 # endif
 298         *reloc_addr = map->l_addr + reloc->r_addend;
 299     }
 300   else
 301 #endif
 302   if (__builtin_expect (r_type == R_390_NONE, 0))
 303     return;
 304   else
 305     {
 306 #ifndef RESOLVE_CONFLICT_FIND_MAP
 307       const Elf32_Sym *const refsym = sym;
 308 #endif
 309       struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
 310       Elf32_Addr value = sym == NULL ? 0 : sym_map->l_addr + sym->st_value;
 311
 312       switch (r_type)
 313         {
 314         case R_390_GLOB_DAT:
 315         case R_390_JMP_SLOT:
 316           *reloc_addr = value + reloc->r_addend;
 317           break;
 318
 319 #if (!defined RTLD_BOOTSTRAP || USE___THREAD) \
 320     && !defined RESOLVE_CONFLICT_FIND_MAP
 321         case R_390_TLS_DTPMOD:
 322 # ifdef RTLD_BOOTSTRAP
 323           /* During startup the dynamic linker is always the module
 324              with index 1.
 325              XXX If this relocation is necessary move before RESOLVE
 326              call.  */
 327           *reloc_addr = 1;
 328 # else
 329           /* Get the information from the link map returned by the
 330              resolv function.  */
 331           if (sym_map != NULL)
 332             *reloc_addr = sym_map->l_tls_modid;
 333 # endif
 334           break;
 335         case R_390_TLS_DTPOFF:
 336 # ifndef RTLD_BOOTSTRAP
 337           /* During relocation all TLS symbols are defined and used.
 338              Therefore the offset is already correct.  */
 339           if (sym != NULL)
 340             *reloc_addr = sym->st_value + reloc->r_addend;
 341 # endif
 342           break;
 343         case R_390_TLS_TPOFF:
 344           /* The offset is negative, forward from the thread pointer.  */
 345 # ifdef RTLD_BOOTSTRAP
 346           *reloc_addr = sym->st_value + reloc->r_addend - map->l_tls_offset;
 347 # else
 348           /* We know the offset of the object the symbol is contained in.
 349              It is a negative value which will be added to the
 350              thread pointer.  */
 351           if (sym != NULL)
 352             {
 353               CHECK_STATIC_TLS (map, sym_map);
 354               *reloc_addr = (sym->st_value + reloc->r_addend
 355                              - sym_map->l_tls_offset);
 356             }
 357 #endif
 358           break;
 359 #endif  /* use TLS */
 360
 361 #ifndef RTLD_BOOTSTRAP
 362 # ifndef RESOLVE_CONFLICT_FIND_MAP
 363         /* Not needed in dl-conflict.c.  */
 364         case R_390_COPY:
 365           if (sym == NULL)
 366             /* This can happen in trace mode if an object could not be
 367                found.  */
 368             break;
 369           if (__builtin_expect (sym->st_size > refsym->st_size, 0)
 370               || (__builtin_expect (sym->st_size < refsym->st_size, 0)
 371                   && __builtin_expect (GLRO(dl_verbose), 0)))
 372             {
 373               const char *strtab;
 374
 375               strtab = (const char *) D_PTR(map,l_info[DT_STRTAB]);
 376               _dl_error_printf ("\
 377 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
 378                                 rtld_progname ?: "<program name unknown>",
 379                                 strtab + refsym->st_name);
 380             }
 381           memcpy (reloc_addr_arg, (void *) value,
 382                   MIN (sym->st_size, refsym->st_size));
 383           break;
 384 # endif
 385         case R_390_32:
 386           *reloc_addr = value + reloc->r_addend;
 387           break;
 388         case R_390_16:
 389           *(unsigned short *) reloc_addr = value + reloc->r_addend;
 390           break;
 391         case R_390_8:
 392           *(char *) reloc_addr = value + reloc->r_addend;
 393           break;
 394 # ifndef RESOLVE_CONFLICT_FIND_MAP
 395         case R_390_PC32:
 396           *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 397           break;
 398         case R_390_PC16DBL:
 399           *(unsigned short *) reloc_addr = (unsigned short)
 400             ((short) (value + reloc->r_addend - (Elf32_Addr) reloc_addr) >> 1);
 401           break;
 402         case R_390_PC32DBL:
 403           *(unsigned int *) reloc_addr = (unsigned int)
 404             ((int) (value + reloc->r_addend - (Elf32_Addr) reloc_addr) >> 1);
 405           break;
 406         case R_390_PC16:
 407           *(unsigned short *) reloc_addr =
 408             value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 409           break;
 410         case R_390_NONE:
 411           break;
 412 # endif
 413 #endif
 414 #if !defined(RTLD_BOOTSTRAP) || defined(_NDEBUG)
 415         default:
 416           /* We add these checks in the version to relocate ld.so only
 417              if we are still debugging.  */
 418           _dl_reloc_bad_type (map, r_type, 0);
 419           break;
 420 #endif
 421         }
 422     }
 423 }
 424
 425 auto inline void
 426 __attribute__ ((always_inline))
 427 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
 428                            void *const reloc_addr_arg)
 429 {
 430   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 431   *reloc_addr = l_addr + reloc->r_addend;
 432 }
 433
 434 auto inline void
 435 __attribute__ ((always_inline))
 436 elf_machine_lazy_rel (struct link_map *map,
 437                       Elf32_Addr l_addr, const Elf32_Rela *reloc)
 438 {
 439   Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
 440   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 441   /* Check for unexpected PLT reloc type.  */
 442   if (__builtin_expect (r_type == R_390_JMP_SLOT, 1))
 443     {
 444       if (__builtin_expect (map->l_mach.plt, 0) == 0)
 445         *reloc_addr += l_addr;
 446       else
 447         *reloc_addr =
 448           map->l_mach.plt
 449           + (((Elf32_Addr) reloc_addr) - map->l_mach.gotplt) * 8;
 450     }
 451   else
 452     _dl_reloc_bad_type (map, r_type, 1);
 453 }
 454
 455 #endif /* RESOLVE_MAP */