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

   1 /* Machine-dependent ELF dynamic relocation inline functions.  S390 Version.
   2    Copyright (C) 2000-2017 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 #if defined HAVE_S390_VX_ASM_SUPPORT
  93   extern void _dl_runtime_resolve_vx (Elf32_Word);
  94   extern void _dl_runtime_profile_vx (Elf32_Word);
  95 #endif
  96
  97
  98   if (l->l_info[DT_JMPREL] && lazy)
  99     {
 100       /* The GOT entries for functions in the PLT have not yet been filled
 101          in.  Their initial contents will arrange when called to push an
 102          offset into the .rel.plt section, push _GLOBAL_OFFSET_TABLE_[1],
 103          and then jump to _GLOBAL_OFFSET_TABLE[2].  */
 104       Elf32_Addr *got;
 105       got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
 106       /* If a library is prelinked but we have to relocate anyway,
 107          we have to be able to undo the prelinking of .got.plt.
 108          The prelinker saved us here address of .plt + 0x2c.  */
 109       if (got[1])
 110         {
 111           l->l_mach.plt = got[1] + l->l_addr;
 112           l->l_mach.jmprel = (const Elf32_Rela *) D_PTR (l, l_info[DT_JMPREL]);
 113         }
 114       got[1] = (Elf32_Addr) l;  /* Identify this shared object.  */
 115
 116       /* The got[2] entry contains the address of a function which gets
 117          called to get the address of a so far unresolved function and
 118          jump to it.  The profiling extension of the dynamic linker allows
 119          to intercept the calls to collect information.  In this case we
 120          don't store the address in the GOT so that all future calls also
 121          end in this function.  */
 122       if (__glibc_unlikely (profile))
 123         {
 124 #if defined HAVE_S390_VX_ASM_SUPPORT
 125           if (GLRO(dl_hwcap) & HWCAP_S390_VX)
 126             got[2] = (Elf32_Addr) &_dl_runtime_profile_vx;
 127           else
 128             got[2] = (Elf32_Addr) &_dl_runtime_profile;
 129 #else
 130           got[2] = (Elf32_Addr) &_dl_runtime_profile;
 131 #endif
 132
 133           if (GLRO(dl_profile) != NULL
 134               && _dl_name_match_p (GLRO(dl_profile), l))
 135             /* This is the object we are looking for.  Say that we really
 136                want profiling and the timers are started.  */
 137             GL(dl_profile_map) = l;
 138         }
 139       else
 140         {
 141           /* This function will get called to fix up the GOT entry indicated by
 142              the offset on the stack, and then jump to the resolved address.  */
 143 #if defined HAVE_S390_VX_ASM_SUPPORT
 144           if (GLRO(dl_hwcap) & HWCAP_S390_VX)
 145             got[2] = (Elf32_Addr) &_dl_runtime_resolve_vx;
 146           else
 147             got[2] = (Elf32_Addr) &_dl_runtime_resolve;
 148 #else
 149           got[2] = (Elf32_Addr) &_dl_runtime_resolve;
 150 #endif
 151         }
 152     }
 153
 154   return lazy;
 155 }
 156
 157 /* Mask identifying addresses reserved for the user program,
 158    where the dynamic linker should not map anything.  */
 159 #define ELF_MACHINE_USER_ADDRESS_MASK   0xf8000000UL
 160
 161 /* Initial entry point code for the dynamic linker.
 162    The C function `_dl_start' is the real entry point;
 163    its return value is the user program's entry point.  */
 164
 165 #define RTLD_START __asm__ ("\n\
 166 .text\n\
 167 .align 4\n\
 168 .globl _start\n\
 169 .globl _dl_start_user\n\
 170 _start:\n\
 171         basr  %r13,0\n\
 172 0:      ahi   %r13,.Llit-0b\n\
 173         lr    %r2,%r15\n\
 174         # Alloc stack frame\n\
 175         ahi   %r15,-96\n\
 176         # Set the back chain to zero\n\
 177         xc    0(4,%r15),0(%r15)\n\
 178         # Call _dl_start with %r2 pointing to arg on stack\n\
 179         l     %r14,.Ladr1-.Llit(%r13)\n\
 180         bas   %r14,0(%r14,%r13)   # call _dl_start\n\
 181 _dl_start_user:\n\
 182         # Save the user entry point address in %r8.\n\
 183         lr    %r8,%r2\n\
 184         # Point %r12 at the GOT.\n\
 185         l     %r12,.Ladr0-.Llit(%r13)\n\
 186         ar    %r12,%r13\n\
 187         # See if we were run as a command with the executable file\n\
 188         # name as an extra leading argument.\n\
 189         l     %r1,_dl_skip_args@GOT(%r12)\n\
 190         l     %r1,0(%r1)        # load _dl_skip_args\n\
 191         ltr   %r1,%r1\n\
 192         je    4f                # Skip the arg adjustment if there were none.\n\
 193         # Get the original argument count.\n\
 194         l     %r0,96(%r15)\n\
 195         # Subtract _dl_skip_args from it.\n\
 196         sr    %r0,%r1\n\
 197         # Store back the modified argument count.\n\
 198         st    %r0,96(%r15)\n\
 199         # Copy argv and envp forward to account for skipped argv entries.\n\
 200         # We skipped at least one argument or we would not get here.\n\
 201         la    %r6,100(%r15)     # Destination pointer i.e. &argv[0]\n\
 202         lr    %r5,%r6\n\
 203         lr    %r0,%r1\n\
 204         sll   %r0,2\n           # Number of skipped bytes.\n\
 205         ar    %r5,%r0           # Source pointer = Dest + Skipped args.\n\
 206         # argv copy loop:\n\
 207 1:      l     %r7,0(%r5)        # Load a word from the source.\n\
 208         st    %r7,0(%r6)        # Store the word in the destination.\n\
 209         ahi   %r5,4\n\
 210         ahi   %r6,4\n\
 211         ltr   %r7,%r7\n\
 212         jne   1b                # Stop after copying the NULL.\n\
 213         # envp copy loop:\n\
 214 2:      l     %r7,0(%r5)        # Load a word from the source.\n\
 215         st    %r7,0(%r6)        # Store the word in the destination.\n\
 216         ahi   %r5,4\n\
 217         ahi   %r6,4\n\
 218         ltr   %r7,%r7\n\
 219         jne   2b                # Stop after copying the NULL.\n\
 220         # Now we have to zero out the envp entries after NULL to allow\n\
 221         # start.S to properly find auxv by skipping zeroes.\n\
 222         # zero out loop:\n\
 223         lhi   %r7,0\n\
 224 3:      st    %r7,0(%r6)        # Store zero.\n\
 225         ahi   %r6,4             # Advance dest pointer.\n\
 226         ahi   %r1,-1            # Subtract one from the word count.\n\
 227         ltr   %r1,%r1\n\
 228         jne    3b               # Keep copying if the word count is non-zero.\n\
 229         # Adjust _dl_argv\n\
 230         la    %r6,100(%r15)\n\
 231         l     %r1,_dl_argv@GOT(%r12)\n\
 232         st    %r6,0(%r1)\n\
 233         # The special initializer gets called with the stack just\n\
 234         # as the application's entry point will see it; it can\n\
 235         # switch stacks if it moves these contents over.\n\
 236 " RTLD_START_SPECIAL_INIT "\n\
 237         # Call the function to run the initializers.\n\
 238         # Load the parameters:\n\
 239         # (%r2, %r3, %r4, %r5) = (_dl_loaded, argc, argv, envp)\n\
 240 4:      l     %r2,_rtld_local@GOT(%r12)\n\
 241         l     %r2,0(%r2)\n\
 242         l     %r3,96(%r15)\n\
 243         la    %r4,100(%r15)\n\
 244         lr    %r5,%r3\n\
 245         sll   %r5,2\n\
 246         la    %r5,104(%r5,%r15)\n\
 247         l     %r1,.Ladr4-.Llit(%r13)\n\
 248         bas   %r14,0(%r1,%r13)\n\
 249         # Pass our finalizer function to the user in %r14, as per ELF ABI.\n\
 250         l     %r14,_dl_fini@GOT(%r12)\n\
 251         # Free stack frame\n\
 252         ahi   %r15,96\n\
 253         # Jump to the user's entry point (saved in %r8).\n\
 254         br    %r8\n\
 255 .Llit:\n\
 256 .Ladr0: .long _GLOBAL_OFFSET_TABLE_-.Llit\n\
 257 .Ladr1: .long _dl_start-.Llit\n\
 258 .Ladr4: .long _dl_init@PLT-.Llit\n\
 259 ");
 260
 261 #ifndef RTLD_START_SPECIAL_INIT
 262 #define RTLD_START_SPECIAL_INIT /* nothing */
 263 #endif
 264
 265 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
 266    TLS variable, so undefined references should not be allowed to
 267    define the value.
 268    ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
 269    of the main executable's symbols, as for a COPY reloc.  */
 270 #define elf_machine_type_class(type) \
 271   ((((type) == R_390_JMP_SLOT || (type) == R_390_TLS_DTPMOD                   \
 272      || (type) == R_390_TLS_DTPOFF || (type) == R_390_TLS_TPOFF)              \
 273     * ELF_RTYPE_CLASS_PLT)                                                    \
 274    | (((type) == R_390_COPY) * ELF_RTYPE_CLASS_COPY))
 275
 276 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 277 #define ELF_MACHINE_JMP_SLOT    R_390_JMP_SLOT
 278
 279 /* The S390 never uses Elf32_Rel relocations.  */
 280 #define ELF_MACHINE_NO_REL 1
 281 #define ELF_MACHINE_NO_RELA 0
 282
 283 /* We define an initialization functions.  This is called very early in
 284    _dl_sysdep_start.  */
 285 #define DL_PLATFORM_INIT dl_platform_init ()
 286
 287 static inline void __attribute__ ((unused))
 288 dl_platform_init (void)
 289 {
 290   if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0')
 291     /* Avoid an empty string which would disturb us.  */
 292     GLRO(dl_platform) = NULL;
 293 }
 294
 295 static inline Elf32_Addr
 296 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 297                        const Elf32_Rela *reloc,
 298                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 299 {
 300   return *reloc_addr = value;
 301 }
 302
 303 /* Return the final value of a plt relocation.  */
 304 static inline Elf32_Addr
 305 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 306                        Elf32_Addr value)
 307 {
 308   return value;
 309 }
 310
 311 /* Names of the architecture-specific auditing callback functions.  */
 312 #define ARCH_LA_PLTENTER s390_32_gnu_pltenter
 313 #define ARCH_LA_PLTEXIT s390_32_gnu_pltexit
 314
 315 #endif /* !dl_machine_h */
 316
 317
 318 #ifdef RESOLVE_MAP
 319
 320 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 321    MAP is the object containing the reloc.  */
 322
 323 auto inline void
 324 __attribute__ ((always_inline))
 325 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 326                   const Elf32_Sym *sym, const struct r_found_version *version,
 327                   void *const reloc_addr_arg, int skip_ifunc)
 328 {
 329   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 330   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 331
 332 #if !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC
 333   if (__glibc_unlikely (r_type == R_390_RELATIVE))
 334     {
 335 # if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC
 336       /* This is defined in rtld.c, but nowhere in the static libc.a;
 337          make the reference weak so static programs can still link.
 338          This declaration cannot be done when compiling rtld.c
 339          (i.e. #ifdef RTLD_BOOTSTRAP) because rtld.c contains the
 340          common defn for _dl_rtld_map, which is incompatible with a
 341          weak decl in the same file.  */
 342 #  ifndef SHARED
 343       weak_extern (GL(dl_rtld_map));
 344 #  endif
 345       if (map != &GL(dl_rtld_map)) /* Already done in rtld itself.  */
 346 # endif
 347         *reloc_addr = map->l_addr + reloc->r_addend;
 348     }
 349   else
 350 #endif
 351   if (__glibc_unlikely (r_type == R_390_NONE))
 352     return;
 353   else
 354     {
 355 #if !defined RTLD_BOOTSTRAP && !defined RESOLVE_CONFLICT_FIND_MAP
 356       /* Only needed for R_390_COPY below.  */
 357       const Elf32_Sym *const refsym = sym;
 358 #endif
 359       struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
 360       Elf32_Addr value = sym == NULL ? 0 : sym_map->l_addr + sym->st_value;
 361
 362       if (sym != NULL
 363           && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0)
 364           && __builtin_expect (sym->st_shndx != SHN_UNDEF, 1)
 365           && __builtin_expect (!skip_ifunc, 1))
 366         value = elf_ifunc_invoke (value);
 367
 368       switch (r_type)
 369         {
 370         case R_390_IRELATIVE:
 371           value = map->l_addr + reloc->r_addend;
 372           if (__glibc_likely (!skip_ifunc))
 373             value = elf_ifunc_invoke (value);
 374           *reloc_addr = value;
 375           break;
 376
 377         case R_390_GLOB_DAT:
 378         case R_390_JMP_SLOT:
 379           *reloc_addr = value + reloc->r_addend;
 380           break;
 381
 382 #ifndef RESOLVE_CONFLICT_FIND_MAP
 383         case R_390_TLS_DTPMOD:
 384 # ifdef RTLD_BOOTSTRAP
 385           /* During startup the dynamic linker is always the module
 386              with index 1.
 387              XXX If this relocation is necessary move before RESOLVE
 388              call.  */
 389           *reloc_addr = 1;
 390 # else
 391           /* Get the information from the link map returned by the
 392              resolv function.  */
 393           if (sym_map != NULL)
 394             *reloc_addr = sym_map->l_tls_modid;
 395 # endif
 396           break;
 397         case R_390_TLS_DTPOFF:
 398 # ifndef RTLD_BOOTSTRAP
 399           /* During relocation all TLS symbols are defined and used.
 400              Therefore the offset is already correct.  */
 401           if (sym != NULL)
 402             *reloc_addr = sym->st_value + reloc->r_addend;
 403 # endif
 404           break;
 405         case R_390_TLS_TPOFF:
 406           /* The offset is negative, forward from the thread pointer.  */
 407 # ifdef RTLD_BOOTSTRAP
 408           *reloc_addr = sym->st_value + reloc->r_addend - map->l_tls_offset;
 409 # else
 410           /* We know the offset of the object the symbol is contained in.
 411              It is a negative value which will be added to the
 412              thread pointer.  */
 413           if (sym != NULL)
 414             {
 415               CHECK_STATIC_TLS (map, sym_map);
 416               *reloc_addr = (sym->st_value + reloc->r_addend
 417                              - sym_map->l_tls_offset);
 418             }
 419 #endif
 420           break;
 421 #endif  /* use TLS */
 422
 423 #ifndef RTLD_BOOTSTRAP
 424 # ifndef RESOLVE_CONFLICT_FIND_MAP
 425         /* Not needed in dl-conflict.c.  */
 426         case R_390_COPY:
 427           if (sym == NULL)
 428             /* This can happen in trace mode if an object could not be
 429                found.  */
 430             break;
 431           if (__builtin_expect (sym->st_size > refsym->st_size, 0)
 432               || (__builtin_expect (sym->st_size < refsym->st_size, 0)
 433                   && __builtin_expect (GLRO(dl_verbose), 0)))
 434             {
 435               const char *strtab;
 436
 437               strtab = (const char *) D_PTR(map,l_info[DT_STRTAB]);
 438               _dl_error_printf ("\
 439 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
 440                                 RTLD_PROGNAME, strtab + refsym->st_name);
 441             }
 442           memcpy (reloc_addr_arg, (void *) value,
 443                   MIN (sym->st_size, refsym->st_size));
 444           break;
 445 # endif
 446         case R_390_32:
 447           *reloc_addr = value + reloc->r_addend;
 448           break;
 449         case R_390_16:
 450           *(unsigned short *) reloc_addr = value + reloc->r_addend;
 451           break;
 452         case R_390_8:
 453           *(char *) reloc_addr = value + reloc->r_addend;
 454           break;
 455 # ifndef RESOLVE_CONFLICT_FIND_MAP
 456         case R_390_PC32:
 457           *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 458           break;
 459         case R_390_PC16DBL:
 460           *(unsigned short *) reloc_addr = (unsigned short)
 461             ((short) (value + reloc->r_addend - (Elf32_Addr) reloc_addr) >> 1);
 462           break;
 463         case R_390_PC32DBL:
 464           *(unsigned int *) reloc_addr = (unsigned int)
 465             ((int) (value + reloc->r_addend - (Elf32_Addr) reloc_addr) >> 1);
 466           break;
 467         case R_390_PC16:
 468           *(unsigned short *) reloc_addr =
 469             value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 470           break;
 471         case R_390_NONE:
 472           break;
 473 # endif
 474 #endif
 475 #if !defined(RTLD_BOOTSTRAP) || defined(_NDEBUG)
 476         default:
 477           /* We add these checks in the version to relocate ld.so only
 478              if we are still debugging.  */
 479           _dl_reloc_bad_type (map, r_type, 0);
 480           break;
 481 #endif
 482         }
 483     }
 484 }
 485
 486 auto inline void
 487 __attribute__ ((always_inline))
 488 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
 489                            void *const reloc_addr_arg)
 490 {
 491   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 492   *reloc_addr = l_addr + reloc->r_addend;
 493 }
 494
 495 auto inline void
 496 __attribute__ ((always_inline))
 497 elf_machine_lazy_rel (struct link_map *map,
 498                       Elf32_Addr l_addr, const Elf32_Rela *reloc,
 499                       int skip_ifunc)
 500 {
 501   Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
 502   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 503   /* Check for unexpected PLT reloc type.  */
 504   if (__glibc_likely (r_type == R_390_JMP_SLOT))
 505     {
 506       if (__builtin_expect (map->l_mach.plt, 0) == 0)
 507         *reloc_addr += l_addr;
 508       else
 509         *reloc_addr = map->l_mach.plt + (reloc - map->l_mach.jmprel) * 32;
 510     }
 511   else if (__glibc_likely (r_type == R_390_IRELATIVE))
 512     {
 513       Elf32_Addr value = map->l_addr + reloc->r_addend;
 514       if (__glibc_likely (!skip_ifunc))
 515         value = elf_ifunc_invoke (value);
 516       *reloc_addr = value;
 517     }
 518   else
 519     _dl_reloc_bad_type (map, r_type, 1);
 520 }
 521
 522 #endif /* RESOLVE_MAP */