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glibc  2.9
dl-machine.h
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00001 /* Machine-dependent ELF dynamic relocation inline functions.  S390 Version.
00002    Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006
00003    Free Software Foundation, Inc.
00004    Contributed by Carl Pederson & Martin Schwidefsky.
00005    This file is part of the GNU C Library.
00006 
00007    The GNU C Library is free software; you can redistribute it and/or
00008    modify it under the terms of the GNU Lesser General Public
00009    License as published by the Free Software Foundation; either
00010    version 2.1 of the License, or (at your option) any later version.
00011 
00012    The GNU C Library is distributed in the hope that it will be useful,
00013    but WITHOUT ANY WARRANTY; without even the implied warranty of
00014    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015    Lesser General Public License for more details.
00016 
00017    You should have received a copy of the GNU Lesser General Public
00018    License along with the GNU C Library; if not, write to the Free
00019    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00020    02111-1307 USA.  */
00021 
00022 #ifndef dl_machine_h
00023 #define dl_machine_h
00024 
00025 #define ELF_MACHINE_NAME "s390"
00026 
00027 #include <sys/param.h>
00028 #include <string.h>
00029 #include <link.h>
00030 
00031 /* This is an older, now obsolete value.  */
00032 #define EM_S390_OLD  0xA390
00033 
00034 /* Return nonzero iff ELF header is compatible with the running host.  */
00035 static inline int
00036 elf_machine_matches_host (const Elf32_Ehdr *ehdr)
00037 {
00038   return (ehdr->e_machine == EM_S390 || ehdr->e_machine == EM_S390_OLD)
00039          && ehdr->e_ident[EI_CLASS] == ELFCLASS32;
00040 }
00041 
00042 
00043 /* Return the link-time address of _DYNAMIC.  Conveniently, this is the
00044    first element of the GOT.  This must be inlined in a function which
00045    uses global data.  */
00046 
00047 static inline Elf32_Addr
00048 elf_machine_dynamic (void)
00049 {
00050   register Elf32_Addr *got;
00051 
00052   asm( "        bras   %0,2f\n"
00053        "1:      .long  _GLOBAL_OFFSET_TABLE_-1b\n"
00054        "2:      al     %0,0(%0)"
00055        : "=&a" (got) : : "0" );
00056 
00057   return *got;
00058 }
00059 
00060 
00061 /* Return the run-time load address of the shared object.  */
00062 static inline Elf32_Addr
00063 elf_machine_load_address (void)
00064 {
00065   Elf32_Addr addr;
00066 
00067   asm( "   bras  1,2f\n"
00068        "1: .long _GLOBAL_OFFSET_TABLE_ - 1b\n"
00069        "   .long _dl_start - 1b - 0x80000000\n"
00070        "2: l     %0,4(1)\n"
00071        "   ar    %0,1\n"
00072        "   al    1,0(1)\n"
00073        "   sl    %0,_dl_start@GOT12(1)"
00074        : "=&d" (addr) : : "1" );
00075   return addr;
00076 }
00077 
00078 /* Set up the loaded object described by L so its unrelocated PLT
00079    entries will jump to the on-demand fixup code in dl-runtime.c.  */
00080 
00081 static inline int __attribute__ ((unused))
00082 elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
00083 {
00084   extern void _dl_runtime_resolve (Elf32_Word);
00085   extern void _dl_runtime_profile (Elf32_Word);
00086 
00087   if (l->l_info[DT_JMPREL] && lazy)
00088     {
00089       /* The GOT entries for functions in the PLT have not yet been filled
00090         in.  Their initial contents will arrange when called to push an
00091         offset into the .rel.plt section, push _GLOBAL_OFFSET_TABLE_[1],
00092         and then jump to _GLOBAL_OFFSET_TABLE[2].  */
00093       Elf32_Addr *got;
00094       got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
00095       /* If a library is prelinked but we have to relocate anyway,
00096         we have to be able to undo the prelinking of .got.plt.
00097         The prelinker saved us here address of .plt + 0x2c.  */
00098       if (got[1])
00099        {
00100          l->l_mach.plt = got[1] + l->l_addr;
00101          l->l_mach.gotplt = (Elf32_Addr) &got[3];
00102        }
00103       got[1] = (Elf32_Addr) l;     /* Identify this shared object.  */
00104 
00105       /* The got[2] entry contains the address of a function which gets
00106         called to get the address of a so far unresolved function and
00107         jump to it.  The profiling extension of the dynamic linker allows
00108         to intercept the calls to collect information.  In this case we
00109         don't store the address in the GOT so that all future calls also
00110         end in this function.  */
00111       if (__builtin_expect (profile, 0))
00112        {
00113          got[2] = (Elf32_Addr) &_dl_runtime_profile;
00114 
00115          if (GLRO(dl_profile) != NULL
00116              && _dl_name_match_p (GLRO(dl_profile), l))
00117            /* This is the object we are looking for.  Say that we really
00118               want profiling and the timers are started.  */
00119            GL(dl_profile_map) = l;
00120        }
00121       else
00122        /* This function will get called to fix up the GOT entry indicated by
00123           the offset on the stack, and then jump to the resolved address.  */
00124        got[2] = (Elf32_Addr) &_dl_runtime_resolve;
00125     }
00126 
00127   return lazy;
00128 }
00129 
00130 /* Mask identifying addresses reserved for the user program,
00131    where the dynamic linker should not map anything.  */
00132 #define ELF_MACHINE_USER_ADDRESS_MASK   0xf8000000UL
00133 
00134 /* Initial entry point code for the dynamic linker.
00135    The C function `_dl_start' is the real entry point;
00136    its return value is the user program's entry point.  */
00137 
00138 #define RTLD_START asm ("\n\
00139 .text\n\
00140 .align 4\n\
00141 .globl _start\n\
00142 .globl _dl_start_user\n\
00143 _start:\n\
00144        basr  %r13,0\n\
00145 .L0:    ahi   %r13,.Llit-.L0\n\
00146        lr    %r2,%r15\n\
00147        # Alloc stack frame\n\
00148        ahi   %r15,-96\n\
00149        # Set the back chain to zero\n\
00150        xc    0(4,%r15),0(%r15)\n\
00151        # Call _dl_start with %r2 pointing to arg on stack\n\
00152        l     %r14,.Ladr1-.Llit(%r13)\n\
00153        bas   %r14,0(%r14,%r13)   # call _dl_start\n\
00154 _dl_start_user:\n\
00155        # Save the user entry point address in %r8.\n\
00156        lr    %r8,%r2\n\
00157        # Point %r12 at the GOT.\n\
00158        l     %r12,.Ladr0-.Llit(%r13)\n\
00159        ar    %r12,%r13\n\
00160        # See if we were run as a command with the executable file\n\
00161        # name as an extra leading argument.\n\
00162        l     %r1,_dl_skip_args@GOT12(0,%r12)\n\
00163        l     %r1,0(%r1)          # load _dl_skip_args\n\
00164        # Get the original argument count.\n\
00165        l     %r0,96(%r15)\n\
00166        # Subtract _dl_skip_args from it.\n\
00167        sr    %r0,%r1\n\
00168        # Adjust the stack pointer to skip _dl_skip_args words.\n\
00169        sll   %r1,2\n\
00170        ar    %r15,%r1\n\
00171        # Set the back chain to zero again\n\
00172        xc    0(4,%r15),0(%r15)\n\
00173        # Store back the modified argument count.\n\
00174        st    %r0,96(%r15)\n\
00175        # The special initializer gets called with the stack just\n\
00176        # as the application's entry point will see it; it can\n\
00177        # switch stacks if it moves these contents over.\n\
00178 " RTLD_START_SPECIAL_INIT "\n\
00179        # Call the function to run the initializers.\n\
00180        # Load the parameters:\n\
00181        # (%r2, %r3, %r4, %r5) = (_dl_loaded, argc, argv, envp)\n\
00182        l     %r2,_rtld_local@GOT(%r12)\n\
00183        l     %r2,0(%r2)\n\
00184        l     %r3,96(%r15)\n\
00185        la    %r4,100(%r15)\n\
00186        lr    %r5,%r3\n\
00187        sll   %r5,2\n\
00188        la    %r5,104(%r5,%r15)\n\
00189        l     %r1,.Ladr4-.Llit(%r13)\n\
00190        bas   %r14,0(%r1,%r13)\n\
00191        # Pass our finalizer function to the user in %r14, as per ELF ABI.\n\
00192        l     %r14,_dl_fini@GOT(%r12)\n\
00193        # Free stack frame\n\
00194        ahi   %r15,96\n\
00195        # Jump to the user's entry point (saved in %r8).\n\
00196        br    %r8\n\
00197 .Llit:\n\
00198 .Ladr0: .long _GLOBAL_OFFSET_TABLE_-.Llit\n\
00199 .Ladr1: .long _dl_start-.Llit\n\
00200 .Ladr4: .long _dl_init_internal@PLT-.Llit\n\
00201 ");
00202 
00203 #ifndef RTLD_START_SPECIAL_INIT
00204 #define RTLD_START_SPECIAL_INIT /* nothing */
00205 #endif
00206 
00207 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
00208    TLS variable, so undefined references should not be allowed to
00209    define the value.
00210    ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one
00211    of the main executable's symbols, as for a COPY reloc.  */
00212 #define elf_machine_type_class(type) \
00213   ((((type) == R_390_JMP_SLOT || (type) == R_390_TLS_DTPMOD                 \
00214      || (type) == R_390_TLS_DTPOFF || (type) == R_390_TLS_TPOFF)            \
00215     * ELF_RTYPE_CLASS_PLT)                                           \
00216    | (((type) == R_390_COPY) * ELF_RTYPE_CLASS_COPY))
00217 
00218 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
00219 #define ELF_MACHINE_JMP_SLOT    R_390_JMP_SLOT
00220 
00221 /* The S390 never uses Elf32_Rel relocations.  */
00222 #define ELF_MACHINE_NO_REL 1
00223 
00224 /* The S390 overlaps DT_RELA and DT_PLTREL.  */
00225 #define ELF_MACHINE_PLTREL_OVERLAP 1
00226 
00227 /* We define an initialization functions.  This is called very early in
00228    _dl_sysdep_start.  */
00229 #define DL_PLATFORM_INIT dl_platform_init ()
00230 
00231 static inline void __attribute__ ((unused))
00232 dl_platform_init (void)
00233 {
00234   if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0')
00235     /* Avoid an empty string which would disturb us.  */
00236     GLRO(dl_platform) = NULL;
00237 }
00238 
00239 static inline Elf32_Addr
00240 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
00241                      const Elf32_Rela *reloc,
00242                      Elf32_Addr *reloc_addr, Elf32_Addr value)
00243 {
00244   return *reloc_addr = value;
00245 }
00246 
00247 /* Return the final value of a plt relocation.  */
00248 static inline Elf32_Addr
00249 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
00250                      Elf32_Addr value)
00251 {
00252   return value;
00253 }
00254 
00255 /* Names of the architecture-specific auditing callback functions.  */
00256 #define ARCH_LA_PLTENTER s390_32_gnu_pltenter
00257 #define ARCH_LA_PLTEXIT s390_32_gnu_pltexit
00258 
00259 #endif /* !dl_machine_h */
00260 
00261 
00262 #ifdef RESOLVE_MAP
00263 
00264 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
00265    MAP is the object containing the reloc.  */
00266 
00267 auto inline void
00268 __attribute__ ((always_inline))
00269 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
00270                 const Elf32_Sym *sym, const struct r_found_version *version,
00271                 void *const reloc_addr_arg)
00272 {
00273   Elf32_Addr *const reloc_addr = reloc_addr_arg;
00274   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
00275 
00276 #if !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC
00277   if (__builtin_expect (r_type == R_390_RELATIVE, 0))
00278     {
00279 # if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC
00280       /* This is defined in rtld.c, but nowhere in the static libc.a;
00281         make the reference weak so static programs can still link.
00282         This declaration cannot be done when compiling rtld.c
00283         (i.e. #ifdef RTLD_BOOTSTRAP) because rtld.c contains the
00284         common defn for _dl_rtld_map, which is incompatible with a
00285         weak decl in the same file.  */
00286 #  ifndef SHARED
00287       weak_extern (GL(dl_rtld_map));
00288 #  endif
00289       if (map != &GL(dl_rtld_map)) /* Already done in rtld itself.  */
00290 # endif
00291        *reloc_addr = map->l_addr + reloc->r_addend;
00292     }
00293   else
00294 #endif
00295   if (__builtin_expect (r_type == R_390_NONE, 0))
00296     return;
00297   else
00298     {
00299 #ifndef RESOLVE_CONFLICT_FIND_MAP
00300       const Elf32_Sym *const refsym = sym;
00301 #endif
00302       struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
00303       Elf32_Addr value = sym == NULL ? 0 : sym_map->l_addr + sym->st_value;
00304 
00305       switch (r_type)
00306        {
00307        case R_390_GLOB_DAT:
00308        case R_390_JMP_SLOT:
00309          *reloc_addr = value + reloc->r_addend;
00310          break;
00311 
00312 #if (!defined RTLD_BOOTSTRAP || USE___THREAD) \
00313     && !defined RESOLVE_CONFLICT_FIND_MAP
00314        case R_390_TLS_DTPMOD:
00315 # ifdef RTLD_BOOTSTRAP
00316          /* During startup the dynamic linker is always the module
00317             with index 1.
00318             XXX If this relocation is necessary move before RESOLVE
00319             call.  */
00320          *reloc_addr = 1;
00321 # else
00322          /* Get the information from the link map returned by the
00323             resolv function.  */
00324          if (sym_map != NULL)
00325            *reloc_addr = sym_map->l_tls_modid;
00326 # endif
00327          break;
00328        case R_390_TLS_DTPOFF:
00329 # ifndef RTLD_BOOTSTRAP
00330          /* During relocation all TLS symbols are defined and used.
00331             Therefore the offset is already correct.  */
00332          if (sym != NULL)
00333            *reloc_addr = sym->st_value + reloc->r_addend;
00334 # endif
00335          break;
00336        case R_390_TLS_TPOFF:
00337          /* The offset is negative, forward from the thread pointer.  */
00338 # ifdef RTLD_BOOTSTRAP
00339          *reloc_addr = sym->st_value + reloc->r_addend - map->l_tls_offset;
00340 # else
00341          /* We know the offset of the object the symbol is contained in.
00342             It is a negative value which will be added to the
00343             thread pointer.  */
00344          if (sym != NULL)
00345            {
00346              CHECK_STATIC_TLS (map, sym_map);
00347              *reloc_addr = (sym->st_value + reloc->r_addend
00348                           - sym_map->l_tls_offset);
00349            }
00350 #endif
00351          break;
00352 #endif  /* use TLS */
00353 
00354 #ifndef RTLD_BOOTSTRAP
00355 # ifndef RESOLVE_CONFLICT_FIND_MAP
00356        /* Not needed in dl-conflict.c.  */
00357        case R_390_COPY:
00358          if (sym == NULL)
00359            /* This can happen in trace mode if an object could not be
00360               found.  */
00361            break;
00362          if (__builtin_expect (sym->st_size > refsym->st_size, 0)
00363              || (__builtin_expect (sym->st_size < refsym->st_size, 0)
00364                 && __builtin_expect (GLRO(dl_verbose), 0)))
00365            {
00366              const char *strtab;
00367 
00368              strtab = (const char *) D_PTR(map,l_info[DT_STRTAB]);
00369              _dl_error_printf ("\
00370 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
00371                             rtld_progname ?: "<program name unknown>",
00372                             strtab + refsym->st_name);
00373            }
00374          memcpy (reloc_addr_arg, (void *) value,
00375                 MIN (sym->st_size, refsym->st_size));
00376          break;
00377 # endif
00378        case R_390_32:
00379          *reloc_addr = value + reloc->r_addend;
00380          break;
00381        case R_390_16:
00382          *(unsigned short *) reloc_addr = value + reloc->r_addend;
00383          break;
00384        case R_390_8:
00385          *(char *) reloc_addr = value + reloc->r_addend;
00386          break;
00387 # ifndef RESOLVE_CONFLICT_FIND_MAP
00388        case R_390_PC32:
00389          *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
00390          break;
00391        case R_390_PC16DBL:
00392        case R_390_PLT16DBL:
00393          *(unsigned short *) reloc_addr = (unsigned short)
00394            ((short) (value + reloc->r_addend - (Elf32_Addr) reloc_addr) >> 1);
00395          break;
00396        case R_390_PC16:
00397          *(unsigned short *) reloc_addr =
00398            value + reloc->r_addend - (Elf32_Addr) reloc_addr;
00399          break;
00400        case R_390_NONE:
00401          break;
00402 # endif
00403 #endif
00404 #if !defined(RTLD_BOOTSTRAP) || defined(_NDEBUG)
00405        default:
00406          /* We add these checks in the version to relocate ld.so only
00407             if we are still debugging.     */
00408          _dl_reloc_bad_type (map, r_type, 0);
00409          break;
00410 #endif
00411        }
00412     }
00413 }
00414 
00415 auto inline void
00416 __attribute__ ((always_inline))
00417 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
00418                         void *const reloc_addr_arg)
00419 {
00420   Elf32_Addr *const reloc_addr = reloc_addr_arg;
00421   *reloc_addr = l_addr + reloc->r_addend;
00422 }
00423 
00424 auto inline void
00425 __attribute__ ((always_inline))
00426 elf_machine_lazy_rel (struct link_map *map,
00427                     Elf32_Addr l_addr, const Elf32_Rela *reloc)
00428 {
00429   Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
00430   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
00431   /* Check for unexpected PLT reloc type.  */
00432   if (__builtin_expect (r_type == R_390_JMP_SLOT, 1))
00433     {
00434       if (__builtin_expect (map->l_mach.plt, 0) == 0)
00435        *reloc_addr += l_addr;
00436       else
00437        *reloc_addr =
00438          map->l_mach.plt
00439          + (((Elf32_Addr) reloc_addr) - map->l_mach.gotplt) * 8;
00440     }
00441   else
00442     _dl_reloc_bad_type (map, r_type, 1);
00443 }
00444 
00445 #endif /* RESOLVE_MAP */