sysdeps/sh/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  SH version.
   2    Copyright (C) 1999-2020 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef dl_machine_h
  20 #define dl_machine_h
  21
  22 #define ELF_MACHINE_NAME "SH"
  23
  24 #include <sys/param.h>
  25 #include <sysdep.h>
  26 #include <assert.h>
  27
  28 /* Return nonzero iff ELF header is compatible with the running host.  */
  29 static inline int __attribute__ ((unused))
  30 elf_machine_matches_host (const Elf32_Ehdr *ehdr)
  31 {
  32   return ehdr->e_machine == EM_SH;
  33 }
  34
  35
  36 /* Return the link-time address of _DYNAMIC.  Conveniently, this is the
  37    first element of the GOT.  This must be inlined in a function which
  38    uses global data.  */
  39 static inline Elf32_Addr __attribute__ ((unused))
  40 elf_machine_dynamic (void)
  41 {
  42   register Elf32_Addr *got;
  43   asm ("mov r12,%0" :"=r" (got));
  44   return *got;
  45 }
  46
  47
  48 /* Return the run-time load address of the shared object.  */
  49 static inline Elf32_Addr __attribute__ ((unused))
  50 elf_machine_load_address (void)
  51 {
  52   Elf32_Addr addr;
  53   asm ("mov.l 1f,r0\n\
  54         mov.l 3f,r2\n\
  55         add r12,r2\n\
  56         mov.l @(r0,r12),r0\n\
  57         bra 2f\n\
  58          sub r0,r2\n\
  59         .align 2\n\
  60         1: .long _dl_start@GOT\n\
  61         3: .long _dl_start@GOTOFF\n\
  62         2: mov r2,%0"
  63        : "=r" (addr) : : "r0", "r1", "r2");
  64   return addr;
  65 }
  66
  67
  68 /* Set up the loaded object described by L so its unrelocated PLT
  69    entries will jump to the on-demand fixup code in dl-runtime.c.  */
  70
  71 static inline int __attribute__ ((unused, always_inline))
  72 elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
  73 {
  74   Elf32_Addr *got;
  75   extern void _dl_runtime_resolve (Elf32_Word);
  76   extern void _dl_runtime_profile (Elf32_Word);
  77
  78   if (l->l_info[DT_JMPREL] && lazy)
  79     {
  80       /* The GOT entries for functions in the PLT have not yet been filled
  81          in.  Their initial contents will arrange when called to load an
  82          offset into the .rela.plt section and _GLOBAL_OFFSET_TABLE_[1],
  83          and then jump to _GLOBAL_OFFSET_TABLE[2].  */
  84       got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
  85       /* If a library is prelinked but we have to relocate anyway,
  86          we have to be able to undo the prelinking of .got.plt.
  87          The prelinker saved us here address of .plt + 36.  */
  88       if (got[1])
  89         {
  90           l->l_mach.plt = got[1] + l->l_addr;
  91           l->l_mach.gotplt = (Elf32_Addr) &got[3];
  92         }
  93       got[1] = (Elf32_Addr) l;  /* Identify this shared object.  */
  94
  95       /* The got[2] entry contains the address of a function which gets
  96          called to get the address of a so far unresolved function and
  97          jump to it.  The profiling extension of the dynamic linker allows
  98          to intercept the calls to collect information.  In this case we
  99          don't store the address in the GOT so that all future calls also
 100          end in this function.  */
 101       if (profile)
 102         {
 103           got[2] = (Elf32_Addr) &_dl_runtime_profile;
 104           /* Say that we really want profiling and the timers are started.  */
 105           if (GLRO(dl_profile) != NULL
 106               && _dl_name_match_p (GLRO(dl_profile), l))
 107             GL(dl_profile_map) = l;
 108         }
 109       else
 110         /* This function will get called to fix up the GOT entry indicated by
 111            the offset on the stack, and then jump to the resolved address.  */
 112         got[2] = (Elf32_Addr) &_dl_runtime_resolve;
 113     }
 114   return lazy;
 115 }
 116
 117 #define ELF_MACHINE_RUNTIME_FIXUP_ARGS int plt_type
 118 #define ELF_MACHINE_RUNTIME_FIXUP_PARAMS plt_type
 119
 120 /* Mask identifying addresses reserved for the user program,
 121    where the dynamic linker should not map anything.  */
 122 #define ELF_MACHINE_USER_ADDRESS_MASK   0x80000000UL
 123
 124 /* Initial entry point code for the dynamic linker.
 125    The C function `_dl_start' is the real entry point;
 126    its return value is the user program's entry point.  */
 127
 128 #define RTLD_START asm ("\
 129 .text\n\
 130 .globl _start\n\
 131 .globl _dl_start_user\n\
 132 _start:\n\
 133         mov r15,r4\n\
 134         mov.l .L_dl_start,r1\n\
 135         mova .L_dl_start,r0\n\
 136         add r1,r0\n\
 137         jsr @r0\n\
 138          nop\n\
 139 _dl_start_user:\n\
 140         ! Save the user entry point address in r8.\n\
 141         mov r0,r8\n\
 142         ! Point r12 at the GOT.\n\
 143         mov.l 1f,r12\n\
 144         mova 1f,r0\n\
 145         bra 2f\n\
 146          add r0,r12\n\
 147         .align 2\n\
 148 1:      .long _GLOBAL_OFFSET_TABLE_\n\
 149 2:      ! See if we were run as a command with the executable file\n\
 150         ! name as an extra leading argument.\n\
 151         mov.l .L_dl_skip_args,r0\n\
 152         mov.l @(r0,r12),r0\n\
 153         mov.l @r0,r0\n\
 154         ! Get the original argument count.\n\
 155         mov.l @r15,r5\n\
 156         ! Subtract _dl_skip_args from it.\n\
 157         sub r0,r5\n\
 158         ! Adjust the stack pointer to skip _dl_skip_args words.\n\
 159         shll2 r0\n\
 160         add r0,r15\n\
 161         ! Store back the modified argument count.\n\
 162         mov.l r5,@r15\n\
 163         ! Compute argv address and envp.\n\
 164         mov r15,r6\n\
 165         add #4,r6\n\
 166         mov r5,r7\n\
 167         shll2 r7\n\
 168         add r15,r7\n\
 169         add #8,r7\n\
 170         mov.l .L_dl_loaded,r0\n\
 171         mov.l @(r0,r12),r0\n\
 172         mov.l @r0,r4\n\
 173         ! Call _dl_init.\n\
 174         mov.l .L_dl_init,r1\n\
 175         mova .L_dl_init,r0\n\
 176         add r1,r0\n\
 177         jsr @r0\n\
 178          nop\n\
 179 1:      ! Pass our finalizer function to the user in r4, as per ELF ABI.\n\
 180         mov.l .L_dl_fini,r0\n\
 181         mov.l @(r0,r12),r4\n\
 182         ! Jump to the user's entry point.\n\
 183         jmp @r8\n\
 184          nop\n\
 185         .align 2\n\
 186 .L_dl_start:\n\
 187         .long _dl_start@PLT\n\
 188 .L_dl_skip_args:\n\
 189         .long _dl_skip_args@GOT\n\
 190 .L_dl_init:\n\
 191         .long _dl_init@PLT\n\
 192 .L_dl_loaded:\n\
 193         .long _rtld_local@GOT\n\
 194 .L_dl_fini:\n\
 195         .long _dl_fini@GOT\n\
 196         .type __fpscr_values,@object\n\
 197         .global __fpscr_values\n\
 198 __fpscr_values:\n\
 199         .long   0\n\
 200         .long   0x80000\n\
 201         .weak __fpscr_values\n\
 202 .previous\n\
 203 ");
 204
 205 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
 206    TLS variable, so undefined references should not be allowed to
 207    define the value.
 208    ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
 209    of the main executable's symbols, as for a COPY reloc.  */
 210 #define elf_machine_type_class(type) \
 211   ((((type) == R_SH_JMP_SLOT || (type) == R_SH_TLS_DTPMOD32                   \
 212      || (type) == R_SH_TLS_DTPOFF32 || (type) == R_SH_TLS_TPOFF32)            \
 213     * ELF_RTYPE_CLASS_PLT)                                                    \
 214    | (((type) == R_SH_COPY) * ELF_RTYPE_CLASS_COPY))
 215
 216 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 217 #define ELF_MACHINE_JMP_SLOT    R_SH_JMP_SLOT
 218
 219 /* We define an initialization functions.  This is called very early in
 220    _dl_sysdep_start.  */
 221 #define DL_PLATFORM_INIT dl_platform_init ()
 222
 223 static inline void __attribute__ ((unused))
 224 dl_platform_init (void)
 225 {
 226   if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0')
 227     /* Avoid an empty string which would disturb us.  */
 228     GLRO(dl_platform) = NULL;
 229 }
 230
 231 static inline Elf32_Addr
 232 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 233                        const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
 234                        const Elf32_Rela *reloc,
 235                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 236 {
 237   return *reloc_addr = value;
 238 }
 239
 240 /* Return the final value of a plt relocation.  */
 241 static inline Elf32_Addr
 242 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 243                        Elf32_Addr value)
 244 {
 245   return value + reloc->r_addend;
 246 }
 247
 248 #define ARCH_LA_PLTENTER sh_gnu_pltenter
 249 #define ARCH_LA_PLTEXIT sh_gnu_pltexit
 250
 251 #endif /* !dl_machine_h */
 252
 253 /* SH never uses Elf32_Rel relocations.  */
 254 #define ELF_MACHINE_NO_REL 1
 255 #define ELF_MACHINE_NO_RELA 0
 256
 257 #ifdef RESOLVE_MAP
 258
 259 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 260    MAP is the object containing the reloc.  */
 261
 262 auto inline void
 263 __attribute ((always_inline))
 264 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 265                   const Elf32_Sym *sym, const struct r_found_version *version,
 266                   void *const reloc_addr_arg, int skip_ifunc)
 267 {
 268   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 269   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 270   Elf32_Addr value;
 271
 272 #define COPY_UNALIGNED_WORD(swp, twp, align) \
 273   { \
 274     void *__s = (swp), *__t = (twp); \
 275     unsigned char *__s1 = __s, *__t1 = __t; \
 276     unsigned short *__s2 = __s, *__t2 = __t; \
 277     unsigned long *__s4 = __s, *__t4 = __t; \
 278     switch ((align)) \
 279     { \
 280     case 0: \
 281       *__t4 = *__s4; \
 282       break; \
 283     case 2: \
 284       *__t2++ = *__s2++; \
 285       *__t2 = *__s2; \
 286       break; \
 287     default: \
 288       *__t1++ = *__s1++; \
 289       *__t1++ = *__s1++; \
 290       *__t1++ = *__s1++; \
 291       *__t1 = *__s1; \
 292       break; \
 293     } \
 294   }
 295
 296   if (__glibc_unlikely (r_type == R_SH_RELATIVE))
 297     {
 298 #ifndef RTLD_BOOTSTRAP
 299       if (map != &GL(dl_rtld_map)) /* Already done in rtld itself.       */
 300 #endif
 301         {
 302           if (reloc->r_addend)
 303             value = map->l_addr + reloc->r_addend;
 304           else
 305             {
 306               COPY_UNALIGNED_WORD (reloc_addr_arg, &value,
 307                                    (int) reloc_addr_arg & 3);
 308               value += map->l_addr;
 309             }
 310           COPY_UNALIGNED_WORD (&value, reloc_addr_arg,
 311                                (int) reloc_addr_arg & 3);
 312         }
 313     }
 314 #ifndef RTLD_BOOTSTRAP
 315   else if (__glibc_unlikely (r_type == R_SH_NONE))
 316     return;
 317 #endif
 318   else
 319     {
 320       const Elf32_Sym *const refsym = sym;
 321       struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
 322
 323       value = SYMBOL_ADDRESS (sym_map, sym, true);
 324       value += reloc->r_addend;
 325
 326       switch (r_type)
 327         {
 328         case R_SH_COPY:
 329           if (sym == NULL)
 330             /* This can happen in trace mode if an object could not be
 331                found.  */
 332             break;
 333           if (sym->st_size > refsym->st_size
 334               || (sym->st_size < refsym->st_size && GLRO(dl_verbose)))
 335             {
 336               const char *strtab;
 337
 338               strtab = (const char *) D_PTR (map, l_info[DT_STRTAB]);
 339               _dl_error_printf ("\
 340 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
 341                                 RTLD_PROGNAME, strtab + refsym->st_name);
 342             }
 343           memcpy (reloc_addr_arg, (void *) value,
 344                   MIN (sym->st_size, refsym->st_size));
 345           break;
 346         case R_SH_GLOB_DAT:
 347         case R_SH_JMP_SLOT:
 348           /* These addresses are always aligned.  */
 349           *reloc_addr = value;
 350           break;
 351           /* XXX Remove TLS relocations which are not needed.  */
 352         case R_SH_TLS_DTPMOD32:
 353 #ifdef RTLD_BOOTSTRAP
 354           /* During startup the dynamic linker is always the module
 355              with index 1.
 356              XXX If this relocation is necessary move before RESOLVE
 357              call.  */
 358           *reloc_addr = 1;
 359 #else
 360           /* Get the information from the link map returned by the
 361              resolv function.  */
 362           if (sym_map != NULL)
 363             *reloc_addr = sym_map->l_tls_modid;
 364 #endif
 365           break;
 366         case R_SH_TLS_DTPOFF32:
 367 #ifndef RTLD_BOOTSTRAP
 368           /* During relocation all TLS symbols are defined and used.
 369              Therefore the offset is already correct.  */
 370           if (sym != NULL)
 371             *reloc_addr = sym->st_value;
 372 #endif
 373           break;
 374         case R_SH_TLS_TPOFF32:
 375           /* The offset is positive, afterward from the thread pointer.  */
 376 #ifdef RTLD_BOOTSTRAP
 377           *reloc_addr = map->l_tls_offset + sym->st_value + reloc->r_addend;
 378 #else
 379           /* We know the offset of object the symbol is contained in.
 380              It is a positive value which will be added to the thread
 381              pointer.  To get the variable position in the TLS block
 382              we add the offset from that of the TLS block.  */
 383           if (sym != NULL)
 384             {
 385               CHECK_STATIC_TLS (map, sym_map);
 386               *reloc_addr = sym_map->l_tls_offset + sym->st_value
 387                             + reloc->r_addend;
 388             }
 389 #endif
 390           break;
 391         case R_SH_DIR32:
 392           {
 393 #if !defined RTLD_BOOTSTRAP && !defined RESOLVE_CONFLICT_FIND_MAP
 394            /* This is defined in rtld.c, but nowhere in the static
 395               libc.a; make the reference weak so static programs can
 396               still link.  This declaration cannot be done when
 397               compiling rtld.c (i.e. #ifdef RTLD_BOOTSTRAP) because
 398               rtld.c contains the common defn for _dl_rtld_map, which
 399               is incompatible with a weak decl in the same file.  */
 400 # ifndef SHARED
 401             weak_extern (_dl_rtld_map);
 402 # endif
 403             if (map == &GL(dl_rtld_map))
 404               /* Undo the relocation done here during bootstrapping.
 405                  Now we will relocate it anew, possibly using a
 406                  binding found in the user program or a loaded library
 407                  rather than the dynamic linker's built-in definitions
 408                  used while loading those libraries.  */
 409               value -= SYMBOL_ADDRESS (map, refsym, true) + reloc->r_addend;
 410 #endif
 411             COPY_UNALIGNED_WORD (&value, reloc_addr_arg,
 412                                  (int) reloc_addr_arg & 3);
 413             break;
 414           }
 415         case R_SH_REL32:
 416           value = (value - (Elf32_Addr) reloc_addr);
 417           COPY_UNALIGNED_WORD (&value, reloc_addr_arg,
 418                                (int) reloc_addr_arg & 3);
 419           break;
 420         default:
 421           _dl_reloc_bad_type (map, r_type, 0);
 422           break;
 423         }
 424     }
 425 }
 426
 427 auto inline void
 428 __attribute__ ((always_inline))
 429 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
 430                            void *const reloc_addr_arg)
 431 {
 432   Elf32_Addr value;
 433
 434   if (reloc->r_addend)
 435     value = l_addr + reloc->r_addend;
 436   else
 437     {
 438       COPY_UNALIGNED_WORD (reloc_addr_arg, &value, (int) reloc_addr_arg & 3);
 439       value += l_addr;
 440     }
 441   COPY_UNALIGNED_WORD (&value, reloc_addr_arg, (int) reloc_addr_arg & 3);
 442
 443 #undef COPY_UNALIGNED_WORD
 444 }
 445
 446 auto inline void
 447 __attribute__ ((always_inline))
 448 elf_machine_lazy_rel (struct link_map *map,
 449                       Elf32_Addr l_addr, const Elf32_Rela *reloc,
 450                       int skip_ifunc)
 451 {
 452   Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
 453   /* Check for unexpected PLT reloc type.  */
 454   if (ELF32_R_TYPE (reloc->r_info) == R_SH_JMP_SLOT)
 455     {
 456       if (__builtin_expect (map->l_mach.plt, 0) == 0)
 457         *reloc_addr += l_addr;
 458       else
 459         *reloc_addr =
 460           map->l_mach.plt
 461           + (((Elf32_Addr) reloc_addr) - map->l_mach.gotplt) * 7;
 462     }
 463   else
 464     _dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 1);
 465 }
 466
 467 #endif /* RESOLVE_MAP */