sysdeps/sh/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  SH version.
   2    Copyright (C) 1999-2023 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 #include <dl-static-tls.h>
  28 #include <dl-machine-rel.h>
  29
  30 /* Return nonzero iff ELF header is compatible with the running host.  */
  31 static inline int __attribute__ ((unused))
  32 elf_machine_matches_host (const Elf32_Ehdr *ehdr)
  33 {
  34   return ehdr->e_machine == EM_SH;
  35 }
  36
  37
  38 /* Return the link-time address of _DYNAMIC.  Conveniently, this is the
  39    first element of the GOT.  This must be inlined in a function which
  40    uses global data.  */
  41 static inline Elf32_Addr __attribute__ ((unused))
  42 elf_machine_dynamic (void)
  43 {
  44   register Elf32_Addr *got;
  45   asm ("mov r12,%0" :"=r" (got));
  46   return *got;
  47 }
  48
  49
  50 /* Return the run-time load address of the shared object.  */
  51 static inline Elf32_Addr __attribute__ ((unused))
  52 elf_machine_load_address (void)
  53 {
  54   Elf32_Addr addr;
  55   asm ("mov.l 1f,r0\n\
  56         mov.l 3f,r2\n\
  57         add r12,r2\n\
  58         mov.l @(r0,r12),r0\n\
  59         bra 2f\n\
  60          sub r0,r2\n\
  61         .align 2\n\
  62         1: .long _dl_start@GOT\n\
  63         3: .long _dl_start@GOTOFF\n\
  64         2: mov r2,%0"
  65        : "=r" (addr) : : "r0", "r1", "r2");
  66   return addr;
  67 }
  68
  69
  70 /* Set up the loaded object described by L so its unrelocated PLT
  71    entries will jump to the on-demand fixup code in dl-runtime.c.  */
  72
  73 static inline int __attribute__ ((unused, always_inline))
  74 elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
  75                            int lazy, int profile)
  76 {
  77   Elf32_Addr *got;
  78   extern void _dl_runtime_resolve (Elf32_Word);
  79   extern void _dl_runtime_profile (Elf32_Word);
  80
  81   if (l->l_info[DT_JMPREL] && lazy)
  82     {
  83       /* The GOT entries for functions in the PLT have not yet been filled
  84          in.  Their initial contents will arrange when called to load an
  85          offset into the .rela.plt section and _GLOBAL_OFFSET_TABLE_[1],
  86          and then jump to _GLOBAL_OFFSET_TABLE[2].  */
  87       got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
  88       /* If a library is prelinked but we have to relocate anyway,
  89          we have to be able to undo the prelinking of .got.plt.
  90          The prelinker saved us here address of .plt + 36.  */
  91       if (got[1])
  92         {
  93           l->l_mach.plt = got[1] + l->l_addr;
  94           l->l_mach.gotplt = (Elf32_Addr) &got[3];
  95         }
  96       got[1] = (Elf32_Addr) l;  /* Identify this shared object.  */
  97
  98       /* The got[2] entry contains the address of a function which gets
  99          called to get the address of a so far unresolved function and
 100          jump to it.  The profiling extension of the dynamic linker allows
 101          to intercept the calls to collect information.  In this case we
 102          don't store the address in the GOT so that all future calls also
 103          end in this function.  */
 104 #ifdef SHARED
 105       if (profile)
 106         {
 107           got[2] = (Elf32_Addr) &_dl_runtime_profile;
 108           /* Say that we really want profiling and the timers are started.  */
 109           if (GLRO(dl_profile) != NULL
 110               && _dl_name_match_p (GLRO(dl_profile), l))
 111             GL(dl_profile_map) = l;
 112         }
 113       else
 114 #endif
 115         /* This function will get called to fix up the GOT entry indicated by
 116            the offset on the stack, and then jump to the resolved address.  */
 117         got[2] = (Elf32_Addr) &_dl_runtime_resolve;
 118     }
 119   return lazy;
 120 }
 121
 122 #define ELF_MACHINE_RUNTIME_FIXUP_ARGS int plt_type
 123 #define ELF_MACHINE_RUNTIME_FIXUP_PARAMS plt_type
 124
 125 /* Mask identifying addresses reserved for the user program,
 126    where the dynamic linker should not map anything.  */
 127 #define ELF_MACHINE_USER_ADDRESS_MASK   0x80000000UL
 128
 129 /* Initial entry point code for the dynamic linker.
 130    The C function `_dl_start' is the real entry point;
 131    its return value is the user program's entry point.  */
 132
 133 #define RTLD_START asm ("\
 134 .text\n\
 135 .globl _start\n\
 136 .globl _dl_start_user\n\
 137 _start:\n\
 138         mov r15,r4\n\
 139         mov.l .L_dl_start,r1\n\
 140         mova .L_dl_start,r0\n\
 141         add r1,r0\n\
 142         jsr @r0\n\
 143          nop\n\
 144 _dl_start_user:\n\
 145         ! Save the user entry point address in r8.\n\
 146         mov r0,r8\n\
 147         ! Point r12 at the GOT.\n\
 148         mov.l 1f,r12\n\
 149         mova 1f,r0\n\
 150         bra 2f\n\
 151          add r0,r12\n\
 152         .align 2\n\
 153 1:      .long _GLOBAL_OFFSET_TABLE_\n\
 154 2:      ! Get the original argument count.\n\
 155         mov.l @r15,r5\n\
 156         ! Compute argv address and envp.\n\
 157         mov r15,r6\n\
 158         add #4,r6\n\
 159         mov r5,r7\n\
 160         shll2 r7\n\
 161         add r15,r7\n\
 162         add #8,r7\n\
 163         mov.l .L_dl_loaded,r0\n\
 164         mov.l @(r0,r12),r0\n\
 165         mov.l @r0,r4\n\
 166         ! Call _dl_init.\n\
 167         mov.l .L_dl_init,r1\n\
 168         mova .L_dl_init,r0\n\
 169         add r1,r0\n\
 170         jsr @r0\n\
 171          nop\n\
 172 1:      ! Pass our finalizer function to the user in r4, as per ELF ABI.\n\
 173         mov.l .L_dl_fini,r0\n\
 174         mov.l @(r0,r12),r4\n\
 175         ! Jump to the user's entry point.\n\
 176         jmp @r8\n\
 177          nop\n\
 178         .align 2\n\
 179 .L_dl_start:\n\
 180         .long _dl_start@PLT\n\
 181 .L_dl_init:\n\
 182         .long _dl_init@PLT\n\
 183 .L_dl_loaded:\n\
 184         .long _rtld_local@GOT\n\
 185 .L_dl_fini:\n\
 186         .long _dl_fini@GOT\n\
 187         .type __fpscr_values,@object\n\
 188         .global __fpscr_values\n\
 189 __fpscr_values:\n\
 190         .long   0\n\
 191         .long   0x80000\n\
 192         .weak __fpscr_values\n\
 193 .previous\n\
 194 ");
 195
 196 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
 197    TLS variable, so undefined references should not be allowed to
 198    define the value.
 199    ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
 200    of the main executable's symbols, as for a COPY reloc.  */
 201 #define elf_machine_type_class(type) \
 202   ((((type) == R_SH_JMP_SLOT || (type) == R_SH_TLS_DTPMOD32                   \
 203      || (type) == R_SH_TLS_DTPOFF32 || (type) == R_SH_TLS_TPOFF32)            \
 204     * ELF_RTYPE_CLASS_PLT)                                                    \
 205    | (((type) == R_SH_COPY) * ELF_RTYPE_CLASS_COPY))
 206
 207 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 208 #define ELF_MACHINE_JMP_SLOT    R_SH_JMP_SLOT
 209
 210 /* We define an initialization functions.  This is called very early in
 211    _dl_sysdep_start.  */
 212 #define DL_PLATFORM_INIT dl_platform_init ()
 213
 214 static inline void __attribute__ ((unused))
 215 dl_platform_init (void)
 216 {
 217   if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0')
 218     /* Avoid an empty string which would disturb us.  */
 219     GLRO(dl_platform) = NULL;
 220 }
 221
 222 static inline Elf32_Addr
 223 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 224                        const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
 225                        const Elf32_Rela *reloc,
 226                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 227 {
 228   return *reloc_addr = value;
 229 }
 230
 231 /* Return the final value of a plt relocation.  */
 232 static inline Elf32_Addr
 233 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 234                        Elf32_Addr value)
 235 {
 236   return value + reloc->r_addend;
 237 }
 238
 239 #define ARCH_LA_PLTENTER sh_gnu_pltenter
 240 #define ARCH_LA_PLTEXIT sh_gnu_pltexit
 241
 242 #endif /* !dl_machine_h */
 243
 244 #ifdef RESOLVE_MAP
 245
 246 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 247    MAP is the object containing the reloc.  */
 248
 249 static inline void
 250 __attribute ((always_inline))
 251 elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
 252                   const Elf32_Rela *reloc, const Elf32_Sym *sym,
 253                   const struct r_found_version *version,
 254                   void *const reloc_addr_arg, int skip_ifunc)
 255 {
 256   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 257   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 258   Elf32_Addr value;
 259
 260 #define COPY_UNALIGNED_WORD(swp, twp, align) \
 261   { \
 262     void *__s = (swp), *__t = (twp); \
 263     unsigned char *__s1 = __s, *__t1 = __t; \
 264     unsigned short *__s2 = __s, *__t2 = __t; \
 265     unsigned long *__s4 = __s, *__t4 = __t; \
 266     switch ((align)) \
 267     { \
 268     case 0: \
 269       *__t4 = *__s4; \
 270       break; \
 271     case 2: \
 272       *__t2++ = *__s2++; \
 273       *__t2 = *__s2; \
 274       break; \
 275     default: \
 276       *__t1++ = *__s1++; \
 277       *__t1++ = *__s1++; \
 278       *__t1++ = *__s1++; \
 279       *__t1 = *__s1; \
 280       break; \
 281     } \
 282   }
 283
 284   if (__glibc_unlikely (r_type == R_SH_RELATIVE))
 285     {
 286 #ifndef RTLD_BOOTSTRAP
 287       if (map != &GL(dl_rtld_map)) /* Already done in rtld itself.       */
 288 #endif
 289         {
 290           if (reloc->r_addend)
 291             value = map->l_addr + reloc->r_addend;
 292           else
 293             {
 294               COPY_UNALIGNED_WORD (reloc_addr_arg, &value,
 295                                    (int) reloc_addr_arg & 3);
 296               value += map->l_addr;
 297             }
 298           COPY_UNALIGNED_WORD (&value, reloc_addr_arg,
 299                                (int) reloc_addr_arg & 3);
 300         }
 301     }
 302 #ifndef RTLD_BOOTSTRAP
 303   else if (__glibc_unlikely (r_type == R_SH_NONE))
 304     return;
 305 #endif
 306   else
 307     {
 308       const Elf32_Sym *const refsym = sym;
 309       struct link_map *sym_map = RESOLVE_MAP (map, scope, &sym, version,
 310                                               r_type);
 311
 312       value = SYMBOL_ADDRESS (sym_map, sym, true);
 313       value += reloc->r_addend;
 314
 315       switch (r_type)
 316         {
 317         case R_SH_COPY:
 318           if (sym == NULL)
 319             /* This can happen in trace mode if an object could not be
 320                found.  */
 321             break;
 322           if (sym->st_size > refsym->st_size
 323               || (sym->st_size < refsym->st_size && GLRO(dl_verbose)))
 324             {
 325               const char *strtab;
 326
 327               strtab = (const char *) D_PTR (map, l_info[DT_STRTAB]);
 328               _dl_error_printf ("\
 329 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
 330                                 RTLD_PROGNAME, strtab + refsym->st_name);
 331             }
 332           memcpy (reloc_addr_arg, (void *) value,
 333                   MIN (sym->st_size, refsym->st_size));
 334           break;
 335         case R_SH_GLOB_DAT:
 336         case R_SH_JMP_SLOT:
 337           /* These addresses are always aligned.  */
 338           *reloc_addr = value;
 339           break;
 340           /* XXX Remove TLS relocations which are not needed.  */
 341         case R_SH_TLS_DTPMOD32:
 342 #ifdef RTLD_BOOTSTRAP
 343           /* During startup the dynamic linker is always the module
 344              with index 1.
 345              XXX If this relocation is necessary move before RESOLVE
 346              call.  */
 347           *reloc_addr = 1;
 348 #else
 349           /* Get the information from the link map returned by the
 350              resolv function.  */
 351           if (sym_map != NULL)
 352             *reloc_addr = sym_map->l_tls_modid;
 353 #endif
 354           break;
 355         case R_SH_TLS_DTPOFF32:
 356 #ifndef RTLD_BOOTSTRAP
 357           /* During relocation all TLS symbols are defined and used.
 358              Therefore the offset is already correct.  */
 359           if (sym != NULL)
 360             *reloc_addr = sym->st_value;
 361 #endif
 362           break;
 363         case R_SH_TLS_TPOFF32:
 364           /* The offset is positive, afterward from the thread pointer.  */
 365 #ifdef RTLD_BOOTSTRAP
 366           *reloc_addr = map->l_tls_offset + sym->st_value + reloc->r_addend;
 367 #else
 368           /* We know the offset of object the symbol is contained in.
 369              It is a positive value which will be added to the thread
 370              pointer.  To get the variable position in the TLS block
 371              we add the offset from that of the TLS block.  */
 372           if (sym != NULL)
 373             {
 374               CHECK_STATIC_TLS (map, sym_map);
 375               *reloc_addr = sym_map->l_tls_offset + sym->st_value
 376                             + reloc->r_addend;
 377             }
 378 #endif
 379           break;
 380         case R_SH_DIR32:
 381           {
 382 #if !defined RTLD_BOOTSTRAP
 383            /* This is defined in rtld.c, but nowhere in the static
 384               libc.a; make the reference weak so static programs can
 385               still link.  This declaration cannot be done when
 386               compiling rtld.c (i.e. #ifdef RTLD_BOOTSTRAP) because
 387               rtld.c contains the common defn for _dl_rtld_map, which
 388               is incompatible with a weak decl in the same file.  */
 389 # ifndef SHARED
 390             weak_extern (_dl_rtld_map);
 391 # endif
 392             if (map == &GL(dl_rtld_map))
 393               /* Undo the relocation done here during bootstrapping.
 394                  Now we will relocate it anew, possibly using a
 395                  binding found in the user program or a loaded library
 396                  rather than the dynamic linker's built-in definitions
 397                  used while loading those libraries.  */
 398               value -= SYMBOL_ADDRESS (map, refsym, true) + reloc->r_addend;
 399 #endif
 400             COPY_UNALIGNED_WORD (&value, reloc_addr_arg,
 401                                  (int) reloc_addr_arg & 3);
 402             break;
 403           }
 404         case R_SH_REL32:
 405           value = (value - (Elf32_Addr) reloc_addr);
 406           COPY_UNALIGNED_WORD (&value, reloc_addr_arg,
 407                                (int) reloc_addr_arg & 3);
 408           break;
 409         default:
 410           _dl_reloc_bad_type (map, r_type, 0);
 411           break;
 412         }
 413     }
 414 }
 415
 416 static inline void
 417 __attribute__ ((always_inline))
 418 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
 419                            void *const reloc_addr_arg)
 420 {
 421   Elf32_Addr value;
 422
 423   if (reloc->r_addend)
 424     value = l_addr + reloc->r_addend;
 425   else
 426     {
 427       COPY_UNALIGNED_WORD (reloc_addr_arg, &value, (int) reloc_addr_arg & 3);
 428       value += l_addr;
 429     }
 430   COPY_UNALIGNED_WORD (&value, reloc_addr_arg, (int) reloc_addr_arg & 3);
 431
 432 #undef COPY_UNALIGNED_WORD
 433 }
 434
 435 static inline void
 436 __attribute__ ((always_inline))
 437 elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
 438                       Elf32_Addr l_addr, const Elf32_Rela *reloc,
 439                       int skip_ifunc)
 440 {
 441   Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
 442   /* Check for unexpected PLT reloc type.  */
 443   if (ELF32_R_TYPE (reloc->r_info) == R_SH_JMP_SLOT)
 444     {
 445       if (__builtin_expect (map->l_mach.plt, 0) == 0)
 446         *reloc_addr += l_addr;
 447       else
 448         *reloc_addr =
 449           map->l_mach.plt
 450           + (((Elf32_Addr) reloc_addr) - map->l_mach.gotplt) * 7;
 451     }
 452   else
 453     _dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 1);
 454 }
 455
 456 #endif /* RESOLVE_MAP */