sysdeps/m68k/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  m68k version.
   2    Copyright (C) 1996-2019 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 "m68k"
  23
  24 #include <sys/param.h>
  25 #include <sysdep.h>
  26 #include <dl-tls.h>
  27
  28 /* Return nonzero iff ELF header is compatible with the running host.  */
  29 static inline int
  30 elf_machine_matches_host (const Elf32_Ehdr *ehdr)
  31 {
  32   return ehdr->e_machine == EM_68K;
  33 }
  34
  35
  36 /* Return the link-time address of _DYNAMIC.
  37    This must be inlined in a function which uses global data.  */
  38 static inline Elf32_Addr
  39 elf_machine_dynamic (void)
  40 {
  41   Elf32_Addr addr;
  42
  43   asm ("move.l _DYNAMIC@GOT.w(%%a5), %0"
  44        : "=a" (addr));
  45   return addr;
  46 }
  47
  48
  49 /* Return the run-time load address of the shared object.  */
  50 static inline Elf32_Addr
  51 elf_machine_load_address (void)
  52 {
  53   Elf32_Addr addr;
  54 #ifdef SHARED
  55   asm (PCREL_OP ("lea", "_dl_start", "%0", "%0", "%%pc") "\n\t"
  56        "sub.l _dl_start@GOT.w(%%a5), %0"
  57        : "=a" (addr));
  58 #else
  59   asm (PCREL_OP ("lea", "_dl_relocate_static_pie", "%0", "%0", "%%pc") "\n\t"
  60        "sub.l _dl_relocate_static_pie@GOT.w(%%a5), %0"
  61        : "=a" (addr));
  62 #endif
  63   return addr;
  64 }
  65
  66
  67 /* Set up the loaded object described by L so its unrelocated PLT
  68    entries will jump to the on-demand fixup code in dl-runtime.c.  */
  69
  70 static inline int __attribute__ ((always_inline))
  71 elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
  72 {
  73   Elf32_Addr *got;
  74   extern void _dl_runtime_resolve (Elf32_Word);
  75   extern void _dl_runtime_profile (Elf32_Word);
  76
  77   if (l->l_info[DT_JMPREL] && lazy)
  78     {
  79       /* The GOT entries for functions in the PLT have not yet been
  80          filled in.  Their initial contents will arrange when called
  81          to push an offset into the .rela.plt section, push
  82          _GLOBAL_OFFSET_TABLE_[1], and then jump to
  83          _GLOBAL_OFFSET_TABLE_[2].  */
  84       got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
  85       got[1] = (Elf32_Addr) l;  /* Identify this shared object.  */
  86
  87       /* The got[2] entry contains the address of a function which gets
  88          called to get the address of a so far unresolved function and
  89          jump to it.  The profiling extension of the dynamic linker allows
  90          to intercept the calls to collect information.  In this case we
  91          don't store the address in the GOT so that all future calls also
  92          end in this function.  */
  93       if (profile)
  94         {
  95           got[2] = (Elf32_Addr) &_dl_runtime_profile;
  96
  97           if (GLRO(dl_profile) != NULL
  98               && _dl_name_match_p (GLRO(dl_profile), l))
  99             {
 100               /* This is the object we are looking for.  Say that we really
 101                  want profiling and the timers are started.  */
 102               GL(dl_profile_map) = l;
 103             }
 104         }
 105       else
 106         /* This function will get called to fix up the GOT entry indicated by
 107            the offset on the stack, and then jump to the resolved address.  */
 108         got[2] = (Elf32_Addr) &_dl_runtime_resolve;
 109     }
 110
 111   return lazy;
 112 }
 113
 114 #define ELF_MACHINE_RUNTIME_FIXUP_ARGS long int save_a0, long int save_a1
 115 #define ELF_MACHINE_RUNTIME_FIXUP_PARAMS save_a0, save_a1
 116
 117
 118 /* Mask identifying addresses reserved for the user program,
 119    where the dynamic linker should not map anything.  */
 120 #define ELF_MACHINE_USER_ADDRESS_MASK   0x80000000UL
 121
 122 /* Initial entry point code for the dynamic linker.
 123    The C function `_dl_start' is the real entry point;
 124    its return value is the user program's entry point.  */
 125
 126 #define RTLD_START asm ("\
 127         .text\n\
 128         .globl _start\n\
 129         .type _start,@function\n\
 130 _start:\n\
 131         sub.l %fp, %fp\n\
 132         move.l %sp, -(%sp)\n\
 133         jbsr _dl_start\n\
 134         addq.l #4, %sp\n\
 135         /* FALLTHRU */\n\
 136 \n\
 137         .globl _dl_start_user\n\
 138         .type _dl_start_user,@function\n\
 139 _dl_start_user:\n\
 140         | Save the user entry point address in %a4.\n\
 141         move.l %d0, %a4\n\
 142         | See if we were run as a command with the executable file\n\
 143         | name as an extra leading argument.\n\
 144         " PCREL_OP ("move.l", "_dl_skip_args", "%d0", "%d0", "%pc") "\n\
 145         | Pop the original argument count\n\
 146         move.l (%sp)+, %d1\n\
 147         | Subtract _dl_skip_args from it.\n\
 148         sub.l %d0, %d1\n\
 149         | Adjust the stack pointer to skip _dl_skip_args words.\n\
 150         lea (%sp, %d0*4), %sp\n\
 151         | Push back the modified argument count.\n\
 152         move.l %d1, -(%sp)\n\
 153         # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
 154         pea 8(%sp, %d1*4)\n\
 155         pea 8(%sp)\n\
 156         move.l %d1, -(%sp)\n\
 157         " PCREL_OP ("move.l", "_rtld_local", "-(%sp)", "%d0", "%pc") "\n\
 158         jbsr _dl_init\n\
 159         addq.l #8, %sp\n\
 160         addq.l #8, %sp\n\
 161         | Pass our finalizer function to the user in %a1.\n\
 162         " PCREL_OP ("lea", "_dl_fini", "%a1", "%a1", "%pc") "\n\
 163         | Initialize %fp with the stack pointer.\n\
 164         move.l %sp, %fp\n\
 165         | Jump to the user's entry point.\n\
 166         jmp (%a4)\n\
 167         .size _dl_start_user, . - _dl_start_user\n\
 168         .previous");
 169
 170 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
 171    TLS variable, so undefined references should not be allowed to
 172    define the value.
 173    ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
 174    of the main executable's symbols, as for a COPY reloc.  */
 175 #define elf_machine_type_class(type) \
 176   ((((type) == R_68K_JMP_SLOT        \
 177      || (type) == R_68K_TLS_DTPMOD32 \
 178      || (type) == R_68K_TLS_DTPREL32 \
 179      || (type) == R_68K_TLS_TPREL32) * ELF_RTYPE_CLASS_PLT)     \
 180    | (((type) == R_68K_COPY) * ELF_RTYPE_CLASS_COPY))
 181
 182 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 183 #define ELF_MACHINE_JMP_SLOT    R_68K_JMP_SLOT
 184
 185 /* The m68k never uses Elf32_Rel relocations.  */
 186 #define ELF_MACHINE_NO_REL 1
 187 #define ELF_MACHINE_NO_RELA 0
 188
 189 static inline Elf32_Addr
 190 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 191                        const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
 192                        const Elf32_Rela *reloc,
 193                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 194 {
 195   return *reloc_addr = value;
 196 }
 197
 198 /* Return the final value of a plt relocation.  On the m68k the JMP_SLOT
 199    relocation ignores the addend.  */
 200 static inline Elf32_Addr
 201 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 202                        Elf32_Addr value)
 203 {
 204   return value;
 205 }
 206
 207 /* Names of the architecture-specific auditing callback functions.  */
 208 #define ARCH_LA_PLTENTER m68k_gnu_pltenter
 209 #define ARCH_LA_PLTEXIT m68k_gnu_pltexit
 210
 211 #endif /* !dl_machine_h */
 212
 213 #ifdef RESOLVE_MAP
 214
 215 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 216    MAP is the object containing the reloc.  */
 217
 218 auto inline void __attribute__ ((unused, always_inline))
 219 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 220                   const Elf32_Sym *sym, const struct r_found_version *version,
 221                   void *const reloc_addr_arg, int skip_ifunc)
 222 {
 223   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 224   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 225
 226   if (__builtin_expect (r_type == R_68K_RELATIVE, 0))
 227     *reloc_addr = map->l_addr + reloc->r_addend;
 228   else
 229     {
 230       const Elf32_Sym *const refsym = sym;
 231       struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
 232       Elf32_Addr value = SYMBOL_ADDRESS (sym_map, sym, true);
 233
 234       switch (r_type)
 235         {
 236         case R_68K_COPY:
 237           if (sym == NULL)
 238             /* This can happen in trace mode if an object could not be
 239                found.  */
 240             break;
 241           if (sym->st_size > refsym->st_size
 242               || (sym->st_size < refsym->st_size && GLRO(dl_verbose)))
 243             {
 244               const char *strtab;
 245
 246               strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
 247               _dl_error_printf ("\
 248 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
 249                                 RTLD_PROGNAME, strtab + refsym->st_name);
 250             }
 251           memcpy (reloc_addr_arg, (void *) value,
 252                   MIN (sym->st_size, refsym->st_size));
 253           break;
 254         case R_68K_GLOB_DAT:
 255         case R_68K_JMP_SLOT:
 256           *reloc_addr = value;
 257           break;
 258         case R_68K_8:
 259           *(char *) reloc_addr = value + reloc->r_addend;
 260           break;
 261         case R_68K_16:
 262           *(short *) reloc_addr = value + reloc->r_addend;
 263           break;
 264         case R_68K_32:
 265           *reloc_addr = value + reloc->r_addend;
 266           break;
 267         case R_68K_PC8:
 268           *(char *) reloc_addr
 269             = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 270           break;
 271         case R_68K_PC16:
 272           *(short *) reloc_addr
 273             = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 274           break;
 275         case R_68K_PC32:
 276           *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 277           break;
 278 #ifndef RTLD_BOOTSTRAP
 279         case R_68K_TLS_DTPMOD32:
 280           /* Get the information from the link map returned by the
 281              resolv function.  */
 282           if (sym_map != NULL)
 283             *reloc_addr = sym_map->l_tls_modid;
 284           break;
 285         case R_68K_TLS_DTPREL32:
 286           if (sym != NULL)
 287             *reloc_addr = TLS_DTPREL_VALUE (sym, reloc);
 288           break;
 289         case R_68K_TLS_TPREL32:
 290           if (sym != NULL)
 291             {
 292               CHECK_STATIC_TLS (map, sym_map);
 293               *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
 294             }
 295           break;
 296 #endif /* !RTLD_BOOTSTRAP */
 297         case R_68K_NONE:                /* Alright, Wilbur.  */
 298           break;
 299         default:
 300           _dl_reloc_bad_type (map, r_type, 0);
 301           break;
 302         }
 303     }
 304 }
 305
 306 auto inline void __attribute__ ((unused, always_inline))
 307 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
 308                            void *const reloc_addr_arg)
 309 {
 310   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 311   *reloc_addr = l_addr + reloc->r_addend;
 312 }
 313
 314 auto inline void __attribute__ ((unused, always_inline))
 315 elf_machine_lazy_rel (struct link_map *map,
 316                       Elf32_Addr l_addr, const Elf32_Rela *reloc,
 317                       int skip_ifunc)
 318 {
 319   Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
 320   if (ELF32_R_TYPE (reloc->r_info) == R_68K_JMP_SLOT)
 321     *reloc_addr += l_addr;
 322   else
 323     _dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 1);
 324 }
 325
 326 #endif /* RESOLVE_MAP */