sysdeps/m68k/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  m68k version.
   2    Copyright (C) 1996-2021 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 #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
  32 elf_machine_matches_host (const Elf32_Ehdr *ehdr)
  33 {
  34   return ehdr->e_machine == EM_68K;
  35 }
  36
  37
  38 /* Return the link-time address of _DYNAMIC.
  39    This must be inlined in a function which uses global data.  */
  40 static inline Elf32_Addr
  41 elf_machine_dynamic (void)
  42 {
  43   Elf32_Addr addr;
  44
  45   asm ("move.l _DYNAMIC@GOT.w(%%a5), %0"
  46        : "=a" (addr));
  47   return addr;
  48 }
  49
  50
  51 /* Return the run-time load address of the shared object.  */
  52 static inline Elf32_Addr
  53 elf_machine_load_address (void)
  54 {
  55   Elf32_Addr addr;
  56 #ifdef SHARED
  57   asm (PCREL_OP ("lea", "_dl_start", "%0", "%0", "%%pc") "\n\t"
  58        "sub.l _dl_start@GOT.w(%%a5), %0"
  59        : "=a" (addr));
  60 #else
  61   asm (PCREL_OP ("lea", "_dl_relocate_static_pie", "%0", "%0", "%%pc") "\n\t"
  62        "sub.l _dl_relocate_static_pie@GOT.w(%%a5), %0"
  63        : "=a" (addr));
  64 #endif
  65   return addr;
  66 }
  67
  68
  69 /* Set up the loaded object described by L so its unrelocated PLT
  70    entries will jump to the on-demand fixup code in dl-runtime.c.  */
  71
  72 static inline int __attribute__ ((always_inline))
  73 elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
  74                            int lazy, int profile)
  75 {
  76   Elf32_Addr *got;
  77   extern void _dl_runtime_resolve (Elf32_Word);
  78   extern void _dl_runtime_profile (Elf32_Word);
  79
  80   if (l->l_info[DT_JMPREL] && lazy)
  81     {
  82       /* The GOT entries for functions in the PLT have not yet been
  83          filled in.  Their initial contents will arrange when called
  84          to push an offset into the .rela.plt section, push
  85          _GLOBAL_OFFSET_TABLE_[1], and then jump to
  86          _GLOBAL_OFFSET_TABLE_[2].  */
  87       got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
  88       got[1] = (Elf32_Addr) l;  /* Identify this shared object.  */
  89
  90       /* The got[2] entry contains the address of a function which gets
  91          called to get the address of a so far unresolved function and
  92          jump to it.  The profiling extension of the dynamic linker allows
  93          to intercept the calls to collect information.  In this case we
  94          don't store the address in the GOT so that all future calls also
  95          end in this function.  */
  96       if (profile)
  97         {
  98           got[2] = (Elf32_Addr) &_dl_runtime_profile;
  99
 100           if (GLRO(dl_profile) != NULL
 101               && _dl_name_match_p (GLRO(dl_profile), l))
 102             {
 103               /* This is the object we are looking for.  Say that we really
 104                  want profiling and the timers are started.  */
 105               GL(dl_profile_map) = l;
 106             }
 107         }
 108       else
 109         /* This function will get called to fix up the GOT entry indicated by
 110            the offset on the stack, and then jump to the resolved address.  */
 111         got[2] = (Elf32_Addr) &_dl_runtime_resolve;
 112     }
 113
 114   return lazy;
 115 }
 116
 117 #define ELF_MACHINE_RUNTIME_FIXUP_ARGS long int save_a0, long int save_a1
 118 #define ELF_MACHINE_RUNTIME_FIXUP_PARAMS save_a0, save_a1
 119
 120
 121 /* Mask identifying addresses reserved for the user program,
 122    where the dynamic linker should not map anything.  */
 123 #define ELF_MACHINE_USER_ADDRESS_MASK   0x80000000UL
 124
 125 /* Initial entry point code for the dynamic linker.
 126    The C function `_dl_start' is the real entry point;
 127    its return value is the user program's entry point.  */
 128
 129 #define RTLD_START asm ("\
 130         .text\n\
 131         .globl _start\n\
 132         .type _start,@function\n\
 133 _start:\n\
 134         sub.l %fp, %fp\n\
 135         move.l %sp, -(%sp)\n\
 136         jbsr _dl_start\n\
 137         addq.l #4, %sp\n\
 138         /* FALLTHRU */\n\
 139 \n\
 140         .globl _dl_start_user\n\
 141         .type _dl_start_user,@function\n\
 142 _dl_start_user:\n\
 143         | Save the user entry point address in %a4.\n\
 144         move.l %d0, %a4\n\
 145         | See if we were run as a command with the executable file\n\
 146         | name as an extra leading argument.\n\
 147         " PCREL_OP ("move.l", "_dl_skip_args", "%d0", "%d0", "%pc") "\n\
 148         | Pop the original argument count\n\
 149         move.l (%sp)+, %d1\n\
 150         | Subtract _dl_skip_args from it.\n\
 151         sub.l %d0, %d1\n\
 152         | Adjust the stack pointer to skip _dl_skip_args words.\n\
 153         lea (%sp, %d0*4), %sp\n\
 154         | Push back the modified argument count.\n\
 155         move.l %d1, -(%sp)\n\
 156         # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
 157         pea 8(%sp, %d1*4)\n\
 158         pea 8(%sp)\n\
 159         move.l %d1, -(%sp)\n\
 160         " PCREL_OP ("move.l", "_rtld_local", "-(%sp)", "%d0", "%pc") "\n\
 161         jbsr _dl_init\n\
 162         addq.l #8, %sp\n\
 163         addq.l #8, %sp\n\
 164         | Pass our finalizer function to the user in %a1.\n\
 165         " PCREL_OP ("lea", "_dl_fini", "%a1", "%a1", "%pc") "\n\
 166         | Initialize %fp with the stack pointer.\n\
 167         move.l %sp, %fp\n\
 168         | Jump to the user's entry point.\n\
 169         jmp (%a4)\n\
 170         .size _dl_start_user, . - _dl_start_user\n\
 171         .previous");
 172
 173 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
 174    TLS variable, so undefined references should not be allowed to
 175    define the value.
 176    ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
 177    of the main executable's symbols, as for a COPY reloc.  */
 178 #define elf_machine_type_class(type) \
 179   ((((type) == R_68K_JMP_SLOT        \
 180      || (type) == R_68K_TLS_DTPMOD32 \
 181      || (type) == R_68K_TLS_DTPREL32 \
 182      || (type) == R_68K_TLS_TPREL32) * ELF_RTYPE_CLASS_PLT)     \
 183    | (((type) == R_68K_COPY) * ELF_RTYPE_CLASS_COPY))
 184
 185 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 186 #define ELF_MACHINE_JMP_SLOT    R_68K_JMP_SLOT
 187
 188 static inline Elf32_Addr
 189 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 190                        const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
 191                        const Elf32_Rela *reloc,
 192                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 193 {
 194   return *reloc_addr = value;
 195 }
 196
 197 /* Return the final value of a plt relocation.  On the m68k the JMP_SLOT
 198    relocation ignores the addend.  */
 199 static inline Elf32_Addr
 200 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 201                        Elf32_Addr value)
 202 {
 203   return value;
 204 }
 205
 206 /* Names of the architecture-specific auditing callback functions.  */
 207 #define ARCH_LA_PLTENTER m68k_gnu_pltenter
 208 #define ARCH_LA_PLTEXIT m68k_gnu_pltexit
 209
 210 #endif /* !dl_machine_h */
 211
 212 #ifdef RESOLVE_MAP
 213
 214 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 215    MAP is the object containing the reloc.  */
 216
 217 static inline void __attribute__ ((unused, always_inline))
 218 elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
 219                   const Elf32_Rela *reloc, const Elf32_Sym *sym,
 220                   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 (map, scope, &sym, version,
 232                                               r_type);
 233       Elf32_Addr value = SYMBOL_ADDRESS (sym_map, sym, true);
 234
 235       switch (r_type)
 236         {
 237         case R_68K_COPY:
 238           if (sym == NULL)
 239             /* This can happen in trace mode if an object could not be
 240                found.  */
 241             break;
 242           if (sym->st_size > refsym->st_size
 243               || (sym->st_size < refsym->st_size && GLRO(dl_verbose)))
 244             {
 245               const char *strtab;
 246
 247               strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
 248               _dl_error_printf ("\
 249 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
 250                                 RTLD_PROGNAME, strtab + refsym->st_name);
 251             }
 252           memcpy (reloc_addr_arg, (void *) value,
 253                   MIN (sym->st_size, refsym->st_size));
 254           break;
 255         case R_68K_GLOB_DAT:
 256         case R_68K_JMP_SLOT:
 257           *reloc_addr = value;
 258           break;
 259         case R_68K_8:
 260           *(char *) reloc_addr = value + reloc->r_addend;
 261           break;
 262         case R_68K_16:
 263           *(short *) reloc_addr = value + reloc->r_addend;
 264           break;
 265         case R_68K_32:
 266           *reloc_addr = value + reloc->r_addend;
 267           break;
 268         case R_68K_PC8:
 269           *(char *) reloc_addr
 270             = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 271           break;
 272         case R_68K_PC16:
 273           *(short *) reloc_addr
 274             = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 275           break;
 276         case R_68K_PC32:
 277           *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 278           break;
 279 #ifndef RTLD_BOOTSTRAP
 280         case R_68K_TLS_DTPMOD32:
 281           /* Get the information from the link map returned by the
 282              resolv function.  */
 283           if (sym_map != NULL)
 284             *reloc_addr = sym_map->l_tls_modid;
 285           break;
 286         case R_68K_TLS_DTPREL32:
 287           if (sym != NULL)
 288             *reloc_addr = TLS_DTPREL_VALUE (sym, reloc);
 289           break;
 290         case R_68K_TLS_TPREL32:
 291           if (sym != NULL)
 292             {
 293               CHECK_STATIC_TLS (map, sym_map);
 294               *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
 295             }
 296           break;
 297 #endif /* !RTLD_BOOTSTRAP */
 298         case R_68K_NONE:                /* Alright, Wilbur.  */
 299           break;
 300         default:
 301           _dl_reloc_bad_type (map, r_type, 0);
 302           break;
 303         }
 304     }
 305 }
 306
 307 static inline void __attribute__ ((unused, always_inline))
 308 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
 309                            void *const reloc_addr_arg)
 310 {
 311   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 312   *reloc_addr = l_addr + reloc->r_addend;
 313 }
 314
 315 static inline void __attribute__ ((unused, always_inline))
 316 elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
 317                       Elf32_Addr l_addr, const Elf32_Rela *reloc,
 318                       int skip_ifunc)
 319 {
 320   Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
 321   if (ELF32_R_TYPE (reloc->r_info) == R_68K_JMP_SLOT)
 322     *reloc_addr += l_addr;
 323   else
 324     _dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 1);
 325 }
 326
 327 #endif /* RESOLVE_MAP */