sysdeps/m68k/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  m68k version.
   2    Copyright (C) 1996-2024 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
  79   if (l->l_info[DT_JMPREL] && lazy)
  80     {
  81       /* The GOT entries for functions in the PLT have not yet been
  82          filled in.  Their initial contents will arrange when called
  83          to push an offset into the .rela.plt section, push
  84          _GLOBAL_OFFSET_TABLE_[1], and then jump to
  85          _GLOBAL_OFFSET_TABLE_[2].  */
  86       got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
  87       got[1] = (Elf32_Addr) l;  /* Identify this shared object.  */
  88
  89       /* The got[2] entry contains the address of a function which gets
  90          called to get the address of a so far unresolved function and
  91          jump to it.  The profiling extension of the dynamic linker allows
  92          to intercept the calls to collect information.  In this case we
  93          don't store the address in the GOT so that all future calls also
  94          end in this function.  */
  95 #ifdef SHARED
  96       extern void _dl_runtime_profile (Elf32_Word);
  97       if (profile)
  98         {
  99           got[2] = (Elf32_Addr) &_dl_runtime_profile;
 100
 101           if (GLRO(dl_profile) != NULL
 102               && _dl_name_match_p (GLRO(dl_profile), l))
 103             {
 104               /* This is the object we are looking for.  Say that we really
 105                  want profiling and the timers are started.  */
 106               GL(dl_profile_map) = l;
 107             }
 108         }
 109       else
 110 #endif
 111         /* This function will get called to fix up the GOT entry indicated by
 112            the offset on the stack, and then jump to the resolved address.  */
 113         got[2] = (Elf32_Addr) &_dl_runtime_resolve;
 114     }
 115
 116   return lazy;
 117 }
 118
 119 #define ELF_MACHINE_RUNTIME_FIXUP_ARGS long int save_a0, long int save_a1
 120 #define ELF_MACHINE_RUNTIME_FIXUP_PARAMS save_a0, save_a1
 121
 122
 123 /* Mask identifying addresses reserved for the user program,
 124    where the dynamic linker should not map anything.  */
 125 #define ELF_MACHINE_USER_ADDRESS_MASK   0x80000000UL
 126
 127 /* Initial entry point code for the dynamic linker.
 128    The C function `_dl_start' is the real entry point;
 129    its return value is the user program's entry point.  */
 130
 131 #define RTLD_START asm ("\
 132         .text\n\
 133         .globl _start\n\
 134         .type _start,@function\n\
 135 _start:\n\
 136         sub.l %fp, %fp\n\
 137         move.l %sp, -(%sp)\n\
 138         jbsr _dl_start\n\
 139         addq.l #4, %sp\n\
 140         /* FALLTHRU */\n\
 141 \n\
 142         .globl _dl_start_user\n\
 143         .type _dl_start_user,@function\n\
 144 _dl_start_user:\n\
 145         | Save the user entry point address in %a4.\n\
 146         move.l %d0, %a4\n\
 147         | Load the adjusted argument count.\n\
 148         move.l (%sp), %d1\n\
 149         # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
 150         pea 8(%sp, %d1*4)\n\
 151         pea 8(%sp)\n\
 152         move.l %d1, -(%sp)\n\
 153         " PCREL_OP ("move.l", "_rtld_local", "-(%sp)", "%d0", "%pc") "\n\
 154         jbsr _dl_init\n\
 155         addq.l #8, %sp\n\
 156         addq.l #8, %sp\n\
 157         | Pass our finalizer function to the user in %a1.\n\
 158         " PCREL_OP ("lea", "_dl_fini", "%a1", "%a1", "%pc") "\n\
 159         | Initialize %fp with the stack pointer.\n\
 160         move.l %sp, %fp\n\
 161         | Jump to the user's entry point.\n\
 162         jmp (%a4)\n\
 163         .size _dl_start_user, . - _dl_start_user\n\
 164         .previous");
 165
 166 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
 167    TLS variable, so undefined references should not be allowed to
 168    define the value.
 169    ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
 170    of the main executable's symbols, as for a COPY reloc.  */
 171 #define elf_machine_type_class(type) \
 172   ((((type) == R_68K_JMP_SLOT        \
 173      || (type) == R_68K_TLS_DTPMOD32 \
 174      || (type) == R_68K_TLS_DTPREL32 \
 175      || (type) == R_68K_TLS_TPREL32) * ELF_RTYPE_CLASS_PLT)     \
 176    | (((type) == R_68K_COPY) * ELF_RTYPE_CLASS_COPY))
 177
 178 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 179 #define ELF_MACHINE_JMP_SLOT    R_68K_JMP_SLOT
 180
 181 static inline Elf32_Addr
 182 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 183                        const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
 184                        const Elf32_Rela *reloc,
 185                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 186 {
 187   return *reloc_addr = value;
 188 }
 189
 190 /* Return the final value of a plt relocation.  On the m68k the JMP_SLOT
 191    relocation ignores the addend.  */
 192 static inline Elf32_Addr
 193 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 194                        Elf32_Addr value)
 195 {
 196   return value;
 197 }
 198
 199 /* Names of the architecture-specific auditing callback functions.  */
 200 #define ARCH_LA_PLTENTER m68k_gnu_pltenter
 201 #define ARCH_LA_PLTEXIT m68k_gnu_pltexit
 202
 203 #endif /* !dl_machine_h */
 204
 205 #ifdef RESOLVE_MAP
 206
 207 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 208    MAP is the object containing the reloc.  */
 209
 210 static inline void __attribute__ ((unused, always_inline))
 211 elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
 212                   const Elf32_Rela *reloc, const Elf32_Sym *sym,
 213                   const struct r_found_version *version,
 214                   void *const reloc_addr_arg, int skip_ifunc)
 215 {
 216   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 217   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 218
 219   if (__builtin_expect (r_type == R_68K_RELATIVE, 0))
 220     *reloc_addr = map->l_addr + reloc->r_addend;
 221   else
 222     {
 223       const Elf32_Sym *const refsym = sym;
 224       struct link_map *sym_map = RESOLVE_MAP (map, scope, &sym, version,
 225                                               r_type);
 226       Elf32_Addr value = SYMBOL_ADDRESS (sym_map, sym, true);
 227
 228       switch (r_type)
 229         {
 230         case R_68K_GLOB_DAT:
 231         case R_68K_JMP_SLOT:
 232           *reloc_addr = value;
 233           break;
 234 #ifndef RTLD_BOOTSTRAP
 235         case R_68K_COPY:
 236           if (sym == NULL)
 237             /* This can happen in trace mode if an object could not be
 238                found.  */
 239             break;
 240           if (sym->st_size > refsym->st_size
 241               || (sym->st_size < refsym->st_size && GLRO(dl_verbose)))
 242             {
 243               const char *strtab;
 244
 245               strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
 246               _dl_error_printf ("\
 247 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
 248                                 RTLD_PROGNAME, strtab + refsym->st_name);
 249             }
 250           memcpy (reloc_addr_arg, (void *) value,
 251                   MIN (sym->st_size, refsym->st_size));
 252           break;
 253         case R_68K_8:
 254           *(char *) reloc_addr = value + reloc->r_addend;
 255           break;
 256         case R_68K_16:
 257           *(short *) reloc_addr = value + reloc->r_addend;
 258           break;
 259         case R_68K_32:
 260           *reloc_addr = value + reloc->r_addend;
 261           break;
 262         case R_68K_PC8:
 263           *(char *) reloc_addr
 264             = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 265           break;
 266         case R_68K_PC16:
 267           *(short *) reloc_addr
 268             = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 269           break;
 270         case R_68K_PC32:
 271           *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 272           break;
 273         case R_68K_TLS_DTPMOD32:
 274           /* Get the information from the link map returned by the
 275              resolv function.  */
 276           if (sym_map != NULL)
 277             *reloc_addr = sym_map->l_tls_modid;
 278           break;
 279         case R_68K_TLS_DTPREL32:
 280           if (sym != NULL)
 281             *reloc_addr = TLS_DTPREL_VALUE (sym, reloc);
 282           break;
 283         case R_68K_TLS_TPREL32:
 284           if (sym != NULL)
 285             {
 286               CHECK_STATIC_TLS (map, sym_map);
 287               *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
 288             }
 289           break;
 290         case R_68K_NONE:                /* Alright, Wilbur.  */
 291           break;
 292 #endif /* !RTLD_BOOTSTRAP */
 293         default:
 294           _dl_reloc_bad_type (map, r_type, 0);
 295           break;
 296         }
 297     }
 298 }
 299
 300 static inline void __attribute__ ((unused, always_inline))
 301 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
 302                            void *const reloc_addr_arg)
 303 {
 304   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 305   *reloc_addr = l_addr + reloc->r_addend;
 306 }
 307
 308 static inline void __attribute__ ((unused, always_inline))
 309 elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
 310                       Elf32_Addr l_addr, const Elf32_Rela *reloc,
 311                       int skip_ifunc)
 312 {
 313   Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
 314   if (ELF32_R_TYPE (reloc->r_info) == R_68K_JMP_SLOT)
 315     *reloc_addr += l_addr;
 316   else
 317     _dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 1);
 318 }
 319
 320 #endif /* RESOLVE_MAP */