sysdeps/m68k/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  m68k version.
   2    Copyright (C) 1996-2023 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 "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         | Load the adjusted argument count.\n\
 146         move.l (%sp), %d1\n\
 147         # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
 148         pea 8(%sp, %d1*4)\n\
 149         pea 8(%sp)\n\
 150         move.l %d1, -(%sp)\n\
 151         " PCREL_OP ("move.l", "_rtld_local", "-(%sp)", "%d0", "%pc") "\n\
 152         jbsr _dl_init\n\
 153         addq.l #8, %sp\n\
 154         addq.l #8, %sp\n\
 155         | Pass our finalizer function to the user in %a1.\n\
 156         " PCREL_OP ("lea", "_dl_fini", "%a1", "%a1", "%pc") "\n\
 157         | Initialize %fp with the stack pointer.\n\
 158         move.l %sp, %fp\n\
 159         | Jump to the user's entry point.\n\
 160         jmp (%a4)\n\
 161         .size _dl_start_user, . - _dl_start_user\n\
 162         .previous");
 163
 164 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
 165    TLS variable, so undefined references should not be allowed to
 166    define the value.
 167    ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
 168    of the main executable's symbols, as for a COPY reloc.  */
 169 #define elf_machine_type_class(type) \
 170   ((((type) == R_68K_JMP_SLOT        \
 171      || (type) == R_68K_TLS_DTPMOD32 \
 172      || (type) == R_68K_TLS_DTPREL32 \
 173      || (type) == R_68K_TLS_TPREL32) * ELF_RTYPE_CLASS_PLT)     \
 174    | (((type) == R_68K_COPY) * ELF_RTYPE_CLASS_COPY))
 175
 176 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 177 #define ELF_MACHINE_JMP_SLOT    R_68K_JMP_SLOT
 178
 179 static inline Elf32_Addr
 180 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 181                        const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
 182                        const Elf32_Rela *reloc,
 183                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 184 {
 185   return *reloc_addr = value;
 186 }
 187
 188 /* Return the final value of a plt relocation.  On the m68k the JMP_SLOT
 189    relocation ignores the addend.  */
 190 static inline Elf32_Addr
 191 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 192                        Elf32_Addr value)
 193 {
 194   return value;
 195 }
 196
 197 /* Names of the architecture-specific auditing callback functions.  */
 198 #define ARCH_LA_PLTENTER m68k_gnu_pltenter
 199 #define ARCH_LA_PLTEXIT m68k_gnu_pltexit
 200
 201 #endif /* !dl_machine_h */
 202
 203 #ifdef RESOLVE_MAP
 204
 205 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 206    MAP is the object containing the reloc.  */
 207
 208 static inline void __attribute__ ((unused, always_inline))
 209 elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
 210                   const Elf32_Rela *reloc, const Elf32_Sym *sym,
 211                   const struct r_found_version *version,
 212                   void *const reloc_addr_arg, int skip_ifunc)
 213 {
 214   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 215   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 216
 217   if (__builtin_expect (r_type == R_68K_RELATIVE, 0))
 218     *reloc_addr = map->l_addr + reloc->r_addend;
 219   else
 220     {
 221       const Elf32_Sym *const refsym = sym;
 222       struct link_map *sym_map = RESOLVE_MAP (map, scope, &sym, version,
 223                                               r_type);
 224       Elf32_Addr value = SYMBOL_ADDRESS (sym_map, sym, true);
 225
 226       switch (r_type)
 227         {
 228         case R_68K_GLOB_DAT:
 229         case R_68K_JMP_SLOT:
 230           *reloc_addr = value;
 231           break;
 232 #ifndef RTLD_BOOTSTRAP
 233         case R_68K_COPY:
 234           if (sym == NULL)
 235             /* This can happen in trace mode if an object could not be
 236                found.  */
 237             break;
 238           if (sym->st_size > refsym->st_size
 239               || (sym->st_size < refsym->st_size && GLRO(dl_verbose)))
 240             {
 241               const char *strtab;
 242
 243               strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
 244               _dl_error_printf ("\
 245 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
 246                                 RTLD_PROGNAME, strtab + refsym->st_name);
 247             }
 248           memcpy (reloc_addr_arg, (void *) value,
 249                   MIN (sym->st_size, refsym->st_size));
 250           break;
 251         case R_68K_8:
 252           *(char *) reloc_addr = value + reloc->r_addend;
 253           break;
 254         case R_68K_16:
 255           *(short *) reloc_addr = value + reloc->r_addend;
 256           break;
 257         case R_68K_32:
 258           *reloc_addr = value + reloc->r_addend;
 259           break;
 260         case R_68K_PC8:
 261           *(char *) reloc_addr
 262             = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 263           break;
 264         case R_68K_PC16:
 265           *(short *) reloc_addr
 266             = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 267           break;
 268         case R_68K_PC32:
 269           *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 270           break;
 271         case R_68K_TLS_DTPMOD32:
 272           /* Get the information from the link map returned by the
 273              resolv function.  */
 274           if (sym_map != NULL)
 275             *reloc_addr = sym_map->l_tls_modid;
 276           break;
 277         case R_68K_TLS_DTPREL32:
 278           if (sym != NULL)
 279             *reloc_addr = TLS_DTPREL_VALUE (sym, reloc);
 280           break;
 281         case R_68K_TLS_TPREL32:
 282           if (sym != NULL)
 283             {
 284               CHECK_STATIC_TLS (map, sym_map);
 285               *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
 286             }
 287           break;
 288         case R_68K_NONE:                /* Alright, Wilbur.  */
 289           break;
 290 #endif /* !RTLD_BOOTSTRAP */
 291         default:
 292           _dl_reloc_bad_type (map, r_type, 0);
 293           break;
 294         }
 295     }
 296 }
 297
 298 static inline void __attribute__ ((unused, always_inline))
 299 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
 300                            void *const reloc_addr_arg)
 301 {
 302   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 303   *reloc_addr = l_addr + reloc->r_addend;
 304 }
 305
 306 static inline void __attribute__ ((unused, always_inline))
 307 elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
 308                       Elf32_Addr l_addr, const Elf32_Rela *reloc,
 309                       int skip_ifunc)
 310 {
 311   Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
 312   if (ELF32_R_TYPE (reloc->r_info) == R_68K_JMP_SLOT)
 313     *reloc_addr += l_addr;
 314   else
 315     _dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 1);
 316 }
 317
 318 #endif /* RESOLVE_MAP */