sysdeps/sparc/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  SPARC version.
   2 Copyright (C) 1996 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 Library General Public License as
   7 published by the Free Software Foundation; either version 2 of the
   8 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 Library General Public License for more details.
  14
  15 You should have received a copy of the GNU Library General Public
  16 License along with the GNU C Library; see the file COPYING.LIB.  If
  17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  18 Cambridge, MA 02139, USA.  */
  19
  20 #define ELF_MACHINE_NAME "sparc"
  21
  22 #include <assert.h>
  23 #include <string.h>
  24 #include <link.h>
  25
  26
  27 /* Some SPARC opcodes we need to use for self-modifying code.  */
  28 #define OPCODE_NOP      0x01000000 /* nop */
  29 #define OPCODE_CALL     0x04000000 /* call ?; add PC-rel word address */
  30 #define OPCODE_SETHI_G1 0x03000000 /* sethi ?, %g1; add value>>10 */
  31 #define OPCODE_JMP_G1   0x81c06000 /* jmp %g1+?; add lo 10 bits of value */
  32 #define OPCODE_SAVE_SP64 0x9de3bfc0 /* save %sp, -64, %sp */
  33
  34
  35 /* Return nonzero iff E_MACHINE is compatible with the running host.  */
  36 static inline int
  37 elf_machine_matches_host (Elf32_Half e_machine)
  38 {
  39   switch (e_machine)
  40     {
  41     case EM_SPARC:
  42       return 1;
  43     default:
  44       return 0;
  45     }
  46 }
  47
  48
  49 /* Return the run-time address of the _GLOBAL_OFFSET_TABLE_.
  50    Must be inlined in a function which uses global data.  */
  51 static inline Elf32_Addr *
  52 elf_machine_got (void)
  53 {
  54   register Elf32_Addr *got asm ("%l7");
  55   return got;
  56 }
  57
  58
  59 /* Return the run-time load address of the shared object.  */
  60 static inline Elf32_Addr
  61 elf_machine_load_address (void)
  62 {
  63   Elf32_Addr addr;
  64 ???
  65   return addr;
  66 }
  67
  68 /* The `subl' insn above will contain an R_68K_RELATIVE relocation
  69    entry intended to insert the run-time address of the label `here'.
  70    This will be the first relocation in the text of the dynamic
  71    linker; we skip it to avoid trying to modify read-only text in this
  72    early stage.  */
  73 #define ELF_MACHINE_BEFORE_RTLD_RELOC(dynamic_info) \
  74   ((dynamic_info)[DT_RELA]->d_un.d_ptr += sizeof (Elf32_Rela), \
  75    (dynamic_info)[DT_RELASZ]->d_un.d_val -= sizeof (Elf32_Rela))
  76
  77 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
  78    MAP is the object containing the reloc.  */
  79
  80 static inline void
  81 elf_machine_rela (struct link_map *map,
  82                   const Elf32_Rela *reloc, const Elf32_Sym *sym,
  83                   Elf32_Addr (*resolve) (const Elf32_Sym **ref,
  84                                          Elf32_Addr reloc_addr,
  85                                          int noplt))
  86 {
  87   Elf32_Addr *const reloc_addr = (void *) (map->l_addr + reloc->r_offset);
  88   Elf32_Addr loadbase;
  89
  90   switch (ELF32_R_TYPE (reloc->r_info))
  91     {
  92     case R_SPARC_COPY:
  93       loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
  94       memcpy (reloc_addr, (void *) (loadbase + sym->st_value), sym->st_size);
  95       break;
  96     case R_SPARC_GLOB_DAT:
  97     case R_SPARC_32:
  98       loadbase = (resolve ? (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0) :
  99                   /* RESOLVE is null during bootstrap relocation.  */
 100                   map->l_addr);
 101       *reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
 102                      + reloc->r_addend);
 103       break;
 104     case R_SPARC_JMP_SLOT:
 105       loadbase = (resolve ? (*resolve) (&sym, (Elf32_Addr) reloc_addr, 1) :
 106                   /* RESOLVE is null during bootstrap relocation.  */
 107                   map->l_addr);
 108       {
 109         Elf32_Addr value = ((sym ? (loadbase + sym->st_value) : 0)
 110                             + reloc->r_addend);
 111         reloc_addr[1] = OPCODE_SETHI | (value >> 10);
 112         reloc_addr[2] = OPCODE_JMP_G1 | (value & 0x3ff);
 113       }
 114       break;
 115     case R_SPARC_8:
 116       loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
 117       *(char *) reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
 118                               + reloc->r_addend);
 119       break;
 120     case R_SPARC_16:
 121       loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
 122       *(short *) reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
 123                                + reloc->r_addend);
 124       break;
 125     case R_SPARC_32:
 126       loadbase = (resolve ? (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0) :
 127                   /* RESOLVE is null during bootstrap relocation.  */
 128                   map->l_addr);
 129       break;
 130     case R_SPARC_RELATIVE:
 131       *reloc_addr = map->l_addr + reloc->r_addend;
 132       break;
 133     case R_SPARC_DISP8:
 134       loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
 135       *(char *) reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
 136                               + reloc->r_addend
 137                               - (Elf32_Addr) reloc_addr);
 138       break;
 139     case R_SPARC_DISP16:
 140       loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
 141       *(short *) reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
 142                                + reloc->r_addend
 143                                - (Elf32_Addr) reloc_addr);
 144       break;
 145     case R_SPARC_DISP32:
 146       loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
 147       *reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
 148                      + reloc->r_addend
 149                      - (Elf32_Addr) reloc_addr);
 150       break;
 151     case R_SPARC_NONE:          /* Alright, Wilbur.  */
 152       break;
 153     default:
 154       assert (! "unexpected dynamic reloc type");
 155       break;
 156     }
 157 }
 158
 159 static inline void
 160 elf_machine_lazy_rel (struct link_map *map, const Elf32_Rela *reloc)
 161 {
 162   switch (ELF32_R_TYPE (reloc->r_info))
 163     {
 164     case R_SPARC_NONE:
 165       break;
 166     case R_SPARC_JMP_SLOT:
 167       break;
 168     default:
 169       assert (! "unexpected PLT reloc type");
 170       break;
 171     }
 172 }
 173
 174 /* Nonzero iff TYPE describes relocation of a PLT entry, so
 175    PLT entries should not be allowed to define the value.  */
 176 #define elf_machine_pltrel_p(type) ((type) == R_SPARC_JMP_SLOT)
 177
 178 /* The SPARC never uses Elf32_Rel relocations.  */
 179 #define ELF_MACHINE_NO_REL 1
 180
 181
 182 /* Set up the loaded object described by L so its unrelocated PLT
 183    entries will jump to the on-demand fixup code in dl-runtime.c.  */
 184
 185 static inline void
 186 elf_machine_runtime_setup (struct link_map *l, int lazy)
 187 {
 188   Elf32_Addr *plt;
 189   extern void _dl_runtime_resolve (Elf32_Word);
 190
 191   if (l->l_info[DT_JMPREL] && lazy)
 192     {
 193       /* The entries for functions in the PLT have not yet been filled in.
 194          Their initial contents will arrange when called to set the high 22
 195          bits of %g1 with an offset into the .rela.plt section and jump to
 196          the beginning of the PLT.  */
 197       plt = (Elf32_Addr *) (l->l_addr + l->l_info[DT_PLTGOT]->d_un.d_ptr);
 198
 199       /* The beginning of the PLT does:
 200
 201                 save %sp, -64, %sp
 202          pltpc: call _dl_runtime_resolve
 203                 nop
 204                 .word MAP
 205
 206          This saves the register window containing the arguments, and the
 207          PC value (pltpc) implicitly saved in %o7 by the call points near the
 208          location where we store the link_map pointer for this object.  */
 209
 210       plt[0] = OPCODE_SAVE_SP64; /* save %sp, -64, %sp */
 211       /* Construct PC-relative word address.  */
 212       plt[1] = OPCODE_CALL | (((Elf32_Addr) &_dl_runtime_resolve -
 213                                (Elf32_Addr) &plt[1]) >> 2);
 214       plt[2] = OPCODE_NOP;      /* Fill call delay slot.  */
 215       plt[3] = l;
 216     }
 217
 218   /* This code is used in dl-runtime.c to call the `fixup' function
 219      and then redirect to the address it returns.  */
 220 #define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\
 221 | Trampoline for _dl_runtime_resolver
 222         .globl _dl_runtime_resolve
 223         .type _dl_runtime_resolve, @function
 224 _dl_runtime_resolve:
 225         | Pass two args to fixup: the PLT address computed from the PC saved
 226         | in the PLT's call insn, and the reloc offset passed in %g1.
 227         ld [%o7 + 8], %o1       | Second arg, loaded from PLTPC[2].
 228         call fixup
 229         shrl %g1, 22, %o0       | First arg, set in delay slot of call.
 230         | Jump to the real function.
 231         jmpl %o0, %g0
 232         | In the delay slot of that jump, restore the register window
 233         | saved by the first insn of the PLT.
 234         restore
 235         .size _dl_runtime_resolve, . - _dl_runtime_resolve
 236 ");
 237 /* The PLT uses Elf32_Rela relocs.  */
 238 #define elf_machine_relplt elf_machine_rela
 239 }
 240
 241
 242 /* Mask identifying addresses reserved for the user program,
 243    where the dynamic linker should not map anything.  */
 244 #define ELF_MACHINE_USER_ADDRESS_MASK   ???
 245
 246 /* Initial entry point code for the dynamic linker.
 247    The C function `_dl_start' is the real entry point;
 248    its return value is the user program's entry point.  */
 249
 250 #define RTLD_START asm (???)