sysdeps/sparc/sparc32/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  SPARC version.
   2    Copyright (C) 1996, 1997 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.,
  18    59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  19
  20 #define ELF_MACHINE_NAME "sparc"
  21
  22 #include <assert.h>
  23 #include <string.h>
  24 #include <link.h>
  25 #include <sys/param.h>
  26
  27
  28 /* Some SPARC opcodes we need to use for self-modifying code.  */
  29 #define OPCODE_NOP      0x01000000 /* nop */
  30 #define OPCODE_CALL     0x40000000 /* call ?; add PC-rel word address */
  31 #define OPCODE_SETHI_G1 0x03000000 /* sethi ?, %g1; add value>>10 */
  32 #define OPCODE_JMP_G1   0x81c06000 /* jmp %g1+?; add lo 10 bits of value */
  33 #define OPCODE_SAVE_SP  0x9de3bfa8 /* save %sp, -(16+6)*4, %sp */
  34
  35
  36 /* Return nonzero iff E_MACHINE is compatible with the running host.  */
  37 static inline int
  38 elf_machine_matches_host (Elf32_Half e_machine)
  39 {
  40   return e_machine == EM_SPARC;
  41 }
  42
  43
  44 /* Return the link-time address of _DYNAMIC.  Conveniently, this is the
  45    first element of the GOT.  This must be inlined in a function which
  46    uses global data.  */
  47 static inline Elf32_Addr
  48 elf_machine_dynamic (void)
  49 {
  50   register Elf32_Addr *got asm ("%l7");
  51   return *got;
  52 }
  53
  54 /* Return the run-time load address of the shared object.  */
  55 static inline Elf32_Addr
  56 elf_machine_load_address (void)
  57 {
  58   register Elf32_Addr pc __asm("%o7"), pic __asm("%l7"), got;
  59
  60   /* Utilize the fact that a local .got entry will be partially
  61      initialized at startup awaiting its RELATIVE fixup.  */
  62
  63   __asm("sethi %%hi(.Load_address),%1\n"
  64         ".Load_address:\n\t"
  65         "call 1f\n\t"
  66         "or %1,%%lo(.Load_address),%1\n"
  67         "1:\tld [%2+%1],%1"
  68         : "=r"(pc), "=r"(got) : "r"(pic));
  69
  70   return pc - got;
  71 }
  72
  73 /* Set up the loaded object described by L so its unrelocated PLT
  74    entries will jump to the on-demand fixup code in dl-runtime.c.  */
  75
  76 static inline int
  77 elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
  78 {
  79   Elf32_Addr *plt;
  80   extern void _dl_runtime_resolve (Elf32_Word);
  81
  82   if (l->l_info[DT_JMPREL] && lazy)
  83     {
  84       /* The entries for functions in the PLT have not yet been filled in.
  85          Their initial contents will arrange when called to set the high 22
  86          bits of %g1 with an offset into the .rela.plt section and jump to
  87          the beginning of the PLT.  */
  88       plt = (Elf32_Addr *) (l->l_addr + l->l_info[DT_PLTGOT]->d_un.d_ptr);
  89
  90       /* The beginning of the PLT does:
  91
  92                 save %sp, -64, %sp
  93          pltpc: call _dl_runtime_resolve
  94                 nop
  95                 .word MAP
  96
  97          This saves the register window containing the arguments, and the
  98          PC value (pltpc) implicitly saved in %o7 by the call points near the
  99          location where we store the link_map pointer for this object.  */
 100
 101       plt[0] = OPCODE_SAVE_SP;
 102       /* Construct PC-relative word address.  */
 103       plt[1] = OPCODE_CALL | (((Elf32_Addr) &_dl_runtime_resolve -
 104                                (Elf32_Addr) &plt[1]) >> 2);
 105       plt[2] = OPCODE_NOP;      /* Fill call delay slot.  */
 106       plt[3] = (Elf32_Addr) l;
 107     }
 108
 109   return lazy;
 110 }
 111
 112 /* This code is used in dl-runtime.c to call the `fixup' function
 113    and then redirect to the address it returns.  */
 114 #define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\
 115         .globl _dl_runtime_resolve
 116         .type _dl_runtime_resolve, @function
 117 _dl_runtime_resolve:
 118         /* Set up the arguments to fixup --
 119            %o0 = link_map out of plt0
 120            %o1 = offset of reloc entry  */
 121         ld      [%o7 + 8], %o0
 122         srl     %g1, 10, %o1
 123         call    fixup
 124          sub    %o1, 4*12, %o1
 125         jmp     %o0
 126          restore
 127         .size _dl_runtime_resolve, . - _dl_runtime_resolve");
 128
 129 /* Nonzero iff TYPE should not be allowed to resolve to one of
 130    the main executable's symbols, as for a COPY reloc.  */
 131 #define elf_machine_lookup_noexec_p(type) ((type) == R_SPARC_COPY)
 132
 133 /* Nonzero iff TYPE describes relocation of a PLT entry, so
 134    PLT entries should not be allowed to define the value.  */
 135 #define elf_machine_lookup_noplt_p(type) ((type) == R_SPARC_JMP_SLOT)
 136
 137 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 138 #define ELF_MACHINE_JMP_SLOT    R_SPARC_JMP_SLOT
 139
 140 /* The SPARC never uses Elf32_Rel relocations.  */
 141 #define ELF_MACHINE_NO_REL 1
 142
 143 /* The SPARC overlaps DT_RELA and DT_PLTREL.  */
 144 #define ELF_MACHINE_PLTREL_OVERLAP 1
 145
 146 /* Initial entry point code for the dynamic linker.
 147    The C function `_dl_start' is the real entry point;
 148    its return value is the user program's entry point.  */
 149
 150 #define RTLD_START __asm__ ("\
 151 .text
 152         .globl _start
 153         .type _start,@function
 154 _start:
 155   /* Allocate space for functions to drop their arguments.  */
 156         sub     %sp, 6*4, %sp
 157   /* Pass pointer to argument block to _dl_start.  */
 158         call    _dl_start
 159          add    %sp, 22*4, %o0
 160         /* FALTHRU */
 161         .globl _dl_start_user
 162         .type _dl_start_user,@function
 163 _dl_start_user:
 164   /* Load the PIC register.  */
 165 1:      call    2f
 166          sethi  %hi(_GLOBAL_OFFSET_TABLE_-(1b-.)), %l7
 167 2:      or      %l7, %lo(_GLOBAL_OFFSET_TABLE_-(1b-.)), %l7
 168         add     %l7, %o7, %l7
 169   /* Save the user entry point address in %l0 */
 170         mov     %o0, %l0
 171   /* See if we were run as a command with the executable file name as an
 172      extra leading argument.  If so, adjust the contents of the stack.  */
 173         sethi   %hi(_dl_skip_args), %g2
 174         or      %g2, %lo(_dl_skip_args), %g2
 175         ld      [%l7+%g2], %i0
 176         ld      [%i0], %i0
 177         tst     %i0
 178         beq     3f
 179          nop
 180         /* Find out how far to shift.  */
 181         ld      [%sp+22*4], %i1         /* load argc */
 182         sub     %i1, %i0, %i1
 183         sll     %i0, 2, %i2
 184         st      %i1, [%sp+22*4]
 185         add     %sp, 23*4, %i1
 186         add     %i1, %i2, %i2
 187         /* Copy down argv */
 188 21:     ld      [%i2], %i3
 189         add     %i2, 4, %i2
 190         tst     %i3
 191         st      %i3, [%i1]
 192         bne     21b
 193          add    %i1, 4, %i1
 194         /* Copy down env */
 195 22:     ld      [%i2], %i3
 196         add     %i2, 4, %i2
 197         tst     %i3
 198         st      %i3, [%i1]
 199         bne     22b
 200          add    %i1, 4, %i1
 201         /* Copy down auxiliary table.  */
 202 23:     ld      [%i2], %i3
 203         ld      [%i2+4], %i4
 204         add     %i2, 8, %i2
 205         tst     %i3
 206         st      %i3, [%i1]
 207         st      %i4, [%i1+4]
 208         bne     23b
 209          add    %i1, 8, %i1
 210   /* Load _dl_default_scope[2] to pass to _dl_init_next.  */
 211 3:      sethi   %hi(_dl_default_scope), %g1
 212         or      %g1, %lo(_dl_default_scope), %g1
 213         ld      [%l7+%g1], %l1
 214         ld      [%l1+2*4], %l1
 215   /* Call _dl_init_next to return the address of an initializer to run.  */
 216 4:      call    _dl_init_next
 217          mov    %l1, %o0
 218         tst     %o0
 219         beq     5f
 220          nop
 221         jmpl    %o0, %o7
 222          nop
 223         ba,a    4b
 224   /* Clear the startup flag.  */
 225 5:      sethi   %hi(_dl_starting_up), %g1
 226         or      %g1, %lo(_dl_starting_up), %g1
 227         ld      [%l7+%g1], %g1
 228         st      %g0, [%g1]
 229   /* Pass our finalizer function to the user in %g1.  */
 230         sethi   %hi(_dl_fini), %g1
 231         or      %g1, %lo(_dl_fini), %g1
 232         ld      [%l7+%g1], %g1
 233   /* Jump to the user's entry point and deallocate the extra stack we got.  */
 234         jmp     %l0
 235          add    %sp, 6*4, %sp
 236         .size   _dl_start_user,.-_dl_start_user
 237 .previous");
 238
 239 static inline void
 240 elf_machine_fixup_plt (struct link_map *map, const Elf32_Rela *reloc,
 241                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 242 {
 243   extern unsigned long _dl_hwcap;
 244
 245   /* For thread safety, write the instructions from the bottom and
 246      flush before we overwrite the critical "b,a".  This of course
 247      need not be done during bootstrapping, since there are no threads.
 248      But we also can't tell if we _can_ use flush, so don't. */
 249
 250   reloc_addr[2] = OPCODE_JMP_G1 | (value & 0x3ff);
 251 #ifndef RTLD_BOOTSTRAP
 252   if (_dl_hwcap & HWCAP_SPARC_FLUSH)
 253     __asm __volatile ("flush %0+8" : : "r"(reloc_addr));
 254 #endif
 255
 256   reloc_addr[1] = OPCODE_SETHI_G1 | (value >> 10);
 257 #ifndef RTLD_BOOTSTRAP
 258   if (_dl_hwcap & HWCAP_SPARC_FLUSH)
 259     __asm __volatile ("flush %0+4" : : "r"(reloc_addr));
 260 #endif
 261 }
 262
 263 /* Return the final value of a plt relocation.  */
 264 static inline Elf32_Addr
 265 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 266                        Elf32_Addr value)
 267 {
 268   return value + reloc->r_addend;
 269 }
 270
 271 #ifdef RESOLVE
 272
 273 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 274    MAP is the object containing the reloc.  */
 275
 276 static inline void
 277 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 278                   const Elf32_Sym *sym, const struct r_found_version *version,
 279                   Elf32_Addr *const reloc_addr)
 280 {
 281   if (ELF32_R_TYPE (reloc->r_info) == R_SPARC_RELATIVE)
 282     {
 283 #ifndef RTLD_BOOTSTRAP
 284       if (map != &_dl_rtld_map) /* Already done in rtld itself. */
 285 #endif
 286         *reloc_addr += map->l_addr + reloc->r_addend;
 287     }
 288   else
 289     {
 290       const Elf32_Sym *const refsym = sym;
 291       Elf32_Addr value;
 292       if (sym->st_shndx != SHN_UNDEF &&
 293           ELF32_ST_BIND (sym->st_info) == STB_LOCAL)
 294         value = map->l_addr;
 295       else
 296         {
 297           value = RESOLVE (&sym, version, ELF32_R_TYPE (reloc->r_info));
 298           if (sym)
 299             value += sym->st_value;
 300         }
 301       value += reloc->r_addend; /* Assume copy relocs have zero addend.  */
 302
 303       switch (ELF32_R_TYPE (reloc->r_info))
 304         {
 305         case R_SPARC_COPY:
 306 #ifndef RTLD_BOOTSTRAP
 307           if (sym->st_size > refsym->st_size
 308               || (_dl_verbose && sym->st_size < refsym->st_size))
 309             {
 310               extern char **_dl_argv;
 311               const char *strtab;
 312
 313               strtab = ((void *) map->l_addr
 314                         + map->l_info[DT_STRTAB]->d_un.d_ptr);
 315               _dl_sysdep_error (_dl_argv[0] ?: "<program name unknown>",
 316                                 ": Symbol `", strtab + refsym->st_name,
 317                                 "' has different size in shared object, "
 318                                 "consider re-linking\n", NULL);
 319             }
 320           memcpy (reloc_addr, (void *) value, MIN (sym->st_size,
 321                                                    refsym->st_size));
 322 #endif
 323           break;
 324         case R_SPARC_GLOB_DAT:
 325         case R_SPARC_32:
 326           *reloc_addr = value;
 327           break;
 328         case R_SPARC_JMP_SLOT:
 329           elf_machine_fixup_plt(map, reloc, reloc_addr, value);
 330           break;
 331         case R_SPARC_8:
 332           *(char *) reloc_addr = value;
 333           break;
 334         case R_SPARC_16:
 335           *(short *) reloc_addr = value;
 336           break;
 337         case R_SPARC_DISP8:
 338           *(char *) reloc_addr = (value - (Elf32_Addr) reloc_addr);
 339           break;
 340         case R_SPARC_DISP16:
 341           *(short *) reloc_addr = (value - (Elf32_Addr) reloc_addr);
 342           break;
 343         case R_SPARC_DISP32:
 344           *reloc_addr = (value - (Elf32_Addr) reloc_addr);
 345           break;
 346         case R_SPARC_LO10:
 347           *reloc_addr = (*reloc_addr & ~0x3ff) | (value & 0x3ff);
 348           break;
 349         case R_SPARC_WDISP30:
 350           *reloc_addr = ((*reloc_addr & 0xc0000000)
 351                          | ((value - (unsigned int) reloc_addr) >> 2));
 352           break;
 353         case R_SPARC_HI22:
 354           *reloc_addr = (*reloc_addr & 0xffc00000) | (value >> 10);
 355           break;
 356         case R_SPARC_NONE:              /* Alright, Wilbur.  */
 357           break;
 358         default:
 359           assert (! "unexpected dynamic reloc type");
 360           break;
 361         }
 362     }
 363 }
 364
 365 static inline void
 366 elf_machine_lazy_rel (struct link_map *map, const Elf32_Rela *reloc)
 367 {
 368   switch (ELF32_R_TYPE (reloc->r_info))
 369     {
 370     case R_SPARC_NONE:
 371       break;
 372     case R_SPARC_JMP_SLOT:
 373       break;
 374     default:
 375       assert (! "unexpected PLT reloc type");
 376       break;
 377     }
 378 }
 379
 380 #endif  /* RESOLVE */