279 lines
8.8 KiB
C
279 lines
8.8 KiB
C
/* Machine-dependent ELF dynamic relocation inline functions. m68k version.
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Copyright (C) 1996, 1997 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc.,
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59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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#ifndef dl_machine_h
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#define dl_machine_h
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#define ELF_MACHINE_NAME "m68k"
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#include <assert.h>
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/* Return nonzero iff E_MACHINE is compatible with the running host. */
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static inline int
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elf_machine_matches_host (Elf32_Half e_machine)
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{
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switch (e_machine)
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{
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case EM_68K:
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return 1;
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default:
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return 0;
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}
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}
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/* Return the link-time address of _DYNAMIC. Conveniently, this is the
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first element of the GOT. This must be inlined in a function which
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uses global data. */
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static inline Elf32_Addr
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elf_machine_dynamic (void)
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{
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register Elf32_Addr *got asm ("%a5");
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return *got;
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}
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/* Return the run-time load address of the shared object. */
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static inline Elf32_Addr
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elf_machine_load_address (void)
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{
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Elf32_Addr addr;
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asm ("here: lea here(%%pc), %0\n"
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" sub.l %#here, %0"
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: "=a" (addr));
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return addr;
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}
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/* The `subl' insn above will contain an R_68K_RELATIVE relocation
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entry intended to insert the run-time address of the label `here'.
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This will be the first relocation in the text of the dynamic
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linker; we skip it to avoid trying to modify read-only text in this
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early stage. */
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#define ELF_MACHINE_BEFORE_RTLD_RELOC(dynamic_info) \
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((dynamic_info)[DT_RELA]->d_un.d_ptr += sizeof (Elf32_Rela), \
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(dynamic_info)[DT_RELASZ]->d_un.d_val -= sizeof (Elf32_Rela))
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/* Set up the loaded object described by L so its unrelocated PLT
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entries will jump to the on-demand fixup code in dl-runtime.c. */
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static inline void
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elf_machine_runtime_setup (struct link_map *l, int lazy)
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{
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Elf32_Addr *got;
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extern void _dl_runtime_resolve (Elf32_Word);
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if (l->l_info[DT_JMPREL] && lazy)
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{
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/* The GOT entries for functions in the PLT have not yet been
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filled in. Their initial contents will arrange when called
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to push an offset into the .rela.plt section, push
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_GLOBAL_OFFSET_TABLE_[1], and then jump to
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_GLOBAL_OFFSET_TABLE_[2]. */
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got = (Elf32_Addr *) (l->l_addr + l->l_info[DT_PLTGOT]->d_un.d_ptr);
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got[1] = (Elf32_Addr) l; /* Identify this shared object. */
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/* This function will get called to fix up the GOT entry
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indicated by the offset on the stack, and then jump to the
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resolved address. */
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got[2] = (Elf32_Addr) &_dl_runtime_resolve;
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}
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/* This code is used in dl-runtime.c to call the `fixup' function
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and then redirect to the address it returns. */
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#define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\
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| Trampoline for _dl_runtime_resolver
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.globl _dl_runtime_resolve
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.type _dl_runtime_resolve, @function
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_dl_runtime_resolve:
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| Save %a0 (struct return address) and %a1.
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move.l %a0, -(%sp)
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move.l %a1, -(%sp)
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| Call the real address resolver.
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jbsr fixup
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| Restore register %a0 and %a1.
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move.l (%sp)+, %a1
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move.l (%sp)+, %a0
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| Pop parameters
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addq.l #8, %sp
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| Call real function.
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jmp (%d0)
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.size _dl_runtime_resolve, . - _dl_runtime_resolve
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");
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#define ELF_MACHINE_RUNTIME_FIXUP_ARGS long int save_a0, long int save_a1
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/* The PLT uses Elf32_Rela relocs. */
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#define elf_machine_relplt elf_machine_rela
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}
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/* Mask identifying addresses reserved for the user program,
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where the dynamic linker should not map anything. */
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#define ELF_MACHINE_USER_ADDRESS_MASK 0x80000000UL
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/* Initial entry point code for the dynamic linker.
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The C function `_dl_start' is the real entry point;
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its return value is the user program's entry point. */
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#define RTLD_START asm ("\
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.text
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.globl _start
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.globl _dl_start_user
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_start:
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move.l %sp, -(%sp)
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jbsr _dl_start
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addq.l #4, %sp
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_dl_start_user:
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| Save the user entry point address in %a4.
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move.l %d0, %a4
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| Point %a5 at the GOT.
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lea _GLOBAL_OFFSET_TABLE_@GOTPC(%pc), %a5
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| See if we were run as a command with the executable file
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| name as an extra leading argument.
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move.l ([_dl_skip_args@GOT, %a5]), %d0
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jeq 0f
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| Pop the original argument count
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move.l (%sp)+, %d1
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| Subtract _dl_skip_args from it.
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sub.l %d0, %d1
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| Adjust the stack pointer to skip _dl_skip_args words.
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lea (%sp, %d0*4), %sp
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| Push back the modified argument count.
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move.l %d1, -(%sp)
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0: | Push _dl_default_scope[2] as argument in _dl_init_next call below.
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move.l ([_dl_default_scope@GOT, %a5], 8), %d2
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0: move.l %d2, -(%sp)
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| Call _dl_init_next to return the address of an initializer
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| function to run.
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bsr.l _dl_init_next@PLTPC
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add.l #4, %sp | Pop argument.
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| Check for zero return, when out of initializers.
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tst.l %d0
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jeq 1f
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| Call the shared object initializer function.
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| NOTE: We depend only on the registers (%d2, %a4 and %a5)
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| and the return address pushed by this call;
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| the initializer is called with the stack just
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| as it appears on entry, and it is free to move
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| the stack around, as long as it winds up jumping to
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| the return address on the top of the stack.
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move.l %d0, %a0
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jsr (%a0)
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| Loop to call _dl_init_next for the next initializer.
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jra 0b
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1: | Clear the startup flag.
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clr.l _dl_starting_up@GOT(%a5)
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| Pass our finalizer function to the user in %a1.
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move.l _dl_fini@GOT(%a5), %a1
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| Initialize %fp with the stack pointer.
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move.l %sp, %fp
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| Jump to the user's entry point.
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jmp (%a4)");
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/* Nonzero iff TYPE describes relocation of a PLT entry, so
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PLT entries should not be allowed to define the value. */
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#define elf_machine_pltrel_p(type) ((type) == R_68K_JMP_SLOT)
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/* The m68k never uses Elf32_Rel relocations. */
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#define ELF_MACHINE_NO_REL 1
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#endif /* !dl_machine_h */
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#ifdef RESOLVE
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/* Perform the relocation specified by RELOC and SYM (which is fully resolved).
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MAP is the object containing the reloc. */
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static inline void
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elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
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const Elf32_Sym *sym, const struct r_found_version *version)
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{
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Elf32_Addr *const reloc_addr = (void *) (map->l_addr + reloc->r_offset);
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Elf32_Addr loadbase;
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switch (ELF32_R_TYPE (reloc->r_info))
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{
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case R_68K_COPY:
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loadbase = RESOLVE (&sym, version, DL_LOOKUP_NOEXEC);
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memcpy (reloc_addr, (void *) (loadbase + sym->st_value), sym->st_size);
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break;
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case R_68K_GLOB_DAT:
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loadbase = RESOLVE (&sym, version, 0);
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*reloc_addr = sym ? (loadbase + sym->st_value) : 0;
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break;
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case R_68K_JMP_SLOT:
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loadbase = RESOLVE (&sym, version, DL_LOOKUP_NOPLT);
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*reloc_addr = sym ? (loadbase + sym->st_value) : 0;
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break;
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case R_68K_8:
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loadbase = RESOLVE (&sym, version, 0);
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*(char *) reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
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+ reloc->r_addend);
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break;
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case R_68K_16:
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loadbase = RESOLVE (&sym, version, 0);
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*(short *) reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
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+ reloc->r_addend);
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break;
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case R_68K_32:
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loadbase = RESOLVE (&sym, version, 0);
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*reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
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+ reloc->r_addend);
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break;
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case R_68K_RELATIVE:
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*reloc_addr = map->l_addr + reloc->r_addend;
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break;
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case R_68K_PC8:
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loadbase = RESOLVE (&sym, version, 0);
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*(char *) reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
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+ reloc->r_addend - (Elf32_Addr) reloc_addr);
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break;
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case R_68K_PC16:
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loadbase = RESOLVE (&sym, version, 0);
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*(short *) reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
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+ reloc->r_addend - (Elf32_Addr) reloc_addr);
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break;
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case R_68K_PC32:
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loadbase = RESOLVE (&sym, version, 0);
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*reloc_addr = ((sym ? (loadbase + sym->st_value) : 0)
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+ reloc->r_addend - (Elf32_Addr) reloc_addr);
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break;
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case R_68K_NONE: /* Alright, Wilbur. */
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break;
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default:
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assert (! "unexpected dynamic reloc type");
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break;
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}
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}
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static inline void
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elf_machine_lazy_rel (struct link_map *map, const Elf32_Rela *reloc)
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{
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Elf32_Addr *const reloc_addr = (void *) (map->l_addr + reloc->r_offset);
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switch (ELF32_R_TYPE (reloc->r_info))
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{
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case R_68K_JMP_SLOT:
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*reloc_addr += map->l_addr;
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break;
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default:
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assert (! "unexpected PLT reloc type");
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break;
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}
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}
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#endif /* RESOLVE */
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