1 /* Machine-dependent ELF dynamic relocation inline functions. PowerPC version.
2 Copyright (C) 1995-2000, 2001 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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.
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.
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 not,
17 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA. */
23 #define ELF_MACHINE_NAME "powerpc"
27 /* Return nonzero iff ELF header is compatible with the running host. */
29 elf_machine_matches_host (const Elf32_Ehdr
*ehdr
)
31 return ehdr
->e_machine
== EM_PPC
;
35 /* Return the link-time address of _DYNAMIC, stored as
36 the first value in the GOT. */
37 static inline Elf32_Addr
38 elf_machine_dynamic (void)
41 asm (" bl _GLOBAL_OFFSET_TABLE_-4@local"
46 /* Return the run-time load address of the shared object. */
47 static inline Elf32_Addr
48 elf_machine_load_address (void)
51 unsigned int *branchaddr
;
53 /* This is much harder than you'd expect. Possibly I'm missing something.
56 Apparently, "bcl 20,31,$+4" is what should be used to load LR
57 with the address of the next instruction.
58 I think this is so that machines that do bl/blr pairing don't
66 : "=b" (addr) : : "r0", "lr");
68 doesn't work, because the linker doesn't have to (and in fact doesn't)
69 update the @ha and @l references; the loader (which runs after this
72 Instead, we use the following trick:
74 The linker puts the _link-time_ address of _DYNAMIC at the first
75 word in the GOT. We could branch to that address, if we wanted,
76 by using an @local reloc; the linker works this out, so it's safe
77 to use now. We can't, of course, actually branch there, because
78 we'd cause an illegal instruction exception; so we need to compute
79 the address ourselves. That gives us the following code: */
81 /* Get address of the 'b _DYNAMIC@local'... */
87 /* ... and the address of the GOT. */
88 asm (" bl _GLOBAL_OFFSET_TABLE_-4@local"
91 /* So now work out the difference between where the branch actually points,
92 and the offset of that location in memory from the start of the file. */
93 return ((Elf32_Addr
)branchaddr
- *got
94 + ((int)(*branchaddr
<< 6 & 0xffffff00) >> 6));
97 #define ELF_MACHINE_BEFORE_RTLD_RELOC(dynamic_info) /* nothing */
99 /* The PLT uses Elf32_Rela relocs. */
100 #define elf_machine_relplt elf_machine_rela
102 /* This code is used in dl-runtime.c to call the `fixup' function
103 and then redirect to the address it returns. It is called
104 from code built in the PLT by elf_machine_runtime_setup. */
105 #define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\
108 .globl _dl_runtime_resolve
109 .type _dl_runtime_resolve,@function
111 # We need to save the registers used to pass parameters, and register 0,
112 # which is used by _mcount; the registers are saved in a stack frame.
117 # The code that calls this has put parameters for `fixup' in r12 and r11.
123 # We also need to save some of the condition register fields.
132 # 'fixup' returns the address we want to branch to.
134 # Put the registers back...
148 # ...unwind the stack frame, and jump to the PLT entry we updated.
151 .size _dl_runtime_resolve,.-_dl_runtime_resolve
154 .globl _dl_prof_resolve
155 .type _dl_prof_resolve,@function
157 # We need to save the registers used to pass parameters, and register 0,
158 # which is used by _mcount; the registers are saved in a stack frame.
163 # The code that calls this has put parameters for `fixup' in r12 and r11.
169 # We also need to save some of the condition register fields.
177 bl profile_fixup@local
178 # 'fixup' returns the address we want to branch to.
180 # Put the registers back...
194 # ...unwind the stack frame, and jump to the PLT entry we updated.
197 .size _dl_prof_resolve,.-_dl_prof_resolve
198 # Undo '.section text'.
202 /* The actual _start code is in dl-start.S. Use a really
203 ugly bit of assembler to let dl-start.o see _dl_start. */
204 #define RTLD_START asm (".globl _dl_start");
206 /* Decide where a relocatable object should be loaded. */
208 __elf_preferred_address(struct link_map
*loader
, size_t maplength
,
209 ElfW(Addr
) mapstartpref
);
210 #define ELF_PREFERRED_ADDRESS(loader, maplength, mapstartpref) \
211 __elf_preferred_address (loader, maplength, mapstartpref)
213 /* Nonzero iff TYPE should not be allowed to resolve to one of
214 the main executable's symbols, as for a COPY reloc. */
215 #define elf_machine_lookup_noexec_p(type) ((type) == R_PPC_COPY)
217 /* Nonzero iff TYPE describes relocation of a PLT entry, so
218 PLT entries should not be allowed to define the value. */
219 /* We never want to use a PLT entry as the destination of a
220 reloc, when what is being relocated is a branch. This is
221 partly for efficiency, but mostly so we avoid loops. */
222 #define elf_machine_lookup_noplt_p(type) ((type) == R_PPC_REL24 || \
223 (type) == R_PPC_ADDR24 || \
224 (type) == R_PPC_JMP_SLOT)
226 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
227 #define ELF_MACHINE_JMP_SLOT R_PPC_JMP_SLOT
229 /* Set up the loaded object described by L so its unrelocated PLT
230 entries will jump to the on-demand fixup code in dl-runtime.c.
231 Also install a small trampoline to be used by entries that have
232 been relocated to an address too far away for a single branch. */
233 extern int __elf_machine_runtime_setup (struct link_map
*map
,
234 int lazy
, int profile
);
235 #define elf_machine_runtime_setup __elf_machine_runtime_setup
238 elf_machine_lazy_rel (struct link_map
*map
,
239 Elf32_Addr l_addr
, const Elf32_Rela
*reloc
)
241 /* elf_machine_runtime_setup handles this. */
244 /* Change the PLT entry whose reloc is 'reloc' to call the actual routine. */
245 extern Elf32_Addr
__elf_machine_fixup_plt (struct link_map
*map
,
246 const Elf32_Rela
*reloc
,
247 Elf32_Addr
*reloc_addr
,
248 Elf32_Addr finaladdr
);
250 static inline Elf32_Addr
251 elf_machine_fixup_plt (struct link_map
*map
, lookup_t t
,
252 const Elf32_Rela
*reloc
,
253 Elf32_Addr
*reloc_addr
, Elf64_Addr finaladdr
)
255 return __elf_machine_fixup_plt (map
, reloc
, reloc_addr
, finaladdr
);
258 /* Return the final value of a plt relocation. */
259 static inline Elf32_Addr
260 elf_machine_plt_value (struct link_map
*map
, const Elf32_Rela
*reloc
,
263 return value
+ reloc
->r_addend
;
266 #endif /* dl_machine_h */
270 /* Do the actual processing of a reloc, once its target address
271 has been determined. */
272 extern void __process_machine_rela (struct link_map
*map
,
273 const Elf32_Rela
*reloc
,
274 const Elf32_Sym
*sym
,
275 const Elf32_Sym
*refsym
,
276 Elf32_Addr
*const reloc_addr
,
277 Elf32_Addr finaladdr
,
280 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
281 LOADADDR is the load address of the object; INFO is an array indexed
282 by DT_* of the .dynamic section info. */
285 elf_machine_rela (struct link_map
*map
, const Elf32_Rela
*reloc
,
286 const Elf32_Sym
*sym
, const struct r_found_version
*version
,
287 Elf32_Addr
*const reloc_addr
)
289 const Elf32_Sym
*const refsym
= sym
;
290 Elf32_Word loadbase
, finaladdr
;
291 const int rinfo
= ELF32_R_TYPE (reloc
->r_info
);
293 if (rinfo
== R_PPC_NONE
)
296 /* The condition on the next two lines is a hack around a bug in Solaris
297 tools on Sparc. It's not clear whether it should really be here at all,
298 but if not the binutils need to be changed. */
299 if (rinfo
== R_PPC_RELATIVE
300 || (sym
->st_shndx
!= SHN_UNDEF
301 && ELF32_ST_BIND (sym
->st_info
) == STB_LOCAL
))
303 /* Has already been relocated. */
304 loadbase
= map
->l_addr
;
305 finaladdr
= loadbase
+ reloc
->r_addend
;
309 loadbase
= (Elf32_Word
) (char *) (RESOLVE (&sym
, version
,
310 ELF32_R_TYPE(reloc
->r_info
)));
313 /* Weak symbol that wasn't actually defined anywhere. */
314 assert(loadbase
== 0);
315 finaladdr
= reloc
->r_addend
;
318 finaladdr
= (loadbase
+ (Elf32_Word
) (char *) sym
->st_value
322 /* A small amount of code is duplicated here for speed. In libc,
323 more than 90% of the relocs are R_PPC_RELATIVE; in the X11 shared
324 libraries, 60% are R_PPC_RELATIVE, 24% are R_PPC_GLOB_DAT or
325 R_PPC_ADDR32, and 16% are R_PPC_JMP_SLOT (which this routine
326 wouldn't usually handle). As an bonus, doing this here allows
327 the switch statement in __process_machine_rela to work. */
328 if (rinfo
== R_PPC_RELATIVE
329 || rinfo
== R_PPC_GLOB_DAT
330 || rinfo
== R_PPC_ADDR32
)
332 *reloc_addr
= finaladdr
;
335 __process_machine_rela (map
, reloc
, sym
, refsym
,
336 reloc_addr
, finaladdr
, rinfo
);
339 #define ELF_MACHINE_NO_REL 1
341 /* The SVR4 ABI specifies that the JMPREL relocs must be inside the
343 #define ELF_MACHINE_PLTREL_OVERLAP 1