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 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.
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.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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. */
106 #define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\n\
107 .section \".text\" \n\
109 .globl _dl_runtime_resolve \n\
110 .type _dl_runtime_resolve,@function \n\
111 _dl_runtime_resolve: \n\
112 # We need to save the registers used to pass parameters, and register 0,\n\
113 # which is used by _mcount; the registers are saved in a stack frame.\n\
118 # The code that calls this has put parameters for `fixup' in r12 and r11.\n\
124 # We also need to save some of the condition register fields.\n\
133 # 'fixup' returns the address we want to branch to.\n\
135 # Put the registers back...\n\
149 # ...unwind the stack frame, and jump to the PLT entry we updated.\n\
152 .size _dl_runtime_resolve,.-_dl_runtime_resolve \n\
155 .globl _dl_prof_resolve \n\
156 .type _dl_prof_resolve,@function \n\
157 _dl_prof_resolve: \n\
158 # We need to save the registers used to pass parameters, and register 0,\n\
159 # which is used by _mcount; the registers are saved in a stack frame.\n\
164 # The code that calls this has put parameters for `fixup' in r12 and r11.\n\
170 # We also need to save some of the condition register fields.\n\
178 bl profile_fixup@local \n\
179 # 'fixup' returns the address we want to branch to.\n\
181 # Put the registers back...\n\
195 # ...unwind the stack frame, and jump to the PLT entry we updated.\n\
198 .size _dl_prof_resolve,.-_dl_prof_resolve \n\
199 # Undo '.section text'.\n\
203 # define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\n\
204 .section \".text\" \n\
206 .globl _dl_runtime_resolve \n\
207 .globl _dl_prof_resolve \n\
208 .type _dl_runtime_resolve,@function \n\
209 .type _dl_prof_resolve,@function \n\
210 _dl_runtime_resolve: \n\
211 _dl_prof_resolve: \n\
212 # We need to save the registers used to pass parameters, and register 0,\n\
213 # which is used by _mcount; the registers are saved in a stack frame.\n\
218 # The code that calls this has put parameters for `fixup' in r12 and r11.\n\
224 # We also need to save some of the condition register fields.\n\
233 # 'fixup' returns the address we want to branch to.\n\
235 # Put the registers back...\n\
249 # ...unwind the stack frame, and jump to the PLT entry we updated.\n\
252 .size _dl_runtime_resolve,.-_dl_runtime_resolve \n\
256 /* The actual _start code is in dl-start.S. Use a really
257 ugly bit of assembler to let dl-start.o see _dl_start. */
258 #define RTLD_START asm (".globl _dl_start");
260 /* Decide where a relocatable object should be loaded. */
262 __elf_preferred_address(struct link_map *loader, size_t maplength,
263 ElfW(Addr) mapstartpref);
264 #define ELF_PREFERRED_ADDRESS(loader, maplength, mapstartpref) \
265 __elf_preferred_address (loader, maplength, mapstartpref)
267 /* Nonzero iff TYPE should not be allowed to resolve to one of
268 the main executable's symbols, as for a COPY reloc. */
269 #define elf_machine_lookup_noexec_p(type) ((type) == R_PPC_COPY)
271 /* Nonzero iff TYPE describes relocation of a PLT entry, so
272 PLT entries should not be allowed to define the value. */
273 /* We never want to use a PLT entry as the destination of a
274 reloc, when what is being relocated is a branch. This is
275 partly for efficiency, but mostly so we avoid loops. */
276 #define elf_machine_lookup_noplt_p(type) ((type) == R_PPC_REL24 || \
277 (type) == R_PPC_ADDR24 || \
278 (type) == R_PPC_JMP_SLOT)
280 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
281 #define ELF_MACHINE_JMP_SLOT R_PPC_JMP_SLOT
283 /* The PowerPC never uses REL relocations. */
284 #define ELF_MACHINE_NO_REL 1
286 /* Set up the loaded object described by L so its unrelocated PLT
287 entries will jump to the on-demand fixup code in dl-runtime.c.
288 Also install a small trampoline to be used by entries that have
289 been relocated to an address too far away for a single branch. */
290 extern int __elf_machine_runtime_setup (struct link_map *map,
291 int lazy, int profile);
292 #define elf_machine_runtime_setup __elf_machine_runtime_setup
295 elf_machine_lazy_rel (struct link_map *map,
296 Elf32_Addr l_addr, const Elf32_Rela *reloc)
298 /* elf_machine_runtime_setup handles this. */
301 /* Change the PLT entry whose reloc is 'reloc' to call the actual routine. */
302 extern Elf32_Addr __elf_machine_fixup_plt (struct link_map *map,
303 const Elf32_Rela *reloc,
304 Elf32_Addr *reloc_addr,
305 Elf32_Addr finaladdr);
307 static inline Elf32_Addr
308 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
309 const Elf32_Rela *reloc,
310 Elf32_Addr *reloc_addr, Elf64_Addr finaladdr)
312 return __elf_machine_fixup_plt (map, reloc, reloc_addr, finaladdr);
315 /* Return the final value of a plt relocation. */
316 static inline Elf32_Addr
317 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
320 return value + reloc->r_addend;
323 #endif /* dl_machine_h */
327 /* Do the actual processing of a reloc, once its target address
328 has been determined. */
329 extern void __process_machine_rela (struct link_map *map,
330 const Elf32_Rela *reloc,
331 const Elf32_Sym *sym,
332 const Elf32_Sym *refsym,
333 Elf32_Addr *const reloc_addr,
334 Elf32_Addr finaladdr,
337 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
338 LOADADDR is the load address of the object; INFO is an array indexed
339 by DT_* of the .dynamic section info. */
342 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
343 const Elf32_Sym *sym, const struct r_found_version *version,
344 Elf32_Addr *const reloc_addr)
346 const Elf32_Sym *const refsym = sym;
347 Elf32_Word loadbase, finaladdr;
348 const int rinfo = ELF32_R_TYPE (reloc->r_info);
350 if (rinfo == R_PPC_NONE)
353 /* The condition on the next two lines is a hack around a bug in Solaris
354 tools on Sparc. It's not clear whether it should really be here at all,
355 but if not the binutils need to be changed. */
356 if (rinfo == R_PPC_RELATIVE
357 || (sym->st_shndx != SHN_UNDEF
358 && ELF32_ST_BIND (sym->st_info) == STB_LOCAL))
360 /* Has already been relocated. */
361 loadbase = map->l_addr;
362 finaladdr = loadbase + reloc->r_addend;
366 loadbase = (Elf32_Word) (char *) (RESOLVE (&sym, version,
367 ELF32_R_TYPE(reloc->r_info)));
370 /* Weak symbol that wasn't actually defined anywhere. */
371 assert(loadbase == 0);
372 finaladdr = reloc->r_addend;
375 finaladdr = (loadbase + (Elf32_Word) (char *) sym->st_value
379 /* A small amount of code is duplicated here for speed. In libc,
380 more than 90% of the relocs are R_PPC_RELATIVE; in the X11 shared
381 libraries, 60% are R_PPC_RELATIVE, 24% are R_PPC_GLOB_DAT or
382 R_PPC_ADDR32, and 16% are R_PPC_JMP_SLOT (which this routine
383 wouldn't usually handle). As an bonus, doing this here allows
384 the switch statement in __process_machine_rela to work. */
385 if (rinfo == R_PPC_RELATIVE
386 || rinfo == R_PPC_GLOB_DAT
387 || rinfo == R_PPC_ADDR32)
389 *reloc_addr = finaladdr;
392 __process_machine_rela (map, reloc, sym, refsym,
393 reloc_addr, finaladdr, rinfo);
397 /* The SVR4 ABI specifies that the JMPREL relocs must be inside the
399 #define ELF_MACHINE_PLTREL_OVERLAP 1