1 /* Machine-dependent ELF dynamic relocation inline functions. PowerPC version.
2 Copyright (C) 1995-2014 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, see
17 <http://www.gnu.org/licenses/>. */
22 #define ELF_MACHINE_NAME "powerpc"
28 /* Translate a processor specific dynamic tag to the index
30 #define DT_PPC(x) (DT_PPC_##x - DT_LOPROC + DT_NUM)
32 /* Return nonzero iff ELF header is compatible with the running host. */
34 elf_machine_matches_host (const Elf32_Ehdr *ehdr)
36 return ehdr->e_machine == EM_PPC;
39 /* Return the value of the GOT pointer. */
40 static inline Elf32_Addr * __attribute__ ((const))
47 " addis %0,%0,_GLOBAL_OFFSET_TABLE_-1b@ha\n"
48 " addi %0,%0,_GLOBAL_OFFSET_TABLE_-1b@l\n"
49 : "=b" (got) : : "lr");
54 /* Return the link-time address of _DYNAMIC, stored as
55 the first value in the GOT. */
56 static inline Elf32_Addr __attribute__ ((const))
57 elf_machine_dynamic (void)
62 /* Return the run-time load address of the shared object. */
63 static inline Elf32_Addr __attribute__ ((const))
64 elf_machine_load_address (void)
66 Elf32_Addr *branchaddr;
67 Elf32_Addr runtime_dynamic;
69 /* This is much harder than you'd expect. Possibly I'm missing something.
72 Apparently, "bcl 20,31,$+4" is what should be used to load LR
73 with the address of the next instruction.
74 I think this is so that machines that do bl/blr pairing don't
82 : "=b" (addr) : : "r0", "lr");
84 doesn't work, because the linker doesn't have to (and in fact doesn't)
85 update the @ha and @l references; the loader (which runs after this
88 Instead, we use the following trick:
90 The linker puts the _link-time_ address of _DYNAMIC at the first
91 word in the GOT. We could branch to that address, if we wanted,
92 by using an @local reloc; the linker works this out, so it's safe
93 to use now. We can't, of course, actually branch there, because
94 we'd cause an illegal instruction exception; so we need to compute
95 the address ourselves. That gives us the following code: */
97 /* Get address of the 'b _DYNAMIC@local'... */
101 : "=l" (branchaddr));
103 /* So now work out the difference between where the branch actually points,
104 and the offset of that location in memory from the start of the file. */
105 runtime_dynamic = ((Elf32_Addr) branchaddr
106 + ((Elf32_Sword) (*branchaddr << 6 & 0xffffff00) >> 6));
108 return runtime_dynamic - elf_machine_dynamic ();
111 #define ELF_MACHINE_BEFORE_RTLD_RELOC(dynamic_info) /* nothing */
113 /* The PLT uses Elf32_Rela relocs. */
114 #define elf_machine_relplt elf_machine_rela
116 /* Mask identifying addresses reserved for the user program,
117 where the dynamic linker should not map anything. */
118 #define ELF_MACHINE_USER_ADDRESS_MASK 0xf0000000UL
120 /* The actual _start code is in dl-start.S. Use a really
121 ugly bit of assembler to let dl-start.o see _dl_start. */
122 #define RTLD_START asm (".globl _dl_start");
124 /* Decide where a relocatable object should be loaded. */
126 __elf_preferred_address(struct link_map *loader, size_t maplength,
127 ElfW(Addr) mapstartpref);
128 #define ELF_PREFERRED_ADDRESS(loader, maplength, mapstartpref) \
129 __elf_preferred_address (loader, maplength, mapstartpref)
131 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry, so
132 PLT entries should not be allowed to define the value.
133 ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one
134 of the main executable's symbols, as for a COPY reloc. */
135 /* We never want to use a PLT entry as the destination of a
136 reloc, when what is being relocated is a branch. This is
137 partly for efficiency, but mostly so we avoid loops. */
138 #define elf_machine_type_class(type) \
139 ((((type) == R_PPC_JMP_SLOT \
140 || (type) == R_PPC_REL24 \
141 || ((type) >= R_PPC_DTPMOD32 /* contiguous TLS */ \
142 && (type) <= R_PPC_DTPREL32) \
143 || (type) == R_PPC_ADDR24) * ELF_RTYPE_CLASS_PLT) \
144 | (((type) == R_PPC_COPY) * ELF_RTYPE_CLASS_COPY))
146 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
147 #define ELF_MACHINE_JMP_SLOT R_PPC_JMP_SLOT
149 /* The PowerPC never uses REL relocations. */
150 #define ELF_MACHINE_NO_REL 1
152 /* Set up the loaded object described by MAP so its unrelocated PLT
153 entries will jump to the on-demand fixup code in dl-runtime.c.
154 Also install a small trampoline to be used by entries that have
155 been relocated to an address too far away for a single branch. */
156 extern int __elf_machine_runtime_setup (struct link_map *map,
157 int lazy, int profile);
160 elf_machine_runtime_setup (struct link_map *map,
161 int lazy, int profile)
163 if (map->l_info[DT_JMPREL] == 0)
166 if (map->l_info[DT_PPC(GOT)] == 0)
167 /* Handle old style PLT. */
168 return __elf_machine_runtime_setup (map, lazy, profile);
170 /* New style non-exec PLT consisting of an array of addresses. */
171 map->l_info[DT_PPC(GOT)]->d_un.d_ptr += map->l_addr;
174 Elf32_Addr *plt, *got, glink;
175 Elf32_Word num_plt_entries;
177 extern void _dl_runtime_resolve (void);
178 extern void _dl_prof_resolve (void);
180 if (__glibc_likely (!profile))
181 dlrr = _dl_runtime_resolve;
184 if (GLRO(dl_profile) != NULL
185 &&_dl_name_match_p (GLRO(dl_profile), map))
186 GL(dl_profile_map) = map;
187 dlrr = _dl_prof_resolve;
189 got = (Elf32_Addr *) map->l_info[DT_PPC(GOT)]->d_un.d_ptr;
191 got[1] = (Elf32_Addr) dlrr;
192 got[2] = (Elf32_Addr) map;
194 /* Relocate everything in .plt by the load address offset. */
195 plt = (Elf32_Addr *) D_PTR (map, l_info[DT_PLTGOT]);
196 num_plt_entries = (map->l_info[DT_PLTRELSZ]->d_un.d_val
197 / sizeof (Elf32_Rela));
199 /* If a library is prelinked but we have to relocate anyway,
200 we have to be able to undo the prelinking of .plt section.
201 The prelinker saved us at got[1] address of .glink
205 glink += map->l_addr;
206 while (num_plt_entries-- != 0)
207 *plt++ = glink, glink += 4;
210 while (num_plt_entries-- != 0)
211 *plt++ += map->l_addr;
216 /* Change the PLT entry whose reloc is 'reloc' to call the actual routine. */
217 extern Elf32_Addr __elf_machine_fixup_plt (struct link_map *map,
218 Elf32_Addr *reloc_addr,
219 Elf32_Addr finaladdr);
221 static inline Elf32_Addr
222 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
223 const Elf32_Rela *reloc,
224 Elf32_Addr *reloc_addr, Elf64_Addr finaladdr)
226 if (map->l_info[DT_PPC(GOT)] == 0)
227 /* Handle old style PLT. */
228 return __elf_machine_fixup_plt (map, reloc_addr, finaladdr);
230 *reloc_addr = finaladdr;
234 /* Return the final value of a plt relocation. */
235 static inline Elf32_Addr
236 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
239 return value + reloc->r_addend;
243 /* Names of the architecture-specific auditing callback functions. */
244 #define ARCH_LA_PLTENTER ppc32_gnu_pltenter
245 #define ARCH_LA_PLTEXIT ppc32_gnu_pltexit
247 #endif /* dl_machine_h */
251 /* Do the actual processing of a reloc, once its target address
252 has been determined. */
253 extern void __process_machine_rela (struct link_map *map,
254 const Elf32_Rela *reloc,
255 struct link_map *sym_map,
256 const Elf32_Sym *sym,
257 const Elf32_Sym *refsym,
258 Elf32_Addr *const reloc_addr,
259 Elf32_Addr finaladdr,
260 int rinfo) attribute_hidden;
262 /* Call _dl_signal_error when a resolved value overflows a relocated area. */
263 extern void _dl_reloc_overflow (struct link_map *map,
265 Elf32_Addr *const reloc_addr,
266 const Elf32_Sym *refsym) attribute_hidden;
268 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
269 LOADADDR is the load address of the object; INFO is an array indexed
270 by DT_* of the .dynamic section info. */
272 auto inline void __attribute__ ((always_inline))
273 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
274 const Elf32_Sym *sym, const struct r_found_version *version,
275 void *const reloc_addr_arg, int skip_ifunc)
277 Elf32_Addr *const reloc_addr = reloc_addr_arg;
278 const Elf32_Sym *const refsym = sym;
280 const int r_type = ELF32_R_TYPE (reloc->r_info);
281 struct link_map *sym_map = NULL;
283 #ifndef RESOLVE_CONFLICT_FIND_MAP
284 if (r_type == R_PPC_RELATIVE)
286 *reloc_addr = map->l_addr + reloc->r_addend;
290 if (__glibc_unlikely (r_type == R_PPC_NONE))
293 /* binutils on ppc32 includes st_value in r_addend for relocations
294 against local symbols. */
295 if (__builtin_expect (ELF32_ST_BIND (sym->st_info) == STB_LOCAL, 0)
296 && sym->st_shndx != SHN_UNDEF)
300 sym_map = RESOLVE_MAP (&sym, version, r_type);
301 value = sym_map == NULL ? 0 : sym_map->l_addr + sym->st_value;
303 value += reloc->r_addend;
305 value = reloc->r_addend;
309 && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0)
310 && __builtin_expect (sym->st_shndx != SHN_UNDEF, 1)
311 && __builtin_expect (!skip_ifunc, 1))
312 value = elf_ifunc_invoke (value);
314 /* A small amount of code is duplicated here for speed. In libc,
315 more than 90% of the relocs are R_PPC_RELATIVE; in the X11 shared
316 libraries, 60% are R_PPC_RELATIVE, 24% are R_PPC_GLOB_DAT or
317 R_PPC_ADDR32, and 16% are R_PPC_JMP_SLOT (which this routine
318 wouldn't usually handle). As an bonus, doing this here allows
319 the switch statement in __process_machine_rela to work. */
327 #ifndef RESOLVE_CONFLICT_FIND_MAP
328 # ifdef RTLD_BOOTSTRAP
329 # define NOT_BOOTSTRAP 0
331 # define NOT_BOOTSTRAP 1
336 /* During startup the dynamic linker is always index 1. */
338 else if (sym_map != NULL)
339 /* Get the information from the link map returned by the
340 RESOLVE_MAP function. */
341 *reloc_addr = sym_map->l_tls_modid;
344 /* During relocation all TLS symbols are defined and used.
345 Therefore the offset is already correct. */
346 if (NOT_BOOTSTRAP && sym_map != NULL)
347 *reloc_addr = TLS_DTPREL_VALUE (sym, reloc);
350 if (!NOT_BOOTSTRAP || sym_map != NULL)
353 CHECK_STATIC_TLS (map, sym_map);
354 *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
360 #ifdef RESOLVE_CONFLICT_FIND_MAP
361 RESOLVE_CONFLICT_FIND_MAP (map, reloc_addr);
363 if (map->l_info[DT_PPC(GOT)] != 0)
371 __process_machine_rela (map, reloc, sym_map, sym, refsym,
372 reloc_addr, value, r_type);
376 auto inline void __attribute__ ((always_inline))
377 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
378 void *const reloc_addr_arg)
380 Elf32_Addr *const reloc_addr = reloc_addr_arg;
381 *reloc_addr = l_addr + reloc->r_addend;
384 auto inline void __attribute__ ((always_inline))
385 elf_machine_lazy_rel (struct link_map *map,
386 Elf32_Addr l_addr, const Elf32_Rela *reloc,
389 /* elf_machine_runtime_setup handles this. */
392 #endif /* RESOLVE_MAP */