1 /* Machine-dependent ELF dynamic relocation inline functions. PowerPC version.
2 Copyright (C) 1995-2021 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 <https://www.gnu.org/licenses/>. */
22 #define ELF_MACHINE_NAME "powerpc"
27 #include <hwcapinfo.h>
29 /* Translate a processor specific dynamic tag to the index
31 #define DT_PPC(x) (DT_PPC_##x - DT_LOPROC + DT_NUM)
33 /* Return nonzero iff ELF header is compatible with the running host. */
35 elf_machine_matches_host (const Elf32_Ehdr *ehdr)
37 return ehdr->e_machine == EM_PPC;
40 /* Return the value of the GOT pointer. */
41 static inline Elf32_Addr * __attribute__ ((const))
48 " addis %0,%0,_GLOBAL_OFFSET_TABLE_-1b@ha\n"
49 " addi %0,%0,_GLOBAL_OFFSET_TABLE_-1b@l\n"
50 : "=b" (got) : : "lr");
55 /* Return the link-time address of _DYNAMIC, stored as
56 the first value in the GOT. */
57 static inline Elf32_Addr __attribute__ ((const))
58 elf_machine_dynamic (void)
63 /* Return the run-time load address of the shared object. */
64 static inline Elf32_Addr __attribute__ ((const))
65 elf_machine_load_address (void)
67 Elf32_Addr *branchaddr;
68 Elf32_Addr runtime_dynamic;
70 /* This is much harder than you'd expect. Possibly I'm missing something.
73 Apparently, "bcl 20,31,$+4" is what should be used to load LR
74 with the address of the next instruction.
75 I think this is so that machines that do bl/blr pairing don't
83 : "=b" (addr) : : "r0", "lr");
85 doesn't work, because the linker doesn't have to (and in fact doesn't)
86 update the @ha and @l references; the loader (which runs after this
89 Instead, we use the following trick:
91 The linker puts the _link-time_ address of _DYNAMIC at the first
92 word in the GOT. We could branch to that address, if we wanted,
93 by using an @local reloc; the linker works this out, so it's safe
94 to use now. We can't, of course, actually branch there, because
95 we'd cause an illegal instruction exception; so we need to compute
96 the address ourselves. That gives us the following code: */
98 /* Get address of the 'b _DYNAMIC@local'... */
102 : "=l" (branchaddr));
104 /* So now work out the difference between where the branch actually points,
105 and the offset of that location in memory from the start of the file. */
106 runtime_dynamic = ((Elf32_Addr) branchaddr
107 + ((Elf32_Sword) (*branchaddr << 6 & 0xffffff00) >> 6));
109 return runtime_dynamic - elf_machine_dynamic ();
112 /* The PLT uses Elf32_Rela relocs. */
113 #define elf_machine_relplt elf_machine_rela
115 /* Mask identifying addresses reserved for the user program,
116 where the dynamic linker should not map anything. */
117 #define ELF_MACHINE_USER_ADDRESS_MASK 0xf0000000UL
119 /* The actual _start code is in dl-start.S. Use a really
120 ugly bit of assembler to let dl-start.o see _dl_start. */
121 #define RTLD_START asm (".globl _dl_start");
123 /* Decide where a relocatable object should be loaded. */
125 __elf_preferred_address(struct link_map *loader, size_t maplength,
126 ElfW(Addr) mapstartpref);
127 #define ELF_PREFERRED_ADDRESS(loader, maplength, mapstartpref) \
128 __elf_preferred_address (loader, maplength, mapstartpref)
130 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry, so
131 PLT entries should not be allowed to define the value.
132 ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
133 of the main executable's symbols, as for a COPY reloc. */
134 /* We never want to use a PLT entry as the destination of a
135 reloc, when what is being relocated is a branch. This is
136 partly for efficiency, but mostly so we avoid loops. */
137 #define elf_machine_type_class(type) \
138 ((((type) == R_PPC_JMP_SLOT \
139 || (type) == R_PPC_REL24 \
140 || ((type) >= R_PPC_DTPMOD32 /* contiguous TLS */ \
141 && (type) <= R_PPC_DTPREL32) \
142 || (type) == R_PPC_ADDR24) * ELF_RTYPE_CLASS_PLT) \
143 | (((type) == R_PPC_COPY) * ELF_RTYPE_CLASS_COPY))
145 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
146 #define ELF_MACHINE_JMP_SLOT R_PPC_JMP_SLOT
148 /* The PowerPC never uses REL relocations. */
149 #define ELF_MACHINE_NO_REL 1
150 #define ELF_MACHINE_NO_RELA 0
152 /* We define an initialization function to initialize HWCAP/HWCAP2 and
153 platform data so it can be copied into the TCB later. This is called
154 very early in _dl_sysdep_start for dynamically linked binaries. */
156 # define DL_PLATFORM_INIT dl_platform_init ()
158 static inline void __attribute__ ((unused))
159 dl_platform_init (void)
161 __tcb_parse_hwcap_and_convert_at_platform ();
165 /* Set up the loaded object described by MAP so its unrelocated PLT
166 entries will jump to the on-demand fixup code in dl-runtime.c.
167 Also install a small trampoline to be used by entries that have
168 been relocated to an address too far away for a single branch. */
169 extern int __elf_machine_runtime_setup (struct link_map *map,
170 int lazy, int profile);
173 elf_machine_runtime_setup (struct link_map *map,
174 int lazy, int profile)
176 if (map->l_info[DT_JMPREL] == 0)
179 if (map->l_info[DT_PPC(GOT)] == 0)
180 /* Handle old style PLT. */
181 return __elf_machine_runtime_setup (map, lazy, profile);
183 /* New style non-exec PLT consisting of an array of addresses. */
184 map->l_info[DT_PPC(GOT)]->d_un.d_ptr += map->l_addr;
187 Elf32_Addr *plt, *got, glink;
188 Elf32_Word num_plt_entries;
190 extern void _dl_runtime_resolve (void);
191 extern void _dl_prof_resolve (void);
193 if (__glibc_likely (!profile))
194 dlrr = _dl_runtime_resolve;
197 if (GLRO(dl_profile) != NULL
198 &&_dl_name_match_p (GLRO(dl_profile), map))
199 GL(dl_profile_map) = map;
200 dlrr = _dl_prof_resolve;
202 got = (Elf32_Addr *) map->l_info[DT_PPC(GOT)]->d_un.d_ptr;
204 got[1] = (Elf32_Addr) dlrr;
205 got[2] = (Elf32_Addr) map;
207 /* Relocate everything in .plt by the load address offset. */
208 plt = (Elf32_Addr *) D_PTR (map, l_info[DT_PLTGOT]);
209 num_plt_entries = (map->l_info[DT_PLTRELSZ]->d_un.d_val
210 / sizeof (Elf32_Rela));
212 /* If a library is prelinked but we have to relocate anyway,
213 we have to be able to undo the prelinking of .plt section.
214 The prelinker saved us at got[1] address of .glink
218 glink += map->l_addr;
219 while (num_plt_entries-- != 0)
220 *plt++ = glink, glink += 4;
223 while (num_plt_entries-- != 0)
224 *plt++ += map->l_addr;
229 /* Change the PLT entry whose reloc is 'reloc' to call the actual routine. */
230 extern Elf32_Addr __elf_machine_fixup_plt (struct link_map *map,
231 Elf32_Addr *reloc_addr,
232 Elf32_Addr finaladdr);
234 static inline Elf32_Addr
235 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
236 const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
237 const Elf32_Rela *reloc,
238 Elf32_Addr *reloc_addr, Elf64_Addr finaladdr)
240 if (map->l_info[DT_PPC(GOT)] == 0)
241 /* Handle old style PLT. */
242 return __elf_machine_fixup_plt (map, reloc_addr, finaladdr);
244 *reloc_addr = finaladdr;
248 /* Return the final value of a plt relocation. */
249 static inline Elf32_Addr
250 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
253 return value + reloc->r_addend;
257 /* Names of the architecture-specific auditing callback functions. */
258 #define ARCH_LA_PLTENTER ppc32_gnu_pltenter
259 #define ARCH_LA_PLTEXIT ppc32_gnu_pltexit
261 #endif /* dl_machine_h */
265 /* Do the actual processing of a reloc, once its target address
266 has been determined. */
267 extern void __process_machine_rela (struct link_map *map,
268 const Elf32_Rela *reloc,
269 struct link_map *sym_map,
270 const Elf32_Sym *sym,
271 const Elf32_Sym *refsym,
272 Elf32_Addr *const reloc_addr,
273 Elf32_Addr finaladdr,
274 int rinfo, bool skip_ifunc)
277 /* Call _dl_signal_error when a resolved value overflows a relocated area. */
278 extern void _dl_reloc_overflow (struct link_map *map,
280 Elf32_Addr *const reloc_addr,
281 const Elf32_Sym *refsym) attribute_hidden;
283 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
284 LOADADDR is the load address of the object; INFO is an array indexed
285 by DT_* of the .dynamic section info. */
287 auto inline void __attribute__ ((always_inline))
288 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
289 const Elf32_Sym *sym, const struct r_found_version *version,
290 void *const reloc_addr_arg, int skip_ifunc)
292 Elf32_Addr *const reloc_addr = reloc_addr_arg;
293 const Elf32_Sym *const refsym = sym;
295 const int r_type = ELF32_R_TYPE (reloc->r_info);
296 struct link_map *sym_map = NULL;
298 #ifndef RESOLVE_CONFLICT_FIND_MAP
299 if (r_type == R_PPC_RELATIVE)
301 *reloc_addr = map->l_addr + reloc->r_addend;
305 if (__glibc_unlikely (r_type == R_PPC_NONE))
308 /* binutils on ppc32 includes st_value in r_addend for relocations
309 against local symbols. */
310 if (__builtin_expect (ELF32_ST_BIND (sym->st_info) == STB_LOCAL, 0)
311 && sym->st_shndx != SHN_UNDEF)
318 sym_map = RESOLVE_MAP (&sym, version, r_type);
319 value = SYMBOL_ADDRESS (sym_map, sym, true);
321 value += reloc->r_addend;
323 value = reloc->r_addend;
327 && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0)
328 && __builtin_expect (sym->st_shndx != SHN_UNDEF, 1)
329 && __builtin_expect (!skip_ifunc, 1))
330 value = elf_ifunc_invoke (value);
332 /* A small amount of code is duplicated here for speed. In libc,
333 more than 90% of the relocs are R_PPC_RELATIVE; in the X11 shared
334 libraries, 60% are R_PPC_RELATIVE, 24% are R_PPC_GLOB_DAT or
335 R_PPC_ADDR32, and 16% are R_PPC_JMP_SLOT (which this routine
336 wouldn't usually handle). As an bonus, doing this here allows
337 the switch statement in __process_machine_rela to work. */
345 #ifndef RESOLVE_CONFLICT_FIND_MAP
346 # ifdef RTLD_BOOTSTRAP
347 # define NOT_BOOTSTRAP 0
349 # define NOT_BOOTSTRAP 1
353 if (map->l_info[DT_PPC(OPT)]
354 && (map->l_info[DT_PPC(OPT)]->d_un.d_val & PPC_OPT_TLS))
359 reloc_addr[1] = (sym_map->l_tls_offset - TLS_TP_OFFSET
363 else if (sym_map != NULL)
366 CHECK_STATIC_TLS (map, sym_map);
368 if (TRY_STATIC_TLS (map, sym_map))
372 /* Set up for local dynamic. */
373 reloc_addr[1] = (sym_map->l_tls_offset - TLS_TP_OFFSET
380 /* During startup the dynamic linker is always index 1. */
382 else if (sym_map != NULL)
383 /* Get the information from the link map returned by the
384 RESOLVE_MAP function. */
385 *reloc_addr = sym_map->l_tls_modid;
388 if (map->l_info[DT_PPC(OPT)]
389 && (map->l_info[DT_PPC(OPT)]->d_un.d_val & PPC_OPT_TLS))
393 *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
396 else if (sym_map != NULL)
398 /* This reloc is always preceded by R_PPC_DTPMOD32. */
400 assert (HAVE_STATIC_TLS (map, sym_map));
402 if (HAVE_STATIC_TLS (map, sym_map))
405 *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
410 /* During relocation all TLS symbols are defined and used.
411 Therefore the offset is already correct. */
412 if (NOT_BOOTSTRAP && sym_map != NULL)
413 *reloc_addr = TLS_DTPREL_VALUE (sym, reloc);
416 if (!NOT_BOOTSTRAP || sym_map != NULL)
419 CHECK_STATIC_TLS (map, sym_map);
420 *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
426 #ifdef RESOLVE_CONFLICT_FIND_MAP
427 RESOLVE_CONFLICT_FIND_MAP (map, reloc_addr);
429 if (map->l_info[DT_PPC(GOT)] != 0)
437 __process_machine_rela (map, reloc, sym_map, sym, refsym,
438 reloc_addr, value, r_type, skip_ifunc);
442 auto inline void __attribute__ ((always_inline))
443 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
444 void *const reloc_addr_arg)
446 Elf32_Addr *const reloc_addr = reloc_addr_arg;
447 *reloc_addr = l_addr + reloc->r_addend;
450 auto inline void __attribute__ ((always_inline))
451 elf_machine_lazy_rel (struct link_map *map,
452 Elf32_Addr l_addr, const Elf32_Rela *reloc,
455 /* elf_machine_runtime_setup handles this. */
458 #endif /* RESOLVE_MAP */