1 /* Machine-dependent ELF dynamic relocation inline functions. PowerPC version.
2 Copyright (C) 1995-2023 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>
28 #include <dl-static-tls.h>
29 #include <dl-machine-rel.h>
31 /* Translate a processor specific dynamic tag to the index
33 #define DT_PPC(x) (DT_PPC_##x - DT_LOPROC + DT_NUM)
35 /* Return nonzero iff ELF header is compatible with the running host. */
37 elf_machine_matches_host (const Elf32_Ehdr
*ehdr
)
39 return ehdr
->e_machine
== EM_PPC
;
42 /* Return the value of the GOT pointer. */
43 static inline Elf32_Addr
* __attribute__ ((const))
50 " addis %0,%0,_GLOBAL_OFFSET_TABLE_-1b@ha\n"
51 " addi %0,%0,_GLOBAL_OFFSET_TABLE_-1b@l\n"
52 : "=b" (got
) : : "lr");
57 /* Return the link-time address of _DYNAMIC, stored as
58 the first value in the GOT. */
59 static inline Elf32_Addr
__attribute__ ((const))
60 elf_machine_dynamic (void)
65 /* Return the run-time load address of the shared object. */
66 static inline Elf32_Addr
__attribute__ ((const))
67 elf_machine_load_address (void)
69 Elf32_Addr
*branchaddr
;
70 Elf32_Addr runtime_dynamic
;
72 /* This is much harder than you'd expect. Possibly I'm missing something.
75 Apparently, "bcl 20,31,$+4" is what should be used to load LR
76 with the address of the next instruction.
77 I think this is so that machines that do bl/blr pairing don't
85 : "=b" (addr) : : "r0", "lr");
87 doesn't work, because the linker doesn't have to (and in fact doesn't)
88 update the @ha and @l references; the loader (which runs after this
91 Instead, we use the following trick:
93 The linker puts the _link-time_ address of _DYNAMIC at the first
94 word in the GOT. We could branch to that address, if we wanted,
95 by using an @local reloc; the linker works this out, so it's safe
96 to use now. We can't, of course, actually branch there, because
97 we'd cause an illegal instruction exception; so we need to compute
98 the address ourselves. That gives us the following code: */
100 /* Get address of the 'b _DYNAMIC@local'... */
104 : "=l" (branchaddr
));
106 /* So now work out the difference between where the branch actually points,
107 and the offset of that location in memory from the start of the file. */
108 runtime_dynamic
= ((Elf32_Addr
) branchaddr
109 + ((Elf32_Sword
) (*branchaddr
<< 6 & 0xffffff00) >> 6));
111 return runtime_dynamic
- elf_machine_dynamic ();
114 /* The PLT uses Elf32_Rela relocs. */
115 #define elf_machine_relplt elf_machine_rela
117 /* Mask identifying addresses reserved for the user program,
118 where the dynamic linker should not map anything. */
119 #define ELF_MACHINE_USER_ADDRESS_MASK 0xf0000000UL
121 /* The actual _start code is in dl-start.S. Use a really
122 ugly bit of assembler to let dl-start.o see _dl_start. */
123 #define RTLD_START asm (".globl _dl_start");
125 /* Decide where a relocatable object should be loaded. */
127 __elf_preferred_address(struct link_map
*loader
, size_t maplength
,
128 ElfW(Addr
) mapstartpref
);
129 #define ELF_PREFERRED_ADDRESS(loader, maplength, mapstartpref) \
130 __elf_preferred_address (loader, maplength, mapstartpref)
132 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry, so
133 PLT entries should not be allowed to define the value.
134 ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
135 of the main executable's symbols, as for a COPY reloc. */
136 /* We never want to use a PLT entry as the destination of a
137 reloc, when what is being relocated is a branch. This is
138 partly for efficiency, but mostly so we avoid loops. */
139 #define elf_machine_type_class(type) \
140 ((((type) == R_PPC_JMP_SLOT \
141 || (type) == R_PPC_REL24 \
142 || ((type) >= R_PPC_DTPMOD32 /* contiguous TLS */ \
143 && (type) <= R_PPC_DTPREL32) \
144 || (type) == R_PPC_ADDR24) * ELF_RTYPE_CLASS_PLT) \
145 | (((type) == R_PPC_COPY) * ELF_RTYPE_CLASS_COPY))
147 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
148 #define ELF_MACHINE_JMP_SLOT R_PPC_JMP_SLOT
150 /* We define an initialization function to initialize HWCAP/HWCAP2 and
151 platform data so it can be copied into the TCB later. This is called
152 very early in _dl_sysdep_start for dynamically linked binaries. */
154 # define DL_PLATFORM_INIT dl_platform_init ()
156 static inline void __attribute__ ((unused
))
157 dl_platform_init (void)
159 __tcb_parse_hwcap_and_convert_at_platform ();
163 /* Set up the loaded object described by MAP so its unrelocated PLT
164 entries will jump to the on-demand fixup code in dl-runtime.c.
165 Also install a small trampoline to be used by entries that have
166 been relocated to an address too far away for a single branch. */
167 extern int __elf_machine_runtime_setup (struct link_map
*map
,
168 int lazy
, int profile
);
171 elf_machine_runtime_setup (struct link_map
*map
, struct r_scope_elem
*scope
[],
172 int lazy
, int profile
)
174 if (map
->l_info
[DT_JMPREL
] == 0)
177 if (map
->l_info
[DT_PPC(GOT
)] == 0)
178 /* Handle old style PLT. */
179 return __elf_machine_runtime_setup (map
, lazy
, profile
);
181 /* New style non-exec PLT consisting of an array of addresses. */
182 map
->l_info
[DT_PPC(GOT
)]->d_un
.d_ptr
+= map
->l_addr
;
185 Elf32_Addr
*plt
, *got
, glink
;
186 Elf32_Word num_plt_entries
;
188 extern void _dl_runtime_resolve (void);
189 extern void _dl_prof_resolve (void);
191 if (__glibc_likely (!profile
))
192 dlrr
= _dl_runtime_resolve
;
195 if (GLRO(dl_profile
) != NULL
196 &&_dl_name_match_p (GLRO(dl_profile
), map
))
197 GL(dl_profile_map
) = map
;
198 dlrr
= _dl_prof_resolve
;
200 got
= (Elf32_Addr
*) map
->l_info
[DT_PPC(GOT
)]->d_un
.d_ptr
;
202 got
[1] = (Elf32_Addr
) dlrr
;
203 got
[2] = (Elf32_Addr
) map
;
205 /* Relocate everything in .plt by the load address offset. */
206 plt
= (Elf32_Addr
*) D_PTR (map
, l_info
[DT_PLTGOT
]);
207 num_plt_entries
= (map
->l_info
[DT_PLTRELSZ
]->d_un
.d_val
208 / sizeof (Elf32_Rela
));
210 /* If a library is prelinked but we have to relocate anyway,
211 we have to be able to undo the prelinking of .plt section.
212 The prelinker saved us at got[1] address of .glink
216 glink
+= map
->l_addr
;
217 while (num_plt_entries
-- != 0)
218 *plt
++ = glink
, glink
+= 4;
221 while (num_plt_entries
-- != 0)
222 *plt
++ += map
->l_addr
;
227 /* Change the PLT entry whose reloc is 'reloc' to call the actual routine. */
228 extern Elf32_Addr
__elf_machine_fixup_plt (struct link_map
*map
,
229 Elf32_Addr
*reloc_addr
,
230 Elf32_Addr finaladdr
);
232 static inline Elf32_Addr
233 elf_machine_fixup_plt (struct link_map
*map
, lookup_t t
,
234 const ElfW(Sym
) *refsym
, const ElfW(Sym
) *sym
,
235 const Elf32_Rela
*reloc
,
236 Elf32_Addr
*reloc_addr
, Elf64_Addr finaladdr
)
238 if (map
->l_info
[DT_PPC(GOT
)] == 0)
239 /* Handle old style PLT. */
240 return __elf_machine_fixup_plt (map
, reloc_addr
, finaladdr
);
242 *reloc_addr
= finaladdr
;
246 /* Return the final value of a plt relocation. */
247 static inline Elf32_Addr
248 elf_machine_plt_value (struct link_map
*map
, const Elf32_Rela
*reloc
,
251 return value
+ reloc
->r_addend
;
255 /* Names of the architecture-specific auditing callback functions. */
256 #define ARCH_LA_PLTENTER ppc32_gnu_pltenter
257 #define ARCH_LA_PLTEXIT ppc32_gnu_pltexit
259 #endif /* dl_machine_h */
263 /* Do the actual processing of a reloc, once its target address
264 has been determined. */
265 extern void __process_machine_rela (struct link_map
*map
,
266 const Elf32_Rela
*reloc
,
267 struct link_map
*sym_map
,
268 const Elf32_Sym
*sym
,
269 const Elf32_Sym
*refsym
,
270 Elf32_Addr
*const reloc_addr
,
271 Elf32_Addr finaladdr
,
272 int rinfo
, bool skip_ifunc
)
275 /* Call _dl_signal_error when a resolved value overflows a relocated area. */
276 extern void _dl_reloc_overflow (struct link_map
*map
,
278 Elf32_Addr
*const reloc_addr
,
279 const Elf32_Sym
*refsym
) attribute_hidden
;
281 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
282 LOADADDR is the load address of the object; INFO is an array indexed
283 by DT_* of the .dynamic section info. */
285 static inline void __attribute__ ((always_inline
))
286 elf_machine_rela (struct link_map
*map
, struct r_scope_elem
*scope
[],
287 const Elf32_Rela
*reloc
, const Elf32_Sym
*sym
,
288 const struct r_found_version
*version
,
289 void *const reloc_addr_arg
, int skip_ifunc
)
291 Elf32_Addr
*const reloc_addr
= reloc_addr_arg
;
292 const Elf32_Sym
*const refsym
= sym
;
294 const int r_type
= ELF32_R_TYPE (reloc
->r_info
);
295 struct link_map
*sym_map
= NULL
;
297 if (r_type
== R_PPC_RELATIVE
)
299 *reloc_addr
= map
->l_addr
+ reloc
->r_addend
;
303 if (__glibc_unlikely (r_type
== R_PPC_NONE
))
306 /* binutils on ppc32 includes st_value in r_addend for relocations
307 against local symbols. */
308 if (__builtin_expect (ELF32_ST_BIND (sym
->st_info
) == STB_LOCAL
, 0)
309 && sym
->st_shndx
!= SHN_UNDEF
)
316 sym_map
= RESOLVE_MAP (map
, scope
, &sym
, version
, r_type
);
317 value
= SYMBOL_ADDRESS (sym_map
, sym
, true);
319 value
+= reloc
->r_addend
;
322 && __builtin_expect (ELFW(ST_TYPE
) (sym
->st_info
) == STT_GNU_IFUNC
, 0)
323 && __builtin_expect (sym
->st_shndx
!= SHN_UNDEF
, 1)
324 && __builtin_expect (!skip_ifunc
, 1))
325 value
= elf_ifunc_invoke (value
);
327 /* A small amount of code is duplicated here for speed. In libc,
328 more than 90% of the relocs are R_PPC_RELATIVE; in the X11 shared
329 libraries, 60% are R_PPC_RELATIVE, 24% are R_PPC_GLOB_DAT or
330 R_PPC_ADDR32, and 16% are R_PPC_JMP_SLOT (which this routine
331 wouldn't usually handle). As an bonus, doing this here allows
332 the switch statement in __process_machine_rela to work. */
340 #ifdef RTLD_BOOTSTRAP
341 # define NOT_BOOTSTRAP 0
343 # define NOT_BOOTSTRAP 1
347 if (map
->l_info
[DT_PPC(OPT
)]
348 && (map
->l_info
[DT_PPC(OPT
)]->d_un
.d_val
& PPC_OPT_TLS
))
353 reloc_addr
[1] = (sym_map
->l_tls_offset
- TLS_TP_OFFSET
357 else if (sym_map
!= NULL
)
360 CHECK_STATIC_TLS (map
, sym_map
);
362 if (TRY_STATIC_TLS (map
, sym_map
))
366 /* Set up for local dynamic. */
367 reloc_addr
[1] = (sym_map
->l_tls_offset
- TLS_TP_OFFSET
374 /* During startup the dynamic linker is always index 1. */
376 else if (sym_map
!= NULL
)
377 /* Get the information from the link map returned by the
378 RESOLVE_MAP function. */
379 *reloc_addr
= sym_map
->l_tls_modid
;
382 if (map
->l_info
[DT_PPC(OPT
)]
383 && (map
->l_info
[DT_PPC(OPT
)]->d_un
.d_val
& PPC_OPT_TLS
))
387 *reloc_addr
= TLS_TPREL_VALUE (sym_map
, sym
, reloc
);
390 else if (sym_map
!= NULL
)
392 /* This reloc is always preceded by R_PPC_DTPMOD32. */
394 assert (HAVE_STATIC_TLS (map
, sym_map
));
396 if (HAVE_STATIC_TLS (map
, sym_map
))
399 *reloc_addr
= TLS_TPREL_VALUE (sym_map
, sym
, reloc
);
404 /* During relocation all TLS symbols are defined and used.
405 Therefore the offset is already correct. */
406 if (NOT_BOOTSTRAP
&& sym_map
!= NULL
)
407 *reloc_addr
= TLS_DTPREL_VALUE (sym
, reloc
);
410 if (!NOT_BOOTSTRAP
|| sym_map
!= NULL
)
413 CHECK_STATIC_TLS (map
, sym_map
);
414 *reloc_addr
= TLS_TPREL_VALUE (sym_map
, sym
, reloc
);
419 if (map
->l_info
[DT_PPC(GOT
)] != 0)
427 __process_machine_rela (map
, reloc
, sym_map
, sym
, refsym
,
428 reloc_addr
, value
, r_type
, skip_ifunc
);
432 static inline void __attribute__ ((always_inline
))
433 elf_machine_rela_relative (Elf32_Addr l_addr
, const Elf32_Rela
*reloc
,
434 void *const reloc_addr_arg
)
436 Elf32_Addr
*const reloc_addr
= reloc_addr_arg
;
437 *reloc_addr
= l_addr
+ reloc
->r_addend
;
440 static inline void __attribute__ ((always_inline
))
441 elf_machine_lazy_rel (struct link_map
*map
, struct r_scope_elem
*scope
[],
442 Elf32_Addr l_addr
, const Elf32_Rela
*reloc
,
445 /* elf_machine_runtime_setup handles this. */
448 #endif /* RESOLVE_MAP */