1 /* Machine-dependent ELF dynamic relocation inline functions. MIPS version.
2 Copyright (C) 1996, 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Kazumoto Kojima <kkojima@info.kanagawa-u.ac.jp>.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
21 /* FIXME: Profiling of shared libraries is not implemented yet. */
25 #define ELF_MACHINE_NAME "MIPS"
27 #define ELF_MACHINE_NO_PLT
32 #error ENTRY_POINT needs to be defined for MIPS.
35 /* The offset of gp from GOT might be system-dependent. It's set by
36 ld. The same value is also */
37 #define OFFSET_GP_GOT 0x7ff0
39 #ifndef _RTLD_PROLOGUE
40 # define _RTLD_PROLOGUE(entry) \
41 ".globl\t" __STRING(entry) "\n\t" \
42 ".ent\t" __STRING(entry) "\n\t" \
43 ".type\t" __STRING(entry) ", @function\n" \
44 __STRING(entry) ":\n\t"
47 #ifndef _RTLD_EPILOGUE
48 # define _RTLD_EPILOGUE(entry) \
49 ".end\t" __STRING(entry) "\n\t" \
50 ".size\t" __STRING(entry) ", . - " __STRING(entry) "\n\t"
53 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.
54 This makes no sense on MIPS but we have to define this to R_MIPS_REL32
55 to avoid the asserts in dl-lookup.c from blowing. */
56 #define ELF_MACHINE_JMP_SLOT R_MIPS_REL32
57 #define elf_machine_lookup_noplt_p(type) (1)
58 #define elf_machine_lookup_noexec_p(type) (0)
60 /* Translate a processor specific dynamic tag to the index
62 #define DT_MIPS(x) (DT_MIPS_##x - DT_LOPROC + DT_NUM)
64 /* If there is a DT_MIPS_RLD_MAP entry in the dynamic section, fill it in
65 with the run-time address of the r_debug structure */
66 #define ELF_MACHINE_DEBUG_SETUP(l,r) \
67 do { if ((l)->l_info[DT_MIPS (RLD_MAP)]) \
68 *(ElfW(Addr) *)((l)->l_info[DT_MIPS (RLD_MAP)]->d_un.d_ptr) = \
72 /* Return nonzero iff ELF header is compatible with the running host. */
73 static inline int __attribute__ ((unused))
74 elf_machine_matches_host (const ElfW(Ehdr) *ehdr)
76 switch (ehdr->e_machine)
86 static inline ElfW(Addr) *
87 elf_mips_got_from_gpreg (ElfW(Addr) gpreg)
89 /* FIXME: the offset of gp from GOT may be system-dependent. */
90 return (ElfW(Addr) *) (gpreg - OFFSET_GP_GOT);
93 /* Return the link-time address of _DYNAMIC. Conveniently, this is the
94 first element of the GOT. This must be inlined in a function which
96 static inline ElfW(Addr)
97 elf_machine_dynamic (void)
99 register ElfW(Addr) gp __asm__ ("$28");
100 return *elf_mips_got_from_gpreg (gp);
104 /* Return the run-time load address of the shared object. */
105 static inline ElfW(Addr)
106 elf_machine_load_address (void)
109 asm (" .set noreorder\n"
113 "here: subu %0, $31, %0\n"
121 /* The MSB of got[1] of a gnu object is set to identify gnu objects. */
122 #define ELF_MIPS_GNU_GOT1_MASK 0x80000000
124 /* We can't rely on elf_machine_got_rel because _dl_object_relocation_scope
125 fiddles with global data. */
126 #define ELF_MACHINE_BEFORE_RTLD_RELOC(dynamic_info) \
128 struct link_map *map = &bootstrap_map; \
133 got = (ElfW(Addr) *) D_PTR (map, l_info[DT_PLTGOT]); \
135 if (__builtin_expect (map->l_addr == 0, 1)) \
138 /* got[0] is reserved. got[1] is also reserved for the dynamic object \
139 generated by gnu ld. Skip these reserved entries from \
141 i = (got[1] & ELF_MIPS_GNU_GOT1_MASK)? 2 : 1; \
142 n = map->l_info[DT_MIPS (LOCAL_GOTNO)]->d_un.d_val; \
144 /* Add the run-time displacement to all local got entries. */ \
146 got[i++] += map->l_addr; \
148 /* Handle global got entries. */ \
150 sym = (ElfW(Sym) *) D_PTR(map, l_info[DT_SYMTAB]) \
151 + map->l_info[DT_MIPS (GOTSYM)]->d_un.d_val; \
152 i = (map->l_info[DT_MIPS (SYMTABNO)]->d_un.d_val \
153 - map->l_info[DT_MIPS (GOTSYM)]->d_un.d_val); \
157 if (sym->st_shndx == SHN_UNDEF || sym->st_shndx == SHN_COMMON) \
158 *got = map->l_addr + sym->st_value; \
159 else if (ELFW(ST_TYPE) (sym->st_info) == STT_FUNC \
160 && *got != sym->st_value) \
161 *got += map->l_addr; \
162 else if (ELFW(ST_TYPE) (sym->st_info) == STT_SECTION) \
164 if (sym->st_other == 0) \
165 *got += map->l_addr; \
168 *got = map->l_addr + sym->st_value; \
177 /* Get link map for callers object containing STUB_PC. */
178 static inline struct link_map *
179 elf_machine_runtime_link_map (ElfW(Addr) gpreg, ElfW(Addr) stub_pc)
181 extern int _dl_mips_gnu_objects;
183 /* got[1] is reserved to keep its link map address for the shared
184 object generated by the gnu linker. If all are such objects, we
185 can find the link map from current GPREG simply. If not so, get
186 the link map for caller's object containing STUB_PC. */
188 if (_dl_mips_gnu_objects)
190 ElfW(Addr) *got = elf_mips_got_from_gpreg (gpreg);
193 g1 = ((ElfW(Word) *) got)[1];
195 if ((g1 & ELF_MIPS_GNU_GOT1_MASK) != 0)
198 (struct link_map *) (g1 & ~ELF_MIPS_GNU_GOT1_MASK);
199 ElfW(Addr) base, limit;
200 const ElfW(Phdr) *p = l->l_phdr;
201 ElfW(Half) this, nent = l->l_phnum;
203 /* For the common case of a stub being called from the containing
204 object, STUB_PC will point to somewhere within the object that
205 is described by the link map fetched via got[1]. Otherwise we
206 have to scan all maps. */
207 for (this = 0; this < nent; this++)
209 if (p[this].p_type == PT_LOAD)
211 base = p[this].p_vaddr + l->l_addr;
212 limit = base + p[this].p_memsz;
213 if (stub_pc >= base && stub_pc < limit)
221 struct link_map *l = _dl_loaded;
225 ElfW(Addr) base, limit;
226 const ElfW(Phdr) *p = l->l_phdr;
227 ElfW(Half) this, nent = l->l_phnum;
229 for (this = 0; this < nent; ++this)
231 if (p[this].p_type == PT_LOAD)
233 base = p[this].p_vaddr + l->l_addr;
234 limit = base + p[this].p_memsz;
235 if (stub_pc >= base && stub_pc < limit)
243 _dl_signal_error (0, NULL, "cannot find runtime link map");
247 /* Define mips specific runtime resolver. The function __dl_runtime_resolve
248 is called from assembler function _dl_runtime_resolve which converts
249 special argument registers t7 ($15) and t8 ($24):
250 t7 address to return to the caller of the function
251 t8 index for this function symbol in .dynsym
252 to usual c arguments.
254 Other architectures call fixup from dl-runtime.c in
255 _dl_runtime_resolve. MIPS instead calls __dl_runtime_resolve. We
256 have to use our own version because of the way the got section is
257 treated on MIPS (we've also got ELF_MACHINE_PLT defined). */
259 #define ELF_MACHINE_RUNTIME_TRAMPOLINE \
260 /* The flag _dl_mips_gnu_objects is set if all dynamic objects are \
261 generated by the gnu linker. */ \
262 int _dl_mips_gnu_objects = 1; \
264 /* This is called from assembly stubs below which the compiler can't see. */ \
266 __dl_runtime_resolve (ElfW(Word), ElfW(Word), ElfW(Addr), ElfW(Addr)) \
267 __attribute__ ((unused)); \
270 __dl_runtime_resolve (ElfW(Word) sym_index, \
271 ElfW(Word) return_address, \
272 ElfW(Addr) old_gpreg, \
273 ElfW(Addr) stub_pc) \
275 struct link_map *l = elf_machine_runtime_link_map (old_gpreg, stub_pc); \
276 const ElfW(Sym) *const symtab \
277 = (const void *) D_PTR (l, l_info[DT_SYMTAB]); \
279 = (const void *) D_PTR (l, l_info[DT_STRTAB]); \
280 const ElfW(Addr) *got \
281 = (const ElfW(Addr) *) D_PTR (l, l_info[DT_PLTGOT]); \
282 const ElfW(Word) local_gotno \
283 = (const ElfW(Word)) l->l_info[DT_MIPS (LOCAL_GOTNO)]->d_un.d_val; \
284 const ElfW(Word) gotsym \
285 = (const ElfW(Word)) l->l_info[DT_MIPS (GOTSYM)]->d_un.d_val; \
286 const ElfW(Sym) *sym = &symtab[sym_index]; \
289 /* FIXME: The symbol versioning stuff is not tested yet. */ \
290 if (__builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0) \
292 switch (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL) \
296 const ElfW(Half) *vernum = \
297 (const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]); \
298 ElfW(Half) ndx = vernum[sym_index]; \
299 const struct r_found_version *version = &l->l_versions[ndx]; \
301 if (version->hash != 0) \
303 value = _dl_lookup_versioned_symbol(strtab + sym->st_name, l, \
304 &sym, l->l_scope, version,\
308 /* Fall through. */ \
311 value = _dl_lookup_symbol (strtab + sym->st_name, l, &sym, \
312 l->l_scope, R_MIPS_REL32, 0); \
315 /* Currently value contains the base load address of the object \
316 that defines sym. Now add in the symbol offset. */ \
317 value = (sym ? value + sym->st_value : 0); \
320 /* We already found the symbol. The module (and therefore its load \
321 address) is also known. */ \
322 value = l->l_addr + sym->st_value; \
324 /* Apply the relocation with that value. */ \
325 *(got + local_gotno + sym_index - gotsym) = value; \
333 .globl _dl_runtime_resolve\n \
334 .type _dl_runtime_resolve,@function\n \
335 .ent _dl_runtime_resolve\n \
336 _dl_runtime_resolve:\n \
337 .frame $29, 40, $31\n \
341 # Modify t9 ($25) so as to point .cpload instruction.\n \
346 # Save slot call pc.\n \
348 # Save arguments and sp value in stack.\n \
360 jal __dl_runtime_resolve\n \
369 .end _dl_runtime_resolve\n \
373 /* Mask identifying addresses reserved for the user program,
374 where the dynamic linker should not map anything. */
375 #define ELF_MACHINE_USER_ADDRESS_MASK 0x80000000UL
379 /* Initial entry point code for the dynamic linker.
380 The C function `_dl_start' is the real entry point;
381 its return value is the user program's entry point.
382 Note how we have to be careful about two things:
384 1) That we allocate a minimal stack of 24 bytes for
385 every function call, the MIPS ABI states that even
386 if all arguments are passed in registers the procedure
387 called can use the 16 byte area pointed to by $sp
388 when it is called to store away the arguments passed
391 2) That under Linux the entry is named __start
392 and not just plain _start. */
394 #define RTLD_START asm (\
396 _RTLD_PROLOGUE(ENTRY_POINT)\
402 # i386 ABI book says that the first entry of GOT holds\n\
403 # the address of the dynamic structure. Though MIPS ABI\n\
404 # doesn't say nothing about this, I emulate this here.\n\
406 # Subtract OFFSET_GP_GOT\n\
407 sw $4, -0x7ff0($28)\n\
413 coff: subu $8, $31, $8\n\
420 # Get the value of label '_dl_start_user' in t9 ($25).\n\
421 la $25, _dl_start_user\n\
422 .globl _dl_start_user\n\
428 # Save the user entry point address in a saved register.\n\
430 # Store the highest stack address\n\
431 sw $29, __libc_stack_end\n\
432 # See if we were run as a command with the executable file\n\
433 # name as an extra leading argument.\n\
434 lw $2, _dl_skip_args\n\
436 # Load the original argument count.\n\
438 # Subtract _dl_skip_args from it.\n\
440 # Adjust the stack pointer to skip _dl_skip_args words.\n\
443 # Save back the modified argument count.\n\
445 1: # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env) \n\
453 # Call the function to run the initializers.\n\
456 # Pass our finalizer function to the user in $2 as per ELF ABI.\n\
458 # Jump to the user entry point.\n\
461 _RTLD_EPILOGUE(ENTRY_POINT)\
465 /* The MIPS never uses Elfxx_Rela relocations. */
466 #define ELF_MACHINE_NO_RELA 1
468 #endif /* !dl_machine_h */
472 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
473 MAP is the object containing the reloc. */
476 elf_machine_rel (struct link_map *map, const ElfW(Rel) *reloc,
477 const ElfW(Sym) *sym, const struct r_found_version *version,
478 ElfW(Addr) *const reloc_addr)
480 #ifndef RTLD_BOOTSTRAP
481 /* This is defined in rtld.c, but nowhere in the static libc.a;
482 make the reference weak so static programs can still link. This
483 declaration cannot be done when compiling rtld.c (i.e. #ifdef
484 RTLD_BOOTSTRAP) because rtld.c contains the common defn for
485 _dl_rtld_map, which is incompatible with a weak decl in the same
487 weak_extern (_dl_rtld_map);
490 switch (ELFW(R_TYPE) (reloc->r_info))
494 int symidx = ELFW(R_SYM) (reloc->r_info);
498 const ElfW(Word) gotsym
499 = (const ElfW(Word)) map->l_info[DT_MIPS (GOTSYM)]->d_un.d_val;
503 #ifndef RTLD_BOOTSTRAP
504 if (map != &_dl_rtld_map)
506 *reloc_addr += sym->st_value + map->l_addr;
510 #ifndef RTLD_BOOTSTRAP
511 const ElfW(Addr) *got
512 = (const ElfW(Addr) *) D_PTR (map, l_info[DT_PLTGOT]);
513 const ElfW(Word) local_gotno
515 map->l_info[DT_MIPS (LOCAL_GOTNO)]->d_un.d_val;
517 *reloc_addr += got[symidx + local_gotno - gotsym];
522 #ifndef RTLD_BOOTSTRAP
523 if (map != &_dl_rtld_map)
525 *reloc_addr += map->l_addr;
528 case R_MIPS_NONE: /* Alright, Wilbur. */
531 _dl_reloc_bad_type (map, ELFW(R_TYPE) (reloc->r_info), 0);
537 elf_machine_lazy_rel (struct link_map *map,
538 ElfW(Addr) l_addr, const ElfW(Rel) *reloc)
543 #ifndef RTLD_BOOTSTRAP
546 elf_machine_got_rel (struct link_map *map, int lazy)
550 const ElfW(Half) *vernum;
553 #define RESOLVE_GOTSYM(sym,vernum,sym_index) \
555 const ElfW(Sym) *ref = sym; \
556 const struct r_found_version *version \
557 = vernum ? &map->l_versions [vernum [sym_index]] : NULL; \
559 value = RESOLVE (&ref, version, R_MIPS_REL32); \
560 (ref)? value + ref->st_value: 0; \
563 if (map->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
564 vernum = (const void *) D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]);
568 got = (ElfW(Addr) *) D_PTR (map, l_info[DT_PLTGOT]);
570 n = map->l_info[DT_MIPS (LOCAL_GOTNO)]->d_un.d_val;
571 /* The dynamic linker's local got entries have already been relocated. */
572 if (map != &_dl_rtld_map)
574 /* got[0] is reserved. got[1] is also reserved for the dynamic object
575 generated by gnu ld. Skip these reserved entries from relocation. */
576 i = (got[1] & ELF_MIPS_GNU_GOT1_MASK)? 2 : 1;
578 /* Add the run-time displacement to all local got entries if
580 if (__builtin_expect (map->l_addr != 0, 0))
583 got[i++] += map->l_addr;
587 /* Handle global got entries. */
589 /* Keep track of the symbol index. */
590 symidx = map->l_info[DT_MIPS (GOTSYM)]->d_un.d_val;
591 sym = (ElfW(Sym) *) D_PTR (map, l_info[DT_SYMTAB]) + symidx;
592 i = (map->l_info[DT_MIPS (SYMTABNO)]->d_un.d_val
593 - map->l_info[DT_MIPS (GOTSYM)]->d_un.d_val);
595 /* This loop doesn't handle Quickstart. */
598 if (sym->st_shndx == SHN_UNDEF)
600 if (ELFW(ST_TYPE) (sym->st_info) == STT_FUNC
601 && sym->st_value && lazy)
602 *got = sym->st_value + map->l_addr;
604 *got = RESOLVE_GOTSYM (sym, vernum, symidx);
606 else if (sym->st_shndx == SHN_COMMON)
607 *got = RESOLVE_GOTSYM (sym, vernum, symidx);
608 else if (ELFW(ST_TYPE) (sym->st_info) == STT_FUNC
609 && *got != sym->st_value
612 else if (ELFW(ST_TYPE) (sym->st_info) == STT_SECTION)
614 if (sym->st_other == 0)
618 *got = RESOLVE_GOTSYM (sym, vernum, symidx);
625 #undef RESOLVE_GOTSYM
629 /* Set up the loaded object described by L so its stub function
630 will jump to the on-demand fixup code __dl_runtime_resolve. */
633 elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
635 # ifndef RTLD_BOOTSTRAP
637 extern void _dl_runtime_resolve (ElfW(Word));
638 extern int _dl_mips_gnu_objects;
642 /* The GOT entries for functions have not yet been filled in.
643 Their initial contents will arrange when called to put an
644 offset into the .dynsym section in t8, the return address
645 in t7 and then jump to _GLOBAL_OFFSET_TABLE[0]. */
646 got = (ElfW(Addr) *) D_PTR (l, l_info[DT_PLTGOT]);
648 /* This function will get called to fix up the GOT entry indicated by
649 the register t8, and then jump to the resolved address. */
650 got[0] = (ElfW(Addr)) &_dl_runtime_resolve;
652 /* Store l to _GLOBAL_OFFSET_TABLE[1] for gnu object. The MSB
653 of got[1] of a gnu object is set to identify gnu objects.
654 Where we can store l for non gnu objects? XXX */
655 if ((got[1] & ELF_MIPS_GNU_GOT1_MASK) != 0)
656 got[1] = (ElfW(Addr)) ((unsigned) l | ELF_MIPS_GNU_GOT1_MASK);
658 _dl_mips_gnu_objects = 0;
661 /* Relocate global offset table. */
662 elf_machine_got_rel (l, lazy);