1 /* Machine-dependent ELF dynamic relocation inline functions. MIPS version.
2 Copyright (C) 1996,1997,1998,1999,2000,2001 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_type_class(type) ELF_RTYPE_CLASS_PLT
59 /* Translate a processor specific dynamic tag to the index
61 #define DT_MIPS(x) (DT_MIPS_##x - DT_LOPROC + DT_NUM)
63 /* If there is a DT_MIPS_RLD_MAP entry in the dynamic section, fill it in
64 with the run-time address of the r_debug structure */
65 #define ELF_MACHINE_DEBUG_SETUP(l,r) \
66 do { if ((l)->l_info[DT_MIPS (RLD_MAP)]) \
67 *(ElfW(Addr) *)((l)->l_info[DT_MIPS (RLD_MAP)]->d_un.d_ptr) = \
71 /* Return nonzero iff ELF header is compatible with the running host. */
72 static inline int __attribute__ ((unused))
73 elf_machine_matches_host (const ElfW(Ehdr) *ehdr)
75 switch (ehdr->e_machine)
85 static inline ElfW(Addr) *
86 elf_mips_got_from_gpreg (ElfW(Addr) gpreg)
88 /* FIXME: the offset of gp from GOT may be system-dependent. */
89 return (ElfW(Addr) *) (gpreg - OFFSET_GP_GOT);
92 /* Return the link-time address of _DYNAMIC. Conveniently, this is the
93 first element of the GOT. This must be inlined in a function which
95 static inline ElfW(Addr)
96 elf_machine_dynamic (void)
98 register ElfW(Addr) gp __asm__ ("$28");
99 return *elf_mips_got_from_gpreg (gp);
103 /* Return the run-time load address of the shared object. */
104 static inline ElfW(Addr)
105 elf_machine_load_address (void)
108 asm (" .set noreorder\n"
112 "here: subu %0, $31, %0\n"
120 /* The MSB of got[1] of a gnu object is set to identify gnu objects. */
121 #define ELF_MIPS_GNU_GOT1_MASK 0x80000000
123 /* We can't rely on elf_machine_got_rel because _dl_object_relocation_scope
124 fiddles with global data. */
125 #define ELF_MACHINE_BEFORE_RTLD_RELOC(dynamic_info) \
127 struct link_map *map = &bootstrap_map; \
132 got = (ElfW(Addr) *) D_PTR (map, l_info[DT_PLTGOT]); \
134 if (__builtin_expect (map->l_addr == 0, 1)) \
137 /* got[0] is reserved. got[1] is also reserved for the dynamic object \
138 generated by gnu ld. Skip these reserved entries from \
140 i = (got[1] & ELF_MIPS_GNU_GOT1_MASK)? 2 : 1; \
141 n = map->l_info[DT_MIPS (LOCAL_GOTNO)]->d_un.d_val; \
143 /* Add the run-time displacement to all local got entries. */ \
145 got[i++] += map->l_addr; \
147 /* Handle global got entries. */ \
149 sym = (ElfW(Sym) *) D_PTR(map, l_info[DT_SYMTAB]) \
150 + map->l_info[DT_MIPS (GOTSYM)]->d_un.d_val; \
151 i = (map->l_info[DT_MIPS (SYMTABNO)]->d_un.d_val \
152 - map->l_info[DT_MIPS (GOTSYM)]->d_un.d_val); \
156 if (sym->st_shndx == SHN_UNDEF || sym->st_shndx == SHN_COMMON) \
157 *got = map->l_addr + sym->st_value; \
158 else if (ELFW(ST_TYPE) (sym->st_info) == STT_FUNC \
159 && *got != sym->st_value) \
160 *got += map->l_addr; \
161 else if (ELFW(ST_TYPE) (sym->st_info) == STT_SECTION) \
163 if (sym->st_other == 0) \
164 *got += map->l_addr; \
167 *got = map->l_addr + sym->st_value; \
176 /* Get link map for callers object containing STUB_PC. */
177 static inline struct link_map *
178 elf_machine_runtime_link_map (ElfW(Addr) gpreg, ElfW(Addr) stub_pc)
180 extern int _dl_mips_gnu_objects;
182 /* got[1] is reserved to keep its link map address for the shared
183 object generated by the gnu linker. If all are such objects, we
184 can find the link map from current GPREG simply. If not so, get
185 the link map for caller's object containing STUB_PC. */
187 if (_dl_mips_gnu_objects)
189 ElfW(Addr) *got = elf_mips_got_from_gpreg (gpreg);
192 g1 = ((ElfW(Word) *) got)[1];
194 if ((g1 & ELF_MIPS_GNU_GOT1_MASK) != 0)
197 (struct link_map *) (g1 & ~ELF_MIPS_GNU_GOT1_MASK);
198 ElfW(Addr) base, limit;
199 const ElfW(Phdr) *p = l->l_phdr;
200 ElfW(Half) this, nent = l->l_phnum;
202 /* For the common case of a stub being called from the containing
203 object, STUB_PC will point to somewhere within the object that
204 is described by the link map fetched via got[1]. Otherwise we
205 have to scan all maps. */
206 for (this = 0; this < nent; this++)
208 if (p[this].p_type == PT_LOAD)
210 base = p[this].p_vaddr + l->l_addr;
211 limit = base + p[this].p_memsz;
212 if (stub_pc >= base && stub_pc < limit)
220 struct link_map *l = _dl_loaded;
224 ElfW(Addr) base, limit;
225 const ElfW(Phdr) *p = l->l_phdr;
226 ElfW(Half) this, nent = l->l_phnum;
228 for (this = 0; this < nent; ++this)
230 if (p[this].p_type == PT_LOAD)
232 base = p[this].p_vaddr + l->l_addr;
233 limit = base + p[this].p_memsz;
234 if (stub_pc >= base && stub_pc < limit)
242 _dl_signal_error (0, NULL, NULL, "cannot find runtime link map");
246 /* Define mips specific runtime resolver. The function __dl_runtime_resolve
247 is called from assembler function _dl_runtime_resolve which converts
248 special argument registers t7 ($15) and t8 ($24):
249 t7 address to return to the caller of the function
250 t8 index for this function symbol in .dynsym
251 to usual c arguments.
253 Other architectures call fixup from dl-runtime.c in
254 _dl_runtime_resolve. MIPS instead calls __dl_runtime_resolve. We
255 have to use our own version because of the way the got section is
256 treated on MIPS (we've also got ELF_MACHINE_PLT defined). */
258 #define ELF_MACHINE_RUNTIME_TRAMPOLINE \
259 /* The flag _dl_mips_gnu_objects is set if all dynamic objects are \
260 generated by the gnu linker. */ \
261 int _dl_mips_gnu_objects = 1; \
263 /* This is called from assembly stubs below which the compiler can't see. */ \
265 __dl_runtime_resolve (ElfW(Word), ElfW(Word), ElfW(Addr), ElfW(Addr)) \
266 __attribute__ ((unused)); \
269 __dl_runtime_resolve (ElfW(Word) sym_index, \
270 ElfW(Word) return_address, \
271 ElfW(Addr) old_gpreg, \
272 ElfW(Addr) stub_pc) \
274 struct link_map *l = elf_machine_runtime_link_map (old_gpreg, stub_pc); \
275 const ElfW(Sym) *const symtab \
276 = (const void *) D_PTR (l, l_info[DT_SYMTAB]); \
278 = (const void *) D_PTR (l, l_info[DT_STRTAB]); \
279 const ElfW(Addr) *got \
280 = (const ElfW(Addr) *) D_PTR (l, l_info[DT_PLTGOT]); \
281 const ElfW(Word) local_gotno \
282 = (const ElfW(Word)) l->l_info[DT_MIPS (LOCAL_GOTNO)]->d_un.d_val; \
283 const ElfW(Word) gotsym \
284 = (const ElfW(Word)) l->l_info[DT_MIPS (GOTSYM)]->d_un.d_val; \
285 const ElfW(Sym) *sym = &symtab[sym_index]; \
288 /* FIXME: The symbol versioning stuff is not tested yet. */ \
289 if (__builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0) \
291 switch (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL) \
295 const ElfW(Half) *vernum = \
296 (const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]); \
297 ElfW(Half) ndx = vernum[sym_index]; \
298 const struct r_found_version *version = &l->l_versions[ndx]; \
300 if (version->hash != 0) \
302 value = _dl_lookup_versioned_symbol(strtab + sym->st_name, l, \
303 &sym, l->l_scope, version,\
304 ELF_RTYPE_CLASS_PLT, 0); \
307 /* Fall through. */ \
310 value = _dl_lookup_symbol (strtab + sym->st_name, l, &sym, \
311 l->l_scope, ELF_RTYPE_CLASS_PLT, 0); \
314 /* Currently value contains the base load address of the object \
315 that defines sym. Now add in the symbol offset. */ \
316 value = (sym ? value + sym->st_value : 0); \
319 /* We already found the symbol. The module (and therefore its load \
320 address) is also known. */ \
321 value = l->l_addr + sym->st_value; \
323 /* Apply the relocation with that value. */ \
324 *(got + local_gotno + sym_index - gotsym) = value; \
332 .globl _dl_runtime_resolve\n \
333 .type _dl_runtime_resolve,@function\n \
334 .ent _dl_runtime_resolve\n \
335 _dl_runtime_resolve:\n \
336 .frame $29, 40, $31\n \
340 # Modify t9 ($25) so as to point .cpload instruction.\n \
345 # Save slot call pc.\n \
347 # Save arguments and sp value in stack.\n \
359 jal __dl_runtime_resolve\n \
368 .end _dl_runtime_resolve\n \
372 /* Mask identifying addresses reserved for the user program,
373 where the dynamic linker should not map anything. */
374 #define ELF_MACHINE_USER_ADDRESS_MASK 0x80000000UL
378 /* Initial entry point code for the dynamic linker.
379 The C function `_dl_start' is the real entry point;
380 its return value is the user program's entry point.
381 Note how we have to be careful about two things:
383 1) That we allocate a minimal stack of 24 bytes for
384 every function call, the MIPS ABI states that even
385 if all arguments are passed in registers the procedure
386 called can use the 16 byte area pointed to by $sp
387 when it is called to store away the arguments passed
390 2) That under Linux the entry is named __start
391 and not just plain _start. */
393 #define RTLD_START asm (\
395 _RTLD_PROLOGUE(ENTRY_POINT)\
401 # i386 ABI book says that the first entry of GOT holds\n\
402 # the address of the dynamic structure. Though MIPS ABI\n\
403 # doesn't say nothing about this, I emulate this here.\n\
405 # Subtract OFFSET_GP_GOT\n\
406 sw $4, -0x7ff0($28)\n\
412 coff: subu $8, $31, $8\n\
419 # Get the value of label '_dl_start_user' in t9 ($25).\n\
420 la $25, _dl_start_user\n\
421 .globl _dl_start_user\n\
427 # Save the user entry point address in a saved register.\n\
429 # Store the highest stack address\n\
430 sw $29, __libc_stack_end\n\
431 # See if we were run as a command with the executable file\n\
432 # name as an extra leading argument.\n\
433 lw $2, _dl_skip_args\n\
435 # Load the original argument count.\n\
437 # Subtract _dl_skip_args from it.\n\
439 # Adjust the stack pointer to skip _dl_skip_args words.\n\
442 # Save back the modified argument count.\n\
444 1: # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env) \n\
452 # Call the function to run the initializers.\n\
455 # Pass our finalizer function to the user in $2 as per ELF ABI.\n\
457 # Jump to the user entry point.\n\
460 _RTLD_EPILOGUE(ENTRY_POINT)\
464 /* The MIPS never uses Elfxx_Rela relocations. */
465 #define ELF_MACHINE_NO_RELA 1
467 #endif /* !dl_machine_h */
471 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
472 MAP is the object containing the reloc. */
475 elf_machine_rel (struct link_map *map, const ElfW(Rel) *reloc,
476 const ElfW(Sym) *sym, const struct r_found_version *version,
477 ElfW(Addr) *const reloc_addr)
479 const unsigned long int r_type = ELFW(R_TYPE) (reloc->r_info);
481 #ifndef RTLD_BOOTSTRAP
482 /* This is defined in rtld.c, but nowhere in the static libc.a;
483 make the reference weak so static programs can still link. This
484 declaration cannot be done when compiling rtld.c (i.e. #ifdef
485 RTLD_BOOTSTRAP) because rtld.c contains the common defn for
486 _dl_rtld_map, which is incompatible with a weak decl in the same
488 weak_extern (_dl_rtld_map);
495 int symidx = ELFW(R_SYM) (reloc->r_info);
499 const ElfW(Word) gotsym
500 = (const ElfW(Word)) map->l_info[DT_MIPS (GOTSYM)]->d_un.d_val;
504 #ifndef RTLD_BOOTSTRAP
505 if (map != &_dl_rtld_map)
507 *reloc_addr += sym->st_value + map->l_addr;
511 #ifndef RTLD_BOOTSTRAP
512 const ElfW(Addr) *got
513 = (const ElfW(Addr) *) D_PTR (map, l_info[DT_PLTGOT]);
514 const ElfW(Word) local_gotno
516 map->l_info[DT_MIPS (LOCAL_GOTNO)]->d_un.d_val;
518 *reloc_addr += got[symidx + local_gotno - gotsym];
523 #ifndef RTLD_BOOTSTRAP
524 if (map != &_dl_rtld_map)
526 *reloc_addr += map->l_addr;
529 case R_MIPS_NONE: /* Alright, Wilbur. */
532 _dl_reloc_bad_type (map, r_type, 0);
538 elf_machine_rel_relative (ElfW(Addr) l_addr, const ElfW(Rel) *reloc,
539 ElfW(Addr) *const reloc_addr)
541 /* XXX Nothing to do. There is no relative relocation, right? */
545 elf_machine_lazy_rel (struct link_map *map,
546 ElfW(Addr) l_addr, const ElfW(Rel) *reloc)
551 #ifndef RTLD_BOOTSTRAP
554 elf_machine_got_rel (struct link_map *map, int lazy)
558 const ElfW(Half) *vernum;
561 #define RESOLVE_GOTSYM(sym,vernum,sym_index) \
563 const ElfW(Sym) *ref = sym; \
564 const struct r_found_version *version \
565 = vernum ? &map->l_versions [vernum [sym_index]] : NULL; \
567 value = RESOLVE (&ref, version, R_MIPS_REL32); \
568 (ref)? value + ref->st_value: 0; \
571 if (map->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
572 vernum = (const void *) D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]);
576 got = (ElfW(Addr) *) D_PTR (map, l_info[DT_PLTGOT]);
578 n = map->l_info[DT_MIPS (LOCAL_GOTNO)]->d_un.d_val;
579 /* The dynamic linker's local got entries have already been relocated. */
580 if (map != &_dl_rtld_map)
582 /* got[0] is reserved. got[1] is also reserved for the dynamic object
583 generated by gnu ld. Skip these reserved entries from relocation. */
584 i = (got[1] & ELF_MIPS_GNU_GOT1_MASK)? 2 : 1;
586 /* Add the run-time displacement to all local got entries if
588 if (__builtin_expect (map->l_addr != 0, 0))
591 got[i++] += map->l_addr;
595 /* Handle global got entries. */
597 /* Keep track of the symbol index. */
598 symidx = map->l_info[DT_MIPS (GOTSYM)]->d_un.d_val;
599 sym = (ElfW(Sym) *) D_PTR (map, l_info[DT_SYMTAB]) + symidx;
600 i = (map->l_info[DT_MIPS (SYMTABNO)]->d_un.d_val
601 - map->l_info[DT_MIPS (GOTSYM)]->d_un.d_val);
603 /* This loop doesn't handle Quickstart. */
606 if (sym->st_shndx == SHN_UNDEF)
608 if (ELFW(ST_TYPE) (sym->st_info) == STT_FUNC
609 && sym->st_value && lazy)
610 *got = sym->st_value + map->l_addr;
612 *got = RESOLVE_GOTSYM (sym, vernum, symidx);
614 else if (sym->st_shndx == SHN_COMMON)
615 *got = RESOLVE_GOTSYM (sym, vernum, symidx);
616 else if (ELFW(ST_TYPE) (sym->st_info) == STT_FUNC
617 && *got != sym->st_value
620 else if (ELFW(ST_TYPE) (sym->st_info) == STT_SECTION)
622 if (sym->st_other == 0)
626 *got = RESOLVE_GOTSYM (sym, vernum, symidx);
633 #undef RESOLVE_GOTSYM
637 /* Set up the loaded object described by L so its stub function
638 will jump to the on-demand fixup code __dl_runtime_resolve. */
641 elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
643 # ifndef RTLD_BOOTSTRAP
645 extern void _dl_runtime_resolve (ElfW(Word));
646 extern int _dl_mips_gnu_objects;
650 /* The GOT entries for functions have not yet been filled in.
651 Their initial contents will arrange when called to put an
652 offset into the .dynsym section in t8, the return address
653 in t7 and then jump to _GLOBAL_OFFSET_TABLE[0]. */
654 got = (ElfW(Addr) *) D_PTR (l, l_info[DT_PLTGOT]);
656 /* This function will get called to fix up the GOT entry indicated by
657 the register t8, and then jump to the resolved address. */
658 got[0] = (ElfW(Addr)) &_dl_runtime_resolve;
660 /* Store l to _GLOBAL_OFFSET_TABLE[1] for gnu object. The MSB
661 of got[1] of a gnu object is set to identify gnu objects.
662 Where we can store l for non gnu objects? XXX */
663 if ((got[1] & ELF_MIPS_GNU_GOT1_MASK) != 0)
664 got[1] = (ElfW(Addr)) ((unsigned) l | ELF_MIPS_GNU_GOT1_MASK);
666 _dl_mips_gnu_objects = 0;
669 /* Relocate global offset table. */
670 elf_machine_got_rel (l, lazy);