2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
3 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 * $FreeBSD: src/libexec/rtld-elf/rtld.c,v 1.43.2.15 2003/02/20 20:42:46 kan Exp $
27 * $DragonFly: src/libexec/rtld-elf/rtld.c,v 1.29 2008/01/08 00:02:04 corecode Exp $
31 * Dynamic linker for ELF.
33 * John Polstra <jdp@polstra.com>.
37 #error "GCC is needed to compile this file"
40 #include <sys/param.h>
43 #include <sys/resident.h>
46 #include <machine/tls.h>
61 #define PATH_RTLD "/usr/libexec/ld-elf.so.2"
62 #define LD_ARY_CACHE 16
65 typedef void (*func_ptr_type
)();
66 typedef void * (*path_enum_proc
) (const char *path
, size_t len
, void *arg
);
69 * This structure provides a reentrant way to keep a list of objects and
70 * check which ones have already been processed in some way.
72 typedef struct Struct_DoneList
{
73 const Obj_Entry
**objs
; /* Array of object pointers */
74 unsigned int num_alloc
; /* Allocated size of the array */
75 unsigned int num_used
; /* Number of array slots used */
79 * Function declarations.
81 static void die(void);
82 static void digest_dynamic(Obj_Entry
*, int);
83 static const char *_getenv_ld(const char *id
);
84 static Obj_Entry
*digest_phdr(const Elf_Phdr
*, int, caddr_t
, const char *);
85 static Obj_Entry
*dlcheck(void *);
86 static int do_search_info(const Obj_Entry
*obj
, int, struct dl_serinfo
*);
87 static bool donelist_check(DoneList
*, const Obj_Entry
*);
88 static void errmsg_restore(char *);
89 static char *errmsg_save(void);
90 static void *fill_search_info(const char *, size_t, void *);
91 static char *find_library(const char *, const Obj_Entry
*);
92 static Obj_Entry
*find_object(const char *);
93 static Obj_Entry
*find_object2(const char *, int *, struct stat
*);
94 static const char *gethints(void);
95 static void init_dag(Obj_Entry
*);
96 static void init_dag1(Obj_Entry
*root
, Obj_Entry
*obj
, DoneList
*);
97 static void init_rtld(caddr_t
);
98 static void initlist_add_neededs(Needed_Entry
*needed
, Objlist
*list
);
99 static void initlist_add_objects(Obj_Entry
*obj
, Obj_Entry
**tail
,
101 static bool is_exported(const Elf_Sym
*);
102 static void linkmap_add(Obj_Entry
*);
103 static void linkmap_delete(Obj_Entry
*);
104 static int load_needed_objects(Obj_Entry
*);
105 static int load_preload_objects(void);
106 static Obj_Entry
*load_object(char *);
107 static void lock_check(void);
108 static Obj_Entry
*obj_from_addr(const void *);
109 static void objlist_call_fini(Objlist
*);
110 static void objlist_call_init(Objlist
*);
111 static void objlist_clear(Objlist
*);
112 static Objlist_Entry
*objlist_find(Objlist
*, const Obj_Entry
*);
113 static void objlist_init(Objlist
*);
114 static void objlist_push_head(Objlist
*, Obj_Entry
*);
115 static void objlist_push_tail(Objlist
*, Obj_Entry
*);
116 static void objlist_remove(Objlist
*, Obj_Entry
*);
117 static void objlist_remove_unref(Objlist
*);
118 static void *path_enumerate(const char *, path_enum_proc
, void *);
119 static int relocate_objects(Obj_Entry
*, bool, Obj_Entry
*);
120 static int rtld_dirname(const char *, char *);
121 static void rtld_exit(void);
122 static char *search_library_path(const char *, const char *);
123 static const void **get_program_var_addr(const char *name
);
124 static void set_program_var(const char *, const void *);
125 static const Elf_Sym
*symlook_default(const char *, unsigned long hash
,
126 const Obj_Entry
*refobj
, const Obj_Entry
**defobj_out
, bool in_plt
);
127 static const Elf_Sym
*symlook_list(const char *, unsigned long,
128 const Objlist
*, const Obj_Entry
**, bool in_plt
, DoneList
*);
129 static const Elf_Sym
*symlook_needed(const char *, unsigned long,
130 const Needed_Entry
*, const Obj_Entry
**, bool in_plt
, DoneList
*);
131 static void trace_loaded_objects(Obj_Entry
*obj
);
132 static void unlink_object(Obj_Entry
*);
133 static void unload_object(Obj_Entry
*);
134 static void unref_dag(Obj_Entry
*);
136 void r_debug_state(struct r_debug
*, struct link_map
*);
141 static char *error_message
; /* Message for dlerror(), or NULL */
142 struct r_debug r_debug
; /* for GDB; */
143 static bool trust
; /* False for setuid and setgid programs */
144 static const char *ld_bind_now
; /* Environment variable for immediate binding */
145 static const char *ld_debug
; /* Environment variable for debugging */
146 static const char *ld_library_path
; /* Environment variable for search path */
147 static char *ld_preload
; /* Environment variable for libraries to
149 static const char *ld_tracing
; /* Called from ldd(1) to print libs */
150 /* Optional function call tracing hook */
151 static int (*rtld_functrace
)(const char *caller_obj
,
152 const char *callee_obj
,
153 const char *callee_func
,
155 static Obj_Entry
*rtld_functrace_obj
; /* Object thereof */
156 static Obj_Entry
*obj_list
; /* Head of linked list of shared objects */
157 static Obj_Entry
**obj_tail
; /* Link field of last object in list */
158 static Obj_Entry
**preload_tail
;
159 static Obj_Entry
*obj_main
; /* The main program shared object */
160 static Obj_Entry obj_rtld
; /* The dynamic linker shared object */
161 static unsigned int obj_count
; /* Number of objects in obj_list */
162 static int ld_resident
; /* Non-zero if resident */
163 static const char *ld_ary
[LD_ARY_CACHE
];
165 static Objlist initlist
;
167 static Objlist list_global
= /* Objects dlopened with RTLD_GLOBAL */
168 STAILQ_HEAD_INITIALIZER(list_global
);
169 static Objlist list_main
= /* Objects loaded at program startup */
170 STAILQ_HEAD_INITIALIZER(list_main
);
171 static Objlist list_fini
= /* Objects needing fini() calls */
172 STAILQ_HEAD_INITIALIZER(list_fini
);
174 static LockInfo lockinfo
;
176 static Elf_Sym sym_zero
; /* For resolving undefined weak refs. */
178 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m);
180 extern Elf_Dyn _DYNAMIC
;
181 #pragma weak _DYNAMIC
184 * These are the functions the dynamic linker exports to application
185 * programs. They are the only symbols the dynamic linker is willing
186 * to export from itself.
188 static func_ptr_type exports
[] = {
189 (func_ptr_type
) &_rtld_error
,
190 (func_ptr_type
) &dlclose
,
191 (func_ptr_type
) &dlerror
,
192 (func_ptr_type
) &dlopen
,
193 (func_ptr_type
) &dlsym
,
194 (func_ptr_type
) &dladdr
,
195 (func_ptr_type
) &dlinfo
,
197 (func_ptr_type
) &___tls_get_addr
,
199 (func_ptr_type
) &__tls_get_addr
,
200 (func_ptr_type
) &__tls_get_addr_tcb
,
201 (func_ptr_type
) &_rtld_allocate_tls
,
202 (func_ptr_type
) &_rtld_free_tls
,
203 (func_ptr_type
) &_rtld_call_init
,
208 * Global declarations normally provided by crt1. The dynamic linker is
209 * not built with crt1, so we have to provide them ourselves.
215 * Globals to control TLS allocation.
217 size_t tls_last_offset
; /* Static TLS offset of last module */
218 size_t tls_last_size
; /* Static TLS size of last module */
219 size_t tls_static_space
; /* Static TLS space allocated */
220 int tls_dtv_generation
= 1; /* Used to detect when dtv size changes */
221 int tls_max_index
= 1; /* Largest module index allocated */
224 * Fill in a DoneList with an allocation large enough to hold all of
225 * the currently-loaded objects. Keep this as a macro since it calls
226 * alloca and we want that to occur within the scope of the caller.
228 #define donelist_init(dlp) \
229 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \
230 assert((dlp)->objs != NULL), \
231 (dlp)->num_alloc = obj_count, \
237 lockinfo
.rlock_acquire(lockinfo
.thelock
);
238 atomic_incr_int(&lockinfo
.rcount
);
245 lockinfo
.wlock_acquire(lockinfo
.thelock
);
246 atomic_incr_int(&lockinfo
.wcount
);
253 atomic_decr_int(&lockinfo
.rcount
);
254 lockinfo
.rlock_release(lockinfo
.thelock
);
260 atomic_decr_int(&lockinfo
.wcount
);
261 lockinfo
.wlock_release(lockinfo
.thelock
);
265 * Main entry point for dynamic linking. The first argument is the
266 * stack pointer. The stack is expected to be laid out as described
267 * in the SVR4 ABI specification, Intel 386 Processor Supplement.
268 * Specifically, the stack pointer points to a word containing
269 * ARGC. Following that in the stack is a null-terminated sequence
270 * of pointers to argument strings. Then comes a null-terminated
271 * sequence of pointers to environment strings. Finally, there is a
272 * sequence of "auxiliary vector" entries.
274 * The second argument points to a place to store the dynamic linker's
275 * exit procedure pointer and the third to a place to store the main
278 * The return value is the main program's entry point.
282 _rtld(Elf_Addr
*sp
, func_ptr_type
*exit_proc
, Obj_Entry
**objp
)
284 Elf_Auxinfo
*aux_info
[AT_COUNT
];
292 Objlist_Entry
*entry
;
296 * On entry, the dynamic linker itself has not been relocated yet.
297 * Be very careful not to reference any global data until after
298 * init_rtld has returned. It is OK to reference file-scope statics
299 * and string constants, and to call static and global functions.
302 /* Find the auxiliary vector on the stack. */
305 sp
+= argc
+ 1; /* Skip over arguments and NULL terminator */
309 * If we aren't already resident we have to dig out some more info.
310 * Note that auxinfo does not exist when we are resident.
312 * I'm not sure about the ld_resident check. It seems to read zero
313 * prior to relocation, which is what we want. When running from a
314 * resident copy everything will be relocated so we are definitely
317 if (ld_resident
== 0) {
318 while (*sp
++ != 0) /* Skip over environment, and NULL terminator */
320 aux
= (Elf_Auxinfo
*) sp
;
322 /* Digest the auxiliary vector. */
323 for (i
= 0; i
< AT_COUNT
; i
++)
325 for (auxp
= aux
; auxp
->a_type
!= AT_NULL
; auxp
++) {
326 if (auxp
->a_type
< AT_COUNT
)
327 aux_info
[auxp
->a_type
] = auxp
;
330 /* Initialize and relocate ourselves. */
331 assert(aux_info
[AT_BASE
] != NULL
);
332 init_rtld((caddr_t
) aux_info
[AT_BASE
]->a_un
.a_ptr
);
335 ld_index
= 0; /* don't use old env cache in case we are resident */
336 __progname
= obj_rtld
.path
;
337 argv0
= argv
[0] != NULL
? argv
[0] : "(null)";
340 trust
= (geteuid() == getuid()) && (getegid() == getgid());
342 ld_bind_now
= _getenv_ld("LD_BIND_NOW");
344 ld_debug
= _getenv_ld("LD_DEBUG");
345 ld_library_path
= _getenv_ld("LD_LIBRARY_PATH");
346 ld_preload
= (char *)_getenv_ld("LD_PRELOAD");
348 ld_tracing
= _getenv_ld("LD_TRACE_LOADED_OBJECTS");
350 if (ld_debug
!= NULL
&& *ld_debug
!= '\0')
352 dbg("%s is initialized, base address = %p", __progname
,
353 (caddr_t
) aux_info
[AT_BASE
]->a_un
.a_ptr
);
354 dbg("RTLD dynamic = %p", obj_rtld
.dynamic
);
355 dbg("RTLD pltgot = %p", obj_rtld
.pltgot
);
358 * If we are resident we can skip work that we have already done.
359 * Note that the stack is reset and there is no Elf_Auxinfo
360 * when running from a resident image, and the static globals setup
361 * between here and resident_skip will have already been setup.
367 * Load the main program, or process its program header if it is
370 if (aux_info
[AT_EXECFD
] != NULL
) { /* Load the main program. */
371 int fd
= aux_info
[AT_EXECFD
]->a_un
.a_val
;
372 dbg("loading main program");
373 obj_main
= map_object(fd
, argv0
, NULL
);
375 if (obj_main
== NULL
)
377 } else { /* Main program already loaded. */
378 const Elf_Phdr
*phdr
;
382 dbg("processing main program's program header");
383 assert(aux_info
[AT_PHDR
] != NULL
);
384 phdr
= (const Elf_Phdr
*) aux_info
[AT_PHDR
]->a_un
.a_ptr
;
385 assert(aux_info
[AT_PHNUM
] != NULL
);
386 phnum
= aux_info
[AT_PHNUM
]->a_un
.a_val
;
387 assert(aux_info
[AT_PHENT
] != NULL
);
388 assert(aux_info
[AT_PHENT
]->a_un
.a_val
== sizeof(Elf_Phdr
));
389 assert(aux_info
[AT_ENTRY
] != NULL
);
390 entry
= (caddr_t
) aux_info
[AT_ENTRY
]->a_un
.a_ptr
;
391 if ((obj_main
= digest_phdr(phdr
, phnum
, entry
, argv0
)) == NULL
)
395 obj_main
->path
= xstrdup(argv0
);
396 obj_main
->mainprog
= true;
399 * Get the actual dynamic linker pathname from the executable if
400 * possible. (It should always be possible.) That ensures that
401 * gdb will find the right dynamic linker even if a non-standard
404 if (obj_main
->interp
!= NULL
&&
405 strcmp(obj_main
->interp
, obj_rtld
.path
) != 0) {
407 obj_rtld
.path
= xstrdup(obj_main
->interp
);
408 __progname
= obj_rtld
.path
;
411 digest_dynamic(obj_main
, 0);
413 linkmap_add(obj_main
);
414 linkmap_add(&obj_rtld
);
416 /* Link the main program into the list of objects. */
417 *obj_tail
= obj_main
;
418 obj_tail
= &obj_main
->next
;
420 obj_main
->refcount
++;
421 /* Make sure we don't call the main program's init and fini functions. */
422 obj_main
->init
= obj_main
->fini
= NULL
;
424 /* Initialize a fake symbol for resolving undefined weak references. */
425 sym_zero
.st_info
= ELF_ST_INFO(STB_GLOBAL
, STT_NOTYPE
);
426 sym_zero
.st_shndx
= SHN_ABS
;
428 dbg("loading LD_PRELOAD libraries");
429 if (load_preload_objects() == -1)
431 preload_tail
= obj_tail
;
433 dbg("loading needed objects");
434 if (load_needed_objects(obj_main
) == -1)
437 /* Make a list of all objects loaded at startup. */
438 for (obj
= obj_list
; obj
!= NULL
; obj
= obj
->next
)
439 objlist_push_tail(&list_main
, obj
);
443 if (ld_tracing
) { /* We're done */
444 trace_loaded_objects(obj_main
);
448 if (ld_resident
) /* XXX clean this up! */
451 if (getenv("LD_DUMP_REL_PRE") != NULL
) {
452 dump_relocations(obj_main
);
456 /* setup TLS for main thread */
457 dbg("initializing initial thread local storage");
458 STAILQ_FOREACH(entry
, &list_main
, link
) {
460 * Allocate all the initial objects out of the static TLS
461 * block even if they didn't ask for it.
463 allocate_tls_offset(entry
->obj
);
466 tls_static_space
= tls_last_offset
+ RTLD_STATIC_TLS_EXTRA
;
469 * Do not try to allocate the TLS here, let libc do it itself.
470 * (crt1 for the program will call _init_tls())
473 if (relocate_objects(obj_main
,
474 ld_bind_now
!= NULL
&& *ld_bind_now
!= '\0', &obj_rtld
) == -1)
477 dbg("doing copy relocations");
478 if (do_copy_relocations(obj_main
) == -1)
483 if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) {
484 if (exec_sys_unregister(-1) < 0) {
485 dbg("exec_sys_unregister failed %d\n", errno
);
488 dbg("exec_sys_unregister success\n");
492 if (getenv("LD_DUMP_REL_POST") != NULL
) {
493 dump_relocations(obj_main
);
497 dbg("initializing key program variables");
498 set_program_var("__progname", argv
[0] != NULL
? basename(argv
[0]) : "");
499 set_program_var("environ", env
);
501 if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) {
502 extern void resident_start(void);
504 if (exec_sys_register(resident_start
) < 0) {
505 dbg("exec_sys_register failed %d\n", errno
);
508 dbg("exec_sys_register success\n");
512 dbg("initializing thread locks");
513 lockdflt_init(&lockinfo
);
514 lockinfo
.thelock
= lockinfo
.lock_create(lockinfo
.context
);
516 /* Make a list of init functions to call. */
517 objlist_init(&initlist
);
518 initlist_add_objects(obj_list
, preload_tail
, &initlist
);
520 r_debug_state(NULL
, &obj_main
->linkmap
); /* say hello to gdb! */
523 * Do NOT call the initlist here, give libc a chance to set up
524 * the initial TLS segment. crt1 will then call _rtld_call_init().
527 dbg("transferring control to program entry point = %p", obj_main
->entry
);
529 /* Return the exit procedure and the program entry point. */
530 *exit_proc
= rtld_exit
;
532 return (func_ptr_type
) obj_main
->entry
;
536 * Call the initialization list for dynamically loaded libraries.
537 * (called from crt1.c).
540 _rtld_call_init(void)
542 objlist_call_init(&initlist
);
544 objlist_clear(&initlist
);
549 _rtld_bind(Obj_Entry
*obj
, Elf_Size reloff
, void *stack
)
553 const Obj_Entry
*defobj
;
560 rel
= (const Elf_Rel
*) ((caddr_t
) obj
->pltrel
+ reloff
);
562 rel
= (const Elf_Rel
*) ((caddr_t
) obj
->pltrela
+ reloff
);
564 where
= (Elf_Addr
*) (obj
->relocbase
+ rel
->r_offset
);
565 def
= find_symdef(ELF_R_SYM(rel
->r_info
), obj
, &defobj
, true, NULL
);
569 target
= (Elf_Addr
)(defobj
->relocbase
+ def
->st_value
);
571 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
572 defobj
->strtab
+ def
->st_name
, basename(obj
->path
),
573 (void *)target
, basename(defobj
->path
));
577 * If we have a function call tracing hook, and the
578 * hook would like to keep tracing this one function,
579 * prevent the relocation so we will wind up here
580 * the next time again.
582 * We don't want to functrace calls from the functracer
583 * to avoid recursive loops.
585 if (rtld_functrace
!= NULL
&& obj
!= rtld_functrace_obj
) {
586 if (rtld_functrace(obj
->path
,
588 defobj
->strtab
+ def
->st_name
,
594 reloc_jmpslot(where
, target
);
599 * Error reporting function. Use it like printf. If formats the message
600 * into a buffer, and sets things up so that the next call to dlerror()
601 * will return the message.
604 _rtld_error(const char *fmt
, ...)
606 static char buf
[512];
610 vsnprintf(buf
, sizeof buf
, fmt
, ap
);
616 * Return a dynamically-allocated copy of the current error message, if any.
621 return error_message
== NULL
? NULL
: xstrdup(error_message
);
625 * Restore the current error message from a copy which was previously saved
626 * by errmsg_save(). The copy is freed.
629 errmsg_restore(char *saved_msg
)
631 if (saved_msg
== NULL
)
632 error_message
= NULL
;
634 _rtld_error("%s", saved_msg
);
640 basename(const char *name
)
642 const char *p
= strrchr(name
, '/');
643 return p
!= NULL
? p
+ 1 : name
;
649 const char *msg
= dlerror();
657 * Process a shared object's DYNAMIC section, and save the important
658 * information in its Obj_Entry structure.
661 digest_dynamic(Obj_Entry
*obj
, int early
)
664 Needed_Entry
**needed_tail
= &obj
->needed
;
665 const Elf_Dyn
*dyn_rpath
= NULL
;
666 int plttype
= DT_REL
;
668 for (dynp
= obj
->dynamic
; dynp
->d_tag
!= DT_NULL
; dynp
++) {
669 switch (dynp
->d_tag
) {
672 obj
->rel
= (const Elf_Rel
*) (obj
->relocbase
+ dynp
->d_un
.d_ptr
);
676 obj
->relsize
= dynp
->d_un
.d_val
;
680 assert(dynp
->d_un
.d_val
== sizeof(Elf_Rel
));
684 obj
->pltrel
= (const Elf_Rel
*)
685 (obj
->relocbase
+ dynp
->d_un
.d_ptr
);
689 obj
->pltrelsize
= dynp
->d_un
.d_val
;
693 obj
->rela
= (const Elf_Rela
*) (obj
->relocbase
+ dynp
->d_un
.d_ptr
);
697 obj
->relasize
= dynp
->d_un
.d_val
;
701 assert(dynp
->d_un
.d_val
== sizeof(Elf_Rela
));
705 plttype
= dynp
->d_un
.d_val
;
706 assert(dynp
->d_un
.d_val
== DT_REL
|| plttype
== DT_RELA
);
710 obj
->symtab
= (const Elf_Sym
*)
711 (obj
->relocbase
+ dynp
->d_un
.d_ptr
);
715 assert(dynp
->d_un
.d_val
== sizeof(Elf_Sym
));
719 obj
->strtab
= (const char *) (obj
->relocbase
+ dynp
->d_un
.d_ptr
);
723 obj
->strsize
= dynp
->d_un
.d_val
;
728 const Elf_Hashelt
*hashtab
= (const Elf_Hashelt
*)
729 (obj
->relocbase
+ dynp
->d_un
.d_ptr
);
730 obj
->nbuckets
= hashtab
[0];
731 obj
->nchains
= hashtab
[1];
732 obj
->buckets
= hashtab
+ 2;
733 obj
->chains
= obj
->buckets
+ obj
->nbuckets
;
739 Needed_Entry
*nep
= NEW(Needed_Entry
);
740 nep
->name
= dynp
->d_un
.d_val
;
745 needed_tail
= &nep
->next
;
750 obj
->pltgot
= (Elf_Addr
*) (obj
->relocbase
+ dynp
->d_un
.d_ptr
);
758 obj
->symbolic
= true;
762 case DT_RUNPATH
: /* XXX: process separately */
764 * We have to wait until later to process this, because we
765 * might not have gotten the address of the string table yet.
771 /* Not used by the dynamic linker. */
775 obj
->init
= (InitFunc
) (obj
->relocbase
+ dynp
->d_un
.d_ptr
);
779 obj
->fini
= (InitFunc
) (obj
->relocbase
+ dynp
->d_un
.d_ptr
);
783 /* XXX - not implemented yet */
785 dbg("Filling in DT_DEBUG entry");
786 ((Elf_Dyn
*)dynp
)->d_un
.d_ptr
= (Elf_Addr
) &r_debug
;
790 if (dynp
->d_un
.d_val
& DF_ORIGIN
) {
791 obj
->origin_path
= xmalloc(PATH_MAX
);
792 if (rtld_dirname(obj
->path
, obj
->origin_path
) == -1)
795 if (dynp
->d_un
.d_val
& DF_SYMBOLIC
)
796 obj
->symbolic
= true;
797 if (dynp
->d_un
.d_val
& DF_TEXTREL
)
799 if (dynp
->d_un
.d_val
& DF_BIND_NOW
)
800 obj
->bind_now
= true;
801 if (dynp
->d_un
.d_val
& DF_STATIC_TLS
)
807 dbg("Ignoring d_tag %d = %#x", dynp
->d_tag
, dynp
->d_tag
);
814 if (plttype
== DT_RELA
) {
815 obj
->pltrela
= (const Elf_Rela
*) obj
->pltrel
;
817 obj
->pltrelasize
= obj
->pltrelsize
;
821 if (dyn_rpath
!= NULL
)
822 obj
->rpath
= obj
->strtab
+ dyn_rpath
->d_un
.d_val
;
826 * Process a shared object's program header. This is used only for the
827 * main program, when the kernel has already loaded the main program
828 * into memory before calling the dynamic linker. It creates and
829 * returns an Obj_Entry structure.
832 digest_phdr(const Elf_Phdr
*phdr
, int phnum
, caddr_t entry
, const char *path
)
835 const Elf_Phdr
*phlimit
= phdr
+ phnum
;
840 for (ph
= phdr
; ph
< phlimit
; ph
++) {
841 switch (ph
->p_type
) {
844 if ((const Elf_Phdr
*)ph
->p_vaddr
!= phdr
) {
845 _rtld_error("%s: invalid PT_PHDR", path
);
848 obj
->phdr
= (const Elf_Phdr
*) ph
->p_vaddr
;
849 obj
->phsize
= ph
->p_memsz
;
853 obj
->interp
= (const char *) ph
->p_vaddr
;
857 if (nsegs
== 0) { /* First load segment */
858 obj
->vaddrbase
= trunc_page(ph
->p_vaddr
);
859 obj
->mapbase
= (caddr_t
) obj
->vaddrbase
;
860 obj
->relocbase
= obj
->mapbase
- obj
->vaddrbase
;
861 obj
->textsize
= round_page(ph
->p_vaddr
+ ph
->p_memsz
) -
863 } else { /* Last load segment */
864 obj
->mapsize
= round_page(ph
->p_vaddr
+ ph
->p_memsz
) -
871 obj
->dynamic
= (const Elf_Dyn
*) ph
->p_vaddr
;
876 obj
->tlssize
= ph
->p_memsz
;
877 obj
->tlsalign
= ph
->p_align
;
878 obj
->tlsinitsize
= ph
->p_filesz
;
879 obj
->tlsinit
= (void*) ph
->p_vaddr
;
884 _rtld_error("%s: too few PT_LOAD segments", path
);
893 dlcheck(void *handle
)
897 for (obj
= obj_list
; obj
!= NULL
; obj
= obj
->next
)
898 if (obj
== (Obj_Entry
*) handle
)
901 if (obj
== NULL
|| obj
->refcount
== 0 || obj
->dl_refcount
== 0) {
902 _rtld_error("Invalid shared object handle %p", handle
);
909 * If the given object is already in the donelist, return true. Otherwise
910 * add the object to the list and return false.
913 donelist_check(DoneList
*dlp
, const Obj_Entry
*obj
)
917 for (i
= 0; i
< dlp
->num_used
; i
++)
918 if (dlp
->objs
[i
] == obj
)
921 * Our donelist allocation should always be sufficient. But if
922 * our threads locking isn't working properly, more shared objects
923 * could have been loaded since we allocated the list. That should
924 * never happen, but we'll handle it properly just in case it does.
926 if (dlp
->num_used
< dlp
->num_alloc
)
927 dlp
->objs
[dlp
->num_used
++] = obj
;
932 * Hash function for symbol table lookup. Don't even think about changing
933 * this. It is specified by the System V ABI.
936 elf_hash(const char *name
)
938 const unsigned char *p
= (const unsigned char *) name
;
944 if ((g
= h
& 0xf0000000) != 0)
952 * Find the library with the given name, and return its full pathname.
953 * The returned string is dynamically allocated. Generates an error
954 * message and returns NULL if the library cannot be found.
956 * If the second argument is non-NULL, then it refers to an already-
957 * loaded shared object, whose library search path will be searched.
959 * The search order is:
961 * rpath in the referencing file
966 find_library(const char *name
, const Obj_Entry
*refobj
)
970 if (strchr(name
, '/') != NULL
) { /* Hard coded pathname */
971 if (name
[0] != '/' && !trust
) {
972 _rtld_error("Absolute pathname required for shared object \"%s\"",
976 return xstrdup(name
);
979 dbg(" Searching for \"%s\"", name
);
981 if ((pathname
= search_library_path(name
, ld_library_path
)) != NULL
||
983 (pathname
= search_library_path(name
, refobj
->rpath
)) != NULL
) ||
984 (pathname
= search_library_path(name
, gethints())) != NULL
||
985 (pathname
= search_library_path(name
, STANDARD_LIBRARY_PATH
)) != NULL
)
988 if(refobj
!= NULL
&& refobj
->path
!= NULL
) {
989 _rtld_error("Shared object \"%s\" not found, required by \"%s\"",
990 name
, basename(refobj
->path
));
992 _rtld_error("Shared object \"%s\" not found", name
);
998 * Given a symbol number in a referencing object, find the corresponding
999 * definition of the symbol. Returns a pointer to the symbol, or NULL if
1000 * no definition was found. Returns a pointer to the Obj_Entry of the
1001 * defining object via the reference parameter DEFOBJ_OUT.
1004 find_symdef(unsigned long symnum
, const Obj_Entry
*refobj
,
1005 const Obj_Entry
**defobj_out
, bool in_plt
, SymCache
*cache
)
1009 const Obj_Entry
*defobj
;
1014 * If we have already found this symbol, get the information from
1017 if (symnum
>= refobj
->nchains
)
1018 return NULL
; /* Bad object */
1019 if (cache
!= NULL
&& cache
[symnum
].sym
!= NULL
) {
1020 *defobj_out
= cache
[symnum
].obj
;
1021 return cache
[symnum
].sym
;
1024 ref
= refobj
->symtab
+ symnum
;
1025 name
= refobj
->strtab
+ ref
->st_name
;
1029 * We don't have to do a full scale lookup if the symbol is local.
1030 * We know it will bind to the instance in this load module; to
1031 * which we already have a pointer (ie ref). By not doing a lookup,
1032 * we not only improve performance, but it also avoids unresolvable
1033 * symbols when local symbols are not in the hash table.
1035 * This might occur for TLS module relocations, which simply use
1038 if (ELF_ST_BIND(ref
->st_info
) != STB_LOCAL
) {
1039 if (ELF_ST_TYPE(ref
->st_info
) == STT_SECTION
) {
1040 _rtld_error("%s: Bogus symbol table entry %lu", refobj
->path
,
1043 hash
= elf_hash(name
);
1044 def
= symlook_default(name
, hash
, refobj
, &defobj
, in_plt
);
1051 * If we found no definition and the reference is weak, treat the
1052 * symbol as having the value zero.
1054 if (def
== NULL
&& ELF_ST_BIND(ref
->st_info
) == STB_WEAK
) {
1060 *defobj_out
= defobj
;
1061 /* Record the information in the cache to avoid subsequent lookups. */
1062 if (cache
!= NULL
) {
1063 cache
[symnum
].sym
= def
;
1064 cache
[symnum
].obj
= defobj
;
1067 _rtld_error("%s: Undefined symbol \"%s\"", refobj
->path
, name
);
1072 * Return the search path from the ldconfig hints file, reading it if
1073 * necessary. Returns NULL if there are problems with the hints file,
1074 * or if the search path there is empty.
1081 if (hints
== NULL
) {
1083 struct elfhints_hdr hdr
;
1086 /* Keep from trying again in case the hints file is bad. */
1089 if ((fd
= open(_PATH_ELF_HINTS
, O_RDONLY
)) == -1)
1091 if (read(fd
, &hdr
, sizeof hdr
) != sizeof hdr
||
1092 hdr
.magic
!= ELFHINTS_MAGIC
||
1097 p
= xmalloc(hdr
.dirlistlen
+ 1);
1098 if (lseek(fd
, hdr
.strtab
+ hdr
.dirlist
, SEEK_SET
) == -1 ||
1099 read(fd
, p
, hdr
.dirlistlen
+ 1) != hdr
.dirlistlen
+ 1) {
1107 return hints
[0] != '\0' ? hints
: NULL
;
1111 init_dag(Obj_Entry
*root
)
1115 donelist_init(&donelist
);
1116 init_dag1(root
, root
, &donelist
);
1120 init_dag1(Obj_Entry
*root
, Obj_Entry
*obj
, DoneList
*dlp
)
1122 const Needed_Entry
*needed
;
1124 if (donelist_check(dlp
, obj
))
1126 objlist_push_tail(&obj
->dldags
, root
);
1127 objlist_push_tail(&root
->dagmembers
, obj
);
1128 for (needed
= obj
->needed
; needed
!= NULL
; needed
= needed
->next
)
1129 if (needed
->obj
!= NULL
)
1130 init_dag1(root
, needed
->obj
, dlp
);
1134 * Initialize the dynamic linker. The argument is the address at which
1135 * the dynamic linker has been mapped into memory. The primary task of
1136 * this function is to relocate the dynamic linker.
1139 init_rtld(caddr_t mapbase
)
1141 Obj_Entry objtmp
; /* Temporary rtld object */
1144 * Conjure up an Obj_Entry structure for the dynamic linker.
1146 * The "path" member can't be initialized yet because string constatns
1147 * cannot yet be acessed. Below we will set it correctly.
1149 memset(&objtmp
, 0, sizeof(objtmp
));
1152 objtmp
.mapbase
= mapbase
;
1154 objtmp
.relocbase
= mapbase
;
1156 if (&_DYNAMIC
!= 0) {
1157 objtmp
.dynamic
= rtld_dynamic(&objtmp
);
1158 digest_dynamic(&objtmp
, 1);
1159 assert(objtmp
.needed
== NULL
);
1160 assert(!objtmp
.textrel
);
1163 * Temporarily put the dynamic linker entry into the object list, so
1164 * that symbols can be found.
1167 relocate_objects(&objtmp
, true, &objtmp
);
1170 /* Initialize the object list. */
1171 obj_tail
= &obj_list
;
1173 /* Now that non-local variables can be accesses, copy out obj_rtld. */
1174 memcpy(&obj_rtld
, &objtmp
, sizeof(obj_rtld
));
1176 /* Replace the path with a dynamically allocated copy. */
1177 obj_rtld
.path
= xstrdup(PATH_RTLD
);
1179 r_debug
.r_brk
= r_debug_state
;
1180 r_debug
.r_state
= RT_CONSISTENT
;
1184 * Add the init functions from a needed object list (and its recursive
1185 * needed objects) to "list". This is not used directly; it is a helper
1186 * function for initlist_add_objects(). The write lock must be held
1187 * when this function is called.
1190 initlist_add_neededs(Needed_Entry
*needed
, Objlist
*list
)
1192 /* Recursively process the successor needed objects. */
1193 if (needed
->next
!= NULL
)
1194 initlist_add_neededs(needed
->next
, list
);
1196 /* Process the current needed object. */
1197 if (needed
->obj
!= NULL
)
1198 initlist_add_objects(needed
->obj
, &needed
->obj
->next
, list
);
1202 * Scan all of the DAGs rooted in the range of objects from "obj" to
1203 * "tail" and add their init functions to "list". This recurses over
1204 * the DAGs and ensure the proper init ordering such that each object's
1205 * needed libraries are initialized before the object itself. At the
1206 * same time, this function adds the objects to the global finalization
1207 * list "list_fini" in the opposite order. The write lock must be
1208 * held when this function is called.
1211 initlist_add_objects(Obj_Entry
*obj
, Obj_Entry
**tail
, Objlist
*list
)
1215 obj
->init_done
= true;
1217 /* Recursively process the successor objects. */
1218 if (&obj
->next
!= tail
)
1219 initlist_add_objects(obj
->next
, tail
, list
);
1221 /* Recursively process the needed objects. */
1222 if (obj
->needed
!= NULL
)
1223 initlist_add_neededs(obj
->needed
, list
);
1225 /* Add the object to the init list. */
1226 if (obj
->init
!= NULL
)
1227 objlist_push_tail(list
, obj
);
1229 /* Add the object to the global fini list in the reverse order. */
1230 if (obj
->fini
!= NULL
)
1231 objlist_push_head(&list_fini
, obj
);
1235 is_exported(const Elf_Sym
*def
)
1238 const func_ptr_type
*p
;
1240 value
= (Elf_Addr
)(obj_rtld
.relocbase
+ def
->st_value
);
1241 for (p
= exports
; *p
!= NULL
; p
++) {
1242 if ((Elf_Addr
)(*p
) == value
)
1249 * Given a shared object, traverse its list of needed objects, and load
1250 * each of them. Returns 0 on success. Generates an error message and
1251 * returns -1 on failure.
1254 load_needed_objects(Obj_Entry
*first
)
1258 for (obj
= first
; obj
!= NULL
; obj
= obj
->next
) {
1259 Needed_Entry
*needed
;
1261 for (needed
= obj
->needed
; needed
!= NULL
; needed
= needed
->next
) {
1262 const char *name
= obj
->strtab
+ needed
->name
;
1263 char *path
= find_library(name
, obj
);
1266 if (path
== NULL
&& !ld_tracing
)
1270 needed
->obj
= load_object(path
);
1271 if (needed
->obj
== NULL
&& !ld_tracing
)
1272 return -1; /* XXX - cleanup */
1280 #define RTLD_FUNCTRACE "_rtld_functrace"
1283 load_preload_objects(void)
1285 char *p
= ld_preload
;
1286 static const char delim
[] = " \t:;";
1291 p
+= strspn(p
, delim
);
1292 while (*p
!= '\0') {
1293 size_t len
= strcspn(p
, delim
);
1301 if ((path
= find_library(p
, NULL
)) == NULL
)
1303 obj
= load_object(path
);
1305 return -1; /* XXX - cleanup */
1308 p
+= strspn(p
, delim
);
1310 /* Check for the magic tracing function */
1311 sym
= symlook_obj(RTLD_FUNCTRACE
, elf_hash(RTLD_FUNCTRACE
), obj
, true);
1313 rtld_functrace
= (void *)(obj
->relocbase
+ sym
->st_value
);
1314 rtld_functrace_obj
= obj
;
1321 * Returns a pointer to the Obj_Entry for the object with the given path.
1322 * Returns NULL if no matching object was found.
1325 find_object(const char *path
)
1329 for (obj
= obj_list
->next
; obj
!= NULL
; obj
= obj
->next
) {
1330 if (strcmp(obj
->path
, path
) == 0)
1337 * Returns a pointer to the Obj_Entry for the object matching device and
1338 * inode of the given path. If no matching object was found, the descriptor
1339 * is returned in fd.
1340 * Returns with obj == NULL && fd == -1 on error.
1343 find_object2(const char *path
, int *fd
, struct stat
*sb
)
1347 if ((*fd
= open(path
, O_RDONLY
)) == -1) {
1348 _rtld_error("Cannot open \"%s\"", path
);
1352 if (fstat(*fd
, sb
) == -1) {
1353 _rtld_error("Cannot fstat \"%s\"", path
);
1359 for (obj
= obj_list
->next
; obj
!= NULL
; obj
= obj
->next
) {
1360 if (obj
->ino
== sb
->st_ino
&& obj
->dev
== sb
->st_dev
) {
1370 * Load a shared object into memory, if it is not already loaded. The
1371 * argument must be a string allocated on the heap. This function assumes
1372 * responsibility for freeing it when necessary.
1374 * Returns a pointer to the Obj_Entry for the object. Returns NULL
1378 load_object(char *path
)
1384 obj
= find_object(path
);
1391 obj
= find_object2(path
, &fd
, &sb
);
1396 } else if (fd
== -1) {
1401 dbg("loading \"%s\"", path
);
1402 obj
= map_object(fd
, path
, &sb
);
1410 digest_dynamic(obj
, 0);
1413 obj_tail
= &obj
->next
;
1415 linkmap_add(obj
); /* for GDB & dlinfo() */
1417 dbg(" %p .. %p: %s", obj
->mapbase
, obj
->mapbase
+ obj
->mapsize
- 1,
1420 dbg(" WARNING: %s has impure text", obj
->path
);
1427 * Check for locking violations and die if one is found.
1434 rcount
= lockinfo
.rcount
;
1435 wcount
= lockinfo
.wcount
;
1436 assert(rcount
>= 0);
1437 assert(wcount
>= 0);
1438 if (wcount
> 1 || (wcount
!= 0 && rcount
!= 0)) {
1439 _rtld_error("Application locking error: %d readers and %d writers"
1440 " in dynamic linker. See DLLOCKINIT(3) in manual pages.",
1447 obj_from_addr(const void *addr
)
1451 for (obj
= obj_list
; obj
!= NULL
; obj
= obj
->next
) {
1452 if (addr
< (void *) obj
->mapbase
)
1454 if (addr
< (void *) (obj
->mapbase
+ obj
->mapsize
))
1461 * Call the finalization functions for each of the objects in "list"
1462 * which are unreferenced. All of the objects are expected to have
1463 * non-NULL fini functions.
1466 objlist_call_fini(Objlist
*list
)
1472 * Preserve the current error message since a fini function might
1473 * call into the dynamic linker and overwrite it.
1475 saved_msg
= errmsg_save();
1476 STAILQ_FOREACH(elm
, list
, link
) {
1477 if (elm
->obj
->refcount
== 0) {
1478 dbg("calling fini function for %s", elm
->obj
->path
);
1479 (*elm
->obj
->fini
)();
1482 errmsg_restore(saved_msg
);
1486 * Call the initialization functions for each of the objects in
1487 * "list". All of the objects are expected to have non-NULL init
1491 objlist_call_init(Objlist
*list
)
1497 * Preserve the current error message since an init function might
1498 * call into the dynamic linker and overwrite it.
1500 saved_msg
= errmsg_save();
1501 STAILQ_FOREACH(elm
, list
, link
) {
1502 dbg("calling init function for %s", elm
->obj
->path
);
1503 (*elm
->obj
->init
)();
1505 errmsg_restore(saved_msg
);
1509 objlist_clear(Objlist
*list
)
1513 while (!STAILQ_EMPTY(list
)) {
1514 elm
= STAILQ_FIRST(list
);
1515 STAILQ_REMOVE_HEAD(list
, link
);
1520 static Objlist_Entry
*
1521 objlist_find(Objlist
*list
, const Obj_Entry
*obj
)
1525 STAILQ_FOREACH(elm
, list
, link
)
1526 if (elm
->obj
== obj
)
1532 objlist_init(Objlist
*list
)
1538 objlist_push_head(Objlist
*list
, Obj_Entry
*obj
)
1542 elm
= NEW(Objlist_Entry
);
1544 STAILQ_INSERT_HEAD(list
, elm
, link
);
1548 objlist_push_tail(Objlist
*list
, Obj_Entry
*obj
)
1552 elm
= NEW(Objlist_Entry
);
1554 STAILQ_INSERT_TAIL(list
, elm
, link
);
1558 objlist_remove(Objlist
*list
, Obj_Entry
*obj
)
1562 if ((elm
= objlist_find(list
, obj
)) != NULL
) {
1563 STAILQ_REMOVE(list
, elm
, Struct_Objlist_Entry
, link
);
1569 * Remove all of the unreferenced objects from "list".
1572 objlist_remove_unref(Objlist
*list
)
1577 STAILQ_INIT(&newlist
);
1578 while (!STAILQ_EMPTY(list
)) {
1579 elm
= STAILQ_FIRST(list
);
1580 STAILQ_REMOVE_HEAD(list
, link
);
1581 if (elm
->obj
->refcount
== 0)
1584 STAILQ_INSERT_TAIL(&newlist
, elm
, link
);
1590 * Relocate newly-loaded shared objects. The argument is a pointer to
1591 * the Obj_Entry for the first such object. All objects from the first
1592 * to the end of the list of objects are relocated. Returns 0 on success,
1596 relocate_objects(Obj_Entry
*first
, bool bind_now
, Obj_Entry
*rtldobj
)
1600 for (obj
= first
; obj
!= NULL
; obj
= obj
->next
) {
1602 dbg("relocating \"%s\"", obj
->path
);
1603 if (obj
->nbuckets
== 0 || obj
->nchains
== 0 || obj
->buckets
== NULL
||
1604 obj
->symtab
== NULL
|| obj
->strtab
== NULL
) {
1605 _rtld_error("%s: Shared object has no run-time symbol table",
1611 /* There are relocations to the write-protected text segment. */
1612 if (mprotect(obj
->mapbase
, obj
->textsize
,
1613 PROT_READ
|PROT_WRITE
|PROT_EXEC
) == -1) {
1614 _rtld_error("%s: Cannot write-enable text segment: %s",
1615 obj
->path
, strerror(errno
));
1620 /* Process the non-PLT relocations. */
1621 if (reloc_non_plt(obj
, rtldobj
))
1625 * Reprotect the text segment. Make sure it is included in the
1626 * core dump since we modified it. This unfortunately causes the
1627 * entire text segment to core-out but we don't have much of a
1628 * choice. We could try to only reenable core dumps on pages
1629 * in which relocations occured but that is likely most of the text
1630 * pages anyway, and even that would not work because the rest of
1631 * the text pages would wind up as a read-only OBJT_DEFAULT object
1632 * (created due to our modifications) backed by the original OBJT_VNODE
1633 * object, and the ELF coredump code is currently only able to dump
1634 * vnode records for pure vnode-backed mappings, not vnode backings
1635 * to memory objects.
1638 madvise(obj
->mapbase
, obj
->textsize
, MADV_CORE
);
1639 if (mprotect(obj
->mapbase
, obj
->textsize
,
1640 PROT_READ
|PROT_EXEC
) == -1) {
1641 _rtld_error("%s: Cannot write-protect text segment: %s",
1642 obj
->path
, strerror(errno
));
1647 /* Process the PLT relocations. */
1648 if (reloc_plt(obj
) == -1)
1650 /* Relocate the jump slots if we are doing immediate binding. */
1651 if (obj
->bind_now
|| bind_now
)
1652 if (reloc_jmpslots(obj
) == -1)
1657 * Set up the magic number and version in the Obj_Entry. These
1658 * were checked in the crt1.o from the original ElfKit, so we
1659 * set them for backward compatibility.
1661 obj
->magic
= RTLD_MAGIC
;
1662 obj
->version
= RTLD_VERSION
;
1664 /* Set the special PLT or GOT entries. */
1672 * Cleanup procedure. It will be called (by the atexit mechanism) just
1673 * before the process exits.
1681 /* Clear all the reference counts so the fini functions will be called. */
1682 for (obj
= obj_list
; obj
!= NULL
; obj
= obj
->next
)
1684 objlist_call_fini(&list_fini
);
1685 /* No need to remove the items from the list, since we are exiting. */
1689 path_enumerate(const char *path
, path_enum_proc callback
, void *arg
)
1694 path
+= strspn(path
, ":;");
1695 while (*path
!= '\0') {
1699 len
= strcspn(path
, ":;");
1700 res
= callback(path
, len
, arg
);
1706 path
+= strspn(path
, ":;");
1712 struct try_library_args
{
1720 try_library_path(const char *dir
, size_t dirlen
, void *param
)
1722 struct try_library_args
*arg
;
1725 if (*dir
== '/' || trust
) {
1728 if (dirlen
+ 1 + arg
->namelen
+ 1 > arg
->buflen
)
1731 pathname
= arg
->buffer
;
1732 strncpy(pathname
, dir
, dirlen
);
1733 pathname
[dirlen
] = '/';
1734 strcpy(pathname
+ dirlen
+ 1, arg
->name
);
1736 dbg(" Trying \"%s\"", pathname
);
1737 if (access(pathname
, F_OK
) == 0) { /* We found it */
1738 pathname
= xmalloc(dirlen
+ 1 + arg
->namelen
+ 1);
1739 strcpy(pathname
, arg
->buffer
);
1747 search_library_path(const char *name
, const char *path
)
1750 struct try_library_args arg
;
1756 arg
.namelen
= strlen(name
);
1757 arg
.buffer
= xmalloc(PATH_MAX
);
1758 arg
.buflen
= PATH_MAX
;
1760 p
= path_enumerate(path
, try_library_path
, &arg
);
1768 dlclose(void *handle
)
1773 root
= dlcheck(handle
);
1779 /* Unreference the object and its dependencies. */
1780 root
->dl_refcount
--;
1783 if (root
->refcount
== 0) {
1785 * The object is no longer referenced, so we must unload it.
1786 * First, call the fini functions with no locks held.
1789 objlist_call_fini(&list_fini
);
1791 objlist_remove_unref(&list_fini
);
1793 /* Finish cleaning up the newly-unreferenced objects. */
1794 GDB_STATE(RT_DELETE
,&root
->linkmap
);
1795 unload_object(root
);
1796 GDB_STATE(RT_CONSISTENT
,NULL
);
1805 char *msg
= error_message
;
1806 error_message
= NULL
;
1811 dlopen(const char *name
, int mode
)
1813 Obj_Entry
**old_obj_tail
;
1818 ld_tracing
= (mode
& RTLD_TRACE
) == 0 ? NULL
: "1";
1819 if (ld_tracing
!= NULL
)
1820 environ
= (char **)*get_program_var_addr("environ");
1822 objlist_init(&initlist
);
1825 GDB_STATE(RT_ADD
,NULL
);
1827 old_obj_tail
= obj_tail
;
1833 char *path
= find_library(name
, obj_main
);
1835 obj
= load_object(path
);
1840 if ((mode
& RTLD_GLOBAL
) && objlist_find(&list_global
, obj
) == NULL
)
1841 objlist_push_tail(&list_global
, obj
);
1842 mode
&= RTLD_MODEMASK
;
1843 if (*old_obj_tail
!= NULL
) { /* We loaded something new. */
1844 assert(*old_obj_tail
== obj
);
1846 result
= load_needed_objects(obj
);
1847 if (result
!= -1 && ld_tracing
)
1851 (init_dag(obj
), relocate_objects(obj
, mode
== RTLD_NOW
,
1852 &obj_rtld
)) == -1) {
1855 if (obj
->refcount
== 0)
1859 /* Make list of init functions to call. */
1860 initlist_add_objects(obj
, &obj
->next
, &initlist
);
1862 } else if (ld_tracing
)
1866 GDB_STATE(RT_CONSISTENT
,obj
? &obj
->linkmap
: NULL
);
1868 /* Call the init functions with no locks held. */
1870 objlist_call_init(&initlist
);
1872 objlist_clear(&initlist
);
1876 trace_loaded_objects(obj
);
1882 dlsym(void *handle
, const char *name
)
1884 const Obj_Entry
*obj
;
1887 const Obj_Entry
*defobj
;
1889 hash
= elf_hash(name
);
1894 if (handle
== NULL
|| handle
== RTLD_NEXT
||
1895 handle
== RTLD_DEFAULT
|| handle
== RTLD_SELF
) {
1898 retaddr
= __builtin_return_address(0); /* __GNUC__ only */
1899 if ((obj
= obj_from_addr(retaddr
)) == NULL
) {
1900 _rtld_error("Cannot determine caller's shared object");
1904 if (handle
== NULL
) { /* Just the caller's shared object. */
1905 def
= symlook_obj(name
, hash
, obj
, true);
1907 } else if (handle
== RTLD_NEXT
|| /* Objects after caller's */
1908 handle
== RTLD_SELF
) { /* ... caller included */
1909 if (handle
== RTLD_NEXT
)
1911 for (; obj
!= NULL
; obj
= obj
->next
) {
1912 if ((def
= symlook_obj(name
, hash
, obj
, true)) != NULL
) {
1918 assert(handle
== RTLD_DEFAULT
);
1919 def
= symlook_default(name
, hash
, obj
, &defobj
, true);
1924 if ((obj
= dlcheck(handle
)) == NULL
) {
1929 donelist_init(&donelist
);
1930 if (obj
->mainprog
) {
1931 /* Search main program and all libraries loaded by it. */
1932 def
= symlook_list(name
, hash
, &list_main
, &defobj
, true,
1937 /* Search the given object and its needed objects. */
1939 fake
.obj
= (Obj_Entry
*)obj
;
1941 def
= symlook_needed(name
, hash
, &fake
, &defobj
, true,
1948 return defobj
->relocbase
+ def
->st_value
;
1951 _rtld_error("Undefined symbol \"%s\"", name
);
1957 dladdr(const void *addr
, Dl_info
*info
)
1959 const Obj_Entry
*obj
;
1962 unsigned long symoffset
;
1965 obj
= obj_from_addr(addr
);
1967 _rtld_error("No shared object contains address");
1971 info
->dli_fname
= obj
->path
;
1972 info
->dli_fbase
= obj
->mapbase
;
1973 info
->dli_saddr
= NULL
;
1974 info
->dli_sname
= NULL
;
1977 * Walk the symbol list looking for the symbol whose address is
1978 * closest to the address sent in.
1980 for (symoffset
= 0; symoffset
< obj
->nchains
; symoffset
++) {
1981 def
= obj
->symtab
+ symoffset
;
1984 * For skip the symbol if st_shndx is either SHN_UNDEF or
1987 if (def
->st_shndx
== SHN_UNDEF
|| def
->st_shndx
== SHN_COMMON
)
1991 * If the symbol is greater than the specified address, or if it
1992 * is further away from addr than the current nearest symbol,
1995 symbol_addr
= obj
->relocbase
+ def
->st_value
;
1996 if (symbol_addr
> addr
|| symbol_addr
< info
->dli_saddr
)
1999 /* Update our idea of the nearest symbol. */
2000 info
->dli_sname
= obj
->strtab
+ def
->st_name
;
2001 info
->dli_saddr
= symbol_addr
;
2004 if (info
->dli_saddr
== addr
)
2012 dlinfo(void *handle
, int request
, void *p
)
2014 const Obj_Entry
*obj
;
2019 if (handle
== NULL
|| handle
== RTLD_SELF
) {
2022 retaddr
= __builtin_return_address(0); /* __GNUC__ only */
2023 if ((obj
= obj_from_addr(retaddr
)) == NULL
)
2024 _rtld_error("Cannot determine caller's shared object");
2026 obj
= dlcheck(handle
);
2035 case RTLD_DI_LINKMAP
:
2036 *((struct link_map
const **)p
) = &obj
->linkmap
;
2038 case RTLD_DI_ORIGIN
:
2039 error
= rtld_dirname(obj
->path
, p
);
2042 case RTLD_DI_SERINFOSIZE
:
2043 case RTLD_DI_SERINFO
:
2044 error
= do_search_info(obj
, request
, (struct dl_serinfo
*)p
);
2048 _rtld_error("Invalid request %d passed to dlinfo()", request
);
2057 struct fill_search_info_args
{
2060 Dl_serinfo
*serinfo
;
2061 Dl_serpath
*serpath
;
2066 fill_search_info(const char *dir
, size_t dirlen
, void *param
)
2068 struct fill_search_info_args
*arg
;
2072 if (arg
->request
== RTLD_DI_SERINFOSIZE
) {
2073 arg
->serinfo
->dls_cnt
++;
2074 arg
->serinfo
->dls_size
+= dirlen
+ 1;
2076 struct dl_serpath
*s_entry
;
2078 s_entry
= arg
->serpath
;
2079 s_entry
->dls_name
= arg
->strspace
;
2080 s_entry
->dls_flags
= arg
->flags
;
2082 strncpy(arg
->strspace
, dir
, dirlen
);
2083 arg
->strspace
[dirlen
] = '\0';
2085 arg
->strspace
+= dirlen
+ 1;
2093 do_search_info(const Obj_Entry
*obj
, int request
, struct dl_serinfo
*info
)
2095 struct dl_serinfo _info
;
2096 struct fill_search_info_args args
;
2098 args
.request
= RTLD_DI_SERINFOSIZE
;
2099 args
.serinfo
= &_info
;
2101 _info
.dls_size
= __offsetof(struct dl_serinfo
, dls_serpath
);
2104 path_enumerate(ld_library_path
, fill_search_info
, &args
);
2105 path_enumerate(obj
->rpath
, fill_search_info
, &args
);
2106 path_enumerate(gethints(), fill_search_info
, &args
);
2107 path_enumerate(STANDARD_LIBRARY_PATH
, fill_search_info
, &args
);
2110 if (request
== RTLD_DI_SERINFOSIZE
) {
2111 info
->dls_size
= _info
.dls_size
;
2112 info
->dls_cnt
= _info
.dls_cnt
;
2116 if (info
->dls_cnt
!= _info
.dls_cnt
|| info
->dls_size
!= _info
.dls_size
) {
2117 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
2121 args
.request
= RTLD_DI_SERINFO
;
2122 args
.serinfo
= info
;
2123 args
.serpath
= &info
->dls_serpath
[0];
2124 args
.strspace
= (char *)&info
->dls_serpath
[_info
.dls_cnt
];
2126 args
.flags
= LA_SER_LIBPATH
;
2127 if (path_enumerate(ld_library_path
, fill_search_info
, &args
) != NULL
)
2130 args
.flags
= LA_SER_RUNPATH
;
2131 if (path_enumerate(obj
->rpath
, fill_search_info
, &args
) != NULL
)
2134 args
.flags
= LA_SER_CONFIG
;
2135 if (path_enumerate(gethints(), fill_search_info
, &args
) != NULL
)
2138 args
.flags
= LA_SER_DEFAULT
;
2139 if (path_enumerate(STANDARD_LIBRARY_PATH
, fill_search_info
, &args
) != NULL
)
2145 rtld_dirname(const char *path
, char *bname
)
2149 /* Empty or NULL string gets treated as "." */
2150 if (path
== NULL
|| *path
== '\0') {
2156 /* Strip trailing slashes */
2157 endp
= path
+ strlen(path
) - 1;
2158 while (endp
> path
&& *endp
== '/')
2161 /* Find the start of the dir */
2162 while (endp
> path
&& *endp
!= '/')
2165 /* Either the dir is "/" or there are no slashes */
2167 bname
[0] = *endp
== '/' ? '/' : '.';
2173 } while (endp
> path
&& *endp
== '/');
2176 if (endp
- path
+ 2 > PATH_MAX
)
2178 _rtld_error("Filename is too long: %s", path
);
2182 strncpy(bname
, path
, endp
- path
+ 1);
2183 bname
[endp
- path
+ 1] = '\0';
2188 linkmap_add(Obj_Entry
*obj
)
2190 struct link_map
*l
= &obj
->linkmap
;
2191 struct link_map
*prev
;
2193 obj
->linkmap
.l_name
= obj
->path
;
2194 obj
->linkmap
.l_addr
= obj
->mapbase
;
2195 obj
->linkmap
.l_ld
= obj
->dynamic
;
2197 /* GDB needs load offset on MIPS to use the symbols */
2198 obj
->linkmap
.l_offs
= obj
->relocbase
;
2201 if (r_debug
.r_map
== NULL
) {
2207 * Scan to the end of the list, but not past the entry for the
2208 * dynamic linker, which we want to keep at the very end.
2210 for (prev
= r_debug
.r_map
;
2211 prev
->l_next
!= NULL
&& prev
->l_next
!= &obj_rtld
.linkmap
;
2212 prev
= prev
->l_next
)
2215 /* Link in the new entry. */
2217 l
->l_next
= prev
->l_next
;
2218 if (l
->l_next
!= NULL
)
2219 l
->l_next
->l_prev
= l
;
2224 linkmap_delete(Obj_Entry
*obj
)
2226 struct link_map
*l
= &obj
->linkmap
;
2228 if (l
->l_prev
== NULL
) {
2229 if ((r_debug
.r_map
= l
->l_next
) != NULL
)
2230 l
->l_next
->l_prev
= NULL
;
2234 if ((l
->l_prev
->l_next
= l
->l_next
) != NULL
)
2235 l
->l_next
->l_prev
= l
->l_prev
;
2239 * Function for the debugger to set a breakpoint on to gain control.
2241 * The two parameters allow the debugger to easily find and determine
2242 * what the runtime loader is doing and to whom it is doing it.
2244 * When the loadhook trap is hit (r_debug_state, set at program
2245 * initialization), the arguments can be found on the stack:
2247 * +8 struct link_map *m
2248 * +4 struct r_debug *rd
2252 r_debug_state(struct r_debug
* rd
, struct link_map
*m
)
2257 * Get address of the pointer variable in the main program.
2259 static const void **
2260 get_program_var_addr(const char *name
)
2262 const Obj_Entry
*obj
;
2265 hash
= elf_hash(name
);
2266 for (obj
= obj_main
; obj
!= NULL
; obj
= obj
->next
) {
2269 if ((def
= symlook_obj(name
, hash
, obj
, false)) != NULL
) {
2272 addr
= (const void **)(obj
->relocbase
+ def
->st_value
);
2280 * Set a pointer variable in the main program to the given value. This
2281 * is used to set key variables such as "environ" before any of the
2282 * init functions are called.
2285 set_program_var(const char *name
, const void *value
)
2289 if ((addr
= get_program_var_addr(name
)) != NULL
) {
2290 dbg("\"%s\": *%p <-- %p", name
, addr
, value
);
2296 * This is a special version of getenv which is far more efficient
2297 * at finding LD_ environment vars.
2301 _getenv_ld(const char *id
)
2305 int idlen
= strlen(id
);
2307 if (ld_index
== LD_ARY_CACHE
)
2309 if (ld_index
== 0) {
2310 for (i
= j
= 0; (envp
= environ
[i
]) != NULL
&& j
< LD_ARY_CACHE
; ++i
) {
2311 if (envp
[0] == 'L' && envp
[1] == 'D' && envp
[2] == '_')
2318 for (i
= ld_index
- 1; i
>= 0; --i
) {
2319 if (strncmp(ld_ary
[i
], id
, idlen
) == 0 && ld_ary
[i
][idlen
] == '=')
2320 return(ld_ary
[i
] + idlen
+ 1);
2326 * Given a symbol name in a referencing object, find the corresponding
2327 * definition of the symbol. Returns a pointer to the symbol, or NULL if
2328 * no definition was found. Returns a pointer to the Obj_Entry of the
2329 * defining object via the reference parameter DEFOBJ_OUT.
2331 static const Elf_Sym
*
2332 symlook_default(const char *name
, unsigned long hash
,
2333 const Obj_Entry
*refobj
, const Obj_Entry
**defobj_out
, bool in_plt
)
2337 const Elf_Sym
*symp
;
2338 const Obj_Entry
*obj
;
2339 const Obj_Entry
*defobj
;
2340 const Objlist_Entry
*elm
;
2343 donelist_init(&donelist
);
2345 /* Look first in the referencing object if linked symbolically. */
2346 if (refobj
->symbolic
&& !donelist_check(&donelist
, refobj
)) {
2347 symp
= symlook_obj(name
, hash
, refobj
, in_plt
);
2354 /* Search all objects loaded at program start up. */
2355 if (def
== NULL
|| ELF_ST_BIND(def
->st_info
) == STB_WEAK
) {
2356 symp
= symlook_list(name
, hash
, &list_main
, &obj
, in_plt
, &donelist
);
2358 (def
== NULL
|| ELF_ST_BIND(symp
->st_info
) != STB_WEAK
)) {
2364 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
2365 STAILQ_FOREACH(elm
, &list_global
, link
) {
2366 if (def
!= NULL
&& ELF_ST_BIND(def
->st_info
) != STB_WEAK
)
2368 symp
= symlook_list(name
, hash
, &elm
->obj
->dagmembers
, &obj
, in_plt
,
2371 (def
== NULL
|| ELF_ST_BIND(symp
->st_info
) != STB_WEAK
)) {
2377 /* Search all dlopened DAGs containing the referencing object. */
2378 STAILQ_FOREACH(elm
, &refobj
->dldags
, link
) {
2379 if (def
!= NULL
&& ELF_ST_BIND(def
->st_info
) != STB_WEAK
)
2381 symp
= symlook_list(name
, hash
, &elm
->obj
->dagmembers
, &obj
, in_plt
,
2384 (def
== NULL
|| ELF_ST_BIND(symp
->st_info
) != STB_WEAK
)) {
2391 * Search the dynamic linker itself, and possibly resolve the
2392 * symbol from there. This is how the application links to
2393 * dynamic linker services such as dlopen. Only the values listed
2394 * in the "exports" array can be resolved from the dynamic linker.
2396 if (def
== NULL
|| ELF_ST_BIND(def
->st_info
) == STB_WEAK
) {
2397 symp
= symlook_obj(name
, hash
, &obj_rtld
, in_plt
);
2398 if (symp
!= NULL
&& is_exported(symp
)) {
2405 *defobj_out
= defobj
;
2409 static const Elf_Sym
*
2410 symlook_list(const char *name
, unsigned long hash
, const Objlist
*objlist
,
2411 const Obj_Entry
**defobj_out
, bool in_plt
, DoneList
*dlp
)
2413 const Elf_Sym
*symp
;
2415 const Obj_Entry
*defobj
;
2416 const Objlist_Entry
*elm
;
2420 STAILQ_FOREACH(elm
, objlist
, link
) {
2421 if (donelist_check(dlp
, elm
->obj
))
2423 if ((symp
= symlook_obj(name
, hash
, elm
->obj
, in_plt
)) != NULL
) {
2424 if (def
== NULL
|| ELF_ST_BIND(symp
->st_info
) != STB_WEAK
) {
2427 if (ELF_ST_BIND(def
->st_info
) != STB_WEAK
)
2433 *defobj_out
= defobj
;
2438 * Search the symbol table of a shared object and all objects needed
2439 * by it for a symbol of the given name. Search order is
2440 * breadth-first. Returns a pointer to the symbol, or NULL if no
2441 * definition was found.
2443 static const Elf_Sym
*
2444 symlook_needed(const char *name
, unsigned long hash
, const Needed_Entry
*needed
,
2445 const Obj_Entry
**defobj_out
, bool in_plt
, DoneList
*dlp
)
2447 const Elf_Sym
*def
, *def_w
;
2448 const Needed_Entry
*n
;
2449 const Obj_Entry
*obj
, *defobj
, *defobj1
;
2453 for (n
= needed
; n
!= NULL
; n
= n
->next
) {
2454 if ((obj
= n
->obj
) == NULL
||
2455 donelist_check(dlp
, obj
) ||
2456 (def
= symlook_obj(name
, hash
, obj
, in_plt
)) == NULL
)
2459 if (ELF_ST_BIND(def
->st_info
) != STB_WEAK
) {
2460 *defobj_out
= defobj
;
2465 * There we come when either symbol definition is not found in
2466 * directly needed objects, or found symbol is weak.
2468 for (n
= needed
; n
!= NULL
; n
= n
->next
) {
2469 if ((obj
= n
->obj
) == NULL
)
2471 def_w
= symlook_needed(name
, hash
, obj
->needed
, &defobj1
,
2475 if (def
== NULL
|| ELF_ST_BIND(def_w
->st_info
) != STB_WEAK
) {
2479 if (ELF_ST_BIND(def_w
->st_info
) != STB_WEAK
)
2483 *defobj_out
= defobj
;
2488 * Search the symbol table of a single shared object for a symbol of
2489 * the given name. Returns a pointer to the symbol, or NULL if no
2490 * definition was found.
2492 * The symbol's hash value is passed in for efficiency reasons; that
2493 * eliminates many recomputations of the hash value.
2496 symlook_obj(const char *name
, unsigned long hash
, const Obj_Entry
*obj
,
2499 if (obj
->buckets
!= NULL
) {
2500 unsigned long symnum
= obj
->buckets
[hash
% obj
->nbuckets
];
2502 while (symnum
!= STN_UNDEF
) {
2503 const Elf_Sym
*symp
;
2506 if (symnum
>= obj
->nchains
)
2507 return NULL
; /* Bad object */
2508 symp
= obj
->symtab
+ symnum
;
2509 strp
= obj
->strtab
+ symp
->st_name
;
2511 if (name
[0] == strp
[0] && strcmp(name
, strp
) == 0)
2512 return symp
->st_shndx
!= SHN_UNDEF
||
2513 (!in_plt
&& symp
->st_value
!= 0 &&
2514 ELF_ST_TYPE(symp
->st_info
) == STT_FUNC
) ? symp
: NULL
;
2516 symnum
= obj
->chains
[symnum
];
2523 trace_loaded_objects(Obj_Entry
*obj
)
2525 const char *fmt1
, *fmt2
, *fmt
, *main_local
;
2528 if ((main_local
= _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL
)
2531 if ((fmt1
= _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL
)
2532 fmt1
= "\t%o => %p (%x)\n";
2534 if ((fmt2
= _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL
)
2535 fmt2
= "\t%o (%x)\n";
2537 for (; obj
; obj
= obj
->next
) {
2538 Needed_Entry
*needed
;
2542 for (needed
= obj
->needed
; needed
; needed
= needed
->next
) {
2543 if (needed
->obj
!= NULL
) {
2544 if (needed
->obj
->traced
)
2546 needed
->obj
->traced
= true;
2547 path
= needed
->obj
->path
;
2551 name
= (char *)obj
->strtab
+ needed
->name
;
2552 is_lib
= strncmp(name
, "lib", 3) == 0; /* XXX - bogus */
2554 fmt
= is_lib
? fmt1
: fmt2
;
2555 while ((c
= *fmt
++) != '\0') {
2581 printf("%s", main_local
);
2584 printf("%s", obj_main
->path
);
2591 printf("%d", sodp
->sod_major
);
2594 printf("%d", sodp
->sod_minor
);
2601 printf("%p", needed
->obj
? needed
->obj
->mapbase
: 0);
2613 * Unload a dlopened object and its dependencies from memory and from
2614 * our data structures. It is assumed that the DAG rooted in the
2615 * object has already been unreferenced, and that the object has a
2616 * reference count of 0.
2619 unload_object(Obj_Entry
*root
)
2624 assert(root
->refcount
== 0);
2627 * Pass over the DAG removing unreferenced objects from
2628 * appropriate lists.
2630 unlink_object(root
);
2632 /* Unmap all objects that are no longer referenced. */
2633 linkp
= &obj_list
->next
;
2634 while ((obj
= *linkp
) != NULL
) {
2635 if (obj
->refcount
== 0) {
2636 dbg("unloading \"%s\"", obj
->path
);
2637 munmap(obj
->mapbase
, obj
->mapsize
);
2638 linkmap_delete(obj
);
2649 unlink_object(Obj_Entry
*root
)
2651 const Needed_Entry
*needed
;
2654 if (root
->refcount
== 0) {
2655 /* Remove the object from the RTLD_GLOBAL list. */
2656 objlist_remove(&list_global
, root
);
2658 /* Remove the object from all objects' DAG lists. */
2659 STAILQ_FOREACH(elm
, &root
->dagmembers
, link
)
2660 objlist_remove(&elm
->obj
->dldags
, root
);
2663 for (needed
= root
->needed
; needed
!= NULL
; needed
= needed
->next
)
2664 if (needed
->obj
!= NULL
)
2665 unlink_object(needed
->obj
);
2669 unref_dag(Obj_Entry
*root
)
2671 const Needed_Entry
*needed
;
2673 if (root
->refcount
== 0)
2676 if (root
->refcount
== 0)
2677 for (needed
= root
->needed
; needed
!= NULL
; needed
= needed
->next
)
2678 if (needed
->obj
!= NULL
)
2679 unref_dag(needed
->obj
);
2683 * Common code for MD __tls_get_addr().
2686 tls_get_addr_common(void **dtvp
, int index
, size_t offset
)
2688 Elf_Addr
* dtv
= *dtvp
;
2690 /* Check dtv generation in case new modules have arrived */
2691 if (dtv
[0] != tls_dtv_generation
) {
2697 newdtv
= calloc(1, (tls_max_index
+ 2) * sizeof(Elf_Addr
));
2699 if (to_copy
> tls_max_index
)
2700 to_copy
= tls_max_index
;
2701 memcpy(&newdtv
[2], &dtv
[2], to_copy
* sizeof(Elf_Addr
));
2702 newdtv
[0] = tls_dtv_generation
;
2703 newdtv
[1] = tls_max_index
;
2710 /* Dynamically allocate module TLS if necessary */
2711 if (!dtv
[index
+ 1]) {
2713 * here we should avoid to be re-entered by signal handler
2714 * code, I assume wlock_acquire will masked all signals,
2715 * otherwise there is race and dead lock thread itself.
2718 if (!dtv
[index
+ 1])
2719 dtv
[index
+ 1] = (Elf_Addr
)allocate_module_tls(index
);
2723 return (void*) (dtv
[index
+ 1] + offset
);
2726 #if defined(RTLD_STATIC_TLS_VARIANT_II)
2729 * Allocate the static TLS area. Return a pointer to the TCB. The
2730 * static area is based on negative offsets relative to the tcb.
2732 * The TCB contains an errno pointer for the system call layer, but because
2733 * we are the RTLD we really have no idea how the caller was compiled so
2734 * the information has to be passed in. errno can either be:
2736 * type 0 errno is a simple non-TLS global pointer.
2737 * (special case for e.g. libc_rtld)
2738 * type 1 errno accessed by GOT entry (dynamically linked programs)
2739 * type 2 errno accessed by %gs:OFFSET (statically linked programs)
2742 allocate_tls(Obj_Entry
*objs
)
2747 struct tls_tcb
*tcb
;
2752 * Allocate the new TCB. static TLS storage is placed just before the
2753 * TCB to support the %gs:OFFSET (negative offset) model.
2755 data_size
= (tls_static_space
+ RTLD_STATIC_TLS_ALIGN_MASK
) &
2756 ~RTLD_STATIC_TLS_ALIGN_MASK
;
2757 tcb
= malloc(data_size
+ sizeof(*tcb
));
2758 tcb
= (void *)((char *)tcb
+ data_size
); /* actual tcb location */
2760 dtv_size
= (tls_max_index
+ 2) * sizeof(Elf_Addr
);
2761 dtv
= malloc(dtv_size
);
2762 bzero(dtv
, dtv_size
);
2764 #ifdef RTLD_TCB_HAS_SELF_POINTER
2765 tcb
->tcb_self
= tcb
;
2768 tcb
->tcb_pthread
= NULL
;
2770 dtv
[0] = tls_dtv_generation
;
2771 dtv
[1] = tls_max_index
;
2773 for (obj
= objs
; obj
; obj
= obj
->next
) {
2774 if (obj
->tlsoffset
) {
2775 addr
= (Elf_Addr
)tcb
- obj
->tlsoffset
;
2776 memset((void *)(addr
+ obj
->tlsinitsize
),
2777 0, obj
->tlssize
- obj
->tlsinitsize
);
2779 memcpy((void*) addr
, obj
->tlsinit
, obj
->tlsinitsize
);
2780 dtv
[obj
->tlsindex
+ 1] = addr
;
2787 free_tls(struct tls_tcb
*tcb
)
2791 Elf_Addr tls_start
, tls_end
;
2794 data_size
= (tls_static_space
+ RTLD_STATIC_TLS_ALIGN_MASK
) &
2795 ~RTLD_STATIC_TLS_ALIGN_MASK
;
2798 tls_end
= (Elf_Addr
)tcb
;
2799 tls_start
= (Elf_Addr
)tcb
- data_size
;
2800 for (i
= 0; i
< dtv_size
; i
++) {
2801 if (dtv
[i
+2] != 0 && (dtv
[i
+2] < tls_start
|| dtv
[i
+2] > tls_end
)) {
2802 free((void *)dtv
[i
+2]);
2805 free((void *)tls_start
);
2809 #error "Unsupported TLS layout"
2813 * Allocate TLS block for module with given index.
2816 allocate_module_tls(int index
)
2821 for (obj
= obj_list
; obj
; obj
= obj
->next
) {
2822 if (obj
->tlsindex
== index
)
2826 _rtld_error("Can't find module with TLS index %d", index
);
2830 p
= malloc(obj
->tlssize
);
2831 memcpy(p
, obj
->tlsinit
, obj
->tlsinitsize
);
2832 memset(p
+ obj
->tlsinitsize
, 0, obj
->tlssize
- obj
->tlsinitsize
);
2838 allocate_tls_offset(Obj_Entry
*obj
)
2845 if (obj
->tlssize
== 0) {
2846 obj
->tls_done
= true;
2850 if (obj
->tlsindex
== 1)
2851 off
= calculate_first_tls_offset(obj
->tlssize
, obj
->tlsalign
);
2853 off
= calculate_tls_offset(tls_last_offset
, tls_last_size
,
2854 obj
->tlssize
, obj
->tlsalign
);
2857 * If we have already fixed the size of the static TLS block, we
2858 * must stay within that size. When allocating the static TLS, we
2859 * leave a small amount of space spare to be used for dynamically
2860 * loading modules which use static TLS.
2862 if (tls_static_space
) {
2863 if (calculate_tls_end(off
, obj
->tlssize
) > tls_static_space
)
2867 tls_last_offset
= obj
->tlsoffset
= off
;
2868 tls_last_size
= obj
->tlssize
;
2869 obj
->tls_done
= true;
2875 free_tls_offset(Obj_Entry
*obj
)
2877 #ifdef RTLD_STATIC_TLS_VARIANT_II
2879 * If we were the last thing to allocate out of the static TLS
2880 * block, we give our space back to the 'allocator'. This is a
2881 * simplistic workaround to allow libGL.so.1 to be loaded and
2882 * unloaded multiple times. We only handle the Variant II
2883 * mechanism for now - this really needs a proper allocator.
2885 if (calculate_tls_end(obj
->tlsoffset
, obj
->tlssize
)
2886 == calculate_tls_end(tls_last_offset
, tls_last_size
)) {
2887 tls_last_offset
-= obj
->tlssize
;
2894 _rtld_allocate_tls(void)
2896 struct tls_tcb
*new_tcb
;
2899 new_tcb
= allocate_tls(obj_list
);
2906 _rtld_free_tls(struct tls_tcb
*tcb
)