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ba384f6e | 1 | /* Register destructors for C++ TLS variables declared with thread_local. |
d4697bc9 | 2 | Copyright (C) 2013-2014 Free Software Foundation, Inc. |
ba384f6e SP |
3 | This file is part of the GNU C Library. |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
6 | modify it under the terms of the GNU Lesser General Public | |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
9 | ||
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | Lesser General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public | |
16 | License along with the GNU C Library; if not, see | |
17 | <http://www.gnu.org/licenses/>. */ | |
18 | ||
19 | #include <stdlib.h> | |
20 | #include <ldsodefs.h> | |
21 | ||
22 | typedef void (*dtor_func) (void *); | |
23 | ||
24 | struct dtor_list | |
25 | { | |
26 | dtor_func func; | |
27 | void *obj; | |
28 | struct link_map *map; | |
29 | struct dtor_list *next; | |
30 | }; | |
31 | ||
32 | static __thread struct dtor_list *tls_dtor_list; | |
33 | static __thread void *dso_symbol_cache; | |
34 | static __thread struct link_map *lm_cache; | |
35 | ||
36 | /* Register a destructor for TLS variables declared with the 'thread_local' | |
37 | keyword. This function is only called from code generated by the C++ | |
38 | compiler. FUNC is the destructor function and OBJ is the object to be | |
39 | passed to the destructor. DSO_SYMBOL is the __dso_handle symbol that each | |
40 | DSO has at a unique address in its map, added from crtbegin.o during the | |
41 | linking phase. */ | |
42 | int | |
43 | __cxa_thread_atexit_impl (dtor_func func, void *obj, void *dso_symbol) | |
44 | { | |
45 | /* Prepend. */ | |
46 | struct dtor_list *new = calloc (1, sizeof (struct dtor_list)); | |
47 | new->func = func; | |
48 | new->obj = obj; | |
49 | new->next = tls_dtor_list; | |
50 | tls_dtor_list = new; | |
51 | ||
52 | /* See if we already encountered the DSO. */ | |
53 | __rtld_lock_lock_recursive (GL(dl_load_lock)); | |
54 | ||
a1ffb40e | 55 | if (__glibc_unlikely (dso_symbol_cache != dso_symbol)) |
ba384f6e SP |
56 | { |
57 | ElfW(Addr) caller = (ElfW(Addr)) dso_symbol; | |
58 | ||
59 | struct link_map *l = _dl_find_dso_for_object (caller); | |
60 | ||
61 | /* If the address is not recognized the call comes from the main | |
62 | program (we hope). */ | |
63 | lm_cache = l ? l : GL(dl_ns)[LM_ID_BASE]._ns_loaded; | |
64 | } | |
65 | /* A destructor could result in a thread_local construction and the former | |
66 | could have cleared the flag. */ | |
67 | if (lm_cache->l_type == lt_loaded && lm_cache->l_tls_dtor_count == 0) | |
68 | lm_cache->l_flags_1 |= DF_1_NODELETE; | |
69 | ||
70 | new->map = lm_cache; | |
71 | new->map->l_tls_dtor_count++; | |
72 | ||
73 | __rtld_lock_unlock_recursive (GL(dl_load_lock)); | |
74 | ||
75 | return 0; | |
76 | } | |
77 | ||
78 | /* Call the destructors. This is called either when a thread returns from the | |
e57b0c61 | 79 | initial function or when the process exits via the exit function. */ |
ba384f6e SP |
80 | void |
81 | __call_tls_dtors (void) | |
82 | { | |
83 | while (tls_dtor_list) | |
84 | { | |
85 | struct dtor_list *cur = tls_dtor_list; | |
86 | tls_dtor_list = tls_dtor_list->next; | |
87 | ||
88 | cur->func (cur->obj); | |
89 | ||
90 | __rtld_lock_lock_recursive (GL(dl_load_lock)); | |
91 | ||
92 | /* Allow DSO unload if count drops to zero. */ | |
93 | cur->map->l_tls_dtor_count--; | |
94 | if (cur->map->l_tls_dtor_count == 0 && cur->map->l_type == lt_loaded) | |
95 | cur->map->l_flags_1 &= ~DF_1_NODELETE; | |
96 | ||
97 | __rtld_lock_unlock_recursive (GL(dl_load_lock)); | |
98 | ||
99 | free (cur); | |
100 | } | |
101 | } | |
102 | libc_hidden_def (__call_tls_dtors) |