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c9ff0187 | 1 | /* Hash table for TLS descriptors. |
581c785b | 2 | Copyright (C) 2005-2022 Free Software Foundation, Inc. |
c9ff0187 | 3 | This file is part of the GNU C Library. |
c9ff0187 UD |
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 | |
59ba27a6 | 16 | License along with the GNU C Library; if not, see |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
c9ff0187 UD |
18 | |
19 | #ifndef TLSDESCHTAB_H | |
20 | # define TLSDESCHTAB_H 1 | |
21 | ||
08325735 SN |
22 | #include <atomic.h> |
23 | ||
c9ff0187 UD |
24 | # ifdef SHARED |
25 | ||
26 | # include <inline-hashtab.h> | |
27 | ||
28 | inline static int | |
29 | hash_tlsdesc (void *p) | |
30 | { | |
31 | struct tlsdesc_dynamic_arg *td = p; | |
32 | ||
33 | /* We know all entries are for the same module, so ti_offset is the | |
34 | only distinguishing entry. */ | |
35 | return td->tlsinfo.ti_offset; | |
36 | } | |
37 | ||
38 | inline static int | |
39 | eq_tlsdesc (void *p, void *q) | |
40 | { | |
41 | struct tlsdesc_dynamic_arg *tdp = p, *tdq = q; | |
42 | ||
43 | return tdp->tlsinfo.ti_offset == tdq->tlsinfo.ti_offset; | |
44 | } | |
45 | ||
f8aeae34 | 46 | inline static size_t |
c9ff0187 UD |
47 | map_generation (struct link_map *map) |
48 | { | |
49 | size_t idx = map->l_tls_modid; | |
50 | struct dtv_slotinfo_list *listp = GL(dl_tls_dtv_slotinfo_list); | |
51 | ||
52 | /* Find the place in the dtv slotinfo list. */ | |
53 | do | |
54 | { | |
55 | /* Does it fit in the array of this list element? */ | |
56 | if (idx < listp->len) | |
57 | { | |
58 | /* We should never get here for a module in static TLS, so | |
59 | we can assume that, if the generation count is zero, we | |
60 | still haven't determined the generation count for this | |
61 | module. */ | |
f8aeae34 | 62 | if (listp->slotinfo[idx].map == map && listp->slotinfo[idx].gen) |
c9ff0187 UD |
63 | return listp->slotinfo[idx].gen; |
64 | else | |
65 | break; | |
66 | } | |
67 | idx -= listp->len; | |
68 | listp = listp->next; | |
69 | } | |
70 | while (listp != NULL); | |
71 | ||
72 | /* If we get to this point, the module still hasn't been assigned an | |
73 | entry in the dtv slotinfo data structures, and it will when we're | |
74 | done with relocations. At that point, the module will get a | |
75 | generation number that is one past the current generation, so | |
76 | return exactly that. */ | |
77 | return GL(dl_tls_generation) + 1; | |
78 | } | |
79 | ||
22080666 SN |
80 | /* Returns the data pointer for a given map and tls offset that is used |
81 | to fill in one of the GOT entries referenced by a TLSDESC relocation | |
82 | when using dynamic TLS. This requires allocation, returns NULL on | |
83 | allocation failure. */ | |
c9ff0187 | 84 | void * |
c9ff0187 UD |
85 | _dl_make_tlsdesc_dynamic (struct link_map *map, size_t ti_offset) |
86 | { | |
87 | struct hashtab *ht; | |
88 | void **entry; | |
89 | struct tlsdesc_dynamic_arg *td, test; | |
90 | ||
c9ff0187 UD |
91 | ht = map->l_mach.tlsdesc_table; |
92 | if (! ht) | |
93 | { | |
94 | ht = htab_create (); | |
95 | if (! ht) | |
22080666 | 96 | return 0; |
c9ff0187 UD |
97 | map->l_mach.tlsdesc_table = ht; |
98 | } | |
99 | ||
100 | test.tlsinfo.ti_module = map->l_tls_modid; | |
101 | test.tlsinfo.ti_offset = ti_offset; | |
102 | entry = htab_find_slot (ht, &test, 1, hash_tlsdesc, eq_tlsdesc); | |
a615be46 | 103 | if (! entry) |
22080666 | 104 | return 0; |
a615be46 | 105 | |
c9ff0187 UD |
106 | if (*entry) |
107 | { | |
108 | td = *entry; | |
c9ff0187 UD |
109 | return td; |
110 | } | |
111 | ||
112 | *entry = td = malloc (sizeof (struct tlsdesc_dynamic_arg)); | |
113 | /* This may be higher than the map's generation, but it doesn't | |
114 | matter much. Worst case, we'll have one extra DTV update per | |
115 | thread. */ | |
116 | td->gen_count = map_generation (map); | |
117 | td->tlsinfo = test.tlsinfo; | |
c9ff0187 UD |
118 | return td; |
119 | } | |
120 | ||
121 | # endif /* SHARED */ | |
122 | ||
c9ff0187 | 123 | #endif |