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dde6fc78 | 1 | /* Manage function descriptors. Generic version. |
568035b7 | 2 | Copyright (C) 1999-2013 Free Software Foundation, Inc. |
dde6fc78 CD |
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, write to the Free | |
17 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
18 | 02111-1307 USA. */ | |
19 | ||
20 | #include <libintl.h> | |
21 | #include <unistd.h> | |
22 | #include <string.h> | |
23 | #include <sys/param.h> | |
24 | #include <sys/mman.h> | |
25 | #include <link.h> | |
26 | #include <ldsodefs.h> | |
27 | #include <elf/dynamic-link.h> | |
28 | #include <dl-fptr.h> | |
29 | #include <atomic.h> | |
30 | ||
31 | #ifndef ELF_MACHINE_BOOT_FPTR_TABLE_LEN | |
32 | /* ELF_MACHINE_BOOT_FPTR_TABLE_LEN should be greater than the number of | |
33 | dynamic symbols in ld.so. */ | |
34 | # define ELF_MACHINE_BOOT_FPTR_TABLE_LEN 256 | |
35 | #endif | |
36 | ||
37 | #ifndef ELF_MACHINE_LOAD_ADDRESS | |
38 | # error "ELF_MACHINE_LOAD_ADDRESS is not defined." | |
39 | #endif | |
40 | ||
41 | #ifndef COMPARE_AND_SWAP | |
42 | # define COMPARE_AND_SWAP(ptr, old, new) \ | |
43 | (catomic_compare_and_exchange_bool_acq (ptr, new, old) == 0) | |
44 | #endif | |
45 | ||
46 | ElfW(Addr) _dl_boot_fptr_table [ELF_MACHINE_BOOT_FPTR_TABLE_LEN]; | |
47 | ||
48 | static struct local | |
49 | { | |
50 | struct fdesc_table *root; | |
51 | struct fdesc *free_list; | |
52 | unsigned int npages; /* # of pages to allocate */ | |
53 | /* the next to members MUST be consecutive! */ | |
54 | struct fdesc_table boot_table; | |
55 | struct fdesc boot_fdescs[1024]; | |
56 | } | |
57 | local = | |
58 | { | |
59 | #ifdef SHARED | |
60 | /* Address of .boot_table is not known until runtime. */ | |
61 | .root = 0, | |
62 | #else | |
63 | .root = &local.boot_table, | |
64 | #endif | |
65 | .npages = 2, | |
66 | .boot_table = | |
67 | { | |
68 | .len = sizeof (local.boot_fdescs) / sizeof (local.boot_fdescs[0]), | |
69 | .first_unused = 0 | |
70 | } | |
71 | }; | |
72 | ||
73 | /* Create a new fdesc table and return a pointer to the first fdesc | |
74 | entry. The fdesc lock must have been acquired already. */ | |
75 | ||
76 | static struct fdesc_table * | |
77 | new_fdesc_table (struct local *l, size_t *size) | |
78 | { | |
79 | size_t old_npages = l->npages; | |
80 | size_t new_npages = old_npages + old_npages; | |
81 | struct fdesc_table *new_table; | |
82 | ||
83 | /* If someone has just created a new table, we return NULL to tell | |
84 | the caller to use the new table. */ | |
85 | if (! COMPARE_AND_SWAP (&l->npages, old_npages, new_npages)) | |
86 | return (struct fdesc_table *) NULL; | |
87 | ||
88 | *size = old_npages * GLRO(dl_pagesize); | |
89 | new_table = __mmap (NULL, *size, | |
90 | PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0); | |
91 | if (new_table == MAP_FAILED) | |
92 | _dl_signal_error (errno, NULL, NULL, | |
93 | N_("cannot map pages for fdesc table")); | |
94 | ||
95 | new_table->len | |
96 | = (*size - sizeof (*new_table)) / sizeof (struct fdesc); | |
97 | new_table->first_unused = 1; | |
98 | return new_table; | |
99 | } | |
100 | ||
101 | /* Must call _dl_fptr_init before using any other function. */ | |
5556231d | 102 | void |
dde6fc78 CD |
103 | _dl_fptr_init (void) |
104 | { | |
105 | struct local *l; | |
106 | ||
107 | ELF_MACHINE_LOAD_ADDRESS (l, local); | |
108 | l->root = &l->boot_table; | |
109 | } | |
110 | ||
111 | static ElfW(Addr) | |
112 | make_fdesc (ElfW(Addr) ip, ElfW(Addr) gp) | |
113 | { | |
114 | struct fdesc *fdesc = NULL; | |
115 | struct fdesc_table *root; | |
116 | unsigned int old; | |
117 | struct local *l; | |
118 | ||
119 | ELF_MACHINE_LOAD_ADDRESS (l, local); | |
120 | ||
121 | retry: | |
122 | root = l->root; | |
123 | while (1) | |
124 | { | |
125 | old = root->first_unused; | |
126 | if (old >= root->len) | |
127 | break; | |
128 | else if (COMPARE_AND_SWAP (&root->first_unused, old, old + 1)) | |
129 | { | |
130 | fdesc = &root->fdesc[old]; | |
131 | goto install; | |
132 | } | |
133 | } | |
134 | ||
135 | if (l->free_list) | |
136 | { | |
137 | /* Get it from free-list. */ | |
138 | do | |
139 | { | |
140 | fdesc = l->free_list; | |
141 | if (fdesc == NULL) | |
142 | goto retry; | |
143 | } | |
144 | while (! COMPARE_AND_SWAP ((ElfW(Addr) *) &l->free_list, | |
145 | (ElfW(Addr)) fdesc, fdesc->ip)); | |
146 | } | |
147 | else | |
148 | { | |
149 | /* Create a new fdesc table. */ | |
150 | size_t size; | |
151 | struct fdesc_table *new_table = new_fdesc_table (l, &size); | |
152 | ||
153 | if (new_table == NULL) | |
154 | goto retry; | |
155 | ||
156 | new_table->next = root; | |
157 | if (! COMPARE_AND_SWAP ((ElfW(Addr) *) &l->root, | |
158 | (ElfW(Addr)) root, | |
159 | (ElfW(Addr)) new_table)) | |
160 | { | |
161 | /* Someone has just installed a new table. Return NULL to | |
162 | tell the caller to use the new table. */ | |
163 | __munmap (new_table, size); | |
164 | goto retry; | |
165 | } | |
166 | ||
167 | /* Note that the first entry was reserved while allocating the | |
168 | memory for the new page. */ | |
169 | fdesc = &new_table->fdesc[0]; | |
170 | } | |
171 | ||
172 | install: | |
173 | fdesc->ip = ip; | |
174 | fdesc->gp = gp; | |
175 | ||
176 | return (ElfW(Addr)) fdesc; | |
177 | } | |
178 | ||
179 | ||
180 | static inline ElfW(Addr) * __attribute__ ((always_inline)) | |
181 | make_fptr_table (struct link_map *map) | |
182 | { | |
183 | const ElfW(Sym) *symtab | |
184 | = (const void *) D_PTR (map, l_info[DT_SYMTAB]); | |
185 | const char *strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]); | |
186 | ElfW(Addr) *fptr_table; | |
187 | size_t size; | |
188 | size_t len; | |
189 | ||
190 | /* XXX Apparently the only way to find out the size of the dynamic | |
191 | symbol section is to assume that the string table follows right | |
192 | afterwards... */ | |
193 | len = ((strtab - (char *) symtab) | |
194 | / map->l_info[DT_SYMENT]->d_un.d_val); | |
195 | size = ((len * sizeof (fptr_table[0]) + GLRO(dl_pagesize) - 1) | |
196 | & -GLRO(dl_pagesize)); | |
197 | /* XXX We don't support here in the moment systems without MAP_ANON. | |
198 | There probably are none for IA-64. In case this is proven wrong | |
199 | we will have to open /dev/null here and use the file descriptor | |
200 | instead of the hard-coded -1. */ | |
201 | fptr_table = __mmap (NULL, size, | |
202 | PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, | |
203 | -1, 0); | |
204 | if (fptr_table == MAP_FAILED) | |
205 | _dl_signal_error (errno, NULL, NULL, | |
206 | N_("cannot map pages for fptr table")); | |
207 | ||
208 | if (COMPARE_AND_SWAP ((ElfW(Addr) *) &map->l_mach.fptr_table, | |
209 | (ElfW(Addr)) NULL, (ElfW(Addr)) fptr_table)) | |
210 | map->l_mach.fptr_table_len = len; | |
211 | else | |
212 | __munmap (fptr_table, len * sizeof (fptr_table[0])); | |
213 | ||
214 | return map->l_mach.fptr_table; | |
215 | } | |
216 | ||
217 | ||
218 | ElfW(Addr) | |
219 | _dl_make_fptr (struct link_map *map, const ElfW(Sym) *sym, | |
220 | ElfW(Addr) ip) | |
221 | { | |
222 | ElfW(Addr) *ftab = map->l_mach.fptr_table; | |
223 | const ElfW(Sym) *symtab; | |
224 | Elf_Symndx symidx; | |
225 | struct local *l; | |
226 | ||
227 | if (__builtin_expect (ftab == NULL, 0)) | |
228 | ftab = make_fptr_table (map); | |
229 | ||
230 | symtab = (const void *) D_PTR (map, l_info[DT_SYMTAB]); | |
231 | symidx = sym - symtab; | |
232 | ||
233 | if (symidx >= map->l_mach.fptr_table_len) | |
234 | _dl_signal_error (0, NULL, NULL, | |
235 | N_("internal error: symidx out of range of fptr table")); | |
236 | ||
237 | while (ftab[symidx] == 0) | |
238 | { | |
239 | /* GOT has already been relocated in elf_get_dynamic_info - | |
240 | don't try to relocate it again. */ | |
241 | ElfW(Addr) fdesc | |
242 | = make_fdesc (ip, map->l_info[DT_PLTGOT]->d_un.d_ptr); | |
243 | ||
244 | if (__builtin_expect (COMPARE_AND_SWAP (&ftab[symidx], (ElfW(Addr)) NULL, | |
245 | fdesc), 1)) | |
246 | { | |
247 | /* Noone has updated the entry and the new function | |
248 | descriptor has been installed. */ | |
249 | #if 0 | |
250 | const char *strtab | |
251 | = (const void *) D_PTR (map, l_info[DT_STRTAB]); | |
252 | ||
253 | ELF_MACHINE_LOAD_ADDRESS (l, local); | |
254 | if (l->root != &l->boot_table | |
255 | || l->boot_table.first_unused > 20) | |
256 | _dl_debug_printf ("created fdesc symbol `%s' at %lx\n", | |
257 | strtab + sym->st_name, ftab[symidx]); | |
258 | #endif | |
259 | break; | |
260 | } | |
261 | else | |
262 | { | |
263 | /* We created a duplicated function descriptor. We put it on | |
264 | free-list. */ | |
265 | struct fdesc *f = (struct fdesc *) fdesc; | |
266 | ||
267 | ELF_MACHINE_LOAD_ADDRESS (l, local); | |
268 | ||
269 | do | |
270 | f->ip = (ElfW(Addr)) l->free_list; | |
271 | while (! COMPARE_AND_SWAP ((ElfW(Addr) *) &l->free_list, | |
272 | f->ip, fdesc)); | |
273 | } | |
274 | } | |
275 | ||
276 | return ftab[symidx]; | |
277 | } | |
278 | ||
279 | ||
280 | void | |
281 | _dl_unmap (struct link_map *map) | |
282 | { | |
283 | ElfW(Addr) *ftab = map->l_mach.fptr_table; | |
284 | struct fdesc *head = NULL, *tail = NULL; | |
285 | size_t i; | |
286 | ||
287 | __munmap ((void *) map->l_map_start, | |
288 | map->l_map_end - map->l_map_start); | |
289 | ||
290 | if (ftab == NULL) | |
291 | return; | |
292 | ||
293 | /* String together the fdesc structures that are being freed. */ | |
294 | for (i = 0; i < map->l_mach.fptr_table_len; ++i) | |
295 | { | |
296 | if (ftab[i]) | |
297 | { | |
298 | *(struct fdesc **) ftab[i] = head; | |
299 | head = (struct fdesc *) ftab[i]; | |
300 | if (tail == NULL) | |
301 | tail = head; | |
302 | } | |
303 | } | |
304 | ||
305 | /* Prepend the new list to the free_list: */ | |
306 | if (tail) | |
307 | do | |
308 | tail->ip = (ElfW(Addr)) local.free_list; | |
309 | while (! COMPARE_AND_SWAP ((ElfW(Addr) *) &local.free_list, | |
310 | tail->ip, (ElfW(Addr)) head)); | |
311 | ||
312 | __munmap (ftab, (map->l_mach.fptr_table_len | |
313 | * sizeof (map->l_mach.fptr_table[0]))); | |
314 | ||
315 | map->l_mach.fptr_table = NULL; | |
316 | } | |
317 | ||
318 | ||
319 | ElfW(Addr) | |
320 | _dl_lookup_address (const void *address) | |
321 | { | |
322 | ElfW(Addr) addr = (ElfW(Addr)) address; | |
323 | struct fdesc_table *t; | |
324 | unsigned long int i; | |
325 | ||
326 | for (t = local.root; t != NULL; t = t->next) | |
327 | { | |
328 | i = (struct fdesc *) addr - &t->fdesc[0]; | |
329 | if (i < t->first_unused && addr == (ElfW(Addr)) &t->fdesc[i]) | |
330 | { | |
331 | addr = t->fdesc[i].ip; | |
332 | break; | |
333 | } | |
334 | } | |
335 | ||
336 | return addr; | |
337 | } |