1 /* Manage function descriptors. Generic version.
2 Copyright (C) 1999-2014 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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.
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.
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/>. */
22 #include <sys/param.h>
26 #include <elf/dynamic-link.h>
28 #include <dl-unmap-segments.h>
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
37 #ifndef ELF_MACHINE_LOAD_ADDRESS
38 # error "ELF_MACHINE_LOAD_ADDRESS is not defined."
41 #ifndef COMPARE_AND_SWAP
42 # define COMPARE_AND_SWAP(ptr, old, new) \
43 (catomic_compare_and_exchange_bool_acq (ptr, new, old) == 0)
46 ElfW(Addr) _dl_boot_fptr_table [ELF_MACHINE_BOOT_FPTR_TABLE_LEN];
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];
59 .root = &local.boot_table,
63 .len = sizeof (local.boot_fdescs) / sizeof (local.boot_fdescs[0]),
68 /* Create a new fdesc table and return a pointer to the first fdesc
69 entry. The fdesc lock must have been acquired already. */
71 static struct fdesc_table *
72 new_fdesc_table (struct local *l, size_t *size)
74 size_t old_npages = l->npages;
75 size_t new_npages = old_npages + old_npages;
76 struct fdesc_table *new_table;
78 /* If someone has just created a new table, we return NULL to tell
79 the caller to use the new table. */
80 if (! COMPARE_AND_SWAP (&l->npages, old_npages, new_npages))
81 return (struct fdesc_table *) NULL;
83 *size = old_npages * GLRO(dl_pagesize);
84 new_table = __mmap (NULL, *size,
85 PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
86 if (new_table == MAP_FAILED)
87 _dl_signal_error (errno, NULL, NULL,
88 N_("cannot map pages for fdesc table"));
91 = (*size - sizeof (*new_table)) / sizeof (struct fdesc);
92 new_table->first_unused = 1;
98 make_fdesc (ElfW(Addr) ip, ElfW(Addr) gp)
100 struct fdesc *fdesc = NULL;
101 struct fdesc_table *root;
105 ELF_MACHINE_LOAD_ADDRESS (l, local);
111 old = root->first_unused;
112 if (old >= root->len)
114 else if (COMPARE_AND_SWAP (&root->first_unused, old, old + 1))
116 fdesc = &root->fdesc[old];
123 /* Get it from free-list. */
126 fdesc = l->free_list;
130 while (! COMPARE_AND_SWAP ((ElfW(Addr) *) &l->free_list,
131 (ElfW(Addr)) fdesc, fdesc->ip));
135 /* Create a new fdesc table. */
137 struct fdesc_table *new_table = new_fdesc_table (l, &size);
139 if (new_table == NULL)
142 new_table->next = root;
143 if (! COMPARE_AND_SWAP ((ElfW(Addr) *) &l->root,
145 (ElfW(Addr)) new_table))
147 /* Someone has just installed a new table. Return NULL to
148 tell the caller to use the new table. */
149 __munmap (new_table, size);
153 /* Note that the first entry was reserved while allocating the
154 memory for the new page. */
155 fdesc = &new_table->fdesc[0];
162 return (ElfW(Addr)) fdesc;
166 static inline ElfW(Addr) * __attribute__ ((always_inline))
167 make_fptr_table (struct link_map *map)
169 const ElfW(Sym) *symtab
170 = (const void *) D_PTR (map, l_info[DT_SYMTAB]);
171 const char *strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
172 ElfW(Addr) *fptr_table;
176 /* XXX Apparently the only way to find out the size of the dynamic
177 symbol section is to assume that the string table follows right
179 len = ((strtab - (char *) symtab)
180 / map->l_info[DT_SYMENT]->d_un.d_val);
181 size = ((len * sizeof (fptr_table[0]) + GLRO(dl_pagesize) - 1)
182 & -GLRO(dl_pagesize));
183 /* XXX We don't support here in the moment systems without MAP_ANON.
184 There probably are none for IA-64. In case this is proven wrong
185 we will have to open /dev/null here and use the file descriptor
186 instead of the hard-coded -1. */
187 fptr_table = __mmap (NULL, size,
188 PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE,
190 if (fptr_table == MAP_FAILED)
191 _dl_signal_error (errno, NULL, NULL,
192 N_("cannot map pages for fptr table"));
194 if (COMPARE_AND_SWAP ((ElfW(Addr) *) &map->l_mach.fptr_table,
195 (ElfW(Addr)) NULL, (ElfW(Addr)) fptr_table))
196 map->l_mach.fptr_table_len = len;
198 __munmap (fptr_table, len * sizeof (fptr_table[0]));
200 return map->l_mach.fptr_table;
205 _dl_make_fptr (struct link_map *map, const ElfW(Sym) *sym,
208 ElfW(Addr) *ftab = map->l_mach.fptr_table;
209 const ElfW(Sym) *symtab;
213 if (__glibc_unlikely (ftab == NULL))
214 ftab = make_fptr_table (map);
216 symtab = (const void *) D_PTR (map, l_info[DT_SYMTAB]);
217 symidx = sym - symtab;
219 if (symidx >= map->l_mach.fptr_table_len)
220 _dl_signal_error (0, NULL, NULL,
221 N_("internal error: symidx out of range of fptr table"));
223 while (ftab[symidx] == 0)
225 /* GOT has already been relocated in elf_get_dynamic_info -
226 don't try to relocate it again. */
228 = make_fdesc (ip, map->l_info[DT_PLTGOT]->d_un.d_ptr);
230 if (__builtin_expect (COMPARE_AND_SWAP (&ftab[symidx], (ElfW(Addr)) NULL,
233 /* Noone has updated the entry and the new function
234 descriptor has been installed. */
237 = (const void *) D_PTR (map, l_info[DT_STRTAB]);
239 ELF_MACHINE_LOAD_ADDRESS (l, local);
240 if (l->root != &l->boot_table
241 || l->boot_table.first_unused > 20)
242 _dl_debug_printf ("created fdesc symbol `%s' at %lx\n",
243 strtab + sym->st_name, ftab[symidx]);
249 /* We created a duplicated function descriptor. We put it on
251 struct fdesc *f = (struct fdesc *) fdesc;
253 ELF_MACHINE_LOAD_ADDRESS (l, local);
256 f->ip = (ElfW(Addr)) l->free_list;
257 while (! COMPARE_AND_SWAP ((ElfW(Addr) *) &l->free_list,
267 _dl_unmap (struct link_map *map)
269 ElfW(Addr) *ftab = map->l_mach.fptr_table;
270 struct fdesc *head = NULL, *tail = NULL;
273 _dl_unmap_segments (map);
278 /* String together the fdesc structures that are being freed. */
279 for (i = 0; i < map->l_mach.fptr_table_len; ++i)
283 *(struct fdesc **) ftab[i] = head;
284 head = (struct fdesc *) ftab[i];
290 /* Prepend the new list to the free_list: */
293 tail->ip = (ElfW(Addr)) local.free_list;
294 while (! COMPARE_AND_SWAP ((ElfW(Addr) *) &local.free_list,
295 tail->ip, (ElfW(Addr)) head));
297 __munmap (ftab, (map->l_mach.fptr_table_len
298 * sizeof (map->l_mach.fptr_table[0])));
300 map->l_mach.fptr_table = NULL;
305 _dl_lookup_address (const void *address)
307 ElfW(Addr) addr = (ElfW(Addr)) address;
308 struct fdesc_table *t;
311 for (t = local.root; t != NULL; t = t->next)
313 i = (struct fdesc *) addr - &t->fdesc[0];
314 if (i < t->first_unused && addr == (ElfW(Addr)) &t->fdesc[i])
316 addr = t->fdesc[i].ip;