1 /* Manage function descriptors. Generic version.
2 Copyright (C) 1999-2013 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, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
23 #include <sys/param.h>
27 #include <elf/dynamic-link.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];
60 /* Address of .boot_table is not known until runtime. */
63 .root
= &local
.boot_table
,
68 .len
= sizeof (local
.boot_fdescs
) / sizeof (local
.boot_fdescs
[0]),
73 /* Create a new fdesc table and return a pointer to the first fdesc
74 entry. The fdesc lock must have been acquired already. */
76 static struct fdesc_table
*
77 new_fdesc_table (struct local
*l
, size_t *size
)
79 size_t old_npages
= l
->npages
;
80 size_t new_npages
= old_npages
+ old_npages
;
81 struct fdesc_table
*new_table
;
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
;
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"));
96 = (*size
- sizeof (*new_table
)) / sizeof (struct fdesc
);
97 new_table
->first_unused
= 1;
101 /* Must call _dl_fptr_init before using any other function. */
107 ELF_MACHINE_LOAD_ADDRESS (l
, local
);
108 l
->root
= &l
->boot_table
;
112 make_fdesc (ElfW(Addr
) ip
, ElfW(Addr
) gp
)
114 struct fdesc
*fdesc
= NULL
;
115 struct fdesc_table
*root
;
119 ELF_MACHINE_LOAD_ADDRESS (l
, local
);
125 old
= root
->first_unused
;
126 if (old
>= root
->len
)
128 else if (COMPARE_AND_SWAP (&root
->first_unused
, old
, old
+ 1))
130 fdesc
= &root
->fdesc
[old
];
137 /* Get it from free-list. */
140 fdesc
= l
->free_list
;
144 while (! COMPARE_AND_SWAP ((ElfW(Addr
) *) &l
->free_list
,
145 (ElfW(Addr
)) fdesc
, fdesc
->ip
));
149 /* Create a new fdesc table. */
151 struct fdesc_table
*new_table
= new_fdesc_table (l
, &size
);
153 if (new_table
== NULL
)
156 new_table
->next
= root
;
157 if (! COMPARE_AND_SWAP ((ElfW(Addr
) *) &l
->root
,
159 (ElfW(Addr
)) new_table
))
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
);
167 /* Note that the first entry was reserved while allocating the
168 memory for the new page. */
169 fdesc
= &new_table
->fdesc
[0];
176 return (ElfW(Addr
)) fdesc
;
180 static inline ElfW(Addr
) * __attribute__ ((always_inline
))
181 make_fptr_table (struct link_map
*map
)
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
;
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
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
,
204 if (fptr_table
== MAP_FAILED
)
205 _dl_signal_error (errno
, NULL
, NULL
,
206 N_("cannot map pages for fptr table"));
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
;
212 __munmap (fptr_table
, len
* sizeof (fptr_table
[0]));
214 return map
->l_mach
.fptr_table
;
219 _dl_make_fptr (struct link_map
*map
, const ElfW(Sym
) *sym
,
222 ElfW(Addr
) *ftab
= map
->l_mach
.fptr_table
;
223 const ElfW(Sym
) *symtab
;
227 if (__builtin_expect (ftab
== NULL
, 0))
228 ftab
= make_fptr_table (map
);
230 symtab
= (const void *) D_PTR (map
, l_info
[DT_SYMTAB
]);
231 symidx
= sym
- symtab
;
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"));
237 while (ftab
[symidx
] == 0)
239 /* GOT has already been relocated in elf_get_dynamic_info -
240 don't try to relocate it again. */
242 = make_fdesc (ip
, map
->l_info
[DT_PLTGOT
]->d_un
.d_ptr
);
244 if (__builtin_expect (COMPARE_AND_SWAP (&ftab
[symidx
], (ElfW(Addr
)) NULL
,
247 /* Noone has updated the entry and the new function
248 descriptor has been installed. */
251 = (const void *) D_PTR (map
, l_info
[DT_STRTAB
]);
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
]);
263 /* We created a duplicated function descriptor. We put it on
265 struct fdesc
*f
= (struct fdesc
*) fdesc
;
267 ELF_MACHINE_LOAD_ADDRESS (l
, local
);
270 f
->ip
= (ElfW(Addr
)) l
->free_list
;
271 while (! COMPARE_AND_SWAP ((ElfW(Addr
) *) &l
->free_list
,
281 _dl_unmap (struct link_map
*map
)
283 ElfW(Addr
) *ftab
= map
->l_mach
.fptr_table
;
284 struct fdesc
*head
= NULL
, *tail
= NULL
;
287 __munmap ((void *) map
->l_map_start
,
288 map
->l_map_end
- map
->l_map_start
);
293 /* String together the fdesc structures that are being freed. */
294 for (i
= 0; i
< map
->l_mach
.fptr_table_len
; ++i
)
298 *(struct fdesc
**) ftab
[i
] = head
;
299 head
= (struct fdesc
*) ftab
[i
];
305 /* Prepend the new list to the free_list: */
308 tail
->ip
= (ElfW(Addr
)) local
.free_list
;
309 while (! COMPARE_AND_SWAP ((ElfW(Addr
) *) &local
.free_list
,
310 tail
->ip
, (ElfW(Addr
)) head
));
312 __munmap (ftab
, (map
->l_mach
.fptr_table_len
313 * sizeof (map
->l_mach
.fptr_table
[0])));
315 map
->l_mach
.fptr_table
= NULL
;
320 _dl_lookup_address (const void *address
)
322 ElfW(Addr
) addr
= (ElfW(Addr
)) address
;
323 struct fdesc_table
*t
;
326 for (t
= local
.root
; t
!= NULL
; t
= t
->next
)
328 i
= (struct fdesc
*) addr
- &t
->fdesc
[0];
329 if (i
< t
->first_unused
&& addr
== (ElfW(Addr
)) &t
->fdesc
[i
])
331 addr
= t
->fdesc
[i
].ip
;