1 /* Copyright (C) 2001, 2002, 2003, 2004, 2005, 2009, 2010, 2011
2 Free Software Foundation, Inc.
3 Contributed by Jakub Jelinek <jakub@redhat.com>.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3, or (at your option)
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 Under Section 7 of GPL version 3, you are granted additional
18 permissions described in the GCC Runtime Library Exception, version
19 3.1, as published by the Free Software Foundation.
21 You should have received a copy of the GNU General Public License and
22 a copy of the GCC Runtime Library Exception along with this program;
23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 <http://www.gnu.org/licenses/>. */
26 /* Locate the FDE entry for a given address, using PT_GNU_EH_FRAME ELF
27 segment and dl_iterate_phdr to avoid register/deregister calls at
36 #if !defined(inhibit_libc) && !defined(__OpenBSD__)
37 #include <elf.h> /* Get DT_CONFIG. */
39 #include "coretypes.h"
41 #include "libgcc_tm.h"
44 #define NO_BASE_OF_ENCODED_VALUE
45 #include "unwind-pe.h"
46 #include "unwind-dw2-fde.h"
47 #include "unwind-compat.h"
50 #if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \
51 && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2) \
52 || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && defined(DT_CONFIG)))
53 # define USE_PT_GNU_EH_FRAME
56 #if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \
57 && defined(TARGET_DL_ITERATE_PHDR) \
58 && (defined(__FreeBSD__) || defined(__DragonFly__))
60 # define USE_PT_GNU_EH_FRAME
63 #if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \
64 && defined(__OpenBSD__)
65 # define ElfW(type) Elf_##type
66 # define USE_PT_GNU_EH_FRAME
69 #if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \
70 && defined(TARGET_DL_ITERATE_PHDR) \
71 && (defined(__OpenBSD__) || defined(__NetBSD__))
72 # define ElfW(n) Elf_##n
73 # define USE_PT_GNU_EH_FRAME
76 #if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \
77 && defined(TARGET_DL_ITERATE_PHDR) \
78 && defined(__sun__) && defined(__svr4__)
79 # define USE_PT_GNU_EH_FRAME
82 #if defined(USE_PT_GNU_EH_FRAME)
86 #ifndef __RELOC_POINTER
87 # define __RELOC_POINTER(ptr, base) ((ptr) + (base))
90 static const fde * _Unwind_Find_registered_FDE (void *pc, struct dwarf_eh_bases *bases);
92 #define _Unwind_Find_FDE _Unwind_Find_registered_FDE
93 #include "unwind-dw2-fde.c"
94 #undef _Unwind_Find_FDE
96 #ifndef PT_GNU_EH_FRAME
97 #define PT_GNU_EH_FRAME (PT_LOOS + 0x474e550)
100 struct unw_eh_callback_data
110 struct unw_eh_frame_hdr
112 unsigned char version;
113 unsigned char eh_frame_ptr_enc;
114 unsigned char fde_count_enc;
115 unsigned char table_enc;
118 #define FRAME_HDR_CACHE_SIZE 8
120 static struct frame_hdr_cache_element
124 _Unwind_Ptr load_base;
125 const ElfW(Phdr) *p_eh_frame_hdr;
126 const ElfW(Phdr) *p_dynamic;
127 struct frame_hdr_cache_element *link;
128 } frame_hdr_cache[FRAME_HDR_CACHE_SIZE];
130 static struct frame_hdr_cache_element *frame_hdr_cache_head;
132 /* Like base_of_encoded_value, but take the base from a struct
133 unw_eh_callback_data instead of an _Unwind_Context. */
136 base_from_cb_data (unsigned char encoding, struct unw_eh_callback_data *data)
138 if (encoding == DW_EH_PE_omit)
141 switch (encoding & 0x70)
143 case DW_EH_PE_absptr:
145 case DW_EH_PE_aligned:
148 case DW_EH_PE_textrel:
149 return (_Unwind_Ptr) data->tbase;
150 case DW_EH_PE_datarel:
151 return (_Unwind_Ptr) data->dbase;
158 _Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr)
160 struct unw_eh_callback_data *data = (struct unw_eh_callback_data *) ptr;
161 const ElfW(Phdr) *phdr, *p_eh_frame_hdr, *p_dynamic;
164 struct elf32_fdpic_loadaddr load_base;
166 _Unwind_Ptr load_base;
168 const unsigned char *p;
169 const struct unw_eh_frame_hdr *hdr;
170 _Unwind_Ptr eh_frame;
172 _Unwind_Ptr pc_low = 0, pc_high = 0;
174 struct ext_dl_phdr_info
176 ElfW(Addr) dlpi_addr;
177 const char *dlpi_name;
178 const ElfW(Phdr) *dlpi_phdr;
179 ElfW(Half) dlpi_phnum;
180 unsigned long long int dlpi_adds;
181 unsigned long long int dlpi_subs;
185 phdr = info->dlpi_phdr;
186 load_base = info->dlpi_addr;
187 p_eh_frame_hdr = NULL;
190 struct frame_hdr_cache_element *prev_cache_entry = NULL,
191 *last_cache_entry = NULL;
193 if (data->check_cache && size >= sizeof (struct ext_dl_phdr_info))
195 static unsigned long long adds = -1ULL, subs;
196 struct ext_dl_phdr_info *einfo = (struct ext_dl_phdr_info *) info;
198 /* We use a least recently used cache replacement policy. Also,
199 the most recently used cache entries are placed at the head
200 of the search chain. */
202 if (einfo->dlpi_adds == adds && einfo->dlpi_subs == subs)
204 /* Find data->pc in shared library cache.
205 Set load_base, p_eh_frame_hdr and p_dynamic
206 plus match from the cache and goto
207 "Read .eh_frame_hdr header." below. */
209 struct frame_hdr_cache_element *cache_entry;
211 for (cache_entry = frame_hdr_cache_head;
213 cache_entry = cache_entry->link)
215 if (data->pc >= cache_entry->pc_low
216 && data->pc < cache_entry->pc_high)
218 load_base = cache_entry->load_base;
219 p_eh_frame_hdr = cache_entry->p_eh_frame_hdr;
220 p_dynamic = cache_entry->p_dynamic;
222 /* And move the entry we're using to the head. */
223 if (cache_entry != frame_hdr_cache_head)
225 prev_cache_entry->link = cache_entry->link;
226 cache_entry->link = frame_hdr_cache_head;
227 frame_hdr_cache_head = cache_entry;
232 last_cache_entry = cache_entry;
233 /* Exit early if we found an unused entry. */
234 if ((cache_entry->pc_low | cache_entry->pc_high) == 0)
236 if (cache_entry->link != NULL)
237 prev_cache_entry = cache_entry;
242 adds = einfo->dlpi_adds;
243 subs = einfo->dlpi_subs;
244 /* Initialize the cache. Create a chain of cache entries,
245 with the final one terminated by a NULL link. */
247 for (i = 0; i < FRAME_HDR_CACHE_SIZE; i++)
249 frame_hdr_cache[i].pc_low = 0;
250 frame_hdr_cache[i].pc_high = 0;
251 frame_hdr_cache[i].link = &frame_hdr_cache[i+1];
253 frame_hdr_cache[i-1].link = NULL;
254 frame_hdr_cache_head = &frame_hdr_cache[0];
255 data->check_cache = 0;
259 /* Make sure struct dl_phdr_info is at least as big as we need. */
260 if (size < offsetof (struct dl_phdr_info, dlpi_phnum)
261 + sizeof (info->dlpi_phnum))
264 /* See if PC falls into one of the loaded segments. Find the eh_frame
265 segment at the same time. */
266 for (n = info->dlpi_phnum; --n >= 0; phdr++)
268 if (phdr->p_type == PT_LOAD)
270 _Unwind_Ptr vaddr = (_Unwind_Ptr)
271 __RELOC_POINTER (phdr->p_vaddr, load_base);
272 if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz)
276 pc_high = vaddr + phdr->p_memsz;
279 else if (phdr->p_type == PT_GNU_EH_FRAME)
280 p_eh_frame_hdr = phdr;
281 #ifdef PT_SUNW_UNWIND
282 /* Sun ld emits PT_SUNW_UNWIND .eh_frame_hdr sections instead of
283 PT_SUNW_EH_FRAME/PT_GNU_EH_FRAME, so accept them as well. */
284 else if (phdr->p_type == PT_SUNW_UNWIND)
285 p_eh_frame_hdr = phdr;
287 else if (phdr->p_type == PT_DYNAMIC)
294 if (size >= sizeof (struct ext_dl_phdr_info))
296 /* Move the cache entry we're about to overwrite to the head of
297 the list. If either last_cache_entry or prev_cache_entry are
298 NULL, that cache entry is already at the head. */
299 if (last_cache_entry != NULL && prev_cache_entry != NULL)
301 prev_cache_entry->link = last_cache_entry->link;
302 last_cache_entry->link = frame_hdr_cache_head;
303 frame_hdr_cache_head = last_cache_entry;
306 frame_hdr_cache_head->load_base = load_base;
307 frame_hdr_cache_head->p_eh_frame_hdr = p_eh_frame_hdr;
308 frame_hdr_cache_head->p_dynamic = p_dynamic;
309 frame_hdr_cache_head->pc_low = pc_low;
310 frame_hdr_cache_head->pc_high = pc_high;
318 /* Read .eh_frame_hdr header. */
319 hdr = (const struct unw_eh_frame_hdr *)
320 __RELOC_POINTER (p_eh_frame_hdr->p_vaddr, load_base);
321 if (hdr->version != 1)
324 #ifdef CRT_GET_RFIB_DATA
329 /* For dynamically linked executables and shared libraries,
330 DT_PLTGOT is the gp value for that object. */
331 ElfW(Dyn) *dyn = (ElfW(Dyn) *)
332 __RELOC_POINTER (p_dynamic->p_vaddr, load_base);
333 for (; dyn->d_tag != DT_NULL ; dyn++)
334 if (dyn->d_tag == DT_PLTGOT)
336 data->dbase = (void *) dyn->d_un.d_ptr;
337 #if defined __linux__
338 /* On IA-32 Linux, _DYNAMIC is writable and GLIBC has
340 #elif defined __sun__ && defined __svr4__
341 /* On Solaris 2/x86, we need to do this ourselves. */
342 data->dbase += load_base;
347 # elif defined __FRV_FDPIC__ && defined __linux__
348 data->dbase = load_base.got_value;
349 # elif defined __x86_64__ && defined __sun__ && defined __svr4__
350 /* While CRT_GET_RFIB_DATA is also defined for 64-bit Solaris 10+/x86, it
351 doesn't apply since it uses DW_EH_PE_pcrel encoding. */
353 # error What is DW_EH_PE_datarel base on this platform?
357 p = read_encoded_value_with_base (hdr->eh_frame_ptr_enc,
358 base_from_cb_data (hdr->eh_frame_ptr_enc,
360 (const unsigned char *) (hdr + 1),
363 /* We require here specific table encoding to speed things up.
364 Also, DW_EH_PE_datarel here means using PT_GNU_EH_FRAME start
365 as base, not the processor specific DW_EH_PE_datarel. */
366 if (hdr->fde_count_enc != DW_EH_PE_omit
367 && hdr->table_enc == (DW_EH_PE_datarel | DW_EH_PE_sdata4))
369 _Unwind_Ptr fde_count;
371 p = read_encoded_value_with_base (hdr->fde_count_enc,
372 base_from_cb_data (hdr->fde_count_enc,
375 /* Shouldn't happen. */
378 if ((((_Unwind_Ptr) p) & 3) == 0)
381 signed initial_loc __attribute__ ((mode (SI)));
382 signed fde __attribute__ ((mode (SI)));
384 const struct fde_table *table = (const struct fde_table *) p;
386 _Unwind_Ptr data_base = (_Unwind_Ptr) hdr;
388 unsigned int f_enc, f_enc_size;
392 if (data->pc < table[0].initial_loc + data_base)
394 else if (data->pc < table[mid].initial_loc + data_base)
402 if (data->pc < table[mid].initial_loc + data_base)
404 else if (data->pc >= table[mid + 1].initial_loc + data_base)
410 gcc_assert (lo < hi);
413 f = (fde *) (table[mid].fde + data_base);
414 f_enc = get_fde_encoding (f);
415 f_enc_size = size_of_encoded_value (f_enc);
416 read_encoded_value_with_base (f_enc & 0x0f, 0,
417 &f->pc_begin[f_enc_size], &range);
418 if (data->pc < table[mid].initial_loc + data_base + range)
420 data->func = (void *) (table[mid].initial_loc + data_base);
425 /* We have no sorted search table, so need to go the slow way.
426 As soon as GLIBC will provide API so to notify that a library has been
427 removed, we could cache this (and thus use search_object). */
429 ob.tbase = data->tbase;
430 ob.dbase = data->dbase;
431 ob.u.single = (fde *) eh_frame;
433 ob.s.b.mixed_encoding = 1; /* Need to assume worst case. */
434 data->ret = linear_search_fdes (&ob, (fde *) eh_frame, (void *) data->pc);
435 if (data->ret != NULL)
438 unsigned int encoding = get_fde_encoding (data->ret);
440 read_encoded_value_with_base (encoding,
441 base_from_cb_data (encoding, data),
442 data->ret->pc_begin, &func);
443 data->func = (void *) func;
449 _Unwind_Find_FDE (void *pc, struct dwarf_eh_bases *bases)
451 struct unw_eh_callback_data data;
454 ret = _Unwind_Find_registered_FDE (pc, bases);
458 data.pc = (_Unwind_Ptr) pc;
463 data.check_cache = 1;
465 if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0)
470 bases->tbase = data.tbase;
471 bases->dbase = data.dbase;
472 bases->func = data.func;
478 /* Prevent multiple include of header files. */
479 #define _Unwind_Find_FDE _Unwind_Find_FDE
480 #include "unwind-dw2-fde.c"
483 #if defined (USE_GAS_SYMVER) && defined (SHARED) && defined (USE_LIBUNWIND_EXCEPTIONS)
484 alias (_Unwind_Find_FDE);