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
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(TARGET_DL_ITERATE_PHDR) \
65 && (defined(__OpenBSD__) || defined(__NetBSD__))
66 # define ElfW(n) Elf_##n
67 # define USE_PT_GNU_EH_FRAME
70 #if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \
71 && defined(TARGET_DL_ITERATE_PHDR) \
72 && defined(__sun__) && defined(__svr4__)
73 # define USE_PT_GNU_EH_FRAME
76 #if defined(USE_PT_GNU_EH_FRAME)
80 #ifndef __RELOC_POINTER
81 # define __RELOC_POINTER(ptr, base) ((ptr) + (base))
84 static const fde * _Unwind_Find_registered_FDE (void *pc, struct dwarf_eh_bases *bases);
86 #define _Unwind_Find_FDE _Unwind_Find_registered_FDE
87 #include "unwind-dw2-fde.c"
88 #undef _Unwind_Find_FDE
90 #ifndef PT_GNU_EH_FRAME
91 #define PT_GNU_EH_FRAME (PT_LOOS + 0x474e550)
94 struct unw_eh_callback_data
104 struct unw_eh_frame_hdr
106 unsigned char version;
107 unsigned char eh_frame_ptr_enc;
108 unsigned char fde_count_enc;
109 unsigned char table_enc;
112 #define FRAME_HDR_CACHE_SIZE 8
114 static struct frame_hdr_cache_element
118 _Unwind_Ptr load_base;
119 const ElfW(Phdr) *p_eh_frame_hdr;
120 const ElfW(Phdr) *p_dynamic;
121 struct frame_hdr_cache_element *link;
122 } frame_hdr_cache[FRAME_HDR_CACHE_SIZE];
124 static struct frame_hdr_cache_element *frame_hdr_cache_head;
126 /* Like base_of_encoded_value, but take the base from a struct
127 unw_eh_callback_data instead of an _Unwind_Context. */
130 base_from_cb_data (unsigned char encoding, struct unw_eh_callback_data *data)
132 if (encoding == DW_EH_PE_omit)
135 switch (encoding & 0x70)
137 case DW_EH_PE_absptr:
139 case DW_EH_PE_aligned:
142 case DW_EH_PE_textrel:
143 return (_Unwind_Ptr) data->tbase;
144 case DW_EH_PE_datarel:
145 return (_Unwind_Ptr) data->dbase;
152 _Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr)
154 struct unw_eh_callback_data *data = (struct unw_eh_callback_data *) ptr;
155 const ElfW(Phdr) *phdr, *p_eh_frame_hdr, *p_dynamic;
158 struct elf32_fdpic_loadaddr load_base;
160 _Unwind_Ptr load_base;
162 const unsigned char *p;
163 const struct unw_eh_frame_hdr *hdr;
164 _Unwind_Ptr eh_frame;
166 _Unwind_Ptr pc_low = 0, pc_high = 0;
168 struct ext_dl_phdr_info
170 ElfW(Addr) dlpi_addr;
171 const char *dlpi_name;
172 const ElfW(Phdr) *dlpi_phdr;
173 ElfW(Half) dlpi_phnum;
174 unsigned long long int dlpi_adds;
175 unsigned long long int dlpi_subs;
179 phdr = info->dlpi_phdr;
180 load_base = info->dlpi_addr;
181 p_eh_frame_hdr = NULL;
184 struct frame_hdr_cache_element *prev_cache_entry = NULL,
185 *last_cache_entry = NULL;
187 if (data->check_cache && size >= sizeof (struct ext_dl_phdr_info))
189 static unsigned long long adds = -1ULL, subs;
190 struct ext_dl_phdr_info *einfo = (struct ext_dl_phdr_info *) info;
192 /* We use a least recently used cache replacement policy. Also,
193 the most recently used cache entries are placed at the head
194 of the search chain. */
196 if (einfo->dlpi_adds == adds && einfo->dlpi_subs == subs)
198 /* Find data->pc in shared library cache.
199 Set load_base, p_eh_frame_hdr and p_dynamic
200 plus match from the cache and goto
201 "Read .eh_frame_hdr header." below. */
203 struct frame_hdr_cache_element *cache_entry;
205 for (cache_entry = frame_hdr_cache_head;
207 cache_entry = cache_entry->link)
209 if (data->pc >= cache_entry->pc_low
210 && data->pc < cache_entry->pc_high)
212 load_base = cache_entry->load_base;
213 p_eh_frame_hdr = cache_entry->p_eh_frame_hdr;
214 p_dynamic = cache_entry->p_dynamic;
216 /* And move the entry we're using to the head. */
217 if (cache_entry != frame_hdr_cache_head)
219 prev_cache_entry->link = cache_entry->link;
220 cache_entry->link = frame_hdr_cache_head;
221 frame_hdr_cache_head = cache_entry;
226 last_cache_entry = cache_entry;
227 /* Exit early if we found an unused entry. */
228 if ((cache_entry->pc_low | cache_entry->pc_high) == 0)
230 if (cache_entry->link != NULL)
231 prev_cache_entry = cache_entry;
236 adds = einfo->dlpi_adds;
237 subs = einfo->dlpi_subs;
238 /* Initialize the cache. Create a chain of cache entries,
239 with the final one terminated by a NULL link. */
241 for (i = 0; i < FRAME_HDR_CACHE_SIZE; i++)
243 frame_hdr_cache[i].pc_low = 0;
244 frame_hdr_cache[i].pc_high = 0;
245 frame_hdr_cache[i].link = &frame_hdr_cache[i+1];
247 frame_hdr_cache[i-1].link = NULL;
248 frame_hdr_cache_head = &frame_hdr_cache[0];
249 data->check_cache = 0;
253 /* Make sure struct dl_phdr_info is at least as big as we need. */
254 if (size < offsetof (struct dl_phdr_info, dlpi_phnum)
255 + sizeof (info->dlpi_phnum))
258 /* See if PC falls into one of the loaded segments. Find the eh_frame
259 segment at the same time. */
260 for (n = info->dlpi_phnum; --n >= 0; phdr++)
262 if (phdr->p_type == PT_LOAD)
264 _Unwind_Ptr vaddr = (_Unwind_Ptr)
265 __RELOC_POINTER (phdr->p_vaddr, load_base);
266 if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz)
270 pc_high = vaddr + phdr->p_memsz;
273 else if (phdr->p_type == PT_GNU_EH_FRAME)
274 p_eh_frame_hdr = phdr;
275 #ifdef PT_SUNW_UNWIND
276 /* Sun ld emits PT_SUNW_UNWIND .eh_frame_hdr sections instead of
277 PT_SUNW_EH_FRAME/PT_GNU_EH_FRAME, so accept them as well. */
278 else if (phdr->p_type == PT_SUNW_UNWIND)
279 p_eh_frame_hdr = phdr;
281 else if (phdr->p_type == PT_DYNAMIC)
288 if (size >= sizeof (struct ext_dl_phdr_info))
290 /* Move the cache entry we're about to overwrite to the head of
291 the list. If either last_cache_entry or prev_cache_entry are
292 NULL, that cache entry is already at the head. */
293 if (last_cache_entry != NULL && prev_cache_entry != NULL)
295 prev_cache_entry->link = last_cache_entry->link;
296 last_cache_entry->link = frame_hdr_cache_head;
297 frame_hdr_cache_head = last_cache_entry;
300 frame_hdr_cache_head->load_base = load_base;
301 frame_hdr_cache_head->p_eh_frame_hdr = p_eh_frame_hdr;
302 frame_hdr_cache_head->p_dynamic = p_dynamic;
303 frame_hdr_cache_head->pc_low = pc_low;
304 frame_hdr_cache_head->pc_high = pc_high;
312 /* Read .eh_frame_hdr header. */
313 hdr = (const struct unw_eh_frame_hdr *)
314 __RELOC_POINTER (p_eh_frame_hdr->p_vaddr, load_base);
315 if (hdr->version != 1)
318 #ifdef CRT_GET_RFIB_DATA
323 /* For dynamically linked executables and shared libraries,
324 DT_PLTGOT is the gp value for that object. */
325 ElfW(Dyn) *dyn = (ElfW(Dyn) *)
326 __RELOC_POINTER (p_dynamic->p_vaddr, load_base);
327 for (; dyn->d_tag != DT_NULL ; dyn++)
328 if (dyn->d_tag == DT_PLTGOT)
330 data->dbase = (void *) dyn->d_un.d_ptr;
331 #if defined __linux__
332 /* On IA-32 Linux, _DYNAMIC is writable and GLIBC has
334 #elif defined __sun__ && defined __svr4__
335 /* On Solaris 2/x86, we need to do this ourselves. */
336 data->dbase += load_base;
341 # elif defined __FRV_FDPIC__ && defined __linux__
342 data->dbase = load_base.got_value;
343 # elif defined __x86_64__ && defined __sun__ && defined __svr4__
344 /* While CRT_GET_RFIB_DATA is also defined for 64-bit Solaris 10+/x86, it
345 doesn't apply since it uses DW_EH_PE_pcrel encoding. */
347 # error What is DW_EH_PE_datarel base on this platform?
351 p = read_encoded_value_with_base (hdr->eh_frame_ptr_enc,
352 base_from_cb_data (hdr->eh_frame_ptr_enc,
354 (const unsigned char *) (hdr + 1),
357 /* We require here specific table encoding to speed things up.
358 Also, DW_EH_PE_datarel here means using PT_GNU_EH_FRAME start
359 as base, not the processor specific DW_EH_PE_datarel. */
360 if (hdr->fde_count_enc != DW_EH_PE_omit
361 && hdr->table_enc == (DW_EH_PE_datarel | DW_EH_PE_sdata4))
363 _Unwind_Ptr fde_count;
365 p = read_encoded_value_with_base (hdr->fde_count_enc,
366 base_from_cb_data (hdr->fde_count_enc,
369 /* Shouldn't happen. */
372 if ((((_Unwind_Ptr) p) & 3) == 0)
375 signed initial_loc __attribute__ ((mode (SI)));
376 signed fde __attribute__ ((mode (SI)));
378 const struct fde_table *table = (const struct fde_table *) p;
380 _Unwind_Ptr data_base = (_Unwind_Ptr) hdr;
382 unsigned int f_enc, f_enc_size;
386 if (data->pc < table[0].initial_loc + data_base)
388 else if (data->pc < table[mid].initial_loc + data_base)
396 if (data->pc < table[mid].initial_loc + data_base)
398 else if (data->pc >= table[mid + 1].initial_loc + data_base)
404 gcc_assert (lo < hi);
407 f = (fde *) (table[mid].fde + data_base);
408 f_enc = get_fde_encoding (f);
409 f_enc_size = size_of_encoded_value (f_enc);
410 read_encoded_value_with_base (f_enc & 0x0f, 0,
411 &f->pc_begin[f_enc_size], &range);
412 if (data->pc < table[mid].initial_loc + data_base + range)
414 data->func = (void *) (table[mid].initial_loc + data_base);
419 /* We have no sorted search table, so need to go the slow way.
420 As soon as GLIBC will provide API so to notify that a library has been
421 removed, we could cache this (and thus use search_object). */
423 ob.tbase = data->tbase;
424 ob.dbase = data->dbase;
425 ob.u.single = (fde *) eh_frame;
427 ob.s.b.mixed_encoding = 1; /* Need to assume worst case. */
428 data->ret = linear_search_fdes (&ob, (fde *) eh_frame, (void *) data->pc);
429 if (data->ret != NULL)
432 unsigned int encoding = get_fde_encoding (data->ret);
434 read_encoded_value_with_base (encoding,
435 base_from_cb_data (encoding, data),
436 data->ret->pc_begin, &func);
437 data->func = (void *) func;
443 _Unwind_Find_FDE (void *pc, struct dwarf_eh_bases *bases)
445 struct unw_eh_callback_data data;
448 ret = _Unwind_Find_registered_FDE (pc, bases);
452 data.pc = (_Unwind_Ptr) pc;
457 data.check_cache = 1;
459 if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0)
464 bases->tbase = data.tbase;
465 bases->dbase = data.dbase;
466 bases->func = data.func;
472 /* Prevent multiple include of header files. */
473 #define _Unwind_Find_FDE _Unwind_Find_FDE
474 #include "unwind-dw2-fde.c"
477 #if defined (USE_GAS_SYMVER) && defined (SHARED) && defined (USE_LIBUNWIND_EXCEPTIONS)
478 alias (_Unwind_Find_FDE);