summaryrefslogtreecommitdiff
path: root/gcc/unwind-dw2-fde-glibc.c
blob: 1d2930df66864de0e087fc0f0b73406e3a7620a6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
/* Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
   Contributed by Jakub Jelinek <jakub@redhat.com>.

   This file is part of GCC.

   GCC is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   GCC is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GCC; see the file COPYING.  If not, write to
   the Free Software Foundation, 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

/* As a special exception, if you link this library with other files,
   some of which are compiled with GCC, to produce an executable,
   this library does not by itself cause the resulting executable
   to be covered by the GNU General Public License.
   This exception does not however invalidate any other reasons why
   the executable file might be covered by the GNU General Public License.  */

/* Locate the FDE entry for a given address, using PT_GNU_EH_FRAME ELF
   segment and dl_iterate_phdr to avoid register/deregister calls at
   DSO load/unload.  */

#ifndef _GNU_SOURCE
#define _GNU_SOURCE 1
#endif

#include "auto-host.h" /* For HAVE_LD_EH_FRAME_HDR.  */
#include "tconfig.h"
#include "tsystem.h"
#ifndef inhibit_libc
#include <link.h>
#endif
#include "coretypes.h"
#include "tm.h"
#include "dwarf2.h"
#include "unwind.h"
#define NO_BASE_OF_ENCODED_VALUE
#include "unwind-pe.h"
#include "unwind-dw2-fde.h"
#include "gthr.h"

#if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \
    && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2) \
	|| (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && defined(DT_CONFIG)))

#ifndef __RELOC_POINTER
# define __RELOC_POINTER(ptr, base) ((ptr) + (base))
#endif

static const fde * _Unwind_Find_registered_FDE (void *pc, struct dwarf_eh_bases *bases);

#define _Unwind_Find_FDE _Unwind_Find_registered_FDE
#include "unwind-dw2-fde.c"
#undef _Unwind_Find_FDE

#ifndef PT_GNU_EH_FRAME
#define PT_GNU_EH_FRAME (PT_LOOS + 0x474e550)
#endif

struct unw_eh_callback_data
{
  _Unwind_Ptr pc;
  void *tbase;
  void *dbase;
  void *func;
  const fde *ret;
};

struct unw_eh_frame_hdr
{
  unsigned char version;
  unsigned char eh_frame_ptr_enc;
  unsigned char fde_count_enc;
  unsigned char table_enc;
};

/* Like base_of_encoded_value, but take the base from a struct
   unw_eh_callback_data instead of an _Unwind_Context.  */

static _Unwind_Ptr
base_from_cb_data (unsigned char encoding, struct unw_eh_callback_data *data)
{
  if (encoding == DW_EH_PE_omit)
    return 0;

  switch (encoding & 0x70)
    {
    case DW_EH_PE_absptr:
    case DW_EH_PE_pcrel:
    case DW_EH_PE_aligned:
      return 0;

    case DW_EH_PE_textrel:
      return (_Unwind_Ptr) data->tbase;
    case DW_EH_PE_datarel:
      return (_Unwind_Ptr) data->dbase;
    }
  abort ();
}

static int
_Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr)
{
  struct unw_eh_callback_data *data = (struct unw_eh_callback_data *) ptr;
  const ElfW(Phdr) *phdr, *p_eh_frame_hdr, *p_dynamic;
  long n, match;
#ifdef __FRV_FDPIC__
  struct elf32_fdpic_loadaddr load_base;
#else
  _Unwind_Ptr load_base;
#endif
  const unsigned char *p;
  const struct unw_eh_frame_hdr *hdr;
  _Unwind_Ptr eh_frame;
  struct object ob;

  /* Make sure struct dl_phdr_info is at least as big as we need.  */
  if (size < offsetof (struct dl_phdr_info, dlpi_phnum)
	     + sizeof (info->dlpi_phnum))
    return -1;

  match = 0;
  phdr = info->dlpi_phdr;
  load_base = info->dlpi_addr;
  p_eh_frame_hdr = NULL;
  p_dynamic = NULL;

  /* See if PC falls into one of the loaded segments.  Find the eh_frame
     segment at the same time.  */
  for (n = info->dlpi_phnum; --n >= 0; phdr++)
    {
      if (phdr->p_type == PT_LOAD)
	{
	  _Unwind_Ptr vaddr = (_Unwind_Ptr)
	    __RELOC_POINTER (phdr->p_vaddr, load_base);
	  if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz)
	    match = 1;
	}
      else if (phdr->p_type == PT_GNU_EH_FRAME)
	p_eh_frame_hdr = phdr;
      else if (phdr->p_type == PT_DYNAMIC)
	p_dynamic = phdr;
    }
  if (!match || !p_eh_frame_hdr)
    return 0;

  /* Read .eh_frame_hdr header.  */
  hdr = (const struct unw_eh_frame_hdr *)
    __RELOC_POINTER (p_eh_frame_hdr->p_vaddr, load_base);
  if (hdr->version != 1)
    return 1;

#ifdef CRT_GET_RFIB_DATA
# ifdef __i386__
  data->dbase = NULL;
  if (p_dynamic)
    {
      /* For dynamically linked executables and shared libraries,
	 DT_PLTGOT is the gp value for that object.  */
      ElfW(Dyn) *dyn = (ElfW(Dyn) *)
	__RELOC_POINTER (p_dynamic->p_vaddr, load_base);
      for (; dyn->d_tag != DT_NULL ; dyn++)
	if (dyn->d_tag == DT_PLTGOT)
	  {
	    /* On IA-32, _DYNAMIC is writable and GLIBC has relocated it.  */
	    data->dbase = (void *) dyn->d_un.d_ptr;
	    break;
	  }
    }
# elif defined __FRV_FDPIC__ && defined __linux__
  data->dbase = load_base.got_value;
# else
#  error What is DW_EH_PE_datarel base on this platform?
# endif
#endif

  p = read_encoded_value_with_base (hdr->eh_frame_ptr_enc,
				    base_from_cb_data (hdr->eh_frame_ptr_enc,
						       data),
				    (const unsigned char *) (hdr + 1),
				    &eh_frame);

  /* We require here specific table encoding to speed things up.
     Also, DW_EH_PE_datarel here means using PT_GNU_EH_FRAME start
     as base, not the processor specific DW_EH_PE_datarel.  */
  if (hdr->fde_count_enc != DW_EH_PE_omit
      && hdr->table_enc == (DW_EH_PE_datarel | DW_EH_PE_sdata4))
    {
      _Unwind_Ptr fde_count;

      p = read_encoded_value_with_base (hdr->fde_count_enc,
					base_from_cb_data (hdr->fde_count_enc,
							   data),
					p, &fde_count);
      /* Shouldn't happen.  */
      if (fde_count == 0)
	return 1;
      if ((((_Unwind_Ptr) p) & 3) == 0)
	{
	  struct fde_table {
	    signed initial_loc __attribute__ ((mode (SI)));
	    signed fde __attribute__ ((mode (SI)));
	  };
	  const struct fde_table *table = (const struct fde_table *) p;
	  size_t lo, hi, mid;
	  _Unwind_Ptr data_base = (_Unwind_Ptr) hdr;
	  fde *f;
	  unsigned int f_enc, f_enc_size;
	  _Unwind_Ptr range;

	  mid = fde_count - 1;
	  if (data->pc < table[0].initial_loc + data_base)
	    return 1;
	  else if (data->pc < table[mid].initial_loc + data_base)
	    {
	      lo = 0;
	      hi = mid;

	      while (lo < hi)
		{
		  mid = (lo + hi) / 2;
		  if (data->pc < table[mid].initial_loc + data_base)
		    hi = mid;
		  else if (data->pc >= table[mid + 1].initial_loc + data_base)
		    lo = mid + 1;
		  else
		    break;
		}

	      if (lo >= hi)
		__gxx_abort ();
	    }

	  f = (fde *) (table[mid].fde + data_base);
	  f_enc = get_fde_encoding (f);
	  f_enc_size = size_of_encoded_value (f_enc);
	  read_encoded_value_with_base (f_enc & 0x0f, 0,
					&f->pc_begin[f_enc_size], &range);
	  if (data->pc < table[mid].initial_loc + data_base + range)
	    data->ret = f;
	  data->func = (void *) (table[mid].initial_loc + data_base);
	  return 1;
	}
    }

  /* We have no sorted search table, so need to go the slow way.
     As soon as GLIBC will provide API so to notify that a library has been
     removed, we could cache this (and thus use search_object).  */
  ob.pc_begin = NULL;
  ob.tbase = data->tbase;
  ob.dbase = data->dbase;
  ob.u.single = (fde *) eh_frame;
  ob.s.i = 0;
  ob.s.b.mixed_encoding = 1;  /* Need to assume worst case.  */
  data->ret = linear_search_fdes (&ob, (fde *) eh_frame, (void *) data->pc);
  if (data->ret != NULL)
    {
      unsigned int encoding = get_fde_encoding (data->ret);
      read_encoded_value_with_base (encoding,
				    base_from_cb_data (encoding, data),
				    data->ret->pc_begin,
				    (_Unwind_Ptr *)&data->func);
    }
  return 1;
}

const fde *
_Unwind_Find_FDE (void *pc, struct dwarf_eh_bases *bases)
{
  struct unw_eh_callback_data data;
  const fde *ret;

  ret = _Unwind_Find_registered_FDE (pc, bases);
  if (ret != NULL)
    return ret;

  data.pc = (_Unwind_Ptr) pc;
  data.tbase = NULL;
  data.dbase = NULL;
  data.func = NULL;
  data.ret = NULL;

  if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0)
    return NULL;

  if (data.ret)
    {
      bases->tbase = data.tbase;
      bases->dbase = data.dbase;
      bases->func = data.func;
    }
  return data.ret;
}

#else
/* Prevent multiple include of header files.  */
#define _Unwind_Find_FDE _Unwind_Find_FDE
#include "unwind-dw2-fde.c"
#endif