1/* Enumerate the PC ranges covered by a DIE.
2   Copyright (C) 2005, 2007, 2009 Red Hat, Inc.
3   This file is part of Red Hat elfutils.
4
5   Red Hat elfutils is free software; you can redistribute it and/or modify
6   it under the terms of the GNU General Public License as published by the
7   Free Software Foundation; version 2 of the License.
8
9   Red Hat elfutils is distributed in the hope that it will be useful, but
10   WITHOUT ANY WARRANTY; without even the implied warranty of
11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12   General Public License for more details.
13
14   You should have received a copy of the GNU General Public License along
15   with Red Hat elfutils; if not, write to the Free Software Foundation,
16   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
17
18   In addition, as a special exception, Red Hat, Inc. gives You the
19   additional right to link the code of Red Hat elfutils with code licensed
20   under any Open Source Initiative certified open source license
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22   distribution of source code with any binary distribution and to
23   distribute linked combinations of the two.  Non-GPL Code permitted under
24   this exception must only link to the code of Red Hat elfutils through
25   those well defined interfaces identified in the file named EXCEPTION
26   found in the source code files (the "Approved Interfaces").  The files
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35   code used in conjunction with Red Hat elfutils except the Non-GPL Code
36   covered by this exception.  If you modify this file, you may extend this
37   exception to your version of the file, but you are not obligated to do
38   so.  If you do not wish to provide this exception without modification,
39   you must delete this exception statement from your version and license
40   this file solely under the GPL without exception.
41
42   Red Hat elfutils is an included package of the Open Invention Network.
43   An included package of the Open Invention Network is a package for which
44   Open Invention Network licensees cross-license their patents.  No patent
45   license is granted, either expressly or impliedly, by designation as an
46   included package.  Should you wish to participate in the Open Invention
47   Network licensing program, please visit www.openinventionnetwork.com
48   <http://www.openinventionnetwork.com>.  */
49
50#ifdef HAVE_CONFIG_H
51# include <config.h>
52#endif
53
54#include "libdwP.h"
55#include <dwarf.h>
56#include <assert.h>
57
58/* Read up begin/end pair and increment read pointer.
59    - If it's normal range record, set up `*beginp' and `*endp' and return 0.
60    - If it's base address selection record, set up `*basep' and return 1.
61    - If it's end of rangelist, don't set anything and return 2
62    - If an error occurs, don't set anything and return -1.  */
63internal_function int
64__libdw_read_begin_end_pair_inc (Dwarf *dbg, int sec_index,
65				 unsigned char **addrp, int width,
66				 Dwarf_Addr *beginp, Dwarf_Addr *endp,
67				 Dwarf_Addr *basep)
68{
69  Dwarf_Addr escape = (width == 8 ? (Elf64_Addr) -1
70		       : (Elf64_Addr) (Elf32_Addr) -1);
71  Dwarf_Addr begin;
72  Dwarf_Addr end;
73
74  unsigned char *addr = *addrp;
75  bool begin_relocated = READ_AND_RELOCATE (__libdw_relocate_address, begin);
76  bool end_relocated = READ_AND_RELOCATE (__libdw_relocate_address, end);
77  *addrp = addr;
78
79  /* Unrelocated escape for begin means base address selection.  */
80  if (begin == escape && !begin_relocated)
81    {
82      if (unlikely (end == escape))
83	{
84	  __libdw_seterrno (DWARF_E_INVALID_DWARF);
85	  return -1;
86	}
87
88      if (basep != NULL)
89	*basep = end;
90      return 1;
91    }
92
93  /* Unrelocated pair of zeroes means end of range list.  */
94  if (begin == 0 && end == 0 && !begin_relocated && !end_relocated)
95    return 2;
96
97  /* Don't check for begin_relocated == end_relocated.  Serve the data
98     to the client even though it may be buggy.  */
99  *beginp = begin;
100  *endp = end;
101
102  return 0;
103}
104
105ptrdiff_t
106dwarf_ranges (Dwarf_Die *die, ptrdiff_t offset, Dwarf_Addr *basep,
107	      Dwarf_Addr *startp, Dwarf_Addr *endp)
108{
109  if (die == NULL)
110    return -1;
111
112  if (offset == 0
113      /* Usually there is a single contiguous range.  */
114      && INTUSE(dwarf_highpc) (die, endp) == 0
115      && INTUSE(dwarf_lowpc) (die, startp) == 0)
116    /* A offset into .debug_ranges will never be 1, it must be at least a
117       multiple of 4.  So we can return 1 as a special case value to mark
118       there are no ranges to look for on the next call.  */
119    return 1;
120
121  if (offset == 1)
122    return 0;
123
124  /* We have to look for a noncontiguous range.  */
125
126  const Elf_Data *d = die->cu->dbg->sectiondata[IDX_debug_ranges];
127  if (d == NULL && offset != 0)
128    {
129      __libdw_seterrno (DWARF_E_NO_DEBUG_RANGES);
130      return -1;
131    }
132
133  unsigned char *readp;
134  unsigned char *readendp;
135  if (offset == 0)
136    {
137      Dwarf_Attribute attr_mem;
138      Dwarf_Attribute *attr = INTUSE(dwarf_attr) (die, DW_AT_ranges,
139						  &attr_mem);
140      if (attr == NULL)
141	/* No PC attributes in this DIE at all, so an empty range list.  */
142	return 0;
143
144      Dwarf_Word start_offset;
145      if ((readp = __libdw_formptr (attr, IDX_debug_ranges,
146				    DWARF_E_NO_DEBUG_RANGES,
147				    &readendp, &start_offset)) == NULL)
148	return -1;
149
150      offset = start_offset;
151      assert ((Dwarf_Word) offset == start_offset);
152
153      /* Fetch the CU's base address.  */
154      Dwarf_Die cudie = CUDIE (attr->cu);
155
156      /* Find the base address of the compilation unit.  It will
157	 normally be specified by DW_AT_low_pc.  In DWARF-3 draft 4,
158	 the base address could be overridden by DW_AT_entry_pc.  It's
159	 been removed, but GCC emits DW_AT_entry_pc and not DW_AT_lowpc
160	 for compilation units with discontinuous ranges.  */
161      if (unlikely (INTUSE(dwarf_lowpc) (&cudie, basep) != 0)
162	  && INTUSE(dwarf_formaddr) (INTUSE(dwarf_attr) (&cudie,
163							 DW_AT_entry_pc,
164							 &attr_mem),
165				     basep) != 0)
166	{
167	  if (INTUSE(dwarf_errno) () == 0)
168	    {
169	    invalid:
170	      __libdw_seterrno (DWARF_E_INVALID_DWARF);
171	    }
172	  return -1;
173	}
174    }
175  else
176    {
177      if (__libdw_offset_in_section (die->cu->dbg,
178				     IDX_debug_ranges, offset, 1))
179	return -1l;
180
181      readp = d->d_buf + offset;
182      readendp = d->d_buf + d->d_size;
183    }
184
185 next:
186  if (readendp - readp < die->cu->address_size * 2)
187    goto invalid;
188
189  Dwarf_Addr begin;
190  Dwarf_Addr end;
191
192  switch (__libdw_read_begin_end_pair_inc (die->cu->dbg, IDX_debug_ranges,
193					   &readp, die->cu->address_size,
194					   &begin, &end, basep))
195    {
196    case 0:
197      break;
198    case 1:
199      goto next;
200    case 2:
201      return 0;
202    default:
203      return -1l;
204    }
205
206  /* We have an address range entry.  */
207  *startp = *basep + begin;
208  *endp = *basep + end;
209  return readp - (unsigned char *) d->d_buf;
210}
211INTDEF (dwarf_ranges)
212