1/* Find entry breakpoint locations for a function.
2   Copyright (C) 2005-2009 Red Hat, Inc.
3   This file is part of elfutils.
4
5   This file is free software; you can redistribute it and/or modify
6   it under the terms of either
7
8     * the GNU Lesser General Public License as published by the Free
9       Software Foundation; either version 3 of the License, or (at
10       your option) any later version
11
12   or
13
14     * the GNU General Public License as published by the Free
15       Software Foundation; either version 2 of the License, or (at
16       your option) any later version
17
18   or both in parallel, as here.
19
20   elfutils is distributed in the hope that it will be useful, but
21   WITHOUT ANY WARRANTY; without even the implied warranty of
22   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
23   General Public License for more details.
24
25   You should have received copies of the GNU General Public License and
26   the GNU Lesser General Public License along with this program.  If
27   not, see <http://www.gnu.org/licenses/>.  */
28
29#ifdef HAVE_CONFIG_H
30# include <config.h>
31#endif
32#include "libdwP.h"
33#include <dwarf.h>
34#include <stdlib.h>
35
36
37/* Add one breakpoint location to the result vector.  */
38static inline int
39add_bkpt (Dwarf_Addr pc, Dwarf_Addr **bkpts, int *pnbkpts)
40{
41  Dwarf_Addr *newlist = realloc (*bkpts, ++(*pnbkpts) * sizeof newlist[0]);
42  if (newlist == NULL)
43    {
44      free (*bkpts);
45      *bkpts = NULL;
46      __libdw_seterrno (DWARF_E_NOMEM);
47      return -1;
48    }
49  newlist[*pnbkpts - 1] = pc;
50  *bkpts = newlist;
51  return *pnbkpts;
52}
53
54/* Fallback result, break at the entrypc/lowpc value.  */
55static inline int
56entrypc_bkpt (Dwarf_Die *die, Dwarf_Addr **bkpts, int *pnbkpts)
57{
58  Dwarf_Addr pc;
59  return INTUSE(dwarf_entrypc) (die, &pc) < 0 ? -1 : add_bkpt (pc, bkpts, pnbkpts);
60}
61
62/* Search a contiguous PC range for prologue-end markers.
63   If DWARF, look for proper markers.
64   Failing that, if ADHOC, look for the ad hoc convention.  */
65static inline int
66search_range (Dwarf_Addr low, Dwarf_Addr high,
67	      bool dwarf, bool adhoc,
68              Dwarf_Lines *lines, size_t nlines,
69              Dwarf_Addr **bkpts, int *pnbkpts)
70{
71      size_t l = 0, u = nlines;
72      while (l < u)
73	{
74	  size_t idx = (l + u) / 2;
75	  if (lines->info[idx].addr < low)
76	    l = idx + 1;
77	  else if (lines->info[idx].addr > low)
78	    u = idx;
79	  else if (lines->info[idx].end_sequence)
80	    l = idx + 1;
81	  else
82	    {
83	      l = idx;
84	      break;
85	    }
86	}
87      if (l < u)
88	{
89	  if (dwarf)
90	    for (size_t i = l; i < u && lines->info[i].addr < high; ++i)
91	      if (lines->info[i].prologue_end
92		  && add_bkpt (lines->info[i].addr, bkpts, pnbkpts) < 0)
93		return -1;
94	  if (adhoc && *pnbkpts == 0)
95	    while (++l < nlines && lines->info[l].addr < high)
96	      if (!lines->info[l].end_sequence)
97		return add_bkpt (lines->info[l].addr, bkpts, pnbkpts);
98	  return *pnbkpts;
99	}
100      __libdw_seterrno (DWARF_E_INVALID_DWARF);
101      return -1;
102}
103
104int
105dwarf_entry_breakpoints (Dwarf_Die *die, Dwarf_Addr **bkpts)
106{
107  int nbkpts = 0;
108  *bkpts = NULL;
109
110  /* Fetch the CU's line records to look for this DIE's addresses.  */
111  Dwarf_Die cudie = CUDIE (die->cu);
112  Dwarf_Lines *lines;
113  size_t nlines;
114  if (INTUSE(dwarf_getsrclines) (&cudie, &lines, &nlines) < 0)
115    {
116      int error = INTUSE (dwarf_errno) ();
117      if (error == 0)		/* CU has no DW_AT_stmt_list.  */
118	return entrypc_bkpt (die, bkpts, &nbkpts);
119      __libdw_seterrno (error);
120      return -1;
121    }
122
123  /* Search each contiguous address range for DWARF prologue_end markers.  */
124
125  Dwarf_Addr base;
126  Dwarf_Addr begin;
127  Dwarf_Addr end;
128  ptrdiff_t offset = INTUSE(dwarf_ranges) (die, 0, &base, &begin, &end);
129  if (offset < 0)
130    return -1;
131
132  /* Most often there is a single contiguous PC range for the DIE.  */
133  if (offset == 1)
134    return search_range (begin, end, true, true, lines, nlines, bkpts, &nbkpts)
135        ?: entrypc_bkpt (die, bkpts, &nbkpts);
136
137  Dwarf_Addr lowpc = (Dwarf_Addr) -1l;
138  Dwarf_Addr highpc = (Dwarf_Addr) -1l;
139  while (offset > 0)
140    {
141      /* We have an address range entry.  */
142      if (search_range (begin, end, true, false,
143                        lines, nlines, bkpts, &nbkpts) < 0)
144	return -1;
145
146      if (begin < lowpc)
147	{
148	  lowpc = begin;
149	  highpc = end;
150	}
151
152      offset = INTUSE(dwarf_ranges) (die, offset, &base, &begin, &end);
153    }
154
155  /* If we didn't find any proper DWARF markers, then look in the
156     lowest-addressed range for an ad hoc marker.  Failing that,
157     fall back to just using the entrypc value.  */
158  return (nbkpts
159	  ?: (lowpc == (Dwarf_Addr) -1l ? 0
160	      : search_range (lowpc, highpc, false, true,
161	                      lines, nlines, bkpts, &nbkpts))
162	  ?: entrypc_bkpt (die, bkpts, &nbkpts));
163}
164