1 /* CIE reading.
2    Copyright (C) 2009-2010 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 
33 #include "cfi.h"
34 #include "encoded-value.h"
35 #include <assert.h>
36 #include <search.h>
37 #include <stdlib.h>
38 
39 
40 static int
compare_cie(const void * a,const void * b)41 compare_cie (const void *a, const void *b)
42 {
43   const struct dwarf_cie *cie1 = a;
44   const struct dwarf_cie *cie2 = b;
45   if (cie1->offset < cie2->offset)
46     return -1;
47   if (cie1->offset > cie2->offset)
48     return 1;
49   return 0;
50 }
51 
52 /* There is no CIE at OFFSET in the tree.  Add it.  */
53 static struct dwarf_cie *
intern_new_cie(Dwarf_CFI * cache,Dwarf_Off offset,const Dwarf_CIE * info)54 intern_new_cie (Dwarf_CFI *cache, Dwarf_Off offset, const Dwarf_CIE *info)
55 {
56   struct dwarf_cie *cie = malloc (sizeof (struct dwarf_cie));
57   if (cie == NULL)
58     {
59       __libdw_seterrno (DWARF_E_NOMEM);
60       return NULL;
61     }
62 
63   cie->offset = offset;
64   cie->code_alignment_factor = info->code_alignment_factor;
65   cie->data_alignment_factor = info->data_alignment_factor;
66   cie->return_address_register = info->return_address_register;
67 
68   cie->fde_augmentation_data_size = 0;
69   cie->sized_augmentation_data = false;
70   cie->signal_frame = false;
71 
72   cie->fde_encoding = DW_EH_PE_absptr;
73   cie->lsda_encoding = DW_EH_PE_omit;
74 
75   /* Grok the augmentation string and its data.  */
76   const uint8_t *data = info->augmentation_data;
77   for (const char *ap = info->augmentation; *ap != '\0'; ++ap)
78     {
79       uint8_t encoding;
80       switch (*ap)
81 	{
82 	case 'z':
83 	  cie->sized_augmentation_data = true;
84 	  continue;
85 
86 	case 'S':
87 	  cie->signal_frame = true;
88 	  continue;
89 
90 	case 'L':		/* LSDA pointer encoding byte.  */
91 	  cie->lsda_encoding = *data++;
92 	  if (!cie->sized_augmentation_data)
93 	    cie->fde_augmentation_data_size
94 	      += encoded_value_size (&cache->data->d, cache->e_ident,
95 				     cie->lsda_encoding, NULL);
96 	  continue;
97 
98 	case 'R':		/* FDE address encoding byte.  */
99 	  cie->fde_encoding = *data++;
100 	  continue;
101 
102 	case 'P':		/* Skip personality routine.  */
103 	  encoding = *data++;
104 	  data += encoded_value_size (&cache->data->d, cache->e_ident,
105 				      encoding, data);
106 	  continue;
107 
108 	default:
109 	  /* Unknown augmentation string.  If we have 'z' we can ignore it,
110 	     otherwise we must bail out.  */
111 	  if (cie->sized_augmentation_data)
112 	    continue;
113 	}
114       /* We only get here when we need to bail out.  */
115       break;
116     }
117 
118   if ((cie->fde_encoding & 0x0f) == DW_EH_PE_absptr)
119     {
120       /* Canonicalize encoding to a specific size.  */
121       assert (DW_EH_PE_absptr == 0);
122 
123       /* XXX should get from dwarf_next_cfi with v4 header.  */
124       uint_fast8_t address_size
125 	= cache->e_ident[EI_CLASS] == ELFCLASS32 ? 4 : 8;
126       switch (address_size)
127 	{
128 	case 8:
129 	  cie->fde_encoding |= DW_EH_PE_udata8;
130 	  break;
131 	case 4:
132 	  cie->fde_encoding |= DW_EH_PE_udata4;
133 	  break;
134 	default:
135 	  free (cie);
136 	  __libdw_seterrno (DWARF_E_INVALID_DWARF);
137 	  return NULL;
138 	}
139     }
140 
141   /* Save the initial instructions to be played out into initial state.  */
142   cie->initial_instructions = info->initial_instructions;
143   cie->initial_instructions_end = info->initial_instructions_end;
144   cie->initial_state = NULL;
145 
146   /* Add the new entry to the search tree.  */
147   if (tsearch (cie, &cache->cie_tree, &compare_cie) == NULL)
148     {
149       free (cie);
150       __libdw_seterrno (DWARF_E_NOMEM);
151       return NULL;
152     }
153 
154   return cie;
155 }
156 
157 /* Look up a CIE_pointer for random access.  */
158 struct dwarf_cie *
159 internal_function
__libdw_find_cie(Dwarf_CFI * cache,Dwarf_Off offset)160 __libdw_find_cie (Dwarf_CFI *cache, Dwarf_Off offset)
161 {
162   const struct dwarf_cie cie_key = { .offset = offset };
163   struct dwarf_cie **found = tfind (&cie_key, &cache->cie_tree, &compare_cie);
164   if (found != NULL)
165     return *found;
166 
167   /* We have not read this CIE yet.  Go find it.  */
168   Dwarf_Off next_offset = offset;
169   Dwarf_CFI_Entry entry;
170   int result = INTUSE(dwarf_next_cfi) (cache->e_ident,
171 				       &cache->data->d, CFI_IS_EH (cache),
172 				       offset, &next_offset, &entry);
173   if (result != 0 || entry.cie.CIE_id != DW_CIE_ID_64)
174     {
175       __libdw_seterrno (DWARF_E_INVALID_DWARF);
176       return NULL;
177     }
178 
179   /* If this happened to be what we would have read next, notice it.  */
180   if (cache->next_offset == offset)
181     cache->next_offset = next_offset;
182 
183   return intern_new_cie (cache, offset, &entry.cie);
184 }
185 
186 /* Enter a CIE encountered while reading through for FDEs.  */
187 void
188 internal_function
__libdw_intern_cie(Dwarf_CFI * cache,Dwarf_Off offset,const Dwarf_CIE * info)189 __libdw_intern_cie (Dwarf_CFI *cache, Dwarf_Off offset, const Dwarf_CIE *info)
190 {
191   const struct dwarf_cie cie_key = { .offset = offset };
192   struct dwarf_cie **found = tfind (&cie_key, &cache->cie_tree, &compare_cie);
193   if (found == NULL)
194     /* We have not read this CIE yet.  Enter it.  */
195     (void) intern_new_cie (cache, offset, info);
196 }
197