libgcc/unwind-dw2-fde.h

   1 /* Subroutines needed for unwinding stack frames for exception handling.  */
   2 /* Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2004, 2009
   3    Free Software Foundation, Inc.
   4    Contributed by Jason Merrill <jason@cygnus.com>.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 Under Section 7 of GPL version 3, you are granted additional
  19 permissions described in the GCC Runtime Library Exception, version
  20 3.1, as published by the Free Software Foundation.
  21
  22 You should have received a copy of the GNU General Public License and
  23 a copy of the GCC Runtime Library Exception along with this program;
  24 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  25 <http://www.gnu.org/licenses/>.  */
  26
  27 #ifndef GCC_UNWIND_DW2_FDE_H
  28 #define GCC_UNWIND_DW2_FDE_H
  29
  30 #ifndef HIDE_EXPORTS
  31 #pragma GCC visibility push(default)
  32 #endif
  33
  34 struct fde_vector
  35 {
  36   const void *orig_data;
  37   size_t count;
  38   const struct dwarf_fde *array[];
  39 };
  40
  41 struct object
  42 {
  43   void *pc_begin;
  44   void *tbase;
  45   void *dbase;
  46   union {
  47     const struct dwarf_fde *single;
  48     struct dwarf_fde **array;
  49     struct fde_vector *sort;
  50   } u;
  51
  52   union {
  53     struct {
  54       unsigned long sorted : 1;
  55       unsigned long from_array : 1;
  56       unsigned long mixed_encoding : 1;
  57       unsigned long encoding : 8;
  58       /* ??? Wish there was an easy way to detect a 64-bit host here;
  59          we've got 32 bits left to play with...  */
  60       unsigned long count : 21;
  61     } b;
  62     size_t i;
  63   } s;
  64
  65 #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
  66   char *fde_end;
  67 #endif
  68
  69   struct object *next;
  70 };
  71
  72 /* This is the original definition of struct object.  While the struct
  73    itself was opaque to users, they did know how large it was, and
  74    allocate one statically in crtbegin for each DSO.  Keep this around
  75    so that we're aware of the static size limitations for the new struct.  */
  76 struct old_object
  77 {
  78   void *pc_begin;
  79   void *pc_end;
  80   struct dwarf_fde *fde_begin;
  81   struct dwarf_fde **fde_array;
  82   size_t count;
  83   struct old_object *next;
  84 };
  85
  86 struct dwarf_eh_bases
  87 {
  88   void *tbase;
  89   void *dbase;
  90   void *func;
  91 };
  92
  93
  94 extern void __register_frame_info_bases (const void *, struct object *,
  95                                          void *, void *);
  96 extern void __register_frame_info (const void *, struct object *);
  97 extern void __register_frame (void *);
  98 extern void __register_frame_info_table_bases (void *, struct object *,
  99                                                void *, void *);
 100 extern void __register_frame_info_table (void *, struct object *);
 101 extern void __register_frame_table (void *);
 102 extern void *__deregister_frame_info (const void *);
 103 extern void *__deregister_frame_info_bases (const void *);
 104 extern void __deregister_frame (void *);
 105
 106 \f
 107 typedef          int  sword __attribute__ ((mode (SI)));
 108 typedef unsigned int  uword __attribute__ ((mode (SI)));
 109 typedef unsigned int  uaddr __attribute__ ((mode (pointer)));
 110 typedef          int  saddr __attribute__ ((mode (pointer)));
 111 typedef unsigned char ubyte;
 112
 113 /* Terminology:
 114    CIE - Common Information Element
 115    FDE - Frame Descriptor Element
 116
 117    There is one per function, and it describes where the function code
 118    is located, and what the register lifetimes and stack layout are
 119    within the function.
 120
 121    The data structures are defined in the DWARF specification, although
 122    not in a very readable way (see LITERATURE).
 123
 124    Every time an exception is thrown, the code needs to locate the FDE
 125    for the current function, and starts to look for exception regions
 126    from that FDE. This works in a two-level search:
 127    a) in a linear search, find the shared image (i.e. DLL) containing
 128       the PC
 129    b) using the FDE table for that shared object, locate the FDE using
 130       binary search (which requires the sorting).  */
 131
 132 /* The first few fields of a CIE.  The CIE_id field is 0 for a CIE,
 133    to distinguish it from a valid FDE.  FDEs are aligned to an addressing
 134    unit boundary, but the fields within are unaligned.  */
 135 struct dwarf_cie
 136 {
 137   uword length;
 138   sword CIE_id;
 139   ubyte version;
 140   unsigned char augmentation[];
 141 } __attribute__ ((packed, aligned (__alignof__ (void *))));
 142
 143 /* The first few fields of an FDE.  */
 144 struct dwarf_fde
 145 {
 146   uword length;
 147   sword CIE_delta;
 148   unsigned char pc_begin[];
 149 } __attribute__ ((packed, aligned (__alignof__ (void *))));
 150
 151 typedef struct dwarf_fde fde;
 152
 153 /* Locate the CIE for a given FDE.  */
 154
 155 static inline const struct dwarf_cie *
 156 get_cie (const struct dwarf_fde *f)
 157 {
 158   return (const void *)&f->CIE_delta - f->CIE_delta;
 159 }
 160
 161 static inline const fde *
 162 next_fde (const fde *f)
 163 {
 164   return (const fde *) ((const char *) f + f->length + sizeof (f->length));
 165 }
 166
 167 extern const fde * _Unwind_Find_FDE (void *, struct dwarf_eh_bases *);
 168
 169 static inline int
 170 last_fde (struct object *obj __attribute__ ((__unused__)), const fde *f)
 171 {
 172 #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
 173   return (char *)f == obj->fde_end || f->length == 0;
 174 #else
 175   return f->length == 0;
 176 #endif
 177 }
 178
 179 #ifndef HIDE_EXPORTS
 180 #pragma GCC visibility pop
 181 #endif
 182
 183 #endif /* unwind-dw2-fde.h */