gcc/unwind-dw2-fde.h

   1 /* Subroutines needed for unwinding stack frames for exception handling.  */
   2 /* Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2004
   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 2, or (at your option) any later
  11 version.
  12
  13 In addition to the permissions in the GNU General Public License, the
  14 Free Software Foundation gives you unlimited permission to link the
  15 compiled version of this file into combinations with other programs,
  16 and to distribute those combinations without any restriction coming
  17 from the use of this file.  (The General Public License restrictions
  18 do apply in other respects; for example, they cover modification of
  19 the file, and distribution when not linked into a combine
  20 executable.)
  21
  22 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  23 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  24 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  25 for more details.
  26
  27 You should have received a copy of the GNU General Public License
  28 along with GCC; see the file COPYING.  If not, write to the Free
  29 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  30 02111-1307, USA.  */
  31
  32 #ifndef GCC_UNWIND_DW2_FDE_H
  33 #define GCC_UNWIND_DW2_FDE_H
  34
  35 #pragma GCC visibility push(default)
  36
  37 struct fde_vector
  38 {
  39   const void *orig_data;
  40   size_t count;
  41   const struct dwarf_fde *array[];
  42 };
  43
  44 struct object
  45 {
  46   void *pc_begin;
  47   void *tbase;
  48   void *dbase;
  49   union {
  50     const struct dwarf_fde *single;
  51     struct dwarf_fde **array;
  52     struct fde_vector *sort;
  53   } u;
  54
  55   union {
  56     struct {
  57       unsigned long sorted : 1;
  58       unsigned long from_array : 1;
  59       unsigned long mixed_encoding : 1;
  60       unsigned long encoding : 8;
  61       /* ??? Wish there was an easy way to detect a 64-bit host here;
  62          we've got 32 bits left to play with...  */
  63       unsigned long count : 21;
  64     } b;
  65     size_t i;
  66   } s;
  67
  68 #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
  69   char *fde_end;
  70 #endif
  71
  72   struct object *next;
  73 };
  74
  75 /* This is the original definition of struct object.  While the struct
  76    itself was opaque to users, they did know how large it was, and
  77    allocate one statically in crtbegin for each DSO.  Keep this around
  78    so that we're aware of the static size limitations for the new struct.  */
  79 struct old_object
  80 {
  81   void *pc_begin;
  82   void *pc_end;
  83   struct dwarf_fde *fde_begin;
  84   struct dwarf_fde **fde_array;
  85   size_t count;
  86   struct old_object *next;
  87 };
  88
  89 struct dwarf_eh_bases
  90 {
  91   void *tbase;
  92   void *dbase;
  93   void *func;
  94 };
  95
  96
  97 extern void __register_frame_info_bases (const void *, struct object *,
  98                                          void *, void *);
  99 extern void __register_frame_info (const void *, struct object *);
 100 extern void __register_frame (void *);
 101 extern void __register_frame_info_table_bases (void *, struct object *,
 102                                                void *, void *);
 103 extern void __register_frame_info_table (void *, struct object *);
 104 extern void __register_frame_table (void *);
 105 extern void *__deregister_frame_info (const void *);
 106 extern void *__deregister_frame_info_bases (const void *);
 107 extern void __deregister_frame (void *);
 108
 109 \f
 110 typedef          int  sword __attribute__ ((mode (SI)));
 111 typedef unsigned int  uword __attribute__ ((mode (SI)));
 112 typedef unsigned int  uaddr __attribute__ ((mode (pointer)));
 113 typedef          int  saddr __attribute__ ((mode (pointer)));
 114 typedef unsigned char ubyte;
 115
 116 /* Terminology:
 117    CIE - Common Information Element
 118    FDE - Frame Descriptor Element
 119
 120    There is one per function, and it describes where the function code
 121    is located, and what the register lifetimes and stack layout are
 122    within the function.
 123
 124    The data structures are defined in the DWARF specification, although
 125    not in a very readable way (see LITERATURE).
 126
 127    Every time an exception is thrown, the code needs to locate the FDE
 128    for the current function, and starts to look for exception regions
 129    from that FDE. This works in a two-level search:
 130    a) in a linear search, find the shared image (i.e. DLL) containing
 131       the PC
 132    b) using the FDE table for that shared object, locate the FDE using
 133       binary search (which requires the sorting).  */
 134
 135 /* The first few fields of a CIE.  The CIE_id field is 0 for a CIE,
 136    to distinguish it from a valid FDE.  FDEs are aligned to an addressing
 137    unit boundary, but the fields within are unaligned.  */
 138 struct dwarf_cie
 139 {
 140   uword length;
 141   sword CIE_id;
 142   ubyte version;
 143   unsigned char augmentation[];
 144 } __attribute__ ((packed, aligned (__alignof__ (void *))));
 145
 146 /* The first few fields of an FDE.  */
 147 struct dwarf_fde
 148 {
 149   uword length;
 150   sword CIE_delta;
 151   unsigned char pc_begin[];
 152 } __attribute__ ((packed, aligned (__alignof__ (void *))));
 153
 154 typedef struct dwarf_fde fde;
 155
 156 /* Locate the CIE for a given FDE.  */
 157
 158 static inline const struct dwarf_cie *
 159 get_cie (const struct dwarf_fde *f)
 160 {
 161   return (void *)&f->CIE_delta - f->CIE_delta;
 162 }
 163
 164 static inline const fde *
 165 next_fde (const fde *f)
 166 {
 167   return (const fde *) ((char *) f + f->length + sizeof (f->length));
 168 }
 169
 170 extern const fde * _Unwind_Find_FDE (void *, struct dwarf_eh_bases *);
 171
 172 static inline int
 173 last_fde (struct object *obj __attribute__ ((__unused__)), const fde *f)
 174 {
 175 #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
 176   return (char *)f == obj->fde_end || f->length == 0;
 177 #else
 178   return f->length == 0;
 179 #endif
 180 }
 181
 182 #pragma GCC visibility pop
 183
 184 #endif /* unwind-dw2-fde.h */