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 struct fde_vector
  36 {
  37   const void *orig_data;
  38   size_t count;
  39   const struct dwarf_fde *array[];
  40 };
  41
  42 struct object
  43 {
  44   void *pc_begin;
  45   void *tbase;
  46   void *dbase;
  47   union {
  48     const struct dwarf_fde *single;
  49     struct dwarf_fde **array;
  50     struct fde_vector *sort;
  51   } u;
  52
  53   union {
  54     struct {
  55       unsigned long sorted : 1;
  56       unsigned long from_array : 1;
  57       unsigned long mixed_encoding : 1;
  58       unsigned long encoding : 8;
  59       /* ??? Wish there was an easy way to detect a 64-bit host here;
  60          we've got 32 bits left to play with...  */
  61       unsigned long count : 21;
  62     } b;
  63     size_t i;
  64   } s;
  65
  66 #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
  67   char *fde_end;
  68 #endif
  69
  70   struct object *next;
  71 };
  72
  73 /* This is the original definition of struct object.  While the struct
  74    itself was opaque to users, they did know how large it was, and
  75    allocate one statically in crtbegin for each DSO.  Keep this around
  76    so that we're aware of the static size limitations for the new struct.  */
  77 struct old_object
  78 {
  79   void *pc_begin;
  80   void *pc_end;
  81   struct dwarf_fde *fde_begin;
  82   struct dwarf_fde **fde_array;
  83   size_t count;
  84   struct old_object *next;
  85 };
  86
  87 struct dwarf_eh_bases
  88 {
  89   void *tbase;
  90   void *dbase;
  91   void *func;
  92 };
  93
  94
  95 extern void __register_frame_info_bases (const void *, struct object *,
  96                                          void *, void *);
  97 extern void __register_frame_info (const void *, struct object *);
  98 extern void __register_frame (void *);
  99 extern void __register_frame_info_table_bases (void *, struct object *,
 100                                                void *, void *);
 101 extern void __register_frame_info_table (void *, struct object *);
 102 extern void __register_frame_table (void *);
 103 extern void *__deregister_frame_info (const void *);
 104 extern void *__deregister_frame_info_bases (const void *);
 105 extern void __deregister_frame (void *);
 106
 107 \f
 108 typedef          int  sword __attribute__ ((mode (SI)));
 109 typedef unsigned int  uword __attribute__ ((mode (SI)));
 110 typedef unsigned int  uaddr __attribute__ ((mode (pointer)));
 111 typedef          int  saddr __attribute__ ((mode (pointer)));
 112 typedef unsigned char ubyte;
 113
 114 /* Terminology:
 115    CIE - Common Information Element
 116    FDE - Frame Descriptor Element
 117
 118    There is one per function, and it describes where the function code
 119    is located, and what the register lifetimes and stack layout are
 120    within the function.
 121
 122    The data structures are defined in the DWARF specification, although
 123    not in a very readable way (see LITERATURE).
 124
 125    Every time an exception is thrown, the code needs to locate the FDE
 126    for the current function, and starts to look for exception regions
 127    from that FDE. This works in a two-level search:
 128    a) in a linear search, find the shared image (i.e. DLL) containing
 129       the PC
 130    b) using the FDE table for that shared object, locate the FDE using
 131       binary search (which requires the sorting).  */
 132
 133 /* The first few fields of a CIE.  The CIE_id field is 0 for a CIE,
 134    to distinguish it from a valid FDE.  FDEs are aligned to an addressing
 135    unit boundary, but the fields within are unaligned.  */
 136 struct dwarf_cie
 137 {
 138   uword length;
 139   sword CIE_id;
 140   ubyte version;
 141   unsigned char augmentation[];
 142 } __attribute__ ((packed, aligned (__alignof__ (void *))));
 143
 144 /* The first few fields of an FDE.  */
 145 struct dwarf_fde
 146 {
 147   uword length;
 148   sword CIE_delta;
 149   unsigned char pc_begin[];
 150 } __attribute__ ((packed, aligned (__alignof__ (void *))));
 151
 152 typedef struct dwarf_fde fde;
 153
 154 /* Locate the CIE for a given FDE.  */
 155
 156 static inline const struct dwarf_cie *
 157 get_cie (const struct dwarf_fde *f)
 158 {
 159   return (void *)&f->CIE_delta - f->CIE_delta;
 160 }
 161
 162 static inline const fde *
 163 next_fde (const fde *f)
 164 {
 165   return (const fde *) ((char *) f + f->length + sizeof (f->length));
 166 }
 167
 168 extern const fde * _Unwind_Find_FDE (void *, struct dwarf_eh_bases *);
 169
 170 static inline int
 171 last_fde (struct object *obj __attribute__ ((__unused__)), const fde *f)
 172 {
 173 #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
 174   return (char *)f == obj->fde_end || f->length == 0;
 175 #else
 176   return f->length == 0;
 177 #endif
 178 }
 179
 180 #endif /* unwind-dw2-fde.h */