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, 51 Franklin Street, Fifth Floor, Boston, MA
  30 02110-1301, USA.  */
  31
  32 #ifndef GCC_UNWIND_DW2_FDE_H
  33 #define GCC_UNWIND_DW2_FDE_H
  34
  35 #ifndef HIDE_EXPORTS
  36 #pragma GCC visibility push(default)
  37 #endif
  38
  39 struct fde_vector
  40 {
  41   const void *orig_data;
  42   size_t count;
  43   const struct dwarf_fde *array[];
  44 };
  45
  46 struct object
  47 {
  48   void *pc_begin;
  49   void *tbase;
  50   void *dbase;
  51   union {
  52     const struct dwarf_fde *single;
  53     struct dwarf_fde **array;
  54     struct fde_vector *sort;
  55   } u;
  56
  57   union {
  58     struct {
  59       unsigned long sorted : 1;
  60       unsigned long from_array : 1;
  61       unsigned long mixed_encoding : 1;
  62       unsigned long encoding : 8;
  63       /* ??? Wish there was an easy way to detect a 64-bit host here;
  64          we've got 32 bits left to play with...  */
  65       unsigned long count : 21;
  66     } b;
  67     size_t i;
  68   } s;
  69
  70 #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
  71   char *fde_end;
  72 #endif
  73
  74   struct object *next;
  75 };
  76
  77 /* This is the original definition of struct object.  While the struct
  78    itself was opaque to users, they did know how large it was, and
  79    allocate one statically in crtbegin for each DSO.  Keep this around
  80    so that we're aware of the static size limitations for the new struct.  */
  81 struct old_object
  82 {
  83   void *pc_begin;
  84   void *pc_end;
  85   struct dwarf_fde *fde_begin;
  86   struct dwarf_fde **fde_array;
  87   size_t count;
  88   struct old_object *next;
  89 };
  90
  91 struct dwarf_eh_bases
  92 {
  93   void *tbase;
  94   void *dbase;
  95   void *func;
  96 };
  97
  98
  99 extern void __register_frame_info_bases (const void *, struct object *,
 100                                          void *, void *);
 101 extern void __register_frame_info (const void *, struct object *);
 102 extern void __register_frame (void *);
 103 extern void __register_frame_info_table_bases (void *, struct object *,
 104                                                void *, void *);
 105 extern void __register_frame_info_table (void *, struct object *);
 106 extern void __register_frame_table (void *);
 107 extern void *__deregister_frame_info (const void *);
 108 extern void *__deregister_frame_info_bases (const void *);
 109 extern void __deregister_frame (void *);
 110
 111 \f
 112 typedef          int  sword __attribute__ ((mode (SI)));
 113 typedef unsigned int  uword __attribute__ ((mode (SI)));
 114 typedef unsigned int  uaddr __attribute__ ((mode (pointer)));
 115 typedef          int  saddr __attribute__ ((mode (pointer)));
 116 typedef unsigned char ubyte;
 117
 118 /* Terminology:
 119    CIE - Common Information Element
 120    FDE - Frame Descriptor Element
 121
 122    There is one per function, and it describes where the function code
 123    is located, and what the register lifetimes and stack layout are
 124    within the function.
 125
 126    The data structures are defined in the DWARF specification, although
 127    not in a very readable way (see LITERATURE).
 128
 129    Every time an exception is thrown, the code needs to locate the FDE
 130    for the current function, and starts to look for exception regions
 131    from that FDE. This works in a two-level search:
 132    a) in a linear search, find the shared image (i.e. DLL) containing
 133       the PC
 134    b) using the FDE table for that shared object, locate the FDE using
 135       binary search (which requires the sorting).  */
 136
 137 /* The first few fields of a CIE.  The CIE_id field is 0 for a CIE,
 138    to distinguish it from a valid FDE.  FDEs are aligned to an addressing
 139    unit boundary, but the fields within are unaligned.  */
 140 struct dwarf_cie
 141 {
 142   uword length;
 143   sword CIE_id;
 144   ubyte version;
 145   unsigned char augmentation[];
 146 } __attribute__ ((packed, aligned (__alignof__ (void *))));
 147
 148 /* The first few fields of an FDE.  */
 149 struct dwarf_fde
 150 {
 151   uword length;
 152   sword CIE_delta;
 153   unsigned char pc_begin[];
 154 } __attribute__ ((packed, aligned (__alignof__ (void *))));
 155
 156 typedef struct dwarf_fde fde;
 157
 158 /* Locate the CIE for a given FDE.  */
 159
 160 static inline const struct dwarf_cie *
 161 get_cie (const struct dwarf_fde *f)
 162 {
 163   return (void *)&f->CIE_delta - f->CIE_delta;
 164 }
 165
 166 static inline const fde *
 167 next_fde (const fde *f)
 168 {
 169   return (const fde *) ((char *) f + f->length + sizeof (f->length));
 170 }
 171
 172 extern const fde * _Unwind_Find_FDE (void *, struct dwarf_eh_bases *);
 173
 174 static inline int
 175 last_fde (struct object *obj __attribute__ ((__unused__)), const fde *f)
 176 {
 177 #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
 178   return (char *)f == obj->fde_end || f->length == 0;
 179 #else
 180   return f->length == 0;
 181 #endif
 182 }
 183
 184 #ifndef HIDE_EXPORTS
 185 #pragma GCC visibility pop
 186 #endif
 187
 188 #endif /* unwind-dw2-fde.h */