sysdeps/generic/unwind-dw2-fde.h

   1 /* Subroutines needed for unwinding stack frames for exception handling.  */
   2 /* Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003
   3    Free Software Foundation, Inc.
   4    Contributed by Jason Merrill <jason@cygnus.com>.
   5
   6    This file is part of the GNU C Library.
   7
   8    The GNU C Library is free software; you can redistribute it and/or
   9    modify it under the terms of the GNU Lesser General Public
  10    License as published by the Free Software Foundation; either
  11    version 2.1 of the License, or (at your option) any later version.
  12
  13    The GNU C Library is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16    Lesser General Public License for more details.
  17
  18    You should have received a copy of the GNU Lesser General Public
  19    License along with the GNU C Library; if not, see
  20    <http://www.gnu.org/licenses/>.  */
  21
  22
  23 struct fde_vector
  24 {
  25   void *orig_data;
  26   size_t count;
  27   struct dwarf_fde *array __flexarr;
  28 };
  29
  30 #ifdef _LIBC
  31 #include <gccframe.h>
  32 #else
  33 struct object
  34 {
  35   void *pc_begin;
  36   void *tbase;
  37   void *dbase;
  38   union {
  39     struct dwarf_fde *single;
  40     struct dwarf_fde **array;
  41     struct fde_vector *sort;
  42   } u;
  43
  44   union {
  45     struct {
  46       unsigned long sorted : 1;
  47       unsigned long from_array : 1;
  48       unsigned long mixed_encoding : 1;
  49       unsigned long encoding : 8;
  50       /* ??? Wish there was an easy way to detect a 64-bit host here;
  51          we've got 32 bits left to play with...  */
  52       unsigned long count : 21;
  53     } b;
  54     size_t i;
  55   } s;
  56
  57 #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
  58   char *fde_end;
  59 #endif
  60
  61   struct object *next;
  62 };
  63 #endif
  64
  65 /* This is the original definition of struct object.  While the struct
  66    itself was opaque to users, they did know how large it was, and
  67    allocate one statically in crtbegin for each DSO.  Keep this around
  68    so that we're aware of the static size limitations for the new struct.  */
  69 struct old_object
  70 {
  71   void *pc_begin;
  72   void *pc_end;
  73   struct dwarf_fde *fde_begin;
  74   struct dwarf_fde **fde_array;
  75   size_t count;
  76   struct old_object *next;
  77 };
  78
  79 struct dwarf_eh_bases
  80 {
  81   void *tbase;
  82   void *dbase;
  83   void *func;
  84 };
  85
  86
  87 extern void __register_frame_info_bases (void *, struct object *,
  88                                          void *, void *);
  89 extern void __register_frame_info (void *, struct object *);
  90 extern void __register_frame (void *);
  91 extern void __register_frame_info_table_bases (void *, struct object *,
  92                                                void *, void *);
  93 extern void __register_frame_info_table (void *, struct object *);
  94 extern void __register_frame_table (void *);
  95 extern void *__deregister_frame_info (void *);
  96 extern void *__deregister_frame_info_bases (void *);
  97 extern void __deregister_frame (void *);
  98
  99 \f
 100 typedef          int  sword __attribute__ ((mode (SI)));
 101 typedef unsigned int  uword __attribute__ ((mode (SI)));
 102 typedef unsigned int  uaddr __attribute__ ((mode (pointer)));
 103 typedef          int  saddr __attribute__ ((mode (pointer)));
 104 typedef unsigned char ubyte;
 105
 106 /* Terminology:
 107    CIE - Common Information Element
 108    FDE - Frame Descriptor Element
 109
 110    There is one per function, and it describes where the function code
 111    is located, and what the register lifetimes and stack layout are
 112    within the function.
 113
 114    The data structures are defined in the DWARF specification, although
 115    not in a very readable way (see LITERATURE).
 116
 117    Every time an exception is thrown, the code needs to locate the FDE
 118    for the current function, and starts to look for exception regions
 119    from that FDE. This works in a two-level search:
 120    a) in a linear search, find the shared image (i.e. DLL) containing
 121       the PC
 122    b) using the FDE table for that shared object, locate the FDE using
 123       binary search (which requires the sorting).  */
 124
 125 /* The first few fields of a CIE.  The CIE_id field is 0 for a CIE,
 126    to distinguish it from a valid FDE.  FDEs are aligned to an addressing
 127    unit boundary, but the fields within are unaligned.  */
 128 struct dwarf_cie
 129 {
 130   uword length;
 131   sword CIE_id;
 132   ubyte version;
 133   unsigned char augmentation __flexarr;
 134 } __attribute__ ((packed, aligned (__alignof__ (void *))));
 135
 136 /* The first few fields of an FDE.  */
 137 struct dwarf_fde
 138 {
 139   uword length;
 140   sword CIE_delta;
 141   unsigned char pc_begin __flexarr;
 142 } __attribute__ ((packed, aligned (__alignof__ (void *))));
 143
 144 typedef struct dwarf_fde fde;
 145
 146 /* Locate the CIE for a given FDE.  */
 147
 148 static inline struct dwarf_cie *
 149 get_cie (struct dwarf_fde *f)
 150 {
 151   return (void *)&f->CIE_delta - f->CIE_delta;
 152 }
 153
 154 static inline fde *
 155 next_fde (fde *f)
 156 {
 157   return (fde *) ((char *) f + f->length + sizeof (f->length));
 158 }
 159
 160 extern fde * _Unwind_Find_FDE (void *, struct dwarf_eh_bases *);
 161
 162 static inline int
 163 last_fde (struct object *obj __attribute__ ((__unused__)), fde *f)
 164 {
 165 #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
 166   return (char *)f == obj->fde_end || f->length == 0;
 167 #else
 168   return f->length == 0;
 169 #endif
 170 }