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, write to the Free
  20    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  21    02111-1307 USA.  */
  22
  23
  24 struct fde_vector
  25 {
  26   void *orig_data;
  27   size_t count;
  28   struct dwarf_fde *array __flexarr;
  29 };
  30
  31 #ifdef _LIBC
  32 #include <gccframe.h>
  33 #else
  34 struct object
  35 {
  36   void *pc_begin;
  37   void *tbase;
  38   void *dbase;
  39   union {
  40     struct dwarf_fde *single;
  41     struct dwarf_fde **array;
  42     struct fde_vector *sort;
  43   } u;
  44
  45   union {
  46     struct {
  47       unsigned long sorted : 1;
  48       unsigned long from_array : 1;
  49       unsigned long mixed_encoding : 1;
  50       unsigned long encoding : 8;
  51       /* ??? Wish there was an easy way to detect a 64-bit host here;
  52          we've got 32 bits left to play with...  */
  53       unsigned long count : 21;
  54     } b;
  55     size_t i;
  56   } s;
  57
  58 #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
  59   char *fde_end;
  60 #endif
  61
  62   struct object *next;
  63 };
  64 #endif
  65
  66 /* This is the original definition of struct object.  While the struct
  67    itself was opaque to users, they did know how large it was, and
  68    allocate one statically in crtbegin for each DSO.  Keep this around
  69    so that we're aware of the static size limitations for the new struct.  */
  70 struct old_object
  71 {
  72   void *pc_begin;
  73   void *pc_end;
  74   struct dwarf_fde *fde_begin;
  75   struct dwarf_fde **fde_array;
  76   size_t count;
  77   struct old_object *next;
  78 };
  79
  80 struct dwarf_eh_bases
  81 {
  82   void *tbase;
  83   void *dbase;
  84   void *func;
  85 };
  86
  87
  88 extern void __register_frame_info_bases (void *, struct object *,
  89                                          void *, void *);
  90 extern void __register_frame_info (void *, struct object *);
  91 extern void __register_frame (void *);
  92 extern void __register_frame_info_table_bases (void *, struct object *,
  93                                                void *, void *);
  94 extern void __register_frame_info_table (void *, struct object *);
  95 extern void __register_frame_table (void *);
  96 extern void *__deregister_frame_info (void *);
  97 extern void *__deregister_frame_info_bases (void *);
  98 extern void __deregister_frame (void *);
  99
 100 \f
 101 typedef          int  sword __attribute__ ((mode (SI)));
 102 typedef unsigned int  uword __attribute__ ((mode (SI)));
 103 typedef unsigned int  uaddr __attribute__ ((mode (pointer)));
 104 typedef          int  saddr __attribute__ ((mode (pointer)));
 105 typedef unsigned char ubyte;
 106
 107 /* Terminology:
 108    CIE - Common Information Element
 109    FDE - Frame Descriptor Element
 110
 111    There is one per function, and it describes where the function code
 112    is located, and what the register lifetimes and stack layout are
 113    within the function.
 114
 115    The data structures are defined in the DWARF specification, although
 116    not in a very readable way (see LITERATURE).
 117
 118    Every time an exception is thrown, the code needs to locate the FDE
 119    for the current function, and starts to look for exception regions
 120    from that FDE. This works in a two-level search:
 121    a) in a linear search, find the shared image (i.e. DLL) containing
 122       the PC
 123    b) using the FDE table for that shared object, locate the FDE using
 124       binary search (which requires the sorting).  */
 125
 126 /* The first few fields of a CIE.  The CIE_id field is 0 for a CIE,
 127    to distinguish it from a valid FDE.  FDEs are aligned to an addressing
 128    unit boundary, but the fields within are unaligned.  */
 129 struct dwarf_cie
 130 {
 131   uword length;
 132   sword CIE_id;
 133   ubyte version;
 134   unsigned char augmentation __flexarr;
 135 } __attribute__ ((packed, aligned (__alignof__ (void *))));
 136
 137 /* The first few fields of an FDE.  */
 138 struct dwarf_fde
 139 {
 140   uword length;
 141   sword CIE_delta;
 142   unsigned char pc_begin __flexarr;
 143 } __attribute__ ((packed, aligned (__alignof__ (void *))));
 144
 145 typedef struct dwarf_fde fde;
 146
 147 /* Locate the CIE for a given FDE.  */
 148
 149 static inline struct dwarf_cie *
 150 get_cie (struct dwarf_fde *f)
 151 {
 152   return (void *)&f->CIE_delta - f->CIE_delta;
 153 }
 154
 155 static inline fde *
 156 next_fde (fde *f)
 157 {
 158   return (fde *) ((char *) f + f->length + sizeof (f->length));
 159 }
 160
 161 extern fde * _Unwind_Find_FDE (void *, struct dwarf_eh_bases *);
 162
 163 static inline int
 164 last_fde (struct object *obj __attribute__ ((__unused__)), fde *f)
 165 {
 166 #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
 167   return (char *)f == obj->fde_end || f->length == 0;
 168 #else
 169   return f->length == 0;
 170 #endif
 171 }