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  1. /* Subroutines needed for unwinding stack frames for exception handling.  */
  2. /* Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2004, 2009
  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 3, or (at your option) any later
  11. version.
  12.  
  13. GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14. WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15. FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16. for more details.
  17.  
  18. Under Section 7 of GPL version 3, you are granted additional
  19. permissions described in the GCC Runtime Library Exception, version
  20. 3.1, as published by the Free Software Foundation.
  21.  
  22. You should have received a copy of the GNU General Public License and
  23. a copy of the GCC Runtime Library Exception along with this program;
  24. see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  25. <http://www.gnu.org/licenses/>.  */
  26.  
  27. #ifndef GCC_UNWIND_DW2_FDE_H
  28. #define GCC_UNWIND_DW2_FDE_H
  29.  
  30. #ifndef HIDE_EXPORTS
  31. #pragma GCC visibility push(default)
  32. #endif
  33.  
  34. struct fde_vector
  35. {
  36.   const void *orig_data;
  37.   size_t count;
  38.   const struct dwarf_fde *array[];
  39. };
  40.  
  41. struct object
  42. {
  43.   void *pc_begin;
  44.   void *tbase;
  45.   void *dbase;
  46.   union {
  47.     const struct dwarf_fde *single;
  48.     struct dwarf_fde **array;
  49.     struct fde_vector *sort;
  50.   } u;
  51.  
  52.   union {
  53.     struct {
  54.       unsigned long sorted : 1;
  55.       unsigned long from_array : 1;
  56.       unsigned long mixed_encoding : 1;
  57.       unsigned long encoding : 8;
  58.       /* ??? Wish there was an easy way to detect a 64-bit host here;
  59.          we've got 32 bits left to play with...  */
  60.       unsigned long count : 21;
  61.     } b;
  62.     size_t i;
  63.   } s;
  64.  
  65. #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
  66.   char *fde_end;
  67. #endif
  68.  
  69.   struct object *next;
  70. };
  71.  
  72. /* This is the original definition of struct object.  While the struct
  73.    itself was opaque to users, they did know how large it was, and
  74.    allocate one statically in crtbegin for each DSO.  Keep this around
  75.    so that we're aware of the static size limitations for the new struct.  */
  76. struct old_object
  77. {
  78.   void *pc_begin;
  79.   void *pc_end;
  80.   struct dwarf_fde *fde_begin;
  81.   struct dwarf_fde **fde_array;
  82.   size_t count;
  83.   struct old_object *next;
  84. };
  85.  
  86. struct dwarf_eh_bases
  87. {
  88.   void *tbase;
  89.   void *dbase;
  90.   void *func;
  91. };
  92.  
  93.  
  94. extern void __register_frame_info_bases (const void *, struct object *,
  95.                                          void *, void *);
  96. extern void __register_frame_info (const void *, struct object *);
  97. extern void __register_frame (void *);
  98. extern void __register_frame_info_table_bases (void *, struct object *,
  99.                                                void *, void *);
  100. extern void __register_frame_info_table (void *, struct object *);
  101. extern void __register_frame_table (void *);
  102. extern void *__deregister_frame_info (const void *);
  103. extern void *__deregister_frame_info_bases (const void *);
  104. extern void __deregister_frame (void *);
  105.  
  107. typedef          int  sword __attribute__ ((mode (SI)));
  108. typedef unsigned int  uword __attribute__ ((mode (SI)));
  109. typedef unsigned int  uaddr __attribute__ ((mode (pointer)));
  110. typedef          int  saddr __attribute__ ((mode (pointer)));
  111. typedef unsigned char ubyte;
  112.  
  113. /* Terminology:
  114.    CIE - Common Information Element
  115.    FDE - Frame Descriptor Element
  116.  
  117.    There is one per function, and it describes where the function code
  118.    is located, and what the register lifetimes and stack layout are
  119.    within the function.
  120.  
  121.    The data structures are defined in the DWARF specification, although
  122.    not in a very readable way (see LITERATURE).
  123.  
  124.    Every time an exception is thrown, the code needs to locate the FDE
  125.    for the current function, and starts to look for exception regions
  126.    from that FDE. This works in a two-level search:
  127.    a) in a linear search, find the shared image (i.e. DLL) containing
  128.       the PC
  129.    b) using the FDE table for that shared object, locate the FDE using
  130.       binary search (which requires the sorting).  */
  131.  
  132. /* The first few fields of a CIE.  The CIE_id field is 0 for a CIE,
  133.    to distinguish it from a valid FDE.  FDEs are aligned to an addressing
  134.    unit boundary, but the fields within are unaligned.  */
  135. struct dwarf_cie
  136. {
  137.   uword length;
  138.   sword CIE_id;
  139.   ubyte version;
  140.   unsigned char augmentation[];
  141. } __attribute__ ((packed, aligned (__alignof__ (void *))));
  142.  
  143. /* The first few fields of an FDE.  */
  144. struct dwarf_fde
  145. {
  146.   uword length;
  147.   sword CIE_delta;
  148.   unsigned char pc_begin[];
  149. } __attribute__ ((packed, aligned (__alignof__ (void *))));
  150.  
  151. typedef struct dwarf_fde fde;
  152.  
  153. /* Locate the CIE for a given FDE.  */
  154.  
  155. static inline const struct dwarf_cie *
  156. get_cie (const struct dwarf_fde *f)
  157. {
  158.   return (const void *)&f->CIE_delta - f->CIE_delta;
  159. }
  160.  
  161. static inline const fde *
  162. next_fde (const fde *f)
  163. {
  164.   return (const fde *) ((const char *) f + f->length + sizeof (f->length));
  165. }
  166.  
  167. extern const fde * _Unwind_Find_FDE (void *, struct dwarf_eh_bases *);
  168.  
  169. static inline int
  170. last_fde (struct object *obj __attribute__ ((__unused__)), const fde *f)
  171. {
  172. #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
  173.   return (char *)f == obj->fde_end || f->length == 0;
  174. #else
  175.   return f->length == 0;
  176. #endif
  177. }
  178.  
  179. #ifndef HIDE_EXPORTS
  180. #pragma GCC visibility pop
  181. #endif
  182.  
  183. #endif /* unwind-dw2-fde.h */
  184.