sysdeps/generic/unwind.h

   1 /* Exception handling and frame unwind runtime interface routines.
   2    Copyright (C) 2001-2024 Free Software Foundation, Inc.
   3
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 /* This is derived from the C++ ABI for IA-64.  Where we diverge
  21    for cross-architecture compatibility are noted with "@@@".  */
  22
  23 #ifndef _UNWIND_H
  24 #define _UNWIND_H       1
  25
  26 #ifdef __cplusplus
  27 extern "C" {
  28 #endif
  29
  30 /* Level 1: Base ABI  */
  31
  32 /* @@@ The IA-64 ABI uses uint64 throughout.  Most places this is
  33    inefficient for 32-bit and smaller machines.  */
  34 typedef unsigned _Unwind_Word __attribute__((__mode__(__unwind_word__)));
  35 typedef signed _Unwind_Sword __attribute__((__mode__(__unwind_word__)));
  36 #if defined(__ia64__) && defined(__hpux__)
  37 typedef unsigned _Unwind_Ptr __attribute__((__mode__(__word__)));
  38 #else
  39 typedef unsigned _Unwind_Ptr __attribute__((__mode__(__pointer__)));
  40 #endif
  41 typedef unsigned _Unwind_Internal_Ptr __attribute__((__mode__(__pointer__)));
  42
  43 /* @@@ The IA-64 ABI uses a 64-bit word to identify the producer and
  44    consumer of an exception.  We'll go along with this for now even on
  45    32-bit machines.  We'll need to provide some other option for
  46    16-bit machines and for machines with > 8 bits per byte.  */
  47 typedef unsigned _Unwind_Exception_Class __attribute__((__mode__(__DI__)));
  48
  49 /* The unwind interface uses reason codes in several contexts to
  50    identify the reasons for failures or other actions.  */
  51 typedef enum
  52 {
  53   _URC_NO_REASON = 0,
  54   _URC_FOREIGN_EXCEPTION_CAUGHT = 1,
  55   _URC_FATAL_PHASE2_ERROR = 2,
  56   _URC_FATAL_PHASE1_ERROR = 3,
  57   _URC_NORMAL_STOP = 4,
  58   _URC_END_OF_STACK = 5,
  59   _URC_HANDLER_FOUND = 6,
  60   _URC_INSTALL_CONTEXT = 7,
  61   _URC_CONTINUE_UNWIND = 8
  62 } _Unwind_Reason_Code;
  63
  64
  65 /* The unwind interface uses a pointer to an exception header object
  66    as its representation of an exception being thrown. In general, the
  67    full representation of an exception object is language- and
  68    implementation-specific, but it will be prefixed by a header
  69    understood by the unwind interface.  */
  70
  71 struct _Unwind_Exception;
  72
  73 typedef void (*_Unwind_Exception_Cleanup_Fn) (_Unwind_Reason_Code,
  74                                               struct _Unwind_Exception *);
  75
  76 struct _Unwind_Exception
  77 {
  78   union
  79   {
  80     struct
  81     {
  82       _Unwind_Exception_Class exception_class;
  83       _Unwind_Exception_Cleanup_Fn exception_cleanup;
  84       _Unwind_Word private_1;
  85       _Unwind_Word private_2;
  86     };
  87
  88     /* The IA-64 ABI says that this structure must be double-word aligned.  */
  89     _Unwind_Word unwind_exception_align[2]
  90       __attribute__ ((__aligned__ (2 * sizeof (_Unwind_Word))));
  91   };
  92 };
  93
  94
  95 /* The ACTIONS argument to the personality routine is a bitwise OR of one
  96    or more of the following constants.  */
  97 typedef int _Unwind_Action;
  98
  99 #define _UA_SEARCH_PHASE        1
 100 #define _UA_CLEANUP_PHASE       2
 101 #define _UA_HANDLER_FRAME       4
 102 #define _UA_FORCE_UNWIND        8
 103 #define _UA_END_OF_STACK        16
 104
 105 /* This is an opaque type used to refer to a system-specific data
 106    structure used by the system unwinder. This context is created and
 107    destroyed by the system, and passed to the personality routine
 108    during unwinding.  */
 109 struct _Unwind_Context;
 110
 111 /* Raise an exception, passing along the given exception object.  */
 112 extern _Unwind_Reason_Code _Unwind_RaiseException (struct _Unwind_Exception *);
 113
 114 /* Raise an exception for forced unwinding.  */
 115
 116 typedef _Unwind_Reason_Code (*_Unwind_Stop_Fn)
 117      (int, _Unwind_Action, _Unwind_Exception_Class,
 118       struct _Unwind_Exception *, struct _Unwind_Context *, void *);
 119
 120 extern _Unwind_Reason_Code _Unwind_ForcedUnwind (struct _Unwind_Exception *,
 121                                                  _Unwind_Stop_Fn,
 122                                                  void *);
 123
 124 /* Helper to invoke the exception_cleanup routine.  */
 125 extern void _Unwind_DeleteException (struct _Unwind_Exception *);
 126
 127 /* Resume propagation of an existing exception.  This is used after
 128    e.g. executing cleanup code, and not to implement rethrowing.  */
 129 extern void _Unwind_Resume (struct _Unwind_Exception *);
 130
 131 /* @@@ Use unwind data to perform a stack backtrace.  The trace callback
 132    is called for every stack frame in the call chain, but no cleanup
 133    actions are performed.  */
 134 typedef _Unwind_Reason_Code (*_Unwind_Trace_Fn)
 135      (struct _Unwind_Context *, void *);
 136
 137 extern _Unwind_Reason_Code _Unwind_Backtrace (_Unwind_Trace_Fn, void *);
 138
 139 /* These functions are used for communicating information about the unwind
 140    context (i.e. the unwind descriptors and the user register state) between
 141    the unwind library and the personality routine and landing pad.  Only
 142    selected registers maybe manipulated.  */
 143
 144 extern _Unwind_Word _Unwind_GetGR (struct _Unwind_Context *, int);
 145 extern void _Unwind_SetGR (struct _Unwind_Context *, int, _Unwind_Word);
 146
 147 extern _Unwind_Ptr _Unwind_GetIP (struct _Unwind_Context *);
 148 extern void _Unwind_SetIP (struct _Unwind_Context *, _Unwind_Ptr);
 149
 150 /* @@@ Retrieve the CFA of the given context.  */
 151 extern _Unwind_Word _Unwind_GetCFA (struct _Unwind_Context *);
 152
 153 extern void *_Unwind_GetLanguageSpecificData (struct _Unwind_Context *);
 154
 155 extern _Unwind_Ptr _Unwind_GetRegionStart (struct _Unwind_Context *);
 156
 157
 158 /* The personality routine is the function in the C++ (or other language)
 159    runtime library which serves as an interface between the system unwind
 160    library and language-specific exception handling semantics.  It is
 161    specific to the code fragment described by an unwind info block, and
 162    it is always referenced via the pointer in the unwind info block, and
 163    hence it has no ABI-specified name.
 164
 165    Note that this implies that two different C++ implementations can
 166    use different names, and have different contents in the language
 167    specific data area.  Moreover, that the language specific data
 168    area contains no version info because name of the function invoked
 169    provides more effective versioning by detecting at link time the
 170    lack of code to handle the different data format.  */
 171
 172 typedef _Unwind_Reason_Code (*_Unwind_Personality_Fn)
 173      (int, _Unwind_Action, _Unwind_Exception_Class,
 174       struct _Unwind_Exception *, struct _Unwind_Context *);
 175
 176 /* @@@ The following alternate entry points are for setjmp/longjmp
 177    based unwinding.  */
 178
 179 struct SjLj_Function_Context;
 180 extern void _Unwind_SjLj_Register (struct SjLj_Function_Context *);
 181 extern void _Unwind_SjLj_Unregister (struct SjLj_Function_Context *);
 182
 183 extern _Unwind_Reason_Code _Unwind_SjLj_RaiseException
 184      (struct _Unwind_Exception *);
 185 extern _Unwind_Reason_Code _Unwind_SjLj_ForcedUnwind
 186      (struct _Unwind_Exception *, _Unwind_Stop_Fn, void *);
 187 extern void _Unwind_SjLj_Resume (struct _Unwind_Exception *);
 188
 189 /* @@@ The following provide access to the base addresses for text
 190    and data-relative addressing in the LDSA.  In order to stay link
 191    compatible with the standard ABI for IA-64, we inline these.  */
 192
 193 #ifdef __ia64__
 194 #include <stdlib.h>
 195
 196 static inline _Unwind_Ptr
 197 _Unwind_GetDataRelBase (struct _Unwind_Context *_C)
 198 {
 199   /* The GP is stored in R1.  */
 200   return _Unwind_GetGR (_C, 1);
 201 }
 202
 203 static inline _Unwind_Ptr
 204 _Unwind_GetTextRelBase (struct _Unwind_Context *_C)
 205 {
 206   abort ();
 207   return 0;
 208 }
 209
 210 /* @@@ Retrieve the Backing Store Pointer of the given context.  */
 211 extern _Unwind_Word _Unwind_GetBSP (struct _Unwind_Context *);
 212 #else
 213 extern _Unwind_Ptr _Unwind_GetDataRelBase (struct _Unwind_Context *);
 214 extern _Unwind_Ptr _Unwind_GetTextRelBase (struct _Unwind_Context *);
 215 #endif
 216
 217 /* @@@ Given an address, return the entry point of the function that
 218    contains it.  */
 219 extern void * _Unwind_FindEnclosingFunction (void *pc);
 220
 221 #ifdef __cplusplus
 222 }
 223 #endif
 224
 225 #endif  /* unwind.h */