1 /* Exception handling and frame unwind runtime interface routines. -*- C -*-
2 Copyright (C) 2001-2017 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3, or (at your option)
11 GCC is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14 License for more details.
16 Under Section 7 of GPL version 3, you are granted additional
17 permissions described in the GCC Runtime Library Exception, version
18 3.1, as published by the Free Software Foundation.
20 You should have received a copy of the GNU General Public License and
21 a copy of the GCC Runtime Library Exception along with this program;
22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 <http://www.gnu.org/licenses/>. */
25 /* This is derived from the C++ ABI for IA-64. Where we diverge
26 for cross-architecture compatibility are noted with "@@@".
27 This file is included from unwind-dw2.c, unwind-sjlj.c or
30 /* Subroutine of _Unwind_RaiseException also invoked from _Unwind_Resume.
32 Unwind the stack calling the personality routine to find both the
33 exception handler and intermediary cleanup code. We'll only locate
34 the first such frame here. Cleanup code will call back into
35 _Unwind_Resume and we'll continue Phase 2 there. */
37 static _Unwind_Reason_Code
38 _Unwind_RaiseException_Phase2(struct _Unwind_Exception *exc,
39 struct _Unwind_Context *context,
40 unsigned long *frames_p)
42 _Unwind_Reason_Code code;
43 unsigned long frames = 1;
47 _Unwind_FrameState fs;
50 code = uw_frame_state_for (context, &fs);
52 /* Identify when we've reached the designated handler context. */
53 match_handler = (uw_identify_context (context) == exc->private_2
54 ? _UA_HANDLER_FRAME : 0);
56 if (code != _URC_NO_REASON)
57 /* Some error encountered. Usually the unwinder doesn't
58 diagnose these and merely crashes. */
59 return _URC_FATAL_PHASE2_ERROR;
61 /* Unwind successful. Run the personality routine, if any. */
64 code = (*fs.personality) (1, _UA_CLEANUP_PHASE | match_handler,
65 exc->exception_class, exc, context);
66 if (code == _URC_INSTALL_CONTEXT)
68 if (code != _URC_CONTINUE_UNWIND)
69 return _URC_FATAL_PHASE2_ERROR;
72 /* Don't let us unwind past the handler context. */
73 gcc_assert (!match_handler);
75 uw_update_context (context, &fs);
83 /* Raise an exception, passing along the given exception object. */
85 _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
86 _Unwind_RaiseException(struct _Unwind_Exception *exc)
88 struct _Unwind_Context this_context, cur_context;
89 _Unwind_Reason_Code code;
92 /* Set up this_context to describe the current stack frame. */
93 uw_init_context (&this_context);
94 cur_context = this_context;
96 /* Phase 1: Search. Unwind the stack, calling the personality routine
97 with the _UA_SEARCH_PHASE flag set. Do not modify the stack yet. */
100 _Unwind_FrameState fs;
102 /* Set up fs to describe the FDE for the caller of cur_context. The
103 first time through the loop, that means __cxa_throw. */
104 code = uw_frame_state_for (&cur_context, &fs);
106 if (code == _URC_END_OF_STACK)
107 /* Hit end of stack with no handler found. */
108 return _URC_END_OF_STACK;
110 if (code != _URC_NO_REASON)
111 /* Some error encountered. Usually the unwinder doesn't
112 diagnose these and merely crashes. */
113 return _URC_FATAL_PHASE1_ERROR;
115 /* Unwind successful. Run the personality routine, if any. */
118 code = (*fs.personality) (1, _UA_SEARCH_PHASE, exc->exception_class,
120 if (code == _URC_HANDLER_FOUND)
122 else if (code != _URC_CONTINUE_UNWIND)
123 return _URC_FATAL_PHASE1_ERROR;
126 /* Update cur_context to describe the same frame as fs. */
127 uw_update_context (&cur_context, &fs);
130 /* Indicate to _Unwind_Resume and associated subroutines that this
131 is not a forced unwind. Further, note where we found a handler. */
133 exc->private_2 = uw_identify_context (&cur_context);
135 cur_context = this_context;
136 code = _Unwind_RaiseException_Phase2 (exc, &cur_context, &frames);
137 if (code != _URC_INSTALL_CONTEXT)
140 uw_install_context (&this_context, &cur_context, frames);
144 /* Subroutine of _Unwind_ForcedUnwind also invoked from _Unwind_Resume. */
146 static _Unwind_Reason_Code
147 _Unwind_ForcedUnwind_Phase2 (struct _Unwind_Exception *exc,
148 struct _Unwind_Context *context,
149 unsigned long *frames_p)
151 _Unwind_Stop_Fn stop = (_Unwind_Stop_Fn) (_Unwind_Ptr) exc->private_1;
152 void *stop_argument = (void *) (_Unwind_Ptr) exc->private_2;
153 _Unwind_Reason_Code code, stop_code;
154 unsigned long frames = 1;
158 _Unwind_FrameState fs;
161 /* Set up fs to describe the FDE for the caller of cur_context. */
162 code = uw_frame_state_for (context, &fs);
163 if (code != _URC_NO_REASON && code != _URC_END_OF_STACK)
164 return _URC_FATAL_PHASE2_ERROR;
166 /* Unwind successful. */
167 action = _UA_FORCE_UNWIND | _UA_CLEANUP_PHASE;
168 if (code == _URC_END_OF_STACK)
169 action |= _UA_END_OF_STACK;
170 stop_code = (*stop) (1, action, exc->exception_class, exc,
171 context, stop_argument);
172 if (stop_code != _URC_NO_REASON)
173 return _URC_FATAL_PHASE2_ERROR;
175 /* Stop didn't want to do anything. Invoke the personality
176 handler, if applicable, to run cleanups. */
177 if (code == _URC_END_OF_STACK)
182 code = (*fs.personality) (1, _UA_FORCE_UNWIND | _UA_CLEANUP_PHASE,
183 exc->exception_class, exc, context);
184 if (code == _URC_INSTALL_CONTEXT)
186 if (code != _URC_CONTINUE_UNWIND)
187 return _URC_FATAL_PHASE2_ERROR;
190 /* Update cur_context to describe the same frame as fs, and discard
191 the previous context if necessary. */
192 uw_advance_context (context, &fs);
201 /* Raise an exception for forced unwinding. */
203 _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
204 _Unwind_ForcedUnwind (struct _Unwind_Exception *exc,
205 _Unwind_Stop_Fn stop, void * stop_argument)
207 struct _Unwind_Context this_context, cur_context;
208 _Unwind_Reason_Code code;
209 unsigned long frames;
211 uw_init_context (&this_context);
212 cur_context = this_context;
214 exc->private_1 = (_Unwind_Ptr) stop;
215 exc->private_2 = (_Unwind_Ptr) stop_argument;
217 code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context, &frames);
218 if (code != _URC_INSTALL_CONTEXT)
221 uw_install_context (&this_context, &cur_context, frames);
225 /* Resume propagation of an existing exception. This is used after
226 e.g. executing cleanup code, and not to implement rethrowing. */
228 void LIBGCC2_UNWIND_ATTRIBUTE
229 _Unwind_Resume (struct _Unwind_Exception *exc)
231 struct _Unwind_Context this_context, cur_context;
232 _Unwind_Reason_Code code;
233 unsigned long frames;
235 uw_init_context (&this_context);
236 cur_context = this_context;
238 /* Choose between continuing to process _Unwind_RaiseException
239 or _Unwind_ForcedUnwind. */
240 if (exc->private_1 == 0)
241 code = _Unwind_RaiseException_Phase2 (exc, &cur_context, &frames);
243 code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context, &frames);
245 gcc_assert (code == _URC_INSTALL_CONTEXT);
247 uw_install_context (&this_context, &cur_context, frames);
251 /* Resume propagation of an FORCE_UNWIND exception, or to rethrow
252 a normal exception that was handled. */
254 _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
255 _Unwind_Resume_or_Rethrow (struct _Unwind_Exception *exc)
257 struct _Unwind_Context this_context, cur_context;
258 _Unwind_Reason_Code code;
259 unsigned long frames;
261 /* Choose between continuing to process _Unwind_RaiseException
262 or _Unwind_ForcedUnwind. */
263 if (exc->private_1 == 0)
264 return _Unwind_RaiseException (exc);
266 uw_init_context (&this_context);
267 cur_context = this_context;
269 code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context, &frames);
271 gcc_assert (code == _URC_INSTALL_CONTEXT);
273 uw_install_context (&this_context, &cur_context, frames);
277 /* A convenience function that calls the exception_cleanup field. */
280 _Unwind_DeleteException (struct _Unwind_Exception *exc)
282 if (exc->exception_cleanup)
283 (*exc->exception_cleanup) (_URC_FOREIGN_EXCEPTION_CAUGHT, exc);
287 /* Perform stack backtrace through unwind data. */
289 _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
290 _Unwind_Backtrace(_Unwind_Trace_Fn trace, void * trace_argument)
292 struct _Unwind_Context context;
293 _Unwind_Reason_Code code;
295 uw_init_context (&context);
299 _Unwind_FrameState fs;
301 /* Set up fs to describe the FDE for the caller of context. */
302 code = uw_frame_state_for (&context, &fs);
303 if (code != _URC_NO_REASON && code != _URC_END_OF_STACK)
304 return _URC_FATAL_PHASE1_ERROR;
306 /* Call trace function. */
307 if ((*trace) (&context, trace_argument) != _URC_NO_REASON)
308 return _URC_FATAL_PHASE1_ERROR;
310 /* We're done at end of stack. */
311 if (code == _URC_END_OF_STACK)
314 /* Update context to describe the same frame as fs. */
315 uw_update_context (&context, &fs);