1/* SJLJ exception handling and frame unwind runtime interface routines.
2   Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
3   Free Software Foundation, Inc.
4
5   This file is part of GCC.
6
7   GCC is free software; you can redistribute it and/or modify it
8   under the terms of the GNU General Public License as published by
9   the Free Software Foundation; either version 2, or (at your option)
10   any later version.
11
12   In addition to the permissions in the GNU General Public License, the
13   Free Software Foundation gives you unlimited permission to link the
14   compiled version of this file into combinations with other programs,
15   and to distribute those combinations without any restriction coming
16   from the use of this file.  (The General Public License restrictions
17   do apply in other respects; for example, they cover modification of
18   the file, and distribution when not linked into a combined
19   executable.)
20
21   GCC is distributed in the hope that it will be useful, but WITHOUT
22   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
23   or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
24   License for more details.
25
26   You should have received a copy of the GNU General Public License
27   along with GCC; see the file COPYING.  If not, write to the Free
28   Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
29   02110-1301, USA.  */
30
31#include "tconfig.h"
32#include "tsystem.h"
33#include "coretypes.h"
34#include "tm.h"
35#include "unwind.h"
36#include "gthr.h"
37
38#ifdef __USING_SJLJ_EXCEPTIONS__
39
40#ifdef DONT_USE_BUILTIN_SETJMP
41#ifndef inhibit_libc
42#include <setjmp.h>
43#else
44typedef void *jmp_buf[JMP_BUF_SIZE];
45extern void longjmp(jmp_buf, int) __attribute__((noreturn));
46#endif
47#else
48#define setjmp __builtin_setjmp
49#define longjmp __builtin_longjmp
50#endif
51
52/* This structure is allocated on the stack of the target function.
53   This must match the definition created in except.c:init_eh.  */
54struct SjLj_Function_Context
55{
56  /* This is the chain through all registered contexts.  It is
57     filled in by _Unwind_SjLj_Register.  */
58  struct SjLj_Function_Context *prev;
59
60  /* This is assigned in by the target function before every call
61     to the index of the call site in the lsda.  It is assigned by
62     the personality routine to the landing pad index.  */
63  int call_site;
64
65  /* This is how data is returned from the personality routine to
66     the target function's handler.  */
67  _Unwind_Word data[4];
68
69  /* These are filled in once by the target function before any
70     exceptions are expected to be handled.  */
71  _Unwind_Personality_Fn personality;
72  void *lsda;
73
74#ifdef DONT_USE_BUILTIN_SETJMP
75  /* We don't know what sort of alignment requirements the system
76     jmp_buf has.  We over estimated in except.c, and now we have
77     to match that here just in case the system *didn't* have more
78     restrictive requirements.  */
79  jmp_buf jbuf __attribute__((aligned));
80#else
81  void *jbuf[];
82#endif
83};
84
85struct _Unwind_Context
86{
87  struct SjLj_Function_Context *fc;
88};
89
90typedef struct
91{
92  _Unwind_Personality_Fn personality;
93} _Unwind_FrameState;
94
95
96/* Manage the chain of registered function contexts.  */
97
98/* Single threaded fallback chain.  */
99static struct SjLj_Function_Context *fc_static;
100
101#if __GTHREADS
102static __gthread_key_t fc_key;
103static int use_fc_key = -1;
104
105static void
106fc_key_init (void)
107{
108  use_fc_key = __gthread_key_create (&fc_key, 0) == 0;
109}
110
111static void
112fc_key_init_once (void)
113{
114  static __gthread_once_t once = __GTHREAD_ONCE_INIT;
115  if (__gthread_once (&once, fc_key_init) != 0 || use_fc_key < 0)
116    use_fc_key = 0;
117}
118#endif
119
120void
121_Unwind_SjLj_Register (struct SjLj_Function_Context *fc)
122{
123#if __GTHREADS
124  if (use_fc_key < 0)
125    fc_key_init_once ();
126
127  if (use_fc_key)
128    {
129      fc->prev = __gthread_getspecific (fc_key);
130      __gthread_setspecific (fc_key, fc);
131    }
132  else
133#endif
134    {
135      fc->prev = fc_static;
136      fc_static = fc;
137    }
138}
139
140static inline struct SjLj_Function_Context *
141_Unwind_SjLj_GetContext (void)
142{
143#if __GTHREADS
144  if (use_fc_key < 0)
145    fc_key_init_once ();
146
147  if (use_fc_key)
148    return __gthread_getspecific (fc_key);
149#endif
150  return fc_static;
151}
152
153static inline void
154_Unwind_SjLj_SetContext (struct SjLj_Function_Context *fc)
155{
156#if __GTHREADS
157  if (use_fc_key < 0)
158    fc_key_init_once ();
159
160  if (use_fc_key)
161    __gthread_setspecific (fc_key, fc);
162  else
163#endif
164    fc_static = fc;
165}
166
167void
168_Unwind_SjLj_Unregister (struct SjLj_Function_Context *fc)
169{
170  _Unwind_SjLj_SetContext (fc->prev);
171}
172
173
174/* Get/set the return data value at INDEX in CONTEXT.  */
175
176_Unwind_Word
177_Unwind_GetGR (struct _Unwind_Context *context, int index)
178{
179  return context->fc->data[index];
180}
181
182/* Get the value of the CFA as saved in CONTEXT.  */
183
184_Unwind_Word
185_Unwind_GetCFA (struct _Unwind_Context *context __attribute__((unused)))
186{
187  /* ??? Ideally __builtin_setjmp places the CFA in the jmpbuf.  */
188
189#ifndef DONT_USE_BUILTIN_SETJMP
190  /* This is a crude imitation of the CFA: the saved stack pointer.
191     This is roughly the CFA of the frame before CONTEXT.  When using the
192     DWARF-2 unwinder _Unwind_GetCFA returns the CFA of the frame described
193     by CONTEXT instead; but for DWARF-2 the cleanups associated with
194     CONTEXT have already been run, and for SJLJ they have not yet been.  */
195  if (context->fc != NULL)
196    return (_Unwind_Word) context->fc->jbuf[2];
197#endif
198
199  /* Otherwise we're out of luck for now.  */
200  return (_Unwind_Word) 0;
201}
202
203void
204_Unwind_SetGR (struct _Unwind_Context *context, int index, _Unwind_Word val)
205{
206  context->fc->data[index] = val;
207}
208
209/* Get the call-site index as saved in CONTEXT.  */
210
211_Unwind_Ptr
212_Unwind_GetIP (struct _Unwind_Context *context)
213{
214  return context->fc->call_site + 1;
215}
216
217/* Set the return landing pad index in CONTEXT.  */
218
219void
220_Unwind_SetIP (struct _Unwind_Context *context, _Unwind_Ptr val)
221{
222  context->fc->call_site = val - 1;
223}
224
225void *
226_Unwind_GetLanguageSpecificData (struct _Unwind_Context *context)
227{
228  return context->fc->lsda;
229}
230
231_Unwind_Ptr
232_Unwind_GetRegionStart (struct _Unwind_Context *context __attribute__((unused)) )
233{
234  return 0;
235}
236
237void *
238_Unwind_FindEnclosingFunction (void *pc __attribute__((unused)))
239{
240  return NULL;
241}
242
243#ifndef __ia64__
244_Unwind_Ptr
245_Unwind_GetDataRelBase (struct _Unwind_Context *context __attribute__((unused)) )
246{
247  return 0;
248}
249
250_Unwind_Ptr
251_Unwind_GetTextRelBase (struct _Unwind_Context *context __attribute__((unused)) )
252{
253  return 0;
254}
255#endif
256
257static inline _Unwind_Reason_Code
258uw_frame_state_for (struct _Unwind_Context *context, _Unwind_FrameState *fs)
259{
260  if (context->fc == NULL)
261    {
262      fs->personality = NULL;
263      return _URC_END_OF_STACK;
264    }
265  else
266    {
267      fs->personality = context->fc->personality;
268      return _URC_NO_REASON;
269    }
270}
271
272static inline void
273uw_update_context (struct _Unwind_Context *context,
274		   _Unwind_FrameState *fs __attribute__((unused)) )
275{
276  context->fc = context->fc->prev;
277}
278
279static void
280uw_advance_context (struct _Unwind_Context *context, _Unwind_FrameState *fs)
281{
282  _Unwind_SjLj_Unregister (context->fc);
283  uw_update_context (context, fs);
284}
285
286static inline void
287uw_init_context (struct _Unwind_Context *context)
288{
289  context->fc = _Unwind_SjLj_GetContext ();
290}
291
292static void __attribute__((noreturn))
293uw_install_context (struct _Unwind_Context *current __attribute__((unused)),
294                    struct _Unwind_Context *target)
295{
296  _Unwind_SjLj_SetContext (target->fc);
297  longjmp (target->fc->jbuf, 1);
298}
299
300static inline _Unwind_Ptr
301uw_identify_context (struct _Unwind_Context *context)
302{
303  return (_Unwind_Ptr) context->fc;
304}
305
306
307/* Play games with unwind symbols so that we can have call frame
308   and sjlj symbols in the same shared library.  Not that you can
309   use them simultaneously...  */
310#define _Unwind_RaiseException		_Unwind_SjLj_RaiseException
311#define _Unwind_ForcedUnwind		_Unwind_SjLj_ForcedUnwind
312#define _Unwind_Resume			_Unwind_SjLj_Resume
313#define _Unwind_Resume_or_Rethrow	_Unwind_SjLj_Resume_or_Rethrow
314
315#include "unwind.inc"
316
317#endif /* USING_SJLJ_EXCEPTIONS */
318