libgcc/unwind-sjlj.c

   1 /* SJLJ exception handling and frame unwind runtime interface routines.
   2    Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2006,
   3    2009, 2011 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 3, or (at your option)
  10    any later version.
  11
  12    GCC is distributed in the hope that it will be useful, but WITHOUT
  13    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  15    License for more details.
  16
  17    Under Section 7 of GPL version 3, you are granted additional
  18    permissions described in the GCC Runtime Library Exception, version
  19    3.1, as published by the Free Software Foundation.
  20
  21    You should have received a copy of the GNU General Public License and
  22    a copy of the GCC Runtime Library Exception along with this program;
  23    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24    <http://www.gnu.org/licenses/>.  */
  25
  26 #include "tconfig.h"
  27 #include "tsystem.h"
  28 #include "coretypes.h"
  29 #include "tm.h"
  30 #include "libgcc_tm.h"
  31 #include "unwind.h"
  32 #include "gthr.h"
  33
  34 #ifdef __USING_SJLJ_EXCEPTIONS__
  35
  36 #ifdef DONT_USE_BUILTIN_SETJMP
  37 #ifndef inhibit_libc
  38 #include <setjmp.h>
  39 #else
  40 typedef void *jmp_buf[JMP_BUF_SIZE];
  41 extern void longjmp(jmp_buf, int) __attribute__((noreturn));
  42 #endif
  43 #else
  44 #define longjmp __builtin_longjmp
  45 #endif
  46
  47 /* The setjmp side is dealt with in the except.c file.  */
  48 #undef setjmp
  49 #define setjmp setjmp_should_not_be_used_in_this_file
  50
  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.  */
  54 struct 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
  85 struct _Unwind_Context
  86 {
  87   struct SjLj_Function_Context *fc;
  88 };
  89
  90 typedef struct
  91 {
  92   _Unwind_Personality_Fn personality;
  93 } _Unwind_FrameState;
  94
  95 \f
  96 /* Manage the chain of registered function contexts.  */
  97
  98 /* Single threaded fallback chain.  */
  99 static struct SjLj_Function_Context *fc_static;
 100
 101 #if __GTHREADS
 102 static __gthread_key_t fc_key;
 103 static int use_fc_key = -1;
 104
 105 static void
 106 fc_key_init (void)
 107 {
 108   use_fc_key = __gthread_key_create (&fc_key, 0) == 0;
 109 }
 110
 111 static void
 112 fc_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
 120 void
 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
 140 static 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
 153 static 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
 167 void
 168 _Unwind_SjLj_Unregister (struct SjLj_Function_Context *fc)
 169 {
 170   _Unwind_SjLj_SetContext (fc->prev);
 171 }
 172
 173 \f
 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
 203 void
 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 _Unwind_Ptr
 218 _Unwind_GetIPInfo (struct _Unwind_Context *context, int *ip_before_insn)
 219 {
 220   *ip_before_insn = 0;
 221   if (context->fc != NULL)
 222     return context->fc->call_site + 1;
 223   else
 224     return 0;
 225 }
 226
 227 /* Set the return landing pad index in CONTEXT.  */
 228
 229 void
 230 _Unwind_SetIP (struct _Unwind_Context *context, _Unwind_Ptr val)
 231 {
 232   context->fc->call_site = val - 1;
 233 }
 234
 235 void *
 236 _Unwind_GetLanguageSpecificData (struct _Unwind_Context *context)
 237 {
 238   return context->fc->lsda;
 239 }
 240
 241 _Unwind_Ptr
 242 _Unwind_GetRegionStart (struct _Unwind_Context *context __attribute__((unused)) )
 243 {
 244   return 0;
 245 }
 246
 247 void *
 248 _Unwind_FindEnclosingFunction (void *pc __attribute__((unused)))
 249 {
 250   return NULL;
 251 }
 252
 253 #ifndef __ia64__
 254 _Unwind_Ptr
 255 _Unwind_GetDataRelBase (struct _Unwind_Context *context __attribute__((unused)) )
 256 {
 257   return 0;
 258 }
 259
 260 _Unwind_Ptr
 261 _Unwind_GetTextRelBase (struct _Unwind_Context *context __attribute__((unused)) )
 262 {
 263   return 0;
 264 }
 265 #endif
 266 \f
 267 static inline _Unwind_Reason_Code
 268 uw_frame_state_for (struct _Unwind_Context *context, _Unwind_FrameState *fs)
 269 {
 270   if (context->fc == NULL)
 271     {
 272       fs->personality = NULL;
 273       return _URC_END_OF_STACK;
 274     }
 275   else
 276     {
 277       fs->personality = context->fc->personality;
 278       return _URC_NO_REASON;
 279     }
 280 }
 281
 282 static inline void
 283 uw_update_context (struct _Unwind_Context *context,
 284                    _Unwind_FrameState *fs __attribute__((unused)) )
 285 {
 286   context->fc = context->fc->prev;
 287 }
 288
 289 static void
 290 uw_advance_context (struct _Unwind_Context *context, _Unwind_FrameState *fs)
 291 {
 292   _Unwind_SjLj_Unregister (context->fc);
 293   uw_update_context (context, fs);
 294 }
 295
 296 static inline void
 297 uw_init_context (struct _Unwind_Context *context)
 298 {
 299   context->fc = _Unwind_SjLj_GetContext ();
 300 }
 301
 302 static void __attribute__((noreturn))
 303 uw_install_context (struct _Unwind_Context *current __attribute__((unused)),
 304                     struct _Unwind_Context *target)
 305 {
 306   _Unwind_SjLj_SetContext (target->fc);
 307   longjmp (target->fc->jbuf, 1);
 308 }
 309
 310 static inline _Unwind_Ptr
 311 uw_identify_context (struct _Unwind_Context *context)
 312 {
 313   return (_Unwind_Ptr) context->fc;
 314 }
 315
 316
 317 /* Play games with unwind symbols so that we can have call frame
 318    and sjlj symbols in the same shared library.  Not that you can
 319    use them simultaneously...  */
 320 #define _Unwind_RaiseException          _Unwind_SjLj_RaiseException
 321 #define _Unwind_ForcedUnwind            _Unwind_SjLj_ForcedUnwind
 322 #define _Unwind_Resume                  _Unwind_SjLj_Resume
 323 #define _Unwind_Resume_or_Rethrow       _Unwind_SjLj_Resume_or_Rethrow
 324
 325 #include "unwind.inc"
 326
 327 #endif /* USING_SJLJ_EXCEPTIONS */