gcc/ada/seh_init.c

   1 /****************************************************************************
   2  *                                                                          *
   3  *                         GNAT COMPILER COMPONENTS                         *
   4  *                                                                          *
   5  *                              S E H - I N I T                             *
   6  *                                                                          *
   7  *                          C Implementation File                           *
   8  *                                                                          *
   9  *           Copyright (C) 2005-2012, Free Software Foundation, Inc.        *
  10  *                                                                          *
  11  * GNAT is free software;  you can  redistribute it  and/or modify it under *
  12  * terms of the  GNU General Public License as published  by the Free Soft- *
  13  * ware  Foundation;  either version 3,  or (at your option) any later ver- *
  14  * sion.  GNAT is distributed in the hope that it will be useful, but WITH- *
  15  * OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY *
  16  * or FITNESS FOR A PARTICULAR PURPOSE.                                     *
  17  *                                                                          *
  18  * As a special exception under Section 7 of GPL version 3, you are granted *
  19  * additional permissions described in the GCC Runtime Library Exception,   *
  20  * version 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  * GNAT was originally developed  by the GNAT team at  New York University. *
  28  * Extensive contributions were provided by Ada Core Technologies Inc.      *
  29  *                                                                          *
  30  ****************************************************************************/
  31
  32 /*  This unit contains support for SEH (Structured Exception Handling).
  33     Right now the only implementation is for Win32.  */
  34
  35 #ifdef __cplusplus
  36 extern "C" {
  37 #endif
  38
  39 #ifdef IN_RTS
  40 #include "tconfig.h"
  41 #include "tsystem.h"
  42
  43 /* We don't have libiberty, so use malloc.  */
  44 #define xmalloc(S) malloc (S)
  45
  46 #else
  47 #include "config.h"
  48 #include "system.h"
  49 #endif
  50
  51 #include "raise.h"
  52
  53 /* Addresses of exception data blocks for predefined exceptions. */
  54 extern struct Exception_Data constraint_error;
  55 extern struct Exception_Data numeric_error;
  56 extern struct Exception_Data program_error;
  57 extern struct Exception_Data storage_error;
  58 extern struct Exception_Data tasking_error;
  59 extern struct Exception_Data _abort_signal;
  60
  61 #define Raise_From_Signal_Handler \
  62                       ada__exceptions__raise_from_signal_handler
  63 extern void Raise_From_Signal_Handler (struct Exception_Data *, const char *);
  64
  65
  66 #if defined (_WIN32)
  67
  68 #include <windows.h>
  69 #include <excpt.h>
  70
  71 /* Prototypes.  */
  72 extern void _global_unwind2 (void *);
  73
  74 EXCEPTION_DISPOSITION __gnat_SEH_error_handler
  75 (struct _EXCEPTION_RECORD*, void*, struct _CONTEXT*, void*);
  76
  77 struct Exception_Data *
  78 __gnat_map_SEH (EXCEPTION_RECORD* ExceptionRecord, const char **msg);
  79
  80 /* Convert an SEH exception to an Ada one.  Return the exception ID
  81    and set MSG with the corresponding message.  */
  82
  83 struct Exception_Data *
  84 __gnat_map_SEH (EXCEPTION_RECORD* ExceptionRecord, const char **msg)
  85 {
  86   switch (ExceptionRecord->ExceptionCode)
  87     {
  88     case EXCEPTION_ACCESS_VIOLATION:
  89       /* If the failing address isn't maximally-aligned or if the page
  90          before the faulting page is not accessible, this is a program error.
  91       */
  92       if ((ExceptionRecord->ExceptionInformation[1] & 3) != 0
  93           || IsBadCodePtr
  94           ((void *)(ExceptionRecord->ExceptionInformation[1] + 4096)))
  95         {
  96           *msg = "EXCEPTION_ACCESS_VIOLATION";
  97           return &program_error;
  98         }
  99       else
 100         {
 101           /* otherwise it is a stack overflow  */
 102           *msg = "stack overflow or erroneous memory access";
 103           return &storage_error;
 104         }
 105
 106     case EXCEPTION_ARRAY_BOUNDS_EXCEEDED:
 107       *msg = "EXCEPTION_ARRAY_BOUNDS_EXCEEDED";
 108       return &constraint_error;
 109
 110     case EXCEPTION_DATATYPE_MISALIGNMENT:
 111       *msg = "EXCEPTION_DATATYPE_MISALIGNMENT";
 112       return &constraint_error;
 113
 114     case EXCEPTION_FLT_DENORMAL_OPERAND:
 115       *msg = "EXCEPTION_FLT_DENORMAL_OPERAND";
 116       return &constraint_error;
 117
 118     case EXCEPTION_FLT_DIVIDE_BY_ZERO:
 119       *msg = "EXCEPTION_FLT_DENORMAL_OPERAND";
 120       return &constraint_error;
 121
 122     case EXCEPTION_FLT_INVALID_OPERATION:
 123       *msg = "EXCEPTION_FLT_INVALID_OPERATION";
 124       return &constraint_error;
 125
 126     case EXCEPTION_FLT_OVERFLOW:
 127       *msg = "EXCEPTION_FLT_OVERFLOW";
 128       return &constraint_error;
 129
 130     case EXCEPTION_FLT_STACK_CHECK:
 131       *msg = "EXCEPTION_FLT_STACK_CHECK";
 132       return &program_error;
 133
 134     case EXCEPTION_FLT_UNDERFLOW:
 135       *msg = "EXCEPTION_FLT_UNDERFLOW";
 136       return &constraint_error;
 137
 138     case EXCEPTION_INT_DIVIDE_BY_ZERO:
 139       *msg = "EXCEPTION_INT_DIVIDE_BY_ZERO";
 140       return &constraint_error;
 141
 142     case EXCEPTION_INT_OVERFLOW:
 143       *msg = "EXCEPTION_INT_OVERFLOW";
 144       return &constraint_error;
 145
 146     case EXCEPTION_INVALID_DISPOSITION:
 147       *msg = "EXCEPTION_INVALID_DISPOSITION";
 148       return &program_error;
 149
 150     case EXCEPTION_NONCONTINUABLE_EXCEPTION:
 151       *msg = "EXCEPTION_NONCONTINUABLE_EXCEPTION";
 152       return &program_error;
 153
 154     case EXCEPTION_PRIV_INSTRUCTION:
 155       *msg = "EXCEPTION_PRIV_INSTRUCTION";
 156       return &program_error;
 157
 158     case EXCEPTION_SINGLE_STEP:
 159       *msg = "EXCEPTION_SINGLE_STEP";
 160       return &program_error;
 161
 162     case EXCEPTION_STACK_OVERFLOW:
 163       *msg = "EXCEPTION_STACK_OVERFLOW";
 164       return &storage_error;
 165
 166     default:
 167       *msg = NULL;
 168       return NULL;
 169     }
 170 }
 171
 172 #if !(defined (_WIN64) && defined (__SEH__))
 173
 174 EXCEPTION_DISPOSITION
 175 __gnat_SEH_error_handler (struct _EXCEPTION_RECORD* ExceptionRecord,
 176                           void *EstablisherFrame ATTRIBUTE_UNUSED,
 177                           struct _CONTEXT* ContextRecord ATTRIBUTE_UNUSED,
 178                           void *DispatcherContext ATTRIBUTE_UNUSED)
 179 {
 180   struct Exception_Data *exception;
 181   const char *msg;
 182
 183   exception = __gnat_map_SEH (ExceptionRecord, &msg);
 184
 185   if (exception == NULL)
 186     {
 187       exception = &program_error;
 188       msg = "unhandled signal";
 189     }
 190
 191 #if ! defined (_WIN64)
 192   /* This call is important as it avoids locking the second time we catch a
 193      signal. Note that this routine is documented as internal to Windows and
 194      should not be used.  */
 195
 196   _global_unwind2 (EstablisherFrame);
 197   /* Call equivalent to RtlUnwind (EstablisherFrame, NULL, NULL, 0); */
 198 #endif
 199
 200   Raise_From_Signal_Handler (exception, msg);
 201   return 0; /* This is never reached, avoid compiler warning  */
 202 }
 203 #endif /* !(defined (_WIN64) && defined (__SEH__)) */
 204
 205 #if defined (_WIN64)
 206 /*  On x86_64 windows exception mechanism is no more based on a chained list
 207     of handlers addresses on the stack. Instead unwinding information is used
 208     to retrieve the exception handler (similar to ZCX GCC mechanism). So in
 209     order to register an exception handler we need to put in the final
 210     executable some unwinding information. This information might be present
 211     statically in the image file inside the .pdata section or registered
 212     through RtlAddFunctionTable API. Currently the GCC toolchain does not
 213     generate the .pdata information for each function. As we don't need to
 214     handle SEH exceptions except for signal handling we are registering a
 215     "fake" unwinding data that associate a SEH exception handler to the
 216     complete .text section. As we never return from the handler, the system
 217     does not try to do the final unwinding using the pdata information. The
 218     unwinding is handled by the runtime using either the GNAT SJLJ mechanism
 219     or the ZCX GCC mechanism.
 220
 221     Solutions based on SetUnhandledExceptionFilter have been discarded as this
 222     function is mostly disabled on last Windows versions.
 223     Using AddVectoredExceptionHandler should also be discarded as it overrides
 224     all SEH exception handlers that might be present in the program itself and
 225     the loaded DLL (for example it results in unexpected behaviors in the
 226     Win32 subsystem.  */
 227
 228 #ifndef __SEH__
 229   /* Don't use this trick when SEH are emitted by gcc, as it will conflict with
 230      them.  */
 231 asm
 232 (
 233  " .section .rdata, \"dr\"\n"
 234  " .align 4\n"
 235  "unwind_info:\n"
 236  " .byte 9\n" /* UNW_FLAG_EHANDLER | UNW_VERSION */
 237  " .byte 0\n" /* Prologue size.  */
 238  " .byte 0\n" /* Count of unwind code.  */
 239  " .byte 0\n" /* Frame register and offset.  */
 240  " .rva __gnat_SEH_error_handler\n"
 241  "\n"
 242  " .section .pdata, \"dr\"\n"
 243  " .align 4\n"
 244  " .long 0\n" /* ImageBase */
 245  " .rva etext\n"
 246  " .rva unwind_info\n"
 247  "\n"
 248  " .text\n"
 249 );
 250 #endif /* __SEH__ */
 251
 252 void __gnat_install_SEH_handler (void *eh ATTRIBUTE_UNUSED)
 253 {
 254   /* Nothing to do, the handler is statically installed by the asm statement
 255      just above.  */
 256 }
 257
 258 #else /* defined (_WIN64) */
 259 /*  Install the Win32 SEH exception handler. Note that the caller must have
 260     allocated 8 bytes on the stack and pass the pointer to this stack
 261     space. This is needed as the SEH exception handler must be on the stack of
 262     the thread.
 263
 264        int buf[2];
 265
 266        __gnat_install_SEH_handler ((void*)buf);
 267
 268        main();
 269
 270    This call must be done before calling the main procedure or the thread
 271    entry. The stack space must exists during all the main run.  */
 272
 273 void
 274 __gnat_install_SEH_handler (void *ER)
 275 {
 276   int *ptr;
 277
 278   /* put current handler in ptr */
 279
 280   asm ("mov %%fs:(0),%0" : "=r" (ptr));
 281
 282   ((int *)ER)[0] = (int)ptr;                       /* previous handler */
 283   ((int *)ER)[1] = (int)__gnat_SEH_error_handler;  /* new handler */
 284
 285   /* ER is the new handler, set fs:(0) with this value */
 286
 287   asm volatile ("mov %0,%%fs:(0)": : "r" (ER));
 288 }
 289 #endif
 290
 291 #else /* defined (_WIN32) */
 292 /* For all non Windows targets we provide a dummy SEH install handler.  */
 293 void __gnat_install_SEH_handler (void *eh ATTRIBUTE_UNUSED)
 294 {
 295 }
 296 #endif
 297
 298 #ifdef __cplusplus
 299 }
 300 #endif