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1 /****************************************************************************
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2 * *
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3 * GNAT COMPILER COMPONENTS *
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4 * *
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5 * S I G T R A M P *
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6 * *
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7 * C Header File *
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8 * *
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131
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9 * Copyright (C) 2011-2018, Free Software Foundation, Inc. *
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111
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10 * *
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11 * GNAT is free software; you can redistribute it and/or modify it under *
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12 * terms of the GNU General Public License as published by the Free Soft- *
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13 * ware Foundation; either version 3, or (at your option) any later ver- *
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14 * sion. GNAT is distributed in the hope that it will be useful, but WITH- *
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15 * OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY *
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16 * or FITNESS FOR A PARTICULAR PURPOSE. *
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17 * *
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18 * As a special exception under Section 7 of GPL version 3, you are granted *
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19 * additional permissions described in the GCC Runtime Library Exception, *
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20 * version 3.1, as published by the Free Software Foundation. *
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21 * *
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22 * You should have received a copy of the GNU General Public License and *
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23 * a copy of the GCC Runtime Library Exception along with this program; *
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24 * see the files COPYING3 and COPYING.RUNTIME respectively. If not, see *
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25 * <http://www.gnu.org/licenses/>. *
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26 * *
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27 * GNAT was originally developed by the GNAT team at New York University. *
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28 * Extensive contributions were provided by Ada Core Technologies Inc. *
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29 * *
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30 ****************************************************************************/
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31
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32 /* On targets where this is implemented, we resort to a signal trampoline to
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33 set up the DWARF Call Frame Information that lets unwinders walk through
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34 the signal frame up into the interrupted user code. This file introduces
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35 the relevant declarations. It should only be #included on targets that do
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36 implement the signal trampoline. */
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37
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38 #ifdef __cplusplus
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39 extern "C" {
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40 #endif
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41
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42 /* This typedef signature sometimes conflicts with the sighandler_t from
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43 system headers so call it something unique. */
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44 typedef void __sigtramphandler_t (int signo, void *siginfo, void *sigcontext);
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45
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46 /* The vxsim target has a different sigcontext structure than the one we're
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47 compiling the run-time with. We thus need to adjust it in this case */
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48 #if defined(__vxworks) && (defined (__i386__) || defined (__x86_64__)) && !defined (VTHREADS)
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49 #define __HANDLE_VXSIM_SC
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50 extern void __gnat_set_is_vxsim(int val);
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51 #endif
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52
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53 extern void __gnat_sigtramp (int signo, void *siginfo, void *sigcontext,
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54 __sigtramphandler_t * handler);
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55
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56 /* The signal trampoline is to be called from an established signal handler.
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57 It sets up the DWARF CFI and calls HANDLER (SIGNO, SIGINFO, SIGCONTEXT).
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58
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59 The trampoline construct makes it so that the unwinder jumps over it + the
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60 signal handler + the kernel frame. For a typical backtrace from the raise
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61 function:
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62
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63 #0 __gnat_Unwind_RaiseException
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64 #1 Raise_From_Signal_Handler
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65 #2 __gnat_map_signal
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66 #3 __gnat_sigtramp
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67 #4 __gnat_error_handler
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68 #5 <kernel frame>
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69 #6 interrupted function
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70
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71 The unwinder will unwind frames 0, 1 and 2 as usual. But the CFI of frame
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72 3 is set up as if the caller of frame 3 was frame 6 so, when frame 3 is
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73 unwound, the unwinder ends up in frame 6 directly. It's possible to do so
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74 because the kernel has saved the context of frame 6 and passed it on to
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75 __gnat_error_handler and __gnat_sigtramp. */
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76
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77 #ifdef __cplusplus
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78 }
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79 #endif
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