1 /**************************************************************************** 2 * * 3 * GNAT COMPILER COMPONENTS * 4 * * 5 * S I G T R A M P * 6 * * 7 * C Header File * 8 * * 9 * Copyright (C) 2011-2015, 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 /* On targets where this is implemented, we resort to a signal trampoline to 33 set up the DWARF Call Frame Information that lets unwinders walk through 34 the signal frame up into the interrupted user code. This file introduces 35 the relevant declarations. It should only be #included on targets that do 36 implement the signal trampoline. */ 37 38 #ifdef __cplusplus 39 extern "C" { 40 #endif 41 42 /* This typedef signature sometimes conflicts with the sighandler_t from 43 system headers so call it something unique. */ 44 typedef void __sigtramphandler_t (int signo, void *siginfo, void *sigcontext); 45 46 #if defined(__vxworks) && (CPU == SIMNT || CPU == SIMPENTIUM || CPU == SIMLINUX) 47 /* Vxsim requires a specially compiled handler. */ 48 extern void __gnat_sigtramp_vxsim (int signo, void *siginfo, void *sigcontext, 49 __sigtramphandler_t * handler); 50 #else 51 extern void __gnat_sigtramp (int signo, void *siginfo, void *sigcontext, 52 __sigtramphandler_t * handler); 53 #endif 54 55 /* The signal trampoline is to be called from an established signal handler. 56 It sets up the DWARF CFI and calls HANDLER (SIGNO, SIGINFO, SIGCONTEXT). 57 58 The trampoline construct makes it so that the unwinder jumps over it + the 59 signal handler + the kernel frame. For a typical backtrace from the raise 60 function: 61 62 #0 __gnat_Unwind_RaiseException 63 #1 Raise_From_Signal_Handler 64 #2 __gnat_map_signal 65 #3 __gnat_sigtramp 66 #4 __gnat_error_handler 67 #5 <kernel frame> 68 #6 interrupted function 69 70 The unwinder will unwind frames 0, 1 and 2 as usual. But the CFI of frame 71 3 is set up as if the caller of frame 3 was frame 6 so, when frame 3 is 72 unwound, the unwinder ends up in frame 6 directly. It's possible to do so 73 because the kernel has saved the context of frame 6 and passed it on to 74 __gnat_error_handler and __gnat_sigtramp. */ 75 76 #ifdef __cplusplus 77 } 78 #endif 79