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) 2011-2014, 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 handler 33 trampoline to set-up the DWARF Call Frame Information that let unwinders 34 walk through the signal frame up into the interrupted application code. 35 This file introduces the relevant declarations. */ 36 37 /* This file should only be #included on targets that do implement the 38 trampoline, which needs to expose the following interface: */ 39 40 #ifdef __cplusplus 41 extern "C" { 42 #endif 43 44 #ifdef __ANDROID__ 45 #include <stdlib.h> 46 #include <asm/signal.h> 47 #include <asm/sigcontext.h> 48 49 /* Android SDK doesn't define these structs */ 50 typedef struct sigcontext mcontext_t; 51 52 typedef struct ucontext 53 { 54 unsigned long uc_flags; 55 struct ucontext *uc_link; 56 stack_t uc_stack; 57 mcontext_t uc_mcontext; 58 } ucontext_t; 59 #endif 60 61 /* This typedef signature sometimes conflicts with the sighandler_t from 62 system headers so call it something unique. */ 63 typedef void __sigtramphandler_t (int signo, void *siginfo, void *sigcontext); 64 65 void __gnat_sigtramp (int signo, void *siginfo, void *sigcontext, 66 __sigtramphandler_t * handler); 67 68 /* To be called from an established signal handler. Setup the DWARF CFI 69 bits letting unwinders walk through the signal frame up into the 70 interrupted application code, and then call HANDLER (SIGNO, SIGINFO, 71 SIGCONTEXT). 72 73 The sigtramp construct makes it so that the unwinder jumps over it + the 74 signal handler + the kernel frame. For a typical backtrace from the raise 75 function: 76 77 #0 __gnat_Unwind_RaiseException 78 #1 Raise_From_Signal_Handler 79 #2 __gnat_map_signal 80 #3 __gnat_sigtramp 81 #4 __gnat_error_handler 82 #5 <kernel frame> 83 #6 interrupted function 84 85 The unwinder will unwind frames 0, 1 and 2 as usual. But the CFI of frame 86 3 is set up as if the caller of frame 3 was frame 6 so, when frame 3 is 87 unwound, the unwinder ends up in frame 6 directly. It's possible to do so 88 since the kernel has saved the context of frame 6 and passed it on to 89 __gnat_sigtramp. */ 90 91 #ifdef __cplusplus 92 } 93 #endif 94