diff options
Diffstat (limited to 'gcc-4.9/gcc/ada/sigtramp.h')
-rw-r--r-- | gcc-4.9/gcc/ada/sigtramp.h | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/gcc-4.9/gcc/ada/sigtramp.h b/gcc-4.9/gcc/ada/sigtramp.h new file mode 100644 index 000000000..cf5f4707e --- /dev/null +++ b/gcc-4.9/gcc/ada/sigtramp.h @@ -0,0 +1,74 @@ +/**************************************************************************** + * * + * GNAT COMPILER COMPONENTS * + * * + * S I G T R A M P * + * * + * C Header File * + * * + * Copyright (C) 2011-2013, Free Software Foundation, Inc. * + * * + * GNAT is free software; you can redistribute it and/or modify it under * + * terms of the GNU General Public License as published by the Free Soft- * + * ware Foundation; either version 3, or (at your option) any later ver- * + * sion. GNAT is distributed in the hope that it will be useful, but WITH- * + * OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * + * or FITNESS FOR A PARTICULAR PURPOSE. * + * * + * As a special exception under Section 7 of GPL version 3, you are granted * + * additional permissions described in the GCC Runtime Library Exception, * + * version 3.1, as published by the Free Software Foundation. * + * * + * You should have received a copy of the GNU General Public License and * + * a copy of the GCC Runtime Library Exception along with this program; * + * see the files COPYING3 and COPYING.RUNTIME respectively. If not, see * + * <http://www.gnu.org/licenses/>. * + * * + * GNAT was originally developed by the GNAT team at New York University. * + * Extensive contributions were provided by Ada Core Technologies Inc. * + * * + ****************************************************************************/ + +/* On targets where this is implemented, we resort to a signal handler + trampoline to set-up the DWARF Call Frame Information that let unwinders + walk through the signal frame up into the interrupted application code. + This file introduces the relevant declarations. */ + +/* This file should only be #included on targets that do implement the + trampoline, which needs to expose the following interface: */ + +#ifdef __cplusplus +extern "C" { +#endif + + typedef void sighandler_t (int signo, void *siginfo, void *sigcontext); + + void __gnat_sigtramp (int signo, void *siginfo, void *sigcontext, + sighandler_t * handler); + + /* To be called from an established signal handler. Setup the DWARF CFI + bits letting unwinders walk through the signal frame up into the + interrupted application code, and then call HANDLER (SIGNO, SIGINFO, + SIGCONTEXT). + + The sigtramp construct makes it so that the unwinder jumps over it + the + signal handler + the kernel frame. For a typical backtrace from the raise + function: + + #0 __gnat_Unwind_RaiseException + #1 Raise_From_Signal_Handler + #2 __gnat_map_signal + #3 __gnat_sigtramp + #4 __gnat_error_handler + #5 <kernel frame> + #6 interrupted function + + The unwinder will unwind frames 0, 1 and 2 as usual. But the CFI of frame + 3 is set up as if the caller of frame 3 was frame 6 so, when frame 3 is + unwound, the unwinder ends up in frame 6 directly. It's possible to do so + since the kernel has saved the context of frame 6 and passed it on to + __gnat_sigtramp. */ + +#ifdef __cplusplus +} +#endif |