------------------------------------------------------------------------------ -- -- -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS -- -- -- -- S Y S T E M . I N T E R R U P T _ M A N A G E M E N T -- -- -- -- B o d y -- -- -- -- Copyright (C) 1992-2020, Free Software Foundation, Inc. -- -- -- -- GNARL 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 -- -- . -- -- -- -- GNARL was developed by the GNARL team at Florida State University. -- -- Extensive contributions were provided by Ada Core Technologies, Inc. -- -- -- ------------------------------------------------------------------------------ -- This is the POSIX threads version of this package -- Make a careful study of all signals available under the OS, to see which -- need to be reserved, kept always unmasked, or kept always unmasked. Be on -- the lookout for special signals that may be used by the thread library. -- Since this is a multi target file, the signal <-> exception mapping -- is simple minded. If you need a more precise and target specific -- signal handling, create a new s-intman.adb that will fit your needs. -- This file assumes that: -- SIGFPE, SIGILL, SIGSEGV and SIGBUS exist. They are mapped as follows: -- SIGPFE => Constraint_Error -- SIGILL => Program_Error -- SIGSEGV => Storage_Error -- SIGBUS => Storage_Error -- SIGINT exists and will be kept unmasked unless the pragma -- Unreserve_All_Interrupts is specified anywhere in the application. -- System.OS_Interface contains the following: -- SIGADAABORT: the signal that will be used to abort tasks. -- Unmasked: the OS specific set of signals that should be unmasked in -- all the threads. SIGADAABORT is unmasked by -- default -- Reserved: the OS specific set of signals that are reserved. with System.Task_Primitives; package body System.Interrupt_Management is use Interfaces.C; use System.OS_Interface; type Interrupt_List is array (Interrupt_ID range <>) of Interrupt_ID; Exception_Interrupts : constant Interrupt_List := (SIGFPE, SIGILL, SIGSEGV, SIGBUS); Unreserve_All_Interrupts : Interfaces.C.int; pragma Import (C, Unreserve_All_Interrupts, "__gl_unreserve_all_interrupts"); ----------------------- -- Local Subprograms -- ----------------------- function State (Int : Interrupt_ID) return Character; pragma Import (C, State, "__gnat_get_interrupt_state"); -- Get interrupt state. Defined in init.c The input argument is the -- interrupt number, and the result is one of the following: User : constant Character := 'u'; Runtime : constant Character := 'r'; Default : constant Character := 's'; -- 'n' this interrupt not set by any Interrupt_State pragma -- 'u' Interrupt_State pragma set state to User -- 'r' Interrupt_State pragma set state to Runtime -- 's' Interrupt_State pragma set state to System (use "default" -- system handler) procedure Notify_Exception (signo : Signal; siginfo : System.Address; ucontext : System.Address); -- This function identifies the Ada exception to be raised using the -- information when the system received a synchronous signal. Since this -- function is machine and OS dependent, different code has to be provided -- for different target. ---------------------- -- Notify_Exception -- ---------------------- Signal_Mask : aliased sigset_t; -- The set of signals handled by Notify_Exception procedure Notify_Exception (signo : Signal; siginfo : System.Address; ucontext : System.Address) is pragma Unreferenced (siginfo); Result : Interfaces.C.int; begin -- With the __builtin_longjmp, the signal mask is not restored, so we -- need to restore it explicitly. Result := pthread_sigmask (SIG_UNBLOCK, Signal_Mask'Access, null); pragma Assert (Result = 0); -- Perform the necessary context adjustments prior to a raise -- from a signal handler. Adjust_Context_For_Raise (signo, ucontext); -- Check that treatment of exception propagation here is consistent with -- treatment of the abort signal in System.Task_Primitives.Operations. case signo is when SIGFPE => raise Constraint_Error; when SIGILL => raise Program_Error; when SIGSEGV => raise Storage_Error; when SIGBUS => raise Storage_Error; when others => null; end case; end Notify_Exception; ---------------- -- Initialize -- ---------------- Initialized : Boolean := False; procedure Initialize is act : aliased struct_sigaction; old_act : aliased struct_sigaction; Result : System.OS_Interface.int; Use_Alternate_Stack : constant Boolean := System.Task_Primitives.Alternate_Stack_Size /= 0; -- Whether to use an alternate signal stack for stack overflows begin if Initialized then return; end if; Initialized := True; -- Need to call pthread_init very early because it is doing signal -- initializations. pthread_init; Abort_Task_Interrupt := SIGADAABORT; act.sa_handler := Notify_Exception'Address; -- Setting SA_SIGINFO asks the kernel to pass more than just the signal -- number argument to the handler when it is called. The set of extra -- parameters includes a pointer to the interrupted context, which the -- ZCX propagation scheme needs. -- Most man pages for sigaction mention that sa_sigaction should be set -- instead of sa_handler when SA_SIGINFO is on. In practice, the two -- fields are actually union'ed and located at the same offset. -- On some targets, we set sa_flags to SA_NODEFER so that during the -- handler execution we do not change the Signal_Mask to be masked for -- the Signal. -- This is a temporary fix to the problem that the Signal_Mask is not -- restored after the exception (longjmp) from the handler. The right -- fix should be made in sigsetjmp so that we save the Signal_Set and -- restore it after a longjmp. -- Since SA_NODEFER is obsolete, instead we reset explicitly the mask -- in the exception handler. Result := sigemptyset (Signal_Mask'Access); pragma Assert (Result = 0); -- Add signals that map to Ada exceptions to the mask for J in Exception_Interrupts'Range loop if State (Exception_Interrupts (J)) /= Default then Result := sigaddset (Signal_Mask'Access, Signal (Exception_Interrupts (J))); pragma Assert (Result = 0); end if; end loop; act.sa_mask := Signal_Mask; pragma Assert (Keep_Unmasked = (Interrupt_ID'Range => False)); pragma Assert (Reserve = (Interrupt_ID'Range => False)); -- Process state of exception signals for J in Exception_Interrupts'Range loop if State (Exception_Interrupts (J)) /= User then Keep_Unmasked (Exception_Interrupts (J)) := True; Reserve (Exception_Interrupts (J)) := True; if State (Exception_Interrupts (J)) /= Default then act.sa_flags := SA_SIGINFO; if Use_Alternate_Stack and then Exception_Interrupts (J) = SIGSEGV then act.sa_flags := act.sa_flags + SA_ONSTACK; end if; Result := sigaction (Signal (Exception_Interrupts (J)), act'Unchecked_Access, old_act'Unchecked_Access); pragma Assert (Result = 0); end if; end if; end loop; if State (Abort_Task_Interrupt) /= User then Keep_Unmasked (Abort_Task_Interrupt) := True; Reserve (Abort_Task_Interrupt) := True; end if; -- Set SIGINT to unmasked state as long as it is not in "User" state. -- Check for Unreserve_All_Interrupts last. if State (SIGINT) /= User then Keep_Unmasked (SIGINT) := True; Reserve (SIGINT) := True; end if; -- Check all signals for state that requires keeping them unmasked and -- reserved. for J in Interrupt_ID'Range loop if State (J) = Default or else State (J) = Runtime then Keep_Unmasked (J) := True; Reserve (J) := True; end if; end loop; -- Add the set of signals that must always be unmasked for this target for J in Unmasked'Range loop Keep_Unmasked (Interrupt_ID (Unmasked (J))) := True; Reserve (Interrupt_ID (Unmasked (J))) := True; end loop; -- Add target-specific reserved signals for J in Reserved'Range loop Reserve (Interrupt_ID (Reserved (J))) := True; end loop; -- Process pragma Unreserve_All_Interrupts. This overrides any settings -- due to pragma Interrupt_State: if Unreserve_All_Interrupts /= 0 then Keep_Unmasked (SIGINT) := False; Reserve (SIGINT) := False; end if; -- We do not really have Signal 0. We just use this value to identify -- non-existent signals (see s-intnam.ads). Therefore, Signal should not -- be used in all signal related operations hence mark it as reserved. Reserve (0) := True; end Initialize; end System.Interrupt_Management;