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-- --
-- --
-- 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) 1992-2021, 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 --
-- --
-- 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 :=
Unreserve_All_Interrupts : constant;
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)
pragma Unreferenced (siginfo);
Result :;
-- 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 :;
Use_Alternate_Stack : constant Boolean :=
System.Task_Primitives.Alternate_Stack_Size /= 0;
-- Whether to use an alternate signal stack for stack overflows
if Initialized then
end if;
Initialized := True;
-- Need to call pthread_init very early because it is doing signal
-- initializations.
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
act.sa_flags := act.sa_flags + SA_ONSTACK;
end if;
Result :=
(Signal (Exception_Interrupts (J)), 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 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;