------------------------------------------------------------------------------ -- -- -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS -- -- -- -- S Y S T E M . I N T E R R U P T S -- -- -- -- 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. -- -- -- ------------------------------------------------------------------------------ -- Invariants: -- All user-handleable interrupts are masked at all times in all tasks/threads -- except possibly for the Interrupt_Manager task. -- When a user task wants to achieve masking/unmasking an interrupt, it must -- call Block_Interrupt/Unblock_Interrupt, which will have the effect of -- unmasking/masking the interrupt in the Interrupt_Manager task. -- Note : Direct calls to sigaction, sigprocmask, pthread_sigsetmask or any -- other low-level interface that changes the interrupt action or -- interrupt mask needs a careful thought. -- One may achieve the effect of system calls first masking RTS blocked -- (by calling Block_Interrupt) for the interrupt under consideration. -- This will make all the tasks in RTS blocked for the Interrupt. -- Once we associate a Server_Task with an interrupt, the task never goes -- away, and we never remove the association. -- There is no more than one interrupt per Server_Task and no more than one -- Server_Task per interrupt. with Ada.Exceptions; with Ada.Task_Identification; with System.Task_Primitives; with System.Interrupt_Management; with System.Interrupt_Management.Operations; pragma Elaborate_All (System.Interrupt_Management.Operations); with System.IO; with System.Task_Primitives.Operations; with System.Task_Primitives.Interrupt_Operations; with System.Storage_Elements; with System.Tasking.Utilities; with System.Tasking.Rendezvous; pragma Elaborate_All (System.Tasking.Rendezvous); with System.Tasking.Initialization; with System.Parameters; with Ada.Unchecked_Conversion; package body System.Interrupts is use Parameters; use Tasking; package POP renames System.Task_Primitives.Operations; package PIO renames System.Task_Primitives.Interrupt_Operations; package IMNG renames System.Interrupt_Management; package IMOP renames System.Interrupt_Management.Operations; function To_System is new Ada.Unchecked_Conversion (Ada.Task_Identification.Task_Id, Task_Id); ----------------- -- Local Tasks -- ----------------- -- WARNING: System.Tasking.Stages performs calls to this task with -- low-level constructs. Do not change this spec without synchronizing it. task Interrupt_Manager is entry Detach_Interrupt_Entries (T : Task_Id); entry Initialize (Mask : IMNG.Interrupt_Mask); entry Attach_Handler (New_Handler : Parameterless_Handler; Interrupt : Interrupt_ID; Static : Boolean; Restoration : Boolean := False); entry Exchange_Handler (Old_Handler : out Parameterless_Handler; New_Handler : Parameterless_Handler; Interrupt : Interrupt_ID; Static : Boolean); entry Detach_Handler (Interrupt : Interrupt_ID; Static : Boolean); entry Bind_Interrupt_To_Entry (T : Task_Id; E : Task_Entry_Index; Interrupt : Interrupt_ID); entry Block_Interrupt (Interrupt : Interrupt_ID); entry Unblock_Interrupt (Interrupt : Interrupt_ID); entry Ignore_Interrupt (Interrupt : Interrupt_ID); entry Unignore_Interrupt (Interrupt : Interrupt_ID); pragma Interrupt_Priority (System.Interrupt_Priority'Last); end Interrupt_Manager; task type Server_Task (Interrupt : Interrupt_ID) is pragma Priority (System.Interrupt_Priority'Last); -- Note: the above pragma Priority is strictly speaking improper since -- it is outside the range of allowed priorities, but the compiler -- treats system units specially and does not apply this range checking -- rule to system units. end Server_Task; type Server_Task_Access is access Server_Task; ------------------------------- -- Local Types and Variables -- ------------------------------- type Entry_Assoc is record T : Task_Id; E : Task_Entry_Index; end record; type Handler_Assoc is record H : Parameterless_Handler; Static : Boolean; -- Indicates static binding; end record; User_Handler : array (Interrupt_ID'Range) of Handler_Assoc := (others => (null, Static => False)); pragma Volatile_Components (User_Handler); -- Holds the protected procedure handler (if any) and its Static -- information for each interrupt. A handler is a Static one if it is -- specified through the pragma Attach_Handler. Attach_Handler. Otherwise, -- not static) User_Entry : array (Interrupt_ID'Range) of Entry_Assoc := (others => (T => Null_Task, E => Null_Task_Entry)); pragma Volatile_Components (User_Entry); -- Holds the task and entry index (if any) for each interrupt Blocked : array (Interrupt_ID'Range) of Boolean := (others => False); pragma Atomic_Components (Blocked); -- True iff the corresponding interrupt is blocked in the process level Ignored : array (Interrupt_ID'Range) of Boolean := (others => False); pragma Atomic_Components (Ignored); -- True iff the corresponding interrupt is blocked in the process level Last_Unblocker : array (Interrupt_ID'Range) of Task_Id := (others => Null_Task); pragma Atomic_Components (Last_Unblocker); -- Holds the ID of the last Task which Unblocked this Interrupt. It -- contains Null_Task if no tasks have ever requested the Unblocking -- operation or the Interrupt is currently Blocked. Server_ID : array (Interrupt_ID'Range) of Task_Id := (others => Null_Task); pragma Atomic_Components (Server_ID); -- Holds the Task_Id of the Server_Task for each interrupt. Task_Id is -- needed to accomplish locking per Interrupt base. Also is needed to -- decide whether to create a new Server_Task. -- Type and Head, Tail of the list containing Registered Interrupt -- Handlers. These definitions are used to register the handlers -- specified by the pragma Interrupt_Handler. type Registered_Handler; type R_Link is access all Registered_Handler; type Registered_Handler is record H : System.Address := System.Null_Address; Next : R_Link := null; end record; Registered_Handler_Head : R_Link := null; Registered_Handler_Tail : R_Link := null; Access_Hold : Server_Task_Access; -- Variable used to allocate Server_Task using "new" ----------------------- -- Local Subprograms -- ----------------------- function Is_Registered (Handler : Parameterless_Handler) return Boolean; -- See if the Handler has been "pragma"ed using Interrupt_Handler. Always -- consider a null handler as registered. -------------------- -- Attach_Handler -- -------------------- -- Calling this procedure with New_Handler = null and Static = True means -- we want to detach the current handler regardless of the previous -- handler's binding status (i.e. do not care if it is a dynamic or static -- handler). -- This option is needed so that during the finalization of a PO, we can -- detach handlers attached through pragma Attach_Handler. procedure Attach_Handler (New_Handler : Parameterless_Handler; Interrupt : Interrupt_ID; Static : Boolean := False) is begin if Is_Reserved (Interrupt) then raise Program_Error with "interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved"; end if; Interrupt_Manager.Attach_Handler (New_Handler, Interrupt, Static); end Attach_Handler; ----------------------------- -- Bind_Interrupt_To_Entry -- ----------------------------- -- This procedure raises a Program_Error if it tries to bind an interrupt -- to which an Entry or a Procedure is already bound. procedure Bind_Interrupt_To_Entry (T : Task_Id; E : Task_Entry_Index; Int_Ref : System.Address) is Interrupt : constant Interrupt_ID := Interrupt_ID (Storage_Elements.To_Integer (Int_Ref)); begin if Is_Reserved (Interrupt) then raise Program_Error with "interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved"; end if; Interrupt_Manager.Bind_Interrupt_To_Entry (T, E, Interrupt); end Bind_Interrupt_To_Entry; --------------------- -- Block_Interrupt -- --------------------- procedure Block_Interrupt (Interrupt : Interrupt_ID) is begin if Is_Reserved (Interrupt) then raise Program_Error with "interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved"; end if; Interrupt_Manager.Block_Interrupt (Interrupt); end Block_Interrupt; --------------------- -- Current_Handler -- --------------------- function Current_Handler (Interrupt : Interrupt_ID) return Parameterless_Handler is begin if Is_Reserved (Interrupt) then raise Program_Error with "interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved"; end if; -- ??? Since Parameterless_Handler is not Atomic, the current -- implementation is wrong. We need a new service in Interrupt_Manager -- to ensure atomicity. return User_Handler (Interrupt).H; end Current_Handler; -------------------- -- Detach_Handler -- -------------------- -- Calling this procedure with Static = True means we want to Detach the -- current handler regardless of the previous handler's binding status -- (i.e. do not care if it is a dynamic or static handler). -- This option is needed so that during the finalization of a PO, we can -- detach handlers attached through pragma Attach_Handler. procedure Detach_Handler (Interrupt : Interrupt_ID; Static : Boolean := False) is begin if Is_Reserved (Interrupt) then raise Program_Error with "interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved"; end if; Interrupt_Manager.Detach_Handler (Interrupt, Static); end Detach_Handler; ------------------------------ -- Detach_Interrupt_Entries -- ------------------------------ procedure Detach_Interrupt_Entries (T : Task_Id) is begin Interrupt_Manager.Detach_Interrupt_Entries (T); end Detach_Interrupt_Entries; ---------------------- -- Exchange_Handler -- ---------------------- -- Calling this procedure with New_Handler = null and Static = True means -- we want to detach the current handler regardless of the previous -- handler's binding status (i.e. do not care if it is a dynamic or static -- handler). -- This option is needed so that during the finalization of a PO, we can -- detach handlers attached through pragma Attach_Handler. procedure Exchange_Handler (Old_Handler : out Parameterless_Handler; New_Handler : Parameterless_Handler; Interrupt : Interrupt_ID; Static : Boolean := False) is begin if Is_Reserved (Interrupt) then raise Program_Error with "interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved"; end if; Interrupt_Manager.Exchange_Handler (Old_Handler, New_Handler, Interrupt, Static); end Exchange_Handler; -------------- -- Finalize -- -------------- procedure Finalize (Object : in out Static_Interrupt_Protection) is function State (Int : System.Interrupt_Management.Interrupt_ID) return Character; pragma Import (C, State, "__gnat_get_interrupt_state"); -- Get interrupt state for interrupt number Int. Defined in init.c Default : constant Character := 's'; -- 's' Interrupt_State pragma set state to System (use "default" -- system handler) begin -- ??? loop to be executed only when we're not doing library level -- finalization, since in this case all interrupt tasks are gone. -- If the Abort_Task signal is set to system, it means that we cannot -- reset interrupt handlers since this would require sending the abort -- signal to the Server_Task if not Interrupt_Manager'Terminated and then State (System.Interrupt_Management.Abort_Task_Interrupt) /= Default then for N in reverse Object.Previous_Handlers'Range loop Interrupt_Manager.Attach_Handler (New_Handler => Object.Previous_Handlers (N).Handler, Interrupt => Object.Previous_Handlers (N).Interrupt, Static => Object.Previous_Handlers (N).Static, Restoration => True); end loop; end if; Tasking.Protected_Objects.Entries.Finalize (Tasking.Protected_Objects.Entries.Protection_Entries (Object)); end Finalize; ------------------------------------- -- Has_Interrupt_Or_Attach_Handler -- ------------------------------------- -- Need comments as to why these always return True ??? function Has_Interrupt_Or_Attach_Handler (Object : access Dynamic_Interrupt_Protection) return Boolean is pragma Unreferenced (Object); begin return True; end Has_Interrupt_Or_Attach_Handler; function Has_Interrupt_Or_Attach_Handler (Object : access Static_Interrupt_Protection) return Boolean is pragma Unreferenced (Object); begin return True; end Has_Interrupt_Or_Attach_Handler; ---------------------- -- Ignore_Interrupt -- ---------------------- procedure Ignore_Interrupt (Interrupt : Interrupt_ID) is begin if Is_Reserved (Interrupt) then raise Program_Error with "interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved"; end if; Interrupt_Manager.Ignore_Interrupt (Interrupt); end Ignore_Interrupt; ---------------------- -- Install_Handlers -- ---------------------- procedure Install_Handlers (Object : access Static_Interrupt_Protection; New_Handlers : New_Handler_Array) is begin for N in New_Handlers'Range loop -- We need a lock around this ??? Object.Previous_Handlers (N).Interrupt := New_Handlers (N).Interrupt; Object.Previous_Handlers (N).Static := User_Handler (New_Handlers (N).Interrupt).Static; -- We call Exchange_Handler and not directly Interrupt_Manager. -- Exchange_Handler so we get the Is_Reserved check. Exchange_Handler (Old_Handler => Object.Previous_Handlers (N).Handler, New_Handler => New_Handlers (N).Handler, Interrupt => New_Handlers (N).Interrupt, Static => True); end loop; end Install_Handlers; --------------------------------- -- Install_Restricted_Handlers -- --------------------------------- procedure Install_Restricted_Handlers (Prio : Any_Priority; Handlers : New_Handler_Array) is pragma Unreferenced (Prio); begin for N in Handlers'Range loop Attach_Handler (Handlers (N).Handler, Handlers (N).Interrupt, True); end loop; end Install_Restricted_Handlers; ---------------- -- Is_Blocked -- ---------------- function Is_Blocked (Interrupt : Interrupt_ID) return Boolean is begin if Is_Reserved (Interrupt) then raise Program_Error with "interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved"; end if; return Blocked (Interrupt); end Is_Blocked; ----------------------- -- Is_Entry_Attached -- ----------------------- function Is_Entry_Attached (Interrupt : Interrupt_ID) return Boolean is begin if Is_Reserved (Interrupt) then raise Program_Error with "interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved"; end if; return User_Entry (Interrupt).T /= Null_Task; end Is_Entry_Attached; ------------------------- -- Is_Handler_Attached -- ------------------------- function Is_Handler_Attached (Interrupt : Interrupt_ID) return Boolean is begin if Is_Reserved (Interrupt) then raise Program_Error with "interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved"; end if; return User_Handler (Interrupt).H /= null; end Is_Handler_Attached; ---------------- -- Is_Ignored -- ---------------- function Is_Ignored (Interrupt : Interrupt_ID) return Boolean is begin if Is_Reserved (Interrupt) then raise Program_Error with "interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved"; end if; return Ignored (Interrupt); end Is_Ignored; ------------------- -- Is_Registered -- ------------------- function Is_Registered (Handler : Parameterless_Handler) return Boolean is type Acc_Proc is access procedure; type Fat_Ptr is record Object_Addr : System.Address; Handler_Addr : Acc_Proc; end record; function To_Fat_Ptr is new Ada.Unchecked_Conversion (Parameterless_Handler, Fat_Ptr); Ptr : R_Link; Fat : Fat_Ptr; begin if Handler = null then return True; end if; Fat := To_Fat_Ptr (Handler); Ptr := Registered_Handler_Head; while Ptr /= null loop if Ptr.H = Fat.Handler_Addr.all'Address then return True; end if; Ptr := Ptr.Next; end loop; return False; end Is_Registered; ----------------- -- Is_Reserved -- ----------------- function Is_Reserved (Interrupt : Interrupt_ID) return Boolean is begin return IMNG.Reserve (IMNG.Interrupt_ID (Interrupt)); end Is_Reserved; --------------- -- Reference -- --------------- function Reference (Interrupt : Interrupt_ID) return System.Address is begin if Is_Reserved (Interrupt) then raise Program_Error with "interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved"; end if; return Storage_Elements.To_Address (Storage_Elements.Integer_Address (Interrupt)); end Reference; --------------------------------- -- Register_Interrupt_Handler -- --------------------------------- procedure Register_Interrupt_Handler (Handler_Addr : System.Address) is New_Node_Ptr : R_Link; begin -- This routine registers the Handler as usable for Dynamic Interrupt -- Handler. Routines attaching and detaching Handler dynamically should -- first consult if the Handler is registered. A Program Error should -- be raised if it is not registered. -- The pragma Interrupt_Handler can only appear in the library level PO -- definition and instantiation. Therefore, we do not need to implement -- Unregistering operation. Neither we need to protect the queue -- structure using a Lock. pragma Assert (Handler_Addr /= System.Null_Address); New_Node_Ptr := new Registered_Handler; New_Node_Ptr.H := Handler_Addr; if Registered_Handler_Head = null then Registered_Handler_Head := New_Node_Ptr; Registered_Handler_Tail := New_Node_Ptr; else Registered_Handler_Tail.Next := New_Node_Ptr; Registered_Handler_Tail := New_Node_Ptr; end if; end Register_Interrupt_Handler; ----------------------- -- Unblock_Interrupt -- ----------------------- procedure Unblock_Interrupt (Interrupt : Interrupt_ID) is begin if Is_Reserved (Interrupt) then raise Program_Error with "interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved"; end if; Interrupt_Manager.Unblock_Interrupt (Interrupt); end Unblock_Interrupt; ------------------ -- Unblocked_By -- ------------------ function Unblocked_By (Interrupt : Interrupt_ID) return System.Tasking.Task_Id is begin if Is_Reserved (Interrupt) then raise Program_Error with "interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved"; end if; return Last_Unblocker (Interrupt); end Unblocked_By; ------------------------ -- Unignore_Interrupt -- ------------------------ procedure Unignore_Interrupt (Interrupt : Interrupt_ID) is begin if Is_Reserved (Interrupt) then raise Program_Error with "interrupt" & Interrupt_ID'Image (Interrupt) & " is reserved"; end if; Interrupt_Manager.Unignore_Interrupt (Interrupt); end Unignore_Interrupt; ----------------------- -- Interrupt_Manager -- ----------------------- task body Interrupt_Manager is -- By making this task independent of master, when the process -- goes away, the Interrupt_Manager will terminate gracefully. Ignore : constant Boolean := System.Tasking.Utilities.Make_Independent; --------------------- -- Local Variables -- --------------------- Intwait_Mask : aliased IMNG.Interrupt_Mask; Ret_Interrupt : Interrupt_ID; Old_Mask : aliased IMNG.Interrupt_Mask; Old_Handler : Parameterless_Handler; -------------------- -- Local Routines -- -------------------- procedure Bind_Handler (Interrupt : Interrupt_ID); -- This procedure does not do anything if the Interrupt is blocked. -- Otherwise, we have to interrupt Server_Task for status change through -- Wakeup interrupt. procedure Unbind_Handler (Interrupt : Interrupt_ID); -- This procedure does not do anything if the Interrupt is blocked. -- Otherwise, we have to interrupt Server_Task for status change -- through abort interrupt. procedure Unprotected_Exchange_Handler (Old_Handler : out Parameterless_Handler; New_Handler : Parameterless_Handler; Interrupt : Interrupt_ID; Static : Boolean; Restoration : Boolean := False); procedure Unprotected_Detach_Handler (Interrupt : Interrupt_ID; Static : Boolean); ------------------ -- Bind_Handler -- ------------------ procedure Bind_Handler (Interrupt : Interrupt_ID) is begin if not Blocked (Interrupt) then -- Mask this task for the given Interrupt so that all tasks -- are masked for the Interrupt and the actual delivery of the -- Interrupt will be caught using "sigwait" by the -- corresponding Server_Task. IMOP.Thread_Block_Interrupt (IMNG.Interrupt_ID (Interrupt)); -- We have installed a Handler or an Entry before we called -- this procedure. If the Handler Task is waiting to be awakened, -- do it here. Otherwise, the interrupt will be discarded. POP.Wakeup (Server_ID (Interrupt), Interrupt_Server_Idle_Sleep); end if; end Bind_Handler; -------------------- -- Unbind_Handler -- -------------------- procedure Unbind_Handler (Interrupt : Interrupt_ID) is Server : System.Tasking.Task_Id; begin if not Blocked (Interrupt) then -- Currently, there is a Handler or an Entry attached and -- corresponding Server_Task is waiting on "sigwait." We have to -- wake up the Server_Task and make it wait on condition variable -- by sending an Abort_Task_Interrupt Server := Server_ID (Interrupt); case Server.Common.State is when Interrupt_Server_Blocked_Interrupt_Sleep | Interrupt_Server_Idle_Sleep => POP.Wakeup (Server, Server.Common.State); when Interrupt_Server_Blocked_On_Event_Flag => POP.Abort_Task (Server); -- Make sure corresponding Server_Task is out of its -- own sigwait state. Ret_Interrupt := Interrupt_ID (IMOP.Interrupt_Wait (Intwait_Mask'Access)); pragma Assert (Ret_Interrupt = Interrupt_ID (IMNG.Abort_Task_Interrupt)); when Runnable => null; when others => pragma Assert (False); null; end case; IMOP.Install_Default_Action (IMNG.Interrupt_ID (Interrupt)); -- Unmake the Interrupt for this task in order to allow default -- action again. IMOP.Thread_Unblock_Interrupt (IMNG.Interrupt_ID (Interrupt)); else IMOP.Install_Default_Action (IMNG.Interrupt_ID (Interrupt)); end if; end Unbind_Handler; -------------------------------- -- Unprotected_Detach_Handler -- -------------------------------- procedure Unprotected_Detach_Handler (Interrupt : Interrupt_ID; Static : Boolean) is Old_Handler : Parameterless_Handler; begin if User_Entry (Interrupt).T /= Null_Task then -- In case we have an Interrupt Entry installed, raise a program -- error, (propagate it to the caller). raise Program_Error with "an interrupt entry is already installed"; end if; -- Note : Static = True will pass the following check. That is the -- case when we want to detach a handler regardless of the static -- status of the current_Handler. if not Static and then User_Handler (Interrupt).Static then -- Tries to detach a static Interrupt Handler. -- raise a program error. raise Program_Error with "trying to detach a static interrupt handler"; end if; -- The interrupt should no longer be ignored if -- it was ever ignored. Ignored (Interrupt) := False; Old_Handler := User_Handler (Interrupt).H; -- The new handler User_Handler (Interrupt).H := null; User_Handler (Interrupt).Static := False; if Old_Handler /= null then Unbind_Handler (Interrupt); end if; end Unprotected_Detach_Handler; ---------------------------------- -- Unprotected_Exchange_Handler -- ---------------------------------- procedure Unprotected_Exchange_Handler (Old_Handler : out Parameterless_Handler; New_Handler : Parameterless_Handler; Interrupt : Interrupt_ID; Static : Boolean; Restoration : Boolean := False) is begin if User_Entry (Interrupt).T /= Null_Task then -- In case we have an Interrupt Entry already installed, raise a -- program error, (propagate it to the caller). raise Program_Error with "an interrupt is already installed"; end if; -- Note : A null handler with Static = True will pass the following -- check. That is the case when we want to Detach a handler -- regardless of the Static status of the current_Handler. -- We don't check anything if Restoration is True, since we may be -- detaching a static handler to restore a dynamic one. if not Restoration and then not Static -- Tries to overwrite a static Interrupt Handler with a dynamic -- Handler and then (User_Handler (Interrupt).Static -- The new handler is not specified as an -- Interrupt Handler by a pragma. or else not Is_Registered (New_Handler)) then raise Program_Error with "trying to overwrite a static Interrupt Handler with a " & "dynamic handler"; end if; -- The interrupt should no longer be ignored if -- it was ever ignored. Ignored (Interrupt) := False; -- Save the old handler Old_Handler := User_Handler (Interrupt).H; -- The new handler User_Handler (Interrupt).H := New_Handler; if New_Handler = null then -- The null handler means we are detaching the handler User_Handler (Interrupt).Static := False; else User_Handler (Interrupt).Static := Static; end if; -- Invoke a corresponding Server_Task if not yet created. -- Place Task_Id info in Server_ID array. if Server_ID (Interrupt) = Null_Task then -- When a new Server_Task is created, it should have its -- signal mask set to the All_Tasks_Mask. IMOP.Set_Interrupt_Mask (IMOP.All_Tasks_Mask'Access, Old_Mask'Access); Access_Hold := new Server_Task (Interrupt); IMOP.Set_Interrupt_Mask (Old_Mask'Access); Server_ID (Interrupt) := To_System (Access_Hold.all'Identity); end if; if New_Handler = null then if Old_Handler /= null then Unbind_Handler (Interrupt); end if; return; end if; if Old_Handler = null then Bind_Handler (Interrupt); end if; end Unprotected_Exchange_Handler; -- Start of processing for Interrupt_Manager begin -- Environment task gets its own interrupt mask, saves it, and then -- masks all interrupts except the Keep_Unmasked set. -- During rendezvous, the Interrupt_Manager receives the old interrupt -- mask of the environment task, and sets its own interrupt mask to that -- value. -- The environment task will call the entry of Interrupt_Manager some -- during elaboration of the body of this package. accept Initialize (Mask : IMNG.Interrupt_Mask) do declare The_Mask : aliased IMNG.Interrupt_Mask; begin IMOP.Copy_Interrupt_Mask (The_Mask, Mask); IMOP.Set_Interrupt_Mask (The_Mask'Access); end; end Initialize; -- Note: All tasks in RTS will have all the Reserve Interrupts being -- masked (except the Interrupt_Manager) and Keep_Unmasked unmasked -- when created. -- Abort_Task_Interrupt is one of the Interrupt unmasked in all tasks. -- We mask the Interrupt in this particular task so that "sigwait" is -- possible to catch an explicitly sent Abort_Task_Interrupt from the -- Server_Tasks. -- This sigwaiting is needed so that we make sure a Server_Task is out -- of its own sigwait state. This extra synchronization is necessary to -- prevent following scenarios. -- 1) Interrupt_Manager sends an Abort_Task_Interrupt to the -- Server_Task then changes its own interrupt mask (OS level). -- If an interrupt (corresponding to the Server_Task) arrives -- in the mean time we have the Interrupt_Manager unmasked and -- the Server_Task waiting on sigwait. -- 2) For unbinding handler, we install a default action in the -- Interrupt_Manager. POSIX.1c states that the result of using -- "sigwait" and "sigaction" simultaneously on the same interrupt -- is undefined. Therefore, we need to be informed from the -- Server_Task of the fact that the Server_Task is out of its -- sigwait stage. IMOP.Empty_Interrupt_Mask (Intwait_Mask'Access); IMOP.Add_To_Interrupt_Mask (Intwait_Mask'Access, IMNG.Abort_Task_Interrupt); IMOP.Thread_Block_Interrupt (IMNG.Abort_Task_Interrupt); loop -- A block is needed to absorb Program_Error exception begin select accept Attach_Handler (New_Handler : Parameterless_Handler; Interrupt : Interrupt_ID; Static : Boolean; Restoration : Boolean := False) do Unprotected_Exchange_Handler (Old_Handler, New_Handler, Interrupt, Static, Restoration); end Attach_Handler; or accept Exchange_Handler (Old_Handler : out Parameterless_Handler; New_Handler : Parameterless_Handler; Interrupt : Interrupt_ID; Static : Boolean) do Unprotected_Exchange_Handler (Old_Handler, New_Handler, Interrupt, Static); end Exchange_Handler; or accept Detach_Handler (Interrupt : Interrupt_ID; Static : Boolean) do Unprotected_Detach_Handler (Interrupt, Static); end Detach_Handler; or accept Bind_Interrupt_To_Entry (T : Task_Id; E : Task_Entry_Index; Interrupt : Interrupt_ID) do -- If there is a binding already (either a procedure or an -- entry), raise Program_Error (propagate it to the caller). if User_Handler (Interrupt).H /= null or else User_Entry (Interrupt).T /= Null_Task then raise Program_Error with "a binding for this interrupt is already present"; end if; -- The interrupt should no longer be ignored if -- it was ever ignored. Ignored (Interrupt) := False; User_Entry (Interrupt) := Entry_Assoc'(T => T, E => E); -- Indicate the attachment of Interrupt Entry in ATCB. -- This is need so that when an Interrupt Entry task -- terminates the binding can be cleaned. The call to -- unbinding must be made by the task before it terminates. T.Interrupt_Entry := True; -- Invoke a corresponding Server_Task if not yet created. -- Place Task_Id info in Server_ID array. if Server_ID (Interrupt) = Null_Task then -- When a new Server_Task is created, it should have its -- signal mask set to the All_Tasks_Mask. IMOP.Set_Interrupt_Mask (IMOP.All_Tasks_Mask'Access, Old_Mask'Access); Access_Hold := new Server_Task (Interrupt); IMOP.Set_Interrupt_Mask (Old_Mask'Access); Server_ID (Interrupt) := To_System (Access_Hold.all'Identity); end if; Bind_Handler (Interrupt); end Bind_Interrupt_To_Entry; or accept Detach_Interrupt_Entries (T : Task_Id) do for J in Interrupt_ID'Range loop if not Is_Reserved (J) then if User_Entry (J).T = T then -- The interrupt should no longer be ignored if -- it was ever ignored. Ignored (J) := False; User_Entry (J) := Entry_Assoc' (T => Null_Task, E => Null_Task_Entry); Unbind_Handler (J); end if; end if; end loop; -- Indicate in ATCB that no Interrupt Entries are attached T.Interrupt_Entry := False; end Detach_Interrupt_Entries; or accept Block_Interrupt (Interrupt : Interrupt_ID) do if Blocked (Interrupt) then return; end if; Blocked (Interrupt) := True; Last_Unblocker (Interrupt) := Null_Task; -- Mask this task for the given Interrupt so that all tasks -- are masked for the Interrupt. IMOP.Thread_Block_Interrupt (IMNG.Interrupt_ID (Interrupt)); if User_Handler (Interrupt).H /= null or else User_Entry (Interrupt).T /= Null_Task then -- This is the case where the Server_Task -- is waiting on"sigwait." Wake it up by sending an -- Abort_Task_Interrupt so that the Server_Task waits -- on Cond. POP.Abort_Task (Server_ID (Interrupt)); -- Make sure corresponding Server_Task is out of its own -- sigwait state. Ret_Interrupt := Interrupt_ID (IMOP.Interrupt_Wait (Intwait_Mask'Access)); pragma Assert (Ret_Interrupt = Interrupt_ID (IMNG.Abort_Task_Interrupt)); end if; end Block_Interrupt; or accept Unblock_Interrupt (Interrupt : Interrupt_ID) do if not Blocked (Interrupt) then return; end if; Blocked (Interrupt) := False; Last_Unblocker (Interrupt) := To_System (Unblock_Interrupt'Caller); if User_Handler (Interrupt).H = null and then User_Entry (Interrupt).T = Null_Task then -- No handler is attached. Unmask the Interrupt so that -- the default action can be carried out. IMOP.Thread_Unblock_Interrupt (IMNG.Interrupt_ID (Interrupt)); else -- The Server_Task must be waiting on the Cond variable -- since it was being blocked and an Interrupt Hander or -- an Entry was there. Wake it up and let it change it -- place of waiting according to its new state. POP.Wakeup (Server_ID (Interrupt), Interrupt_Server_Blocked_Interrupt_Sleep); end if; end Unblock_Interrupt; or accept Ignore_Interrupt (Interrupt : Interrupt_ID) do if Ignored (Interrupt) then return; end if; Ignored (Interrupt) := True; -- If there is a handler associated with the Interrupt, -- detach it first. In this way we make sure that the -- Server_Task is not on sigwait. This is legal since -- Unignore_Interrupt is to install the default action. if User_Handler (Interrupt).H /= null then Unprotected_Detach_Handler (Interrupt => Interrupt, Static => True); elsif User_Entry (Interrupt).T /= Null_Task then User_Entry (Interrupt) := Entry_Assoc' (T => Null_Task, E => Null_Task_Entry); Unbind_Handler (Interrupt); end if; IMOP.Install_Ignore_Action (IMNG.Interrupt_ID (Interrupt)); end Ignore_Interrupt; or accept Unignore_Interrupt (Interrupt : Interrupt_ID) do Ignored (Interrupt) := False; -- If there is a handler associated with the Interrupt, -- detach it first. In this way we make sure that the -- Server_Task is not on sigwait. This is legal since -- Unignore_Interrupt is to install the default action. if User_Handler (Interrupt).H /= null then Unprotected_Detach_Handler (Interrupt => Interrupt, Static => True); elsif User_Entry (Interrupt).T /= Null_Task then User_Entry (Interrupt) := Entry_Assoc' (T => Null_Task, E => Null_Task_Entry); Unbind_Handler (Interrupt); end if; IMOP.Install_Default_Action (IMNG.Interrupt_ID (Interrupt)); end Unignore_Interrupt; end select; exception -- If there is a program error we just want to propagate it to -- the caller and do not want to stop this task. when Program_Error => null; when X : others => System.IO.Put_Line ("Exception in Interrupt_Manager"); System.IO.Put_Line (Ada.Exceptions.Exception_Information (X)); pragma Assert (False); end; end loop; end Interrupt_Manager; ----------------- -- Server_Task -- ----------------- task body Server_Task is -- By making this task independent of master, when the process goes -- away, the Server_Task will terminate gracefully. Ignore : constant Boolean := System.Tasking.Utilities.Make_Independent; Intwait_Mask : aliased IMNG.Interrupt_Mask; Ret_Interrupt : Interrupt_ID; Self_ID : constant Task_Id := Self; Tmp_Handler : Parameterless_Handler; Tmp_ID : Task_Id; Tmp_Entry_Index : Task_Entry_Index; begin -- Install default action in system level IMOP.Install_Default_Action (IMNG.Interrupt_ID (Interrupt)); -- Note: All tasks in RTS will have all the Reserve Interrupts being -- masked (except the Interrupt_Manager) and Keep_Unmasked unmasked when -- created. -- Abort_Task_Interrupt is one of the Interrupt unmasked in all tasks. -- We mask the Interrupt in this particular task so that "sigwait" is -- possible to catch an explicitly sent Abort_Task_Interrupt from the -- Interrupt_Manager. -- There are two Interrupt interrupts that this task catch through -- "sigwait." One is the Interrupt this task is designated to catch -- in order to execute user handler or entry. The other one is -- the Abort_Task_Interrupt. This interrupt is being sent from the -- Interrupt_Manager to inform status changes (e.g: become Blocked, -- Handler or Entry is to be detached). -- Prepare a mask to used for sigwait IMOP.Empty_Interrupt_Mask (Intwait_Mask'Access); IMOP.Add_To_Interrupt_Mask (Intwait_Mask'Access, IMNG.Interrupt_ID (Interrupt)); IMOP.Add_To_Interrupt_Mask (Intwait_Mask'Access, IMNG.Abort_Task_Interrupt); IMOP.Thread_Block_Interrupt (IMNG.Abort_Task_Interrupt); PIO.Set_Interrupt_ID (IMNG.Interrupt_ID (Interrupt), Self_ID); loop System.Tasking.Initialization.Defer_Abort (Self_ID); POP.Write_Lock (Self_ID); if User_Handler (Interrupt).H = null and then User_Entry (Interrupt).T = Null_Task then -- No Interrupt binding. If there is an interrupt, -- Interrupt_Manager will take default action. Self_ID.Common.State := Interrupt_Server_Blocked_Interrupt_Sleep; POP.Sleep (Self_ID, Interrupt_Server_Idle_Sleep); Self_ID.Common.State := Runnable; elsif Blocked (Interrupt) then -- Interrupt is blocked, stay here, so we won't catch it Self_ID.Common.State := Interrupt_Server_Blocked_Interrupt_Sleep; POP.Sleep (Self_ID, Interrupt_Server_Blocked_Interrupt_Sleep); Self_ID.Common.State := Runnable; else -- A Handler or an Entry is installed. At this point all tasks -- mask for the Interrupt is masked. Catch the Interrupt using -- sigwait. -- This task may wake up from sigwait by receiving an interrupt -- (Abort_Task_Interrupt) from the Interrupt_Manager for unbinding -- a Procedure Handler or an Entry. Or it could be a wake up -- from status change (Unblocked -> Blocked). If that is not -- the case, we should execute the attached Procedure or Entry. Self_ID.Common.State := Interrupt_Server_Blocked_On_Event_Flag; POP.Unlock (Self_ID); -- Avoid race condition when terminating application and -- System.Parameters.No_Abort is True. if Parameters.No_Abort and then Self_ID.Pending_Action then Initialization.Do_Pending_Action (Self_ID); end if; Ret_Interrupt := Interrupt_ID (IMOP.Interrupt_Wait (Intwait_Mask'Access)); Self_ID.Common.State := Runnable; if Ret_Interrupt = Interrupt_ID (IMNG.Abort_Task_Interrupt) then -- Inform the Interrupt_Manager of wakeup from above sigwait POP.Abort_Task (Interrupt_Manager_ID); POP.Write_Lock (Self_ID); else POP.Write_Lock (Self_ID); if Ret_Interrupt /= Interrupt then -- On some systems (e.g. recent linux kernels), sigwait -- may return unexpectedly (with errno set to EINTR). null; else -- Even though we have received an Interrupt the status may -- have changed already before we got the Self_ID lock above -- Therefore we make sure a Handler or an Entry is still -- there and make appropriate call. -- If there is no calls to make we need to regenerate the -- Interrupt in order not to lose it. if User_Handler (Interrupt).H /= null then Tmp_Handler := User_Handler (Interrupt).H; -- RTS calls should not be made with self being locked POP.Unlock (Self_ID); Tmp_Handler.all; POP.Write_Lock (Self_ID); elsif User_Entry (Interrupt).T /= Null_Task then Tmp_ID := User_Entry (Interrupt).T; Tmp_Entry_Index := User_Entry (Interrupt).E; -- RTS calls should not be made with self being locked POP.Unlock (Self_ID); System.Tasking.Rendezvous.Call_Simple (Tmp_ID, Tmp_Entry_Index, System.Null_Address); POP.Write_Lock (Self_ID); else -- This is a situation that this task wakes up receiving -- an Interrupt and before it gets the lock the Interrupt -- is blocked. We do not want to lose the interrupt in -- this case so we regenerate the Interrupt to process -- level. IMOP.Interrupt_Self_Process (IMNG.Interrupt_ID (Interrupt)); end if; end if; end if; end if; POP.Unlock (Self_ID); System.Tasking.Initialization.Undefer_Abort (Self_ID); if Self_ID.Pending_Action then Initialization.Do_Pending_Action (Self_ID); end if; -- Undefer abort here to allow a window for this task to be aborted -- at the time of system shutdown. We also explicitly test for -- Pending_Action in case System.Parameters.No_Abort is True. end loop; end Server_Task; -- Elaboration code for package System.Interrupts begin -- Get Interrupt_Manager's ID so that Abort_Interrupt can be sent Interrupt_Manager_ID := To_System (Interrupt_Manager'Identity); -- During the elaboration of this package body we want the RTS -- to inherit the interrupt mask from the Environment Task. IMOP.Setup_Interrupt_Mask; -- The environment task should have gotten its mask from the enclosing -- process during the RTS start up. (See processing in s-inmaop.adb). Pass -- the Interrupt_Mask of the environment task to the Interrupt_Manager. -- Note: At this point we know that all tasks are masked for non-reserved -- signals. Only the Interrupt_Manager will have masks set up differently -- inheriting the original environment task's mask. Interrupt_Manager.Initialize (IMOP.Environment_Mask); end System.Interrupts;