gcc/ada/s-interr-vms.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS               --
   4 --                                                                          --
   5 --                     S Y S T E M . I N T E R R U P T S                    --
   6 --                                                                          --
   7 --                                  B o d y                                 --
   8 --                                                                          --
   9 --         Copyright (C) 1992-2004, Free Software Foundation, Inc.          --
  10 --                                                                          --
  11 -- GNARL 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- --
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  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
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  20 -- MA 02111-1307, USA.                                                      --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNARL was developed by the GNARL team at Florida State University.       --
  30 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  This is an OpenVMS/Alpha version of this package.
  35
  36 --  Invariants:
  37
  38 --  Once we associate a Server_Task with an interrupt, the task never
  39 --  goes away, and we never remove the association.
  40
  41 --  There is no more than one interrupt per Server_Task and no more than
  42 --  one Server_Task per interrupt.
  43
  44 --  Within this package, the lock L is used to protect the various status
  45 --  tables. If there is a Server_Task associated with an interrupt, we use
  46 --  the per-task lock of the Server_Task instead so that we protect the
  47 --  status between Interrupt_Manager and Server_Task. Protection among
  48 --  service requests are done using User Request to Interrupt_Manager
  49 --  rendezvous.
  50
  51 with Ada.Task_Identification;
  52 --  used for Task_Id type
  53
  54 with Ada.Exceptions;
  55 --  used for Raise_Exception
  56
  57 with System.Task_Primitives;
  58 --  used for RTS_Lock
  59 --           Self
  60
  61 with System.Interrupt_Management;
  62 --  used for Reserve
  63 --           Interrupt_ID
  64 --           Interrupt_Mask
  65 --           Abort_Task_Interrupt
  66
  67 with System.Interrupt_Management.Operations;
  68 --  used for Thread_Block_Interrupt
  69 --           Thread_Unblock_Interrupt
  70 --           Install_Default_Action
  71 --           Install_Ignore_Action
  72 --           Copy_Interrupt_Mask
  73 --           Set_Interrupt_Mask
  74 --           Empty_Interrupt_Mask
  75 --           Fill_Interrupt_Mask
  76 --           Add_To_Interrupt_Mask
  77 --           Delete_From_Interrupt_Mask
  78 --           Interrupt_Wait
  79 --           Interrupt_Self_Process
  80 --           Get_Interrupt_Mask
  81 --           Set_Interrupt_Mask
  82 --           IS_Member
  83 --           Environment_Mask
  84 pragma Elaborate_All (System.Interrupt_Management.Operations);
  85
  86 with System.Task_Primitives.Operations;
  87 --  used for Write_Lock
  88 --           Unlock
  89 --           Abort
  90 --           Wakeup_Task
  91 --           Sleep
  92 --           Initialize_Lock
  93
  94 with System.Task_Primitives.Interrupt_Operations;
  95 --  used for Set_Interrupt_ID
  96
  97 with System.Storage_Elements;
  98 --  used for To_Address
  99 --           To_Integer
 100 --           Integer_Address
 101
 102 with System.Tasking;
 103 --  used for Task_Id
 104 --           Task_Entry_Index
 105 --           Null_Task
 106 --           Self
 107 --           Interrupt_Manager_ID
 108
 109 with System.Tasking.Utilities;
 110 --  used for Make_Independent
 111
 112 with System.Tasking.Rendezvous;
 113 --  used for Call_Simple
 114 pragma Elaborate_All (System.Tasking.Rendezvous);
 115
 116 with System.Tasking.Initialization;
 117 --  used for Defer_Abort
 118 --           Undefer_Abort
 119
 120 with System.Parameters;
 121 --  used for Single_Lock
 122
 123 with Unchecked_Conversion;
 124
 125 package body System.Interrupts is
 126
 127    use Tasking;
 128    use System.Parameters;
 129    use Ada.Exceptions;
 130
 131    package POP renames System.Task_Primitives.Operations;
 132    package PIO renames System.Task_Primitives.Interrupt_Operations;
 133    package IMNG renames System.Interrupt_Management;
 134    package IMOP renames System.Interrupt_Management.Operations;
 135
 136    function To_System is new Unchecked_Conversion
 137      (Ada.Task_Identification.Task_Id, Task_Id);
 138
 139    -----------------
 140    -- Local Tasks --
 141    -----------------
 142
 143    --  WARNING: System.Tasking.Stages performs calls to this task
 144    --  with low-level constructs. Do not change this spec without synchro-
 145    --  nizing it.
 146
 147    task Interrupt_Manager is
 148       entry Detach_Interrupt_Entries (T : Task_Id);
 149
 150       entry Initialize (Mask : IMNG.Interrupt_Mask);
 151
 152       entry Attach_Handler
 153         (New_Handler : Parameterless_Handler;
 154          Interrupt   : Interrupt_ID;
 155          Static      : Boolean;
 156          Restoration : Boolean := False);
 157
 158       entry Exchange_Handler
 159         (Old_Handler : out Parameterless_Handler;
 160          New_Handler : Parameterless_Handler;
 161          Interrupt   : Interrupt_ID;
 162          Static      : Boolean);
 163
 164       entry Detach_Handler
 165         (Interrupt   : Interrupt_ID;
 166          Static      : Boolean);
 167
 168       entry Bind_Interrupt_To_Entry
 169         (T         : Task_Id;
 170          E         : Task_Entry_Index;
 171          Interrupt : Interrupt_ID);
 172
 173       entry Block_Interrupt (Interrupt : Interrupt_ID);
 174
 175       entry Unblock_Interrupt (Interrupt : Interrupt_ID);
 176
 177       entry Ignore_Interrupt (Interrupt : Interrupt_ID);
 178
 179       entry Unignore_Interrupt (Interrupt : Interrupt_ID);
 180
 181       pragma Interrupt_Priority (System.Interrupt_Priority'Last);
 182    end Interrupt_Manager;
 183
 184    task type Server_Task (Interrupt : Interrupt_ID) is
 185       pragma Priority (System.Interrupt_Priority'Last);
 186       --  Note: the above pragma Priority is strictly speaking improper
 187       --  since it is outside the range of allowed priorities, but the
 188       --  compiler treats system units specially and does not apply
 189       --  this range checking rule to system units.
 190
 191    end Server_Task;
 192
 193    type Server_Task_Access is access Server_Task;
 194
 195    -------------------------------
 196    -- Local Types and Variables --
 197    -------------------------------
 198
 199    type Entry_Assoc is record
 200       T : Task_Id;
 201       E : Task_Entry_Index;
 202    end record;
 203
 204    type Handler_Assoc is record
 205       H      : Parameterless_Handler;
 206       Static : Boolean;   --  Indicates static binding;
 207    end record;
 208
 209    User_Handler : array (Interrupt_ID'Range) of Handler_Assoc :=
 210                     (others => (null, Static => False));
 211    pragma Volatile_Components (User_Handler);
 212    --  Holds the protected procedure handler (if any) and its Static
 213    --  information  for each interrupt. A handler is a Static one if
 214    --  it is specified through the pragma Attach_Handler.
 215    --  Attach_Handler. Otherwise, not static)
 216
 217    User_Entry : array (Interrupt_ID'Range) of Entry_Assoc :=
 218                   (others => (T => Null_Task, E => Null_Task_Entry));
 219    pragma Volatile_Components (User_Entry);
 220    --  Holds the task and entry index (if any) for each interrupt
 221
 222    Blocked : constant array (Interrupt_ID'Range) of Boolean :=
 223      (others => False);
 224 --  ??? pragma Volatile_Components (Blocked);
 225    --  True iff the corresponding interrupt is blocked in the process level
 226
 227    Ignored : array (Interrupt_ID'Range) of Boolean := (others => False);
 228    pragma Volatile_Components (Ignored);
 229    --  True iff the corresponding interrupt is blocked in the process level
 230
 231    Last_Unblocker : constant array (Interrupt_ID'Range) of Task_Id :=
 232      (others => Null_Task);
 233 --  ??? pragma Volatile_Components (Last_Unblocker);
 234    --  Holds the ID of the last Task which Unblocked this Interrupt.
 235    --  It contains Null_Task if no tasks have ever requested the
 236    --  Unblocking operation or the Interrupt is currently Blocked.
 237
 238    Server_ID : array (Interrupt_ID'Range) of Task_Id :=
 239                  (others => Null_Task);
 240    pragma Atomic_Components (Server_ID);
 241    --  Holds the Task_Id of the Server_Task for each interrupt.
 242    --  Task_Id is needed to accomplish locking per Interrupt base. Also
 243    --  is needed to decide whether to create a new Server_Task.
 244
 245    --  Type and Head, Tail of the list containing Registered Interrupt
 246    --  Handlers. These definitions are used to register the handlers
 247    --  specified by the pragma Interrupt_Handler.
 248
 249    type Registered_Handler;
 250    type R_Link is access all Registered_Handler;
 251
 252    type Registered_Handler is record
 253       H :    System.Address := System.Null_Address;
 254       Next : R_Link := null;
 255    end record;
 256
 257    Registered_Handler_Head : R_Link := null;
 258    Registered_Handler_Tail : R_Link := null;
 259
 260    Access_Hold : Server_Task_Access;
 261    --  variable used to allocate Server_Task using "new".
 262
 263    -----------------------
 264    -- Local Subprograms --
 265    -----------------------
 266
 267    function Is_Registered (Handler : Parameterless_Handler) return Boolean;
 268    --  See if the Handler has been "pragma"ed using Interrupt_Handler.
 269    --  Always consider a null handler as registered.
 270
 271    --------------------------------
 272    -- Register_Interrupt_Handler --
 273    --------------------------------
 274
 275    procedure Register_Interrupt_Handler (Handler_Addr : System.Address) is
 276       New_Node_Ptr : R_Link;
 277    begin
 278       --  This routine registers the Handler as usable for Dynamic
 279       --  Interrupt Handler. Routines attaching and detaching Handler
 280       --  dynamically should first consult if the Handler is rgistered.
 281       --  A Program Error should be raised if it is not registered.
 282
 283       --  The pragma Interrupt_Handler can only appear in the library
 284       --  level PO definition and instantiation. Therefore, we do not need
 285       --  to implement Unregistering operation. Neither we need to
 286       --  protect the queue structure using a Lock.
 287
 288       pragma Assert (Handler_Addr /= System.Null_Address);
 289
 290       New_Node_Ptr := new Registered_Handler;
 291       New_Node_Ptr.H := Handler_Addr;
 292
 293       if Registered_Handler_Head = null then
 294          Registered_Handler_Head := New_Node_Ptr;
 295          Registered_Handler_Tail := New_Node_Ptr;
 296
 297       else
 298          Registered_Handler_Tail.Next := New_Node_Ptr;
 299          Registered_Handler_Tail := New_Node_Ptr;
 300       end if;
 301    end Register_Interrupt_Handler;
 302
 303    -------------------
 304    -- Is_Registered --
 305    -------------------
 306
 307    function Is_Registered (Handler : Parameterless_Handler) return Boolean is
 308       type Fat_Ptr is record
 309          Object_Addr  : System.Address;
 310          Handler_Addr : System.Address;
 311       end record;
 312
 313       function To_Fat_Ptr is new Unchecked_Conversion
 314         (Parameterless_Handler, Fat_Ptr);
 315
 316       Ptr : R_Link;
 317       Fat : Fat_Ptr;
 318
 319    begin
 320       if Handler = null then
 321          return True;
 322       end if;
 323
 324       Fat := To_Fat_Ptr (Handler);
 325
 326       Ptr := Registered_Handler_Head;
 327
 328       while Ptr /= null loop
 329          if Ptr.H = Fat.Handler_Addr then
 330             return True;
 331          end if;
 332
 333          Ptr := Ptr.Next;
 334       end loop;
 335
 336       return False;
 337
 338    end Is_Registered;
 339
 340    -----------------
 341    -- Is_Reserved --
 342    -----------------
 343
 344    function Is_Reserved (Interrupt : Interrupt_ID) return Boolean is
 345    begin
 346       return IMNG.Reserve (IMNG.Interrupt_ID (Interrupt));
 347    end Is_Reserved;
 348
 349    -----------------------
 350    -- Is_Entry_Attached --
 351    -----------------------
 352
 353    function Is_Entry_Attached (Interrupt : Interrupt_ID) return Boolean is
 354    begin
 355       if Is_Reserved (Interrupt) then
 356          Raise_Exception (Program_Error'Identity, "Interrupt" &
 357            Interrupt_ID'Image (Interrupt) & " is reserved");
 358       end if;
 359
 360       return User_Entry (Interrupt).T /= Null_Task;
 361    end Is_Entry_Attached;
 362
 363    -------------------------
 364    -- Is_Handler_Attached --
 365    -------------------------
 366
 367    function Is_Handler_Attached (Interrupt : Interrupt_ID) return Boolean is
 368    begin
 369       if Is_Reserved (Interrupt) then
 370          Raise_Exception (Program_Error'Identity, "Interrupt" &
 371            Interrupt_ID'Image (Interrupt) & " is reserved");
 372       end if;
 373
 374       return User_Handler (Interrupt).H /= null;
 375    end Is_Handler_Attached;
 376
 377    ----------------
 378    -- Is_Blocked --
 379    ----------------
 380
 381    function Is_Blocked (Interrupt : Interrupt_ID) return Boolean is
 382    begin
 383       if Is_Reserved (Interrupt) then
 384          Raise_Exception (Program_Error'Identity, "Interrupt" &
 385            Interrupt_ID'Image (Interrupt) & " is reserved");
 386       end if;
 387
 388       return Blocked (Interrupt);
 389    end Is_Blocked;
 390
 391    ----------------
 392    -- Is_Ignored --
 393    ----------------
 394
 395    function Is_Ignored (Interrupt : Interrupt_ID) return Boolean is
 396    begin
 397       if Is_Reserved (Interrupt) then
 398          Raise_Exception (Program_Error'Identity, "Interrupt" &
 399            Interrupt_ID'Image (Interrupt) & " is reserved");
 400       end if;
 401
 402       return Ignored (Interrupt);
 403    end Is_Ignored;
 404
 405    ---------------------
 406    -- Current_Handler --
 407    ---------------------
 408
 409    function Current_Handler
 410      (Interrupt : Interrupt_ID) return Parameterless_Handler
 411    is
 412    begin
 413       if Is_Reserved (Interrupt) then
 414          Raise_Exception (Program_Error'Identity, "Interrupt" &
 415            Interrupt_ID'Image (Interrupt) & " is reserved");
 416       end if;
 417
 418       --  ??? Since Parameterless_Handler is not Atomic, the
 419       --  current implementation is wrong. We need a new service in
 420       --  Interrupt_Manager to ensure atomicity.
 421
 422       return User_Handler (Interrupt).H;
 423    end Current_Handler;
 424
 425    --------------------
 426    -- Attach_Handler --
 427    --------------------
 428
 429    --  Calling this procedure with New_Handler = null and Static = True
 430    --  means we want to detach the current handler regardless of the
 431    --  previous handler's binding status (ie. do not care if it is a
 432    --  dynamic or static handler).
 433
 434    --  This option is needed so that during the finalization of a PO, we
 435    --  can detach handlers attached through pragma Attach_Handler.
 436
 437    procedure Attach_Handler
 438      (New_Handler : Parameterless_Handler;
 439       Interrupt   : Interrupt_ID;
 440       Static      : Boolean := False) is
 441    begin
 442       if Is_Reserved (Interrupt) then
 443          Raise_Exception (Program_Error'Identity, "Interrupt" &
 444            Interrupt_ID'Image (Interrupt) & " is reserved");
 445       end if;
 446
 447       Interrupt_Manager.Attach_Handler (New_Handler, Interrupt, Static);
 448
 449    end Attach_Handler;
 450
 451    ----------------------
 452    -- Exchange_Handler --
 453    ----------------------
 454
 455    --  Calling this procedure with New_Handler = null and Static = True
 456    --  means we want to detach the current handler regardless of the
 457    --  previous handler's binding status (ie. do not care if it is a
 458    --  dynamic or static handler).
 459
 460    --  This option is needed so that during the finalization of a PO, we
 461    --  can detach handlers attached through pragma Attach_Handler.
 462
 463    procedure Exchange_Handler
 464      (Old_Handler : out Parameterless_Handler;
 465       New_Handler : Parameterless_Handler;
 466       Interrupt   : Interrupt_ID;
 467       Static      : Boolean := False) is
 468    begin
 469       if Is_Reserved (Interrupt) then
 470          Raise_Exception (Program_Error'Identity, "Interrupt" &
 471            Interrupt_ID'Image (Interrupt) & " is reserved");
 472       end if;
 473
 474       Interrupt_Manager.Exchange_Handler
 475         (Old_Handler, New_Handler, Interrupt, Static);
 476
 477    end Exchange_Handler;
 478
 479    --------------------
 480    -- Detach_Handler --
 481    --------------------
 482
 483    --  Calling this procedure with Static = True means we want to Detach the
 484    --  current handler regardless of the previous handler's binding status
 485    --  (i.e. do not care if it is a dynamic or static handler).
 486
 487    --  This option is needed so that during the finalization of a PO, we can
 488    --  detach handlers attached through pragma Attach_Handler.
 489
 490    procedure Detach_Handler
 491      (Interrupt : Interrupt_ID;
 492       Static    : Boolean := False)
 493    is
 494    begin
 495       if Is_Reserved (Interrupt) then
 496          Raise_Exception (Program_Error'Identity, "Interrupt" &
 497            Interrupt_ID'Image (Interrupt) & " is reserved");
 498       end if;
 499
 500       Interrupt_Manager.Detach_Handler (Interrupt, Static);
 501    end Detach_Handler;
 502
 503    ---------------
 504    -- Reference --
 505    ---------------
 506
 507    function Reference (Interrupt : Interrupt_ID) return System.Address is
 508    begin
 509       if Is_Reserved (Interrupt) then
 510          Raise_Exception (Program_Error'Identity, "Interrupt" &
 511            Interrupt_ID'Image (Interrupt) & " is reserved");
 512       end if;
 513
 514       return Storage_Elements.To_Address
 515         (Storage_Elements.Integer_Address (Interrupt));
 516    end Reference;
 517
 518    -----------------------------
 519    -- Bind_Interrupt_To_Entry --
 520    -----------------------------
 521
 522    --  This procedure raises a Program_Error if it tries to
 523    --  bind an interrupt to which an Entry or a Procedure is
 524    --  already bound.
 525
 526    procedure Bind_Interrupt_To_Entry
 527      (T       : Task_Id;
 528       E       : Task_Entry_Index;
 529       Int_Ref : System.Address)
 530    is
 531       Interrupt : constant Interrupt_ID :=
 532         Interrupt_ID (Storage_Elements.To_Integer (Int_Ref));
 533
 534    begin
 535       if Is_Reserved (Interrupt) then
 536          Raise_Exception (Program_Error'Identity, "Interrupt" &
 537            Interrupt_ID'Image (Interrupt) & " is reserved");
 538       end if;
 539
 540       Interrupt_Manager.Bind_Interrupt_To_Entry (T, E, Interrupt);
 541
 542    end Bind_Interrupt_To_Entry;
 543
 544    ------------------------------
 545    -- Detach_Interrupt_Entries --
 546    ------------------------------
 547
 548    procedure Detach_Interrupt_Entries (T : Task_Id) is
 549    begin
 550       Interrupt_Manager.Detach_Interrupt_Entries (T);
 551    end Detach_Interrupt_Entries;
 552
 553    ---------------------
 554    -- Block_Interrupt --
 555    ---------------------
 556
 557    procedure Block_Interrupt (Interrupt : Interrupt_ID) is
 558    begin
 559       if Is_Reserved (Interrupt) then
 560          Raise_Exception (Program_Error'Identity, "Interrupt" &
 561            Interrupt_ID'Image (Interrupt) & " is reserved");
 562       end if;
 563
 564       Interrupt_Manager.Block_Interrupt (Interrupt);
 565    end Block_Interrupt;
 566
 567    -----------------------
 568    -- Unblock_Interrupt --
 569    -----------------------
 570
 571    procedure Unblock_Interrupt (Interrupt : Interrupt_ID) is
 572    begin
 573       if Is_Reserved (Interrupt) then
 574          Raise_Exception (Program_Error'Identity, "Interrupt" &
 575            Interrupt_ID'Image (Interrupt) & " is reserved");
 576       end if;
 577
 578       Interrupt_Manager.Unblock_Interrupt (Interrupt);
 579    end Unblock_Interrupt;
 580
 581    ------------------
 582    -- Unblocked_By --
 583    ------------------
 584
 585    function Unblocked_By
 586      (Interrupt : Interrupt_ID) return System.Tasking.Task_Id is
 587    begin
 588       if Is_Reserved (Interrupt) then
 589          Raise_Exception (Program_Error'Identity, "Interrupt" &
 590            Interrupt_ID'Image (Interrupt) & " is reserved");
 591       end if;
 592
 593       return Last_Unblocker (Interrupt);
 594    end Unblocked_By;
 595
 596    ----------------------
 597    -- Ignore_Interrupt --
 598    ----------------------
 599
 600    procedure Ignore_Interrupt (Interrupt : Interrupt_ID) is
 601    begin
 602       if Is_Reserved (Interrupt) then
 603          Raise_Exception (Program_Error'Identity, "Interrupt" &
 604            Interrupt_ID'Image (Interrupt) & " is reserved");
 605       end if;
 606
 607       Interrupt_Manager.Ignore_Interrupt (Interrupt);
 608    end Ignore_Interrupt;
 609
 610    ------------------------
 611    -- Unignore_Interrupt --
 612    ------------------------
 613
 614    procedure Unignore_Interrupt (Interrupt : Interrupt_ID) is
 615    begin
 616       if Is_Reserved (Interrupt) then
 617          Raise_Exception (Program_Error'Identity, "Interrupt" &
 618            Interrupt_ID'Image (Interrupt) & " is reserved");
 619       end if;
 620
 621       Interrupt_Manager.Unignore_Interrupt (Interrupt);
 622    end Unignore_Interrupt;
 623
 624    -----------------------
 625    -- Interrupt_Manager --
 626    -----------------------
 627
 628    task body Interrupt_Manager is
 629
 630       --------------------
 631       -- Local Routines --
 632       --------------------
 633
 634       procedure Unprotected_Exchange_Handler
 635         (Old_Handler : out Parameterless_Handler;
 636          New_Handler : Parameterless_Handler;
 637          Interrupt   : Interrupt_ID;
 638          Static      : Boolean;
 639          Restoration : Boolean := False);
 640
 641       procedure Unprotected_Detach_Handler
 642         (Interrupt : Interrupt_ID;
 643          Static    : Boolean);
 644
 645       ----------------------------------
 646       -- Unprotected_Exchange_Handler --
 647       ----------------------------------
 648
 649       procedure Unprotected_Exchange_Handler
 650         (Old_Handler : out Parameterless_Handler;
 651          New_Handler : Parameterless_Handler;
 652          Interrupt   : Interrupt_ID;
 653          Static      : Boolean;
 654          Restoration : Boolean := False)
 655       is
 656       begin
 657          if User_Entry (Interrupt).T /= Null_Task then
 658             --  In case we have an Interrupt Entry already installed.
 659             --  raise a program error. (propagate it to the caller).
 660
 661             Raise_Exception (Program_Error'Identity,
 662               "An interrupt is already installed");
 663          end if;
 664
 665          --  Note : A null handler with Static = True will
 666          --  pass the following check. That is the case when we want to
 667          --  Detach a handler regardless of the Static status
 668          --  of the current_Handler.
 669          --  We don't check anything if Restoration is True, since we
 670          --  may be detaching a static handler to restore a dynamic one.
 671
 672          if not Restoration and then not Static
 673             --  Tries to overwrite a static Interrupt Handler with a
 674             --  dynamic Handler
 675
 676            and then (User_Handler (Interrupt).Static
 677
 678                         --  The new handler is not specified as an
 679                         --  Interrupt Handler by a pragma.
 680
 681                         or else not Is_Registered (New_Handler))
 682          then
 683             Raise_Exception (Program_Error'Identity,
 684               "Trying to overwrite a static Interrupt Handler with a " &
 685               "dynamic Handler");
 686          end if;
 687
 688          --  The interrupt should no longer be ingnored if
 689          --  it was ever ignored.
 690
 691          Ignored (Interrupt) := False;
 692
 693          --  Save the old handler
 694
 695          Old_Handler := User_Handler (Interrupt).H;
 696
 697          --  The new handler
 698
 699          User_Handler (Interrupt).H := New_Handler;
 700
 701          if New_Handler = null then
 702
 703             --  The null handler means we are detaching the handler.
 704
 705             User_Handler (Interrupt).Static := False;
 706
 707          else
 708             User_Handler (Interrupt).Static := Static;
 709          end if;
 710
 711          --  Invoke a corresponding Server_Task if not yet created.
 712          --  Place Task_Id info in Server_ID array.
 713
 714          if Server_ID (Interrupt) = Null_Task then
 715             Access_Hold := new Server_Task (Interrupt);
 716             Server_ID (Interrupt) := To_System (Access_Hold.all'Identity);
 717          else
 718             POP.Wakeup (Server_ID (Interrupt), Interrupt_Server_Idle_Sleep);
 719          end if;
 720
 721       end Unprotected_Exchange_Handler;
 722
 723       --------------------------------
 724       -- Unprotected_Detach_Handler --
 725       --------------------------------
 726
 727       procedure Unprotected_Detach_Handler
 728         (Interrupt   : Interrupt_ID;
 729          Static      : Boolean)
 730       is
 731       begin
 732          if User_Entry (Interrupt).T /= Null_Task then
 733             --  In case we have an Interrupt Entry installed.
 734             --  raise a program error. (propagate it to the caller).
 735
 736             Raise_Exception (Program_Error'Identity,
 737               "An interrupt entry is already installed");
 738          end if;
 739
 740          --  Note : Static = True will pass the following check. That is the
 741          --  case when we want to detach a handler regardless of the static
 742          --  status of the current_Handler.
 743
 744          if not Static and then User_Handler (Interrupt).Static then
 745             --  Tries to detach a static Interrupt Handler.
 746             --  raise a program error.
 747
 748             Raise_Exception (Program_Error'Identity,
 749               "Trying to detach a static Interrupt Handler");
 750          end if;
 751
 752          --  The interrupt should no longer be ignored if
 753          --  it was ever ignored.
 754
 755          Ignored (Interrupt) := False;
 756
 757          --  The new handler
 758
 759          User_Handler (Interrupt).H := null;
 760          User_Handler (Interrupt).Static := False;
 761          IMOP.Interrupt_Self_Process (IMNG.Interrupt_ID (Interrupt));
 762
 763       end Unprotected_Detach_Handler;
 764
 765    --  Start of processing for Interrupt_Manager
 766
 767    begin
 768       --  By making this task independent of master, when the process
 769       --  goes away, the Interrupt_Manager will terminate gracefully.
 770
 771       System.Tasking.Utilities.Make_Independent;
 772
 773       --  Environmen task gets its own interrupt mask, saves it,
 774       --  and then masks all interrupts except the Keep_Unmasked set.
 775
 776       --  During rendezvous, the Interrupt_Manager receives the old
 777       --  interrupt mask of the environment task, and sets its own
 778       --  interrupt mask to that value.
 779
 780       --  The environment task will call the entry of Interrupt_Manager some
 781       --  during elaboration of the body of this package.
 782
 783       accept Initialize (Mask : IMNG.Interrupt_Mask) do
 784          pragma Warnings (Off, Mask);
 785          null;
 786       end Initialize;
 787
 788       --  Note: All tasks in RTS will have all the Reserve Interrupts
 789       --  being masked (except the Interrupt_Manager) and Keep_Unmasked
 790       --  unmasked when created.
 791
 792       --  Abort_Task_Interrupt is one of the Interrupt unmasked
 793       --  in all tasks. We mask the Interrupt in this particular task
 794       --  so that "sigwait" is possible to catch an explicitely sent
 795       --  Abort_Task_Interrupt from the Server_Tasks.
 796
 797       --  This sigwaiting is needed so that we make sure a Server_Task is
 798       --  out of its own sigwait state. This extra synchronization is
 799       --  necessary to prevent following senarios.
 800
 801       --   1) Interrupt_Manager sends an Abort_Task_Interrupt to the
 802       --      Server_Task then changes its own interrupt mask (OS level).
 803       --      If an interrupt (corresponding to the Server_Task) arrives
 804       --      in the nean time we have the Interrupt_Manager umnasked and
 805       --      the Server_Task waiting on sigwait.
 806
 807       --   2) For unbinding handler, we install a default action in the
 808       --      Interrupt_Manager. POSIX.1c states that the result of using
 809       --      "sigwait" and "sigaction" simaltaneously on the same interrupt
 810       --      is undefined. Therefore, we need to be informed from the
 811       --      Server_Task of the fact that the Server_Task is out of its
 812       --      sigwait stage.
 813
 814       loop
 815          --  A block is needed to absorb Program_Error exception
 816
 817          declare
 818             Old_Handler : Parameterless_Handler;
 819          begin
 820             select
 821
 822             accept Attach_Handler
 823                (New_Handler : Parameterless_Handler;
 824                 Interrupt   : Interrupt_ID;
 825                 Static      : Boolean;
 826                 Restoration : Boolean := False)
 827             do
 828                Unprotected_Exchange_Handler
 829                  (Old_Handler, New_Handler, Interrupt, Static, Restoration);
 830             end Attach_Handler;
 831
 832             or accept Exchange_Handler
 833                (Old_Handler : out Parameterless_Handler;
 834                 New_Handler : Parameterless_Handler;
 835                 Interrupt   : Interrupt_ID;
 836                 Static      : Boolean)
 837             do
 838                Unprotected_Exchange_Handler
 839                  (Old_Handler, New_Handler, Interrupt, Static);
 840             end Exchange_Handler;
 841
 842             or accept Detach_Handler
 843                (Interrupt   : Interrupt_ID;
 844                 Static      : Boolean)
 845             do
 846                Unprotected_Detach_Handler (Interrupt, Static);
 847             end Detach_Handler;
 848
 849             or accept Bind_Interrupt_To_Entry
 850               (T       : Task_Id;
 851                E       : Task_Entry_Index;
 852                Interrupt : Interrupt_ID)
 853             do
 854                --  if there is a binding already (either a procedure or an
 855                --  entry), raise Program_Error (propagate it to the caller).
 856
 857                if User_Handler (Interrupt).H /= null
 858                  or else User_Entry (Interrupt).T /= Null_Task
 859                then
 860                   Raise_Exception (Program_Error'Identity,
 861                     "A binding for this interrupt is already present");
 862                end if;
 863
 864                --  The interrupt should no longer be ingnored if
 865                --  it was ever ignored.
 866
 867                Ignored (Interrupt) := False;
 868                User_Entry (Interrupt) := Entry_Assoc'(T => T, E => E);
 869
 870                --  Indicate the attachment of Interrupt Entry in ATCB.
 871                --  This is need so that when an Interrupt Entry task
 872                --  terminates the binding can be cleaned.
 873                --  The call to unbinding must be
 874                --  make by the task before it terminates.
 875
 876                T.Interrupt_Entry := True;
 877
 878                --  Invoke a corresponding Server_Task if not yet created.
 879                --  Place Task_Id info in Server_ID array.
 880
 881                if Server_ID (Interrupt) = Null_Task then
 882
 883                   Access_Hold := new Server_Task (Interrupt);
 884                   Server_ID (Interrupt) :=
 885                     To_System (Access_Hold.all'Identity);
 886                else
 887                   POP.Wakeup (Server_ID (Interrupt),
 888                               Interrupt_Server_Idle_Sleep);
 889                end if;
 890             end Bind_Interrupt_To_Entry;
 891
 892             or accept Detach_Interrupt_Entries (T : Task_Id)
 893             do
 894                for J in Interrupt_ID'Range loop
 895                   if not Is_Reserved (J) then
 896                      if User_Entry (J).T = T then
 897
 898                         --  The interrupt should no longer be ignored if
 899                         --  it was ever ignored.
 900
 901                         Ignored (J) := False;
 902                         User_Entry (J) :=
 903                           Entry_Assoc'(T => Null_Task, E => Null_Task_Entry);
 904                         IMOP.Interrupt_Self_Process (IMNG.Interrupt_ID (J));
 905                      end if;
 906                   end if;
 907                end loop;
 908
 909                --  Indicate in ATCB that no Interrupt Entries are attached.
 910
 911                T.Interrupt_Entry := False;
 912             end Detach_Interrupt_Entries;
 913
 914             or accept Block_Interrupt (Interrupt : Interrupt_ID) do
 915                pragma Warnings (Off, Interrupt);
 916                raise Program_Error;
 917             end Block_Interrupt;
 918
 919             or accept Unblock_Interrupt (Interrupt : Interrupt_ID) do
 920                pragma Warnings (Off, Interrupt);
 921                raise Program_Error;
 922             end Unblock_Interrupt;
 923
 924             or accept Ignore_Interrupt (Interrupt : Interrupt_ID) do
 925                pragma Warnings (Off, Interrupt);
 926                raise Program_Error;
 927             end Ignore_Interrupt;
 928
 929             or accept Unignore_Interrupt (Interrupt : Interrupt_ID) do
 930                pragma Warnings (Off, Interrupt);
 931                raise Program_Error;
 932             end Unignore_Interrupt;
 933
 934             end select;
 935
 936          exception
 937             --  If there is a program error we just want to propagate it
 938             --  to the caller and do not want to stop this task.
 939
 940             when Program_Error =>
 941                null;
 942
 943             when others =>
 944                pragma Assert (False);
 945                null;
 946          end;
 947       end loop;
 948    end Interrupt_Manager;
 949
 950    -----------------
 951    -- Server_Task --
 952    -----------------
 953
 954    task body Server_Task is
 955       Self_ID         : constant Task_Id := Self;
 956       Tmp_Handler     : Parameterless_Handler;
 957       Tmp_ID          : Task_Id;
 958       Tmp_Entry_Index : Task_Entry_Index;
 959       Intwait_Mask    : aliased IMNG.Interrupt_Mask;
 960
 961    begin
 962       --  By making this task independent of master, when the process
 963       --  goes away, the Server_Task will terminate gracefully.
 964
 965       System.Tasking.Utilities.Make_Independent;
 966
 967       --  Install default action in system level.
 968
 969       IMOP.Install_Default_Action (IMNG.Interrupt_ID (Interrupt));
 970
 971       --  Set up the mask (also clears the event flag)
 972
 973       IMOP.Empty_Interrupt_Mask (Intwait_Mask'Access);
 974       IMOP.Add_To_Interrupt_Mask
 975         (Intwait_Mask'Access, IMNG.Interrupt_ID (Interrupt));
 976
 977       --  Remember the Interrupt_ID for Abort_Task.
 978
 979       PIO.Set_Interrupt_ID (IMNG.Interrupt_ID (Interrupt), Self_ID);
 980
 981       --  Note: All tasks in RTS will have all the Reserve Interrupts
 982       --  being masked (except the Interrupt_Manager) and Keep_Unmasked
 983       --  unmasked when created.
 984
 985       loop
 986          System.Tasking.Initialization.Defer_Abort (Self_ID);
 987
 988          --  A Handler or an Entry is installed. At this point all tasks
 989          --  mask for the Interrupt is masked. Catch the Interrupt using
 990          --  sigwait.
 991
 992          --  This task may wake up from sigwait by receiving an interrupt
 993          --  (Abort_Task_Interrupt) from the Interrupt_Manager for unbinding
 994          --  a Procedure Handler or an Entry. Or it could be a wake up
 995          --  from status change (Unblocked -> Blocked). If that is not
 996          --  the case, we should exceute the attached Procedure or Entry.
 997
 998          if Single_Lock then
 999             POP.Lock_RTS;
1000          end if;
1001
1002          POP.Write_Lock (Self_ID);
1003
1004          if User_Handler (Interrupt).H = null
1005            and then User_Entry (Interrupt).T = Null_Task
1006          then
1007             --  No Interrupt binding. If there is an interrupt,
1008             --  Interrupt_Manager will take default action.
1009
1010             Self_ID.Common.State := Interrupt_Server_Idle_Sleep;
1011             POP.Sleep (Self_ID, Interrupt_Server_Idle_Sleep);
1012             Self_ID.Common.State := Runnable;
1013
1014          else
1015             Self_ID.Common.State := Interrupt_Server_Blocked_On_Event_Flag;
1016             Self_ID.Common.State := Runnable;
1017
1018             if not (Self_ID.Deferral_Level = 0
1019                     and then Self_ID.Pending_ATC_Level
1020                              < Self_ID.ATC_Nesting_Level)
1021             then
1022                if User_Handler (Interrupt).H /= null then
1023                   Tmp_Handler := User_Handler (Interrupt).H;
1024
1025                   --  RTS calls should not be made with self being locked.
1026
1027                   POP.Unlock (Self_ID);
1028
1029                   if Single_Lock then
1030                      POP.Unlock_RTS;
1031                   end if;
1032
1033                   Tmp_Handler.all;
1034
1035                   if Single_Lock then
1036                      POP.Lock_RTS;
1037                   end if;
1038
1039                   POP.Write_Lock (Self_ID);
1040
1041                elsif User_Entry (Interrupt).T /= Null_Task then
1042                   Tmp_ID := User_Entry (Interrupt).T;
1043                   Tmp_Entry_Index := User_Entry (Interrupt).E;
1044
1045                   --  RTS calls should not be made with self being locked.
1046
1047                   POP.Unlock (Self_ID);
1048
1049                   if Single_Lock then
1050                      POP.Unlock_RTS;
1051                   end if;
1052
1053                   System.Tasking.Rendezvous.Call_Simple
1054                     (Tmp_ID, Tmp_Entry_Index, System.Null_Address);
1055
1056                   if Single_Lock then
1057                      POP.Lock_RTS;
1058                   end if;
1059
1060                   POP.Write_Lock (Self_ID);
1061                end if;
1062             end if;
1063          end if;
1064
1065          POP.Unlock (Self_ID);
1066
1067          if Single_Lock then
1068             POP.Unlock_RTS;
1069          end if;
1070
1071          System.Tasking.Initialization.Undefer_Abort (Self_ID);
1072
1073          --  Undefer abort here to allow a window for this task
1074          --  to be aborted  at the time of system shutdown.
1075       end loop;
1076    end Server_Task;
1077
1078    -------------------------------------
1079    -- Has_Interrupt_Or_Attach_Handler --
1080    -------------------------------------
1081
1082    function Has_Interrupt_Or_Attach_Handler
1083      (Object : access Dynamic_Interrupt_Protection) return Boolean
1084    is
1085       pragma Warnings (Off, Object);
1086
1087    begin
1088       return True;
1089    end Has_Interrupt_Or_Attach_Handler;
1090
1091    --------------
1092    -- Finalize --
1093    --------------
1094
1095    procedure Finalize (Object : in out Static_Interrupt_Protection) is
1096    begin
1097       --  ??? loop to be executed only when we're not doing library level
1098       --  finalization, since in this case all interrupt tasks are gone.
1099
1100       if not Interrupt_Manager'Terminated then
1101          for N in reverse Object.Previous_Handlers'Range loop
1102             Interrupt_Manager.Attach_Handler
1103               (New_Handler => Object.Previous_Handlers (N).Handler,
1104                Interrupt   => Object.Previous_Handlers (N).Interrupt,
1105                Static      => Object.Previous_Handlers (N).Static,
1106                Restoration => True);
1107          end loop;
1108       end if;
1109
1110       Tasking.Protected_Objects.Entries.Finalize
1111         (Tasking.Protected_Objects.Entries.Protection_Entries (Object));
1112    end Finalize;
1113
1114    -------------------------------------
1115    -- Has_Interrupt_Or_Attach_Handler --
1116    -------------------------------------
1117
1118    function Has_Interrupt_Or_Attach_Handler
1119      (Object : access Static_Interrupt_Protection) return Boolean
1120    is
1121       pragma Warnings (Off, Object);
1122    begin
1123       return True;
1124    end Has_Interrupt_Or_Attach_Handler;
1125
1126    ----------------------
1127    -- Install_Handlers --
1128    ----------------------
1129
1130    procedure Install_Handlers
1131      (Object       : access Static_Interrupt_Protection;
1132       New_Handlers : New_Handler_Array)
1133    is
1134    begin
1135       for N in New_Handlers'Range loop
1136
1137          --  We need a lock around this ???
1138
1139          Object.Previous_Handlers (N).Interrupt := New_Handlers (N).Interrupt;
1140          Object.Previous_Handlers (N).Static    := User_Handler
1141            (New_Handlers (N).Interrupt).Static;
1142
1143          --  We call Exchange_Handler and not directly Interrupt_Manager.
1144          --  Exchange_Handler so we get the Is_Reserved check.
1145
1146          Exchange_Handler
1147            (Old_Handler => Object.Previous_Handlers (N).Handler,
1148             New_Handler => New_Handlers (N).Handler,
1149             Interrupt   => New_Handlers (N).Interrupt,
1150             Static      => True);
1151       end loop;
1152    end Install_Handlers;
1153
1154 --  Elaboration code for package System.Interrupts
1155 begin
1156
1157    --  Get Interrupt_Manager's ID so that Abort_Interrupt can be sent.
1158
1159    Interrupt_Manager_ID := To_System (Interrupt_Manager'Identity);
1160
1161    --  During the elaboration of this package body we want RTS to
1162    --  inherit the interrupt mask from the Environment Task.
1163
1164    --  The Environment Task should have gotten its mask from
1165    --  the enclosing process during the RTS start up. (See
1166    --  in s-inmaop.adb). Pass the Interrupt_Mask of the Environment
1167    --  task to the Interrupt_Manager.
1168
1169    --  Note : At this point we know that all tasks (including
1170    --  RTS internal servers) are masked for non-reserved signals
1171    --  (see s-taprop.adb). Only the Interrupt_Manager will have
1172    --  masks set up differently inheriting the original Environment
1173    --  Task's mask.
1174
1175    Interrupt_Manager.Initialize (IMOP.Environment_Mask);
1176 end System.Interrupts;