gcc/ada/s-taprop-vxworks.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                  GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                --
   4 --                                                                          --
   5 --     S Y S T E M . T A S K _ P R I M I T I V E S . O P E R A T I O N S    --
   6 --                                                                          --
   7 --                                  B o d y                                 --
   8 --                                                                          --
   9 --         Copyright (C) 1992-2009, 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- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNARL was developed by the GNARL team at Florida State University.       --
  28 -- Extensive contributions were provided by Ada Core Technologies, Inc.     --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  This is the VxWorks version of this package
  33
  34 --  This package contains all the GNULL primitives that interface directly with
  35 --  the underlying OS.
  36
  37 pragma Polling (Off);
  38 --  Turn off polling, we do not want ATC polling to take place during tasking
  39 --  operations. It causes infinite loops and other problems.
  40
  41 with Ada.Unchecked_Conversion;
  42 with Ada.Unchecked_Deallocation;
  43
  44 with Interfaces.C;
  45
  46 with System.Tasking.Debug;
  47 with System.Interrupt_Management;
  48
  49 with System.Soft_Links;
  50 --  We use System.Soft_Links instead of System.Tasking.Initialization
  51 --  because the later is a higher level package that we shouldn't depend
  52 --  on. For example when using the restricted run time, it is replaced by
  53 --  System.Tasking.Restricted.Stages.
  54
  55 with System.VxWorks.Ext;
  56
  57 package body System.Task_Primitives.Operations is
  58
  59    package SSL renames System.Soft_Links;
  60
  61    use System.Tasking.Debug;
  62    use System.Tasking;
  63    use System.OS_Interface;
  64    use System.Parameters;
  65    use type System.VxWorks.Ext.t_id;
  66    use type Interfaces.C.int;
  67
  68    subtype int is System.OS_Interface.int;
  69
  70    Relative : constant := 0;
  71
  72    ----------------
  73    -- Local Data --
  74    ----------------
  75
  76    --  The followings are logically constants, but need to be initialized at
  77    --  run time.
  78
  79    Single_RTS_Lock : aliased RTS_Lock;
  80    --  This is a lock to allow only one thread of control in the RTS at a
  81    --  time; it is used to execute in mutual exclusion from all other tasks.
  82    --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List
  83
  84    Environment_Task_Id : Task_Id;
  85    --  A variable to hold Task_Id for the environment task
  86
  87    Unblocked_Signal_Mask : aliased sigset_t;
  88    --  The set of signals that should unblocked in all tasks
  89
  90    --  The followings are internal configuration constants needed
  91
  92    Time_Slice_Val : Integer;
  93    pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");
  94
  95    Locking_Policy : Character;
  96    pragma Import (C, Locking_Policy, "__gl_locking_policy");
  97
  98    Dispatching_Policy : Character;
  99    pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");
 100
 101    function Get_Policy (Prio : System.Any_Priority) return Character;
 102    pragma Import (C, Get_Policy, "__gnat_get_specific_dispatching");
 103    --  Get priority specific dispatching policy
 104
 105    Mutex_Protocol : Priority_Type;
 106
 107    Foreign_Task_Elaborated : aliased Boolean := True;
 108    --  Used to identified fake tasks (i.e., non-Ada Threads)
 109
 110    type Set_Stack_Limit_Proc_Acc is access procedure;
 111    pragma Convention (C, Set_Stack_Limit_Proc_Acc);
 112
 113    Set_Stack_Limit_Hook : Set_Stack_Limit_Proc_Acc;
 114    pragma Import (C, Set_Stack_Limit_Hook, "__gnat_set_stack_limit_hook");
 115    --  Procedure to be called when a task is created to set stack
 116    --  limit.
 117
 118    --------------------
 119    -- Local Packages --
 120    --------------------
 121
 122    package Specific is
 123
 124       procedure Initialize;
 125       pragma Inline (Initialize);
 126       --  Initialize task specific data
 127
 128       function Is_Valid_Task return Boolean;
 129       pragma Inline (Is_Valid_Task);
 130       --  Does executing thread have a TCB?
 131
 132       procedure Set (Self_Id : Task_Id);
 133       pragma Inline (Set);
 134       --  Set the self id for the current task
 135
 136       procedure Delete;
 137       pragma Inline (Delete);
 138       --  Delete the task specific data associated with the current task
 139
 140       function Self return Task_Id;
 141       pragma Inline (Self);
 142       --  Return a pointer to the Ada Task Control Block of the calling task
 143
 144    end Specific;
 145
 146    package body Specific is separate;
 147    --  The body of this package is target specific
 148
 149    ---------------------------------
 150    -- Support for foreign threads --
 151    ---------------------------------
 152
 153    function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id;
 154    --  Allocate and Initialize a new ATCB for the current Thread
 155
 156    function Register_Foreign_Thread
 157      (Thread : Thread_Id) return Task_Id is separate;
 158
 159    -----------------------
 160    -- Local Subprograms --
 161    -----------------------
 162
 163    procedure Abort_Handler (signo : Signal);
 164    --  Handler for the abort (SIGABRT) signal to handle asynchronous abort
 165
 166    procedure Install_Signal_Handlers;
 167    --  Install the default signal handlers for the current task
 168
 169    function To_Address is
 170      new Ada.Unchecked_Conversion (Task_Id, System.Address);
 171
 172    -------------------
 173    -- Abort_Handler --
 174    -------------------
 175
 176    procedure Abort_Handler (signo : Signal) is
 177       pragma Unreferenced (signo);
 178
 179       Self_ID : constant Task_Id := Self;
 180       Old_Set : aliased sigset_t;
 181
 182       Result : int;
 183       pragma Warnings (Off, Result);
 184
 185    begin
 186       --  It is not safe to raise an exception when using ZCX and the GCC
 187       --  exception handling mechanism.
 188
 189       if ZCX_By_Default and then GCC_ZCX_Support then
 190          return;
 191       end if;
 192
 193       if Self_ID.Deferral_Level = 0
 194         and then Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
 195         and then not Self_ID.Aborting
 196       then
 197          Self_ID.Aborting := True;
 198
 199          --  Make sure signals used for RTS internal purpose are unmasked
 200
 201          Result :=
 202            pthread_sigmask
 203              (SIG_UNBLOCK,
 204               Unblocked_Signal_Mask'Access,
 205               Old_Set'Access);
 206          pragma Assert (Result = 0);
 207
 208          raise Standard'Abort_Signal;
 209       end if;
 210    end Abort_Handler;
 211
 212    -----------------
 213    -- Stack_Guard --
 214    -----------------
 215
 216    procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is
 217       pragma Unreferenced (T);
 218       pragma Unreferenced (On);
 219
 220    begin
 221       --  Nothing needed (why not???)
 222
 223       null;
 224    end Stack_Guard;
 225
 226    -------------------
 227    -- Get_Thread_Id --
 228    -------------------
 229
 230    function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is
 231    begin
 232       return T.Common.LL.Thread;
 233    end Get_Thread_Id;
 234
 235    ----------
 236    -- Self --
 237    ----------
 238
 239    function Self return Task_Id renames Specific.Self;
 240
 241    -----------------------------
 242    -- Install_Signal_Handlers --
 243    -----------------------------
 244
 245    procedure Install_Signal_Handlers is
 246       act     : aliased struct_sigaction;
 247       old_act : aliased struct_sigaction;
 248       Tmp_Set : aliased sigset_t;
 249       Result  : int;
 250
 251    begin
 252       act.sa_flags := 0;
 253       act.sa_handler := Abort_Handler'Address;
 254
 255       Result := sigemptyset (Tmp_Set'Access);
 256       pragma Assert (Result = 0);
 257       act.sa_mask := Tmp_Set;
 258
 259       Result :=
 260         sigaction
 261           (Signal (Interrupt_Management.Abort_Task_Interrupt),
 262            act'Unchecked_Access,
 263            old_act'Unchecked_Access);
 264       pragma Assert (Result = 0);
 265
 266       Interrupt_Management.Initialize_Interrupts;
 267    end Install_Signal_Handlers;
 268
 269    ---------------------
 270    -- Initialize_Lock --
 271    ---------------------
 272
 273    procedure Initialize_Lock
 274      (Prio : System.Any_Priority;
 275       L    : not null access Lock)
 276    is
 277    begin
 278       L.Mutex := semMCreate (SEM_Q_PRIORITY + SEM_INVERSION_SAFE);
 279       L.Prio_Ceiling := int (Prio);
 280       L.Protocol := Mutex_Protocol;
 281       pragma Assert (L.Mutex /= 0);
 282    end Initialize_Lock;
 283
 284    procedure Initialize_Lock
 285      (L     : not null access RTS_Lock;
 286       Level : Lock_Level)
 287    is
 288       pragma Unreferenced (Level);
 289    begin
 290       L.Mutex := semMCreate (SEM_Q_PRIORITY + SEM_INVERSION_SAFE);
 291       L.Prio_Ceiling := int (System.Any_Priority'Last);
 292       L.Protocol := Mutex_Protocol;
 293       pragma Assert (L.Mutex /= 0);
 294    end Initialize_Lock;
 295
 296    -------------------
 297    -- Finalize_Lock --
 298    -------------------
 299
 300    procedure Finalize_Lock (L : not null access Lock) is
 301       Result : int;
 302    begin
 303       Result := semDelete (L.Mutex);
 304       pragma Assert (Result = 0);
 305    end Finalize_Lock;
 306
 307    procedure Finalize_Lock (L : not null access RTS_Lock) is
 308       Result : int;
 309    begin
 310       Result := semDelete (L.Mutex);
 311       pragma Assert (Result = 0);
 312    end Finalize_Lock;
 313
 314    ----------------
 315    -- Write_Lock --
 316    ----------------
 317
 318    procedure Write_Lock
 319      (L                 : not null access Lock;
 320       Ceiling_Violation : out Boolean)
 321    is
 322       Result : int;
 323
 324    begin
 325       if L.Protocol = Prio_Protect
 326         and then int (Self.Common.Current_Priority) > L.Prio_Ceiling
 327       then
 328          Ceiling_Violation := True;
 329          return;
 330       else
 331          Ceiling_Violation := False;
 332       end if;
 333
 334       Result := semTake (L.Mutex, WAIT_FOREVER);
 335       pragma Assert (Result = 0);
 336    end Write_Lock;
 337
 338    procedure Write_Lock
 339      (L           : not null access RTS_Lock;
 340       Global_Lock : Boolean := False)
 341    is
 342       Result : int;
 343    begin
 344       if not Single_Lock or else Global_Lock then
 345          Result := semTake (L.Mutex, WAIT_FOREVER);
 346          pragma Assert (Result = 0);
 347       end if;
 348    end Write_Lock;
 349
 350    procedure Write_Lock (T : Task_Id) is
 351       Result : int;
 352    begin
 353       if not Single_Lock then
 354          Result := semTake (T.Common.LL.L.Mutex, WAIT_FOREVER);
 355          pragma Assert (Result = 0);
 356       end if;
 357    end Write_Lock;
 358
 359    ---------------
 360    -- Read_Lock --
 361    ---------------
 362
 363    procedure Read_Lock
 364      (L                 : not null access Lock;
 365       Ceiling_Violation : out Boolean)
 366    is
 367    begin
 368       Write_Lock (L, Ceiling_Violation);
 369    end Read_Lock;
 370
 371    ------------
 372    -- Unlock --
 373    ------------
 374
 375    procedure Unlock (L : not null access Lock) is
 376       Result : int;
 377    begin
 378       Result := semGive (L.Mutex);
 379       pragma Assert (Result = 0);
 380    end Unlock;
 381
 382    procedure Unlock
 383      (L           : not null access RTS_Lock;
 384       Global_Lock : Boolean := False)
 385    is
 386       Result : int;
 387    begin
 388       if not Single_Lock or else Global_Lock then
 389          Result := semGive (L.Mutex);
 390          pragma Assert (Result = 0);
 391       end if;
 392    end Unlock;
 393
 394    procedure Unlock (T : Task_Id) is
 395       Result : int;
 396    begin
 397       if not Single_Lock then
 398          Result := semGive (T.Common.LL.L.Mutex);
 399          pragma Assert (Result = 0);
 400       end if;
 401    end Unlock;
 402
 403    -----------------
 404    -- Set_Ceiling --
 405    -----------------
 406
 407    --  Dynamic priority ceilings are not supported by the underlying system
 408
 409    procedure Set_Ceiling
 410      (L    : not null access Lock;
 411       Prio : System.Any_Priority)
 412    is
 413       pragma Unreferenced (L, Prio);
 414    begin
 415       null;
 416    end Set_Ceiling;
 417
 418    -----------
 419    -- Sleep --
 420    -----------
 421
 422    procedure Sleep (Self_ID : Task_Id; Reason : System.Tasking.Task_States) is
 423       pragma Unreferenced (Reason);
 424
 425       Result : int;
 426
 427    begin
 428       pragma Assert (Self_ID = Self);
 429
 430       --  Release the mutex before sleeping
 431
 432       if Single_Lock then
 433          Result := semGive (Single_RTS_Lock.Mutex);
 434       else
 435          Result := semGive (Self_ID.Common.LL.L.Mutex);
 436       end if;
 437
 438       pragma Assert (Result = 0);
 439
 440       --  Perform a blocking operation to take the CV semaphore. Note that a
 441       --  blocking operation in VxWorks will reenable task scheduling. When we
 442       --  are no longer blocked and control is returned, task scheduling will
 443       --  again be disabled.
 444
 445       Result := semTake (Self_ID.Common.LL.CV, WAIT_FOREVER);
 446       pragma Assert (Result = 0);
 447
 448       --  Take the mutex back
 449
 450       if Single_Lock then
 451          Result := semTake (Single_RTS_Lock.Mutex, WAIT_FOREVER);
 452       else
 453          Result := semTake (Self_ID.Common.LL.L.Mutex, WAIT_FOREVER);
 454       end if;
 455
 456       pragma Assert (Result = 0);
 457    end Sleep;
 458
 459    -----------------
 460    -- Timed_Sleep --
 461    -----------------
 462
 463    --  This is for use within the run-time system, so abort is assumed to be
 464    --  already deferred, and the caller should be holding its own ATCB lock.
 465
 466    procedure Timed_Sleep
 467      (Self_ID  : Task_Id;
 468       Time     : Duration;
 469       Mode     : ST.Delay_Modes;
 470       Reason   : System.Tasking.Task_States;
 471       Timedout : out Boolean;
 472       Yielded  : out Boolean)
 473    is
 474       pragma Unreferenced (Reason);
 475
 476       Orig     : constant Duration := Monotonic_Clock;
 477       Absolute : Duration;
 478       Ticks    : int;
 479       Result   : int;
 480       Wakeup   : Boolean := False;
 481
 482    begin
 483       Timedout := False;
 484       Yielded  := True;
 485
 486       if Mode = Relative then
 487          Absolute := Orig + Time;
 488
 489          --  Systematically add one since the first tick will delay *at most*
 490          --  1 / Rate_Duration seconds, so we need to add one to be on the
 491          --  safe side.
 492
 493          Ticks := To_Clock_Ticks (Time);
 494
 495          if Ticks > 0 and then Ticks < int'Last then
 496             Ticks := Ticks + 1;
 497          end if;
 498
 499       else
 500          Absolute := Time;
 501          Ticks    := To_Clock_Ticks (Time - Monotonic_Clock);
 502       end if;
 503
 504       if Ticks > 0 then
 505          loop
 506             --  Release the mutex before sleeping
 507
 508             if Single_Lock then
 509                Result := semGive (Single_RTS_Lock.Mutex);
 510             else
 511                Result := semGive (Self_ID.Common.LL.L.Mutex);
 512             end if;
 513
 514             pragma Assert (Result = 0);
 515
 516             --  Perform a blocking operation to take the CV semaphore. Note
 517             --  that a blocking operation in VxWorks will reenable task
 518             --  scheduling. When we are no longer blocked and control is
 519             --  returned, task scheduling will again be disabled.
 520
 521             Result := semTake (Self_ID.Common.LL.CV, Ticks);
 522
 523             if Result = 0 then
 524
 525                --  Somebody may have called Wakeup for us
 526
 527                Wakeup := True;
 528
 529             else
 530                if errno /= S_objLib_OBJ_TIMEOUT then
 531                   Wakeup := True;
 532
 533                else
 534                   --  If Ticks = int'last, it was most probably truncated so
 535                   --  let's make another round after recomputing Ticks from
 536                   --  the absolute time.
 537
 538                   if Ticks /= int'Last then
 539                      Timedout := True;
 540
 541                   else
 542                      Ticks := To_Clock_Ticks (Absolute - Monotonic_Clock);
 543
 544                      if Ticks < 0 then
 545                         Timedout := True;
 546                      end if;
 547                   end if;
 548                end if;
 549             end if;
 550
 551             --  Take the mutex back
 552
 553             if Single_Lock then
 554                Result := semTake (Single_RTS_Lock.Mutex, WAIT_FOREVER);
 555             else
 556                Result := semTake (Self_ID.Common.LL.L.Mutex, WAIT_FOREVER);
 557             end if;
 558
 559             pragma Assert (Result = 0);
 560
 561             exit when Timedout or Wakeup;
 562          end loop;
 563
 564       else
 565          Timedout := True;
 566
 567          --  Should never hold a lock while yielding
 568
 569          if Single_Lock then
 570             Result := semGive (Single_RTS_Lock.Mutex);
 571             taskDelay (0);
 572             Result := semTake (Single_RTS_Lock.Mutex, WAIT_FOREVER);
 573
 574          else
 575             Result := semGive (Self_ID.Common.LL.L.Mutex);
 576             taskDelay (0);
 577             Result := semTake (Self_ID.Common.LL.L.Mutex, WAIT_FOREVER);
 578          end if;
 579       end if;
 580    end Timed_Sleep;
 581
 582    -----------------
 583    -- Timed_Delay --
 584    -----------------
 585
 586    --  This is for use in implementing delay statements, so we assume the
 587    --  caller is holding no locks.
 588
 589    procedure Timed_Delay
 590      (Self_ID : Task_Id;
 591       Time    : Duration;
 592       Mode    : ST.Delay_Modes)
 593    is
 594       Orig     : constant Duration := Monotonic_Clock;
 595       Absolute : Duration;
 596       Ticks    : int;
 597       Timedout : Boolean;
 598       Aborted  : Boolean := False;
 599
 600       Result : int;
 601       pragma Warnings (Off, Result);
 602
 603    begin
 604       if Mode = Relative then
 605          Absolute := Orig + Time;
 606          Ticks    := To_Clock_Ticks (Time);
 607
 608          if Ticks > 0 and then Ticks < int'Last then
 609
 610             --  First tick will delay anytime between 0 and 1 / sysClkRateGet
 611             --  seconds, so we need to add one to be on the safe side.
 612
 613             Ticks := Ticks + 1;
 614          end if;
 615
 616       else
 617          Absolute := Time;
 618          Ticks    := To_Clock_Ticks (Time - Orig);
 619       end if;
 620
 621       if Ticks > 0 then
 622
 623          --  Modifying State, locking the TCB
 624
 625          if Single_Lock then
 626             Result := semTake (Single_RTS_Lock.Mutex, WAIT_FOREVER);
 627          else
 628             Result := semTake (Self_ID.Common.LL.L.Mutex, WAIT_FOREVER);
 629          end if;
 630
 631          pragma Assert (Result = 0);
 632
 633          Self_ID.Common.State := Delay_Sleep;
 634          Timedout := False;
 635
 636          loop
 637             Aborted := Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level;
 638
 639             --  Release the TCB before sleeping
 640
 641             if Single_Lock then
 642                Result := semGive (Single_RTS_Lock.Mutex);
 643             else
 644                Result := semGive (Self_ID.Common.LL.L.Mutex);
 645             end if;
 646             pragma Assert (Result = 0);
 647
 648             exit when Aborted;
 649
 650             Result := semTake (Self_ID.Common.LL.CV, Ticks);
 651
 652             if Result /= 0 then
 653
 654                --  If Ticks = int'last, it was most probably truncated
 655                --  so let's make another round after recomputing Ticks
 656                --  from the absolute time.
 657
 658                if errno = S_objLib_OBJ_TIMEOUT and then Ticks /= int'Last then
 659                   Timedout := True;
 660                else
 661                   Ticks := To_Clock_Ticks (Absolute - Monotonic_Clock);
 662
 663                   if Ticks < 0 then
 664                      Timedout := True;
 665                   end if;
 666                end if;
 667             end if;
 668
 669             --  Take back the lock after having slept, to protect further
 670             --  access to Self_ID.
 671
 672             if Single_Lock then
 673                Result := semTake (Single_RTS_Lock.Mutex, WAIT_FOREVER);
 674             else
 675                Result := semTake (Self_ID.Common.LL.L.Mutex, WAIT_FOREVER);
 676             end if;
 677
 678             pragma Assert (Result = 0);
 679
 680             exit when Timedout;
 681          end loop;
 682
 683          Self_ID.Common.State := Runnable;
 684
 685          if Single_Lock then
 686             Result := semGive (Single_RTS_Lock.Mutex);
 687          else
 688             Result := semGive (Self_ID.Common.LL.L.Mutex);
 689          end if;
 690
 691       else
 692          taskDelay (0);
 693       end if;
 694    end Timed_Delay;
 695
 696    ---------------------
 697    -- Monotonic_Clock --
 698    ---------------------
 699
 700    function Monotonic_Clock return Duration is
 701       TS     : aliased timespec;
 702       Result : int;
 703    begin
 704       Result := clock_gettime (CLOCK_REALTIME, TS'Unchecked_Access);
 705       pragma Assert (Result = 0);
 706       return To_Duration (TS);
 707    end Monotonic_Clock;
 708
 709    -------------------
 710    -- RT_Resolution --
 711    -------------------
 712
 713    function RT_Resolution return Duration is
 714    begin
 715       return 1.0 / Duration (sysClkRateGet);
 716    end RT_Resolution;
 717
 718    ------------
 719    -- Wakeup --
 720    ------------
 721
 722    procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is
 723       pragma Unreferenced (Reason);
 724       Result : int;
 725    begin
 726       Result := semGive (T.Common.LL.CV);
 727       pragma Assert (Result = 0);
 728    end Wakeup;
 729
 730    -----------
 731    -- Yield --
 732    -----------
 733
 734    procedure Yield (Do_Yield : Boolean := True) is
 735       pragma Unreferenced (Do_Yield);
 736       Result : int;
 737       pragma Unreferenced (Result);
 738    begin
 739       Result := taskDelay (0);
 740    end Yield;
 741
 742    ------------------
 743    -- Set_Priority --
 744    ------------------
 745
 746    type Prio_Array_Type is array (System.Any_Priority) of Integer;
 747    pragma Atomic_Components (Prio_Array_Type);
 748
 749    Prio_Array : Prio_Array_Type;
 750    --  Global array containing the id of the currently running task for each
 751    --  priority. Note that we assume that we are on a single processor with
 752    --  run-till-blocked scheduling.
 753
 754    procedure Set_Priority
 755      (T                   : Task_Id;
 756       Prio                : System.Any_Priority;
 757       Loss_Of_Inheritance : Boolean := False)
 758    is
 759       Array_Item : Integer;
 760       Result     : int;
 761
 762    begin
 763       Result :=
 764         taskPrioritySet
 765           (T.Common.LL.Thread, To_VxWorks_Priority (int (Prio)));
 766       pragma Assert (Result = 0);
 767
 768       if (Dispatching_Policy = 'F' or else Get_Policy (Prio) = 'F')
 769         and then Loss_Of_Inheritance
 770         and then Prio < T.Common.Current_Priority
 771       then
 772          --  Annex D requirement (RM D.2.2(9)):
 773
 774          --    If the task drops its priority due to the loss of inherited
 775          --    priority, it is added at the head of the ready queue for its
 776          --    new active priority.
 777
 778          Array_Item := Prio_Array (T.Common.Base_Priority) + 1;
 779          Prio_Array (T.Common.Base_Priority) := Array_Item;
 780
 781          loop
 782             --  Give some processes a chance to arrive
 783
 784             taskDelay (0);
 785
 786             --  Then wait for our turn to proceed
 787
 788             exit when Array_Item = Prio_Array (T.Common.Base_Priority)
 789               or else Prio_Array (T.Common.Base_Priority) = 1;
 790          end loop;
 791
 792          Prio_Array (T.Common.Base_Priority) :=
 793            Prio_Array (T.Common.Base_Priority) - 1;
 794       end if;
 795
 796       T.Common.Current_Priority := Prio;
 797    end Set_Priority;
 798
 799    ------------------
 800    -- Get_Priority --
 801    ------------------
 802
 803    function Get_Priority (T : Task_Id) return System.Any_Priority is
 804    begin
 805       return T.Common.Current_Priority;
 806    end Get_Priority;
 807
 808    ----------------
 809    -- Enter_Task --
 810    ----------------
 811
 812    procedure Enter_Task (Self_ID : Task_Id) is
 813       procedure Init_Float;
 814       pragma Import (C, Init_Float, "__gnat_init_float");
 815       --  Properly initializes the FPU for PPC/MIPS systems
 816
 817    begin
 818       --  Store the user-level task id in the Thread field (to be used
 819       --  internally by the run-time system) and the kernel-level task id in
 820       --  the LWP field (to be used by the debugger).
 821
 822       Self_ID.Common.LL.Thread := taskIdSelf;
 823       Self_ID.Common.LL.LWP := getpid;
 824
 825       Specific.Set (Self_ID);
 826
 827       Init_Float;
 828
 829       --  Install the signal handlers
 830
 831       --  This is called for each task since there is no signal inheritance
 832       --  between VxWorks tasks.
 833
 834       Install_Signal_Handlers;
 835
 836       --  If stack checking is enabled, set the stack limit for this task
 837
 838       if Set_Stack_Limit_Hook /= null then
 839          Set_Stack_Limit_Hook.all;
 840       end if;
 841    end Enter_Task;
 842
 843    --------------
 844    -- New_ATCB --
 845    --------------
 846
 847    function New_ATCB (Entry_Num : Task_Entry_Index) return Task_Id is
 848    begin
 849       return new Ada_Task_Control_Block (Entry_Num);
 850    end New_ATCB;
 851
 852    -------------------
 853    -- Is_Valid_Task --
 854    -------------------
 855
 856    function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;
 857
 858    -----------------------------
 859    -- Register_Foreign_Thread --
 860    -----------------------------
 861
 862    function Register_Foreign_Thread return Task_Id is
 863    begin
 864       if Is_Valid_Task then
 865          return Self;
 866       else
 867          return Register_Foreign_Thread (taskIdSelf);
 868       end if;
 869    end Register_Foreign_Thread;
 870
 871    --------------------
 872    -- Initialize_TCB --
 873    --------------------
 874
 875    procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is
 876    begin
 877       Self_ID.Common.LL.CV := semBCreate (SEM_Q_PRIORITY, SEM_EMPTY);
 878       Self_ID.Common.LL.Thread := 0;
 879
 880       if Self_ID.Common.LL.CV = 0 then
 881          Succeeded := False;
 882
 883       else
 884          Succeeded := True;
 885
 886          if not Single_Lock then
 887             Initialize_Lock (Self_ID.Common.LL.L'Access, ATCB_Level);
 888          end if;
 889       end if;
 890    end Initialize_TCB;
 891
 892    -----------------
 893    -- Create_Task --
 894    -----------------
 895
 896    procedure Create_Task
 897      (T          : Task_Id;
 898       Wrapper    : System.Address;
 899       Stack_Size : System.Parameters.Size_Type;
 900       Priority   : System.Any_Priority;
 901       Succeeded  : out Boolean)
 902    is
 903       Adjusted_Stack_Size : size_t;
 904    begin
 905       --  Ask for four extra bytes of stack space so that the ATCB pointer can
 906       --  be stored below the stack limit, plus extra space for the frame of
 907       --  Task_Wrapper. This is so the user gets the amount of stack requested
 908       --  exclusive of the needs.
 909
 910       --  We also have to allocate n more bytes for the task name storage and
 911       --  enough space for the Wind Task Control Block which is around 0x778
 912       --  bytes. VxWorks also seems to carve out additional space, so use 2048
 913       --  as a nice round number. We might want to increment to the nearest
 914       --  page size in case we ever support VxVMI.
 915
 916       --  ??? - we should come back and visit this so we can set the task name
 917       --        to something appropriate.
 918
 919       Adjusted_Stack_Size := size_t (Stack_Size) + 2048;
 920
 921       --  Since the initial signal mask of a thread is inherited from the
 922       --  creator, and the Environment task has all its signals masked, we do
 923       --  not need to manipulate caller's signal mask at this point. All tasks
 924       --  in RTS will have All_Tasks_Mask initially.
 925
 926       --  We now compute the VxWorks task name and options, then spawn ...
 927
 928       declare
 929          Name         : aliased String (1 .. T.Common.Task_Image_Len + 1);
 930          Name_Address : System.Address;
 931          --  Task name we are going to hand down to VxWorks
 932
 933          function Get_Task_Options return int;
 934          pragma Import (C, Get_Task_Options, "__gnat_get_task_options");
 935          --  Function that returns the options to be set for the task that we
 936          --  are creating. We fetch the options assigned to the current task,
 937          --  so offering some user level control over the options for a task
 938          --  hierarchy, and force VX_FP_TASK because it is almost always
 939          --  required.
 940
 941       begin
 942          --  If there is no Ada task name handy, let VxWorks choose one.
 943          --  Otherwise, tell VxWorks what the Ada task name is.
 944
 945          if T.Common.Task_Image_Len = 0 then
 946             Name_Address := System.Null_Address;
 947          else
 948             Name (1 .. Name'Last - 1) :=
 949               T.Common.Task_Image (1 .. T.Common.Task_Image_Len);
 950             Name (Name'Last) := ASCII.NUL;
 951             Name_Address := Name'Address;
 952          end if;
 953
 954          --  Now spawn the VxWorks task for real
 955
 956          T.Common.LL.Thread :=
 957            taskSpawn
 958              (Name_Address,
 959               To_VxWorks_Priority (int (Priority)),
 960               Get_Task_Options,
 961               Adjusted_Stack_Size,
 962               Wrapper,
 963               To_Address (T));
 964       end;
 965
 966       if T.Common.LL.Thread = -1 then
 967          Succeeded := False;
 968       else
 969          Succeeded := True;
 970          Task_Creation_Hook (T.Common.LL.Thread);
 971          Set_Priority (T, Priority);
 972       end if;
 973    end Create_Task;
 974
 975    ------------------
 976    -- Finalize_TCB --
 977    ------------------
 978
 979    procedure Finalize_TCB (T : Task_Id) is
 980       Result  : int;
 981       Tmp     : Task_Id          := T;
 982       Is_Self : constant Boolean := (T = Self);
 983
 984       procedure Free is new
 985         Ada.Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id);
 986
 987    begin
 988       if not Single_Lock then
 989          Result := semDelete (T.Common.LL.L.Mutex);
 990          pragma Assert (Result = 0);
 991       end if;
 992
 993       T.Common.LL.Thread := 0;
 994
 995       Result := semDelete (T.Common.LL.CV);
 996       pragma Assert (Result = 0);
 997
 998       if T.Known_Tasks_Index /= -1 then
 999          Known_Tasks (T.Known_Tasks_Index) := null;
1000       end if;
1001
1002       Free (Tmp);
1003
1004       if Is_Self then
1005          Specific.Delete;
1006       end if;
1007    end Finalize_TCB;
1008
1009    ---------------
1010    -- Exit_Task --
1011    ---------------
1012
1013    procedure Exit_Task is
1014    begin
1015       Specific.Set (null);
1016    end Exit_Task;
1017
1018    ----------------
1019    -- Abort_Task --
1020    ----------------
1021
1022    procedure Abort_Task (T : Task_Id) is
1023       Result : int;
1024    begin
1025       Result :=
1026         kill
1027           (T.Common.LL.Thread,
1028            Signal (Interrupt_Management.Abort_Task_Interrupt));
1029       pragma Assert (Result = 0);
1030    end Abort_Task;
1031
1032    ----------------
1033    -- Initialize --
1034    ----------------
1035
1036    procedure Initialize (S : in out Suspension_Object) is
1037    begin
1038       --  Initialize internal state (always to False (RM D.10(6)))
1039
1040       S.State := False;
1041       S.Waiting := False;
1042
1043       --  Initialize internal mutex
1044
1045       --  Use simpler binary semaphore instead of VxWorks
1046       --  mutual exclusion semaphore, because we don't need
1047       --  the fancier semantics and their overhead.
1048
1049       S.L := semBCreate (SEM_Q_FIFO, SEM_FULL);
1050
1051       --  Initialize internal condition variable
1052
1053       S.CV := semBCreate (SEM_Q_FIFO, SEM_EMPTY);
1054    end Initialize;
1055
1056    --------------
1057    -- Finalize --
1058    --------------
1059
1060    procedure Finalize (S : in out Suspension_Object) is
1061       pragma Unmodified (S);
1062       --  S may be modified on other targets, but not on VxWorks
1063
1064       Result : STATUS;
1065
1066    begin
1067       --  Destroy internal mutex
1068
1069       Result := semDelete (S.L);
1070       pragma Assert (Result = OK);
1071
1072       --  Destroy internal condition variable
1073
1074       Result := semDelete (S.CV);
1075       pragma Assert (Result = OK);
1076    end Finalize;
1077
1078    -------------------
1079    -- Current_State --
1080    -------------------
1081
1082    function Current_State (S : Suspension_Object) return Boolean is
1083    begin
1084       --  We do not want to use lock on this read operation. State is marked
1085       --  as Atomic so that we ensure that the value retrieved is correct.
1086
1087       return S.State;
1088    end Current_State;
1089
1090    ---------------
1091    -- Set_False --
1092    ---------------
1093
1094    procedure Set_False (S : in out Suspension_Object) is
1095       Result : STATUS;
1096
1097    begin
1098       SSL.Abort_Defer.all;
1099
1100       Result := semTake (S.L, WAIT_FOREVER);
1101       pragma Assert (Result = OK);
1102
1103       S.State := False;
1104
1105       Result := semGive (S.L);
1106       pragma Assert (Result = OK);
1107
1108       SSL.Abort_Undefer.all;
1109    end Set_False;
1110
1111    --------------
1112    -- Set_True --
1113    --------------
1114
1115    procedure Set_True (S : in out Suspension_Object) is
1116       Result : STATUS;
1117
1118    begin
1119       SSL.Abort_Defer.all;
1120
1121       Result := semTake (S.L, WAIT_FOREVER);
1122       pragma Assert (Result = OK);
1123
1124       --  If there is already a task waiting on this suspension object then
1125       --  we resume it, leaving the state of the suspension object to False,
1126       --  as it is specified in ARM D.10 par. 9. Otherwise, it just leaves
1127       --  the state to True.
1128
1129       if S.Waiting then
1130          S.Waiting := False;
1131          S.State := False;
1132
1133          Result := semGive (S.CV);
1134          pragma Assert (Result = OK);
1135       else
1136          S.State := True;
1137       end if;
1138
1139       Result := semGive (S.L);
1140       pragma Assert (Result = OK);
1141
1142       SSL.Abort_Undefer.all;
1143    end Set_True;
1144
1145    ------------------------
1146    -- Suspend_Until_True --
1147    ------------------------
1148
1149    procedure Suspend_Until_True (S : in out Suspension_Object) is
1150       Result : STATUS;
1151
1152    begin
1153       SSL.Abort_Defer.all;
1154
1155       Result := semTake (S.L, WAIT_FOREVER);
1156
1157       if S.Waiting then
1158
1159          --  Program_Error must be raised upon calling Suspend_Until_True
1160          --  if another task is already waiting on that suspension object
1161          --  (ARM D.10 par. 10).
1162
1163          Result := semGive (S.L);
1164          pragma Assert (Result = OK);
1165
1166          SSL.Abort_Undefer.all;
1167
1168          raise Program_Error;
1169
1170       else
1171          --  Suspend the task if the state is False. Otherwise, the task
1172          --  continues its execution, and the state of the suspension object
1173          --  is set to False (ARM D.10 par. 9).
1174
1175          if S.State then
1176             S.State := False;
1177
1178             Result := semGive (S.L);
1179             pragma Assert (Result = 0);
1180
1181             SSL.Abort_Undefer.all;
1182
1183          else
1184             S.Waiting := True;
1185
1186             --  Release the mutex before sleeping
1187
1188             Result := semGive (S.L);
1189             pragma Assert (Result = OK);
1190
1191             SSL.Abort_Undefer.all;
1192
1193             Result := semTake (S.CV, WAIT_FOREVER);
1194             pragma Assert (Result = 0);
1195          end if;
1196       end if;
1197    end Suspend_Until_True;
1198
1199    ----------------
1200    -- Check_Exit --
1201    ----------------
1202
1203    --  Dummy version
1204
1205    function Check_Exit (Self_ID : ST.Task_Id) return Boolean is
1206       pragma Unreferenced (Self_ID);
1207    begin
1208       return True;
1209    end Check_Exit;
1210
1211    --------------------
1212    -- Check_No_Locks --
1213    --------------------
1214
1215    function Check_No_Locks (Self_ID : ST.Task_Id) return Boolean is
1216       pragma Unreferenced (Self_ID);
1217    begin
1218       return True;
1219    end Check_No_Locks;
1220
1221    ----------------------
1222    -- Environment_Task --
1223    ----------------------
1224
1225    function Environment_Task return Task_Id is
1226    begin
1227       return Environment_Task_Id;
1228    end Environment_Task;
1229
1230    --------------
1231    -- Lock_RTS --
1232    --------------
1233
1234    procedure Lock_RTS is
1235    begin
1236       Write_Lock (Single_RTS_Lock'Access, Global_Lock => True);
1237    end Lock_RTS;
1238
1239    ----------------
1240    -- Unlock_RTS --
1241    ----------------
1242
1243    procedure Unlock_RTS is
1244    begin
1245       Unlock (Single_RTS_Lock'Access, Global_Lock => True);
1246    end Unlock_RTS;
1247
1248    ------------------
1249    -- Suspend_Task --
1250    ------------------
1251
1252    function Suspend_Task
1253      (T           : ST.Task_Id;
1254       Thread_Self : Thread_Id) return Boolean
1255    is
1256    begin
1257       if T.Common.LL.Thread /= 0
1258         and then T.Common.LL.Thread /= Thread_Self
1259       then
1260          return taskSuspend (T.Common.LL.Thread) = 0;
1261       else
1262          return True;
1263       end if;
1264    end Suspend_Task;
1265
1266    -----------------
1267    -- Resume_Task --
1268    -----------------
1269
1270    function Resume_Task
1271      (T           : ST.Task_Id;
1272       Thread_Self : Thread_Id) return Boolean
1273    is
1274    begin
1275       if T.Common.LL.Thread /= 0
1276         and then T.Common.LL.Thread /= Thread_Self
1277       then
1278          return taskResume (T.Common.LL.Thread) = 0;
1279       else
1280          return True;
1281       end if;
1282    end Resume_Task;
1283
1284    --------------------
1285    -- Stop_All_Tasks --
1286    --------------------
1287
1288    procedure Stop_All_Tasks
1289    is
1290       Thread_Self : constant Thread_Id := taskIdSelf;
1291       C           : Task_Id;
1292
1293       Dummy : int;
1294       pragma Unreferenced (Dummy);
1295
1296    begin
1297       Dummy := Int_Lock;
1298
1299       C := All_Tasks_List;
1300       while C /= null loop
1301          if C.Common.LL.Thread /= 0
1302            and then C.Common.LL.Thread /= Thread_Self
1303          then
1304             Dummy := Task_Stop (C.Common.LL.Thread);
1305          end if;
1306
1307          C := C.Common.All_Tasks_Link;
1308       end loop;
1309
1310       Dummy := Int_Unlock;
1311    end Stop_All_Tasks;
1312
1313    ---------------
1314    -- Stop_Task --
1315    ---------------
1316
1317    function Stop_Task (T : ST.Task_Id) return Boolean is
1318    begin
1319       if T.Common.LL.Thread /= 0 then
1320          return Task_Stop (T.Common.LL.Thread) = 0;
1321       else
1322          return True;
1323       end if;
1324    end Stop_Task;
1325
1326    -------------------
1327    -- Continue_Task --
1328    -------------------
1329
1330    function Continue_Task (T : ST.Task_Id) return Boolean
1331    is
1332    begin
1333       if T.Common.LL.Thread /= 0 then
1334          return Task_Cont (T.Common.LL.Thread) = 0;
1335       else
1336          return True;
1337       end if;
1338    end Continue_Task;
1339
1340    ----------------
1341    -- Initialize --
1342    ----------------
1343
1344    procedure Initialize (Environment_Task : Task_Id) is
1345       Result : int;
1346
1347    begin
1348       Environment_Task_Id := Environment_Task;
1349
1350       Interrupt_Management.Initialize;
1351       Specific.Initialize;
1352
1353       if Locking_Policy = 'C' then
1354          Mutex_Protocol := Prio_Protect;
1355       elsif Locking_Policy = 'I' then
1356          Mutex_Protocol := Prio_Inherit;
1357       else
1358          Mutex_Protocol := Prio_None;
1359       end if;
1360
1361       if Time_Slice_Val > 0 then
1362          Result :=
1363            Set_Time_Slice
1364              (To_Clock_Ticks
1365                 (Duration (Time_Slice_Val) / Duration (1_000_000.0)));
1366
1367       elsif Dispatching_Policy = 'R' then
1368          Result := Set_Time_Slice (To_Clock_Ticks (0.01));
1369
1370       end if;
1371
1372       Result := sigemptyset (Unblocked_Signal_Mask'Access);
1373       pragma Assert (Result = 0);
1374
1375       for J in Interrupt_Management.Signal_ID loop
1376          if System.Interrupt_Management.Keep_Unmasked (J) then
1377             Result := sigaddset (Unblocked_Signal_Mask'Access, Signal (J));
1378             pragma Assert (Result = 0);
1379          end if;
1380       end loop;
1381
1382       --  Initialize the lock used to synchronize chain of all ATCBs
1383
1384       Initialize_Lock (Single_RTS_Lock'Access, RTS_Lock_Level);
1385
1386       --  Make environment task known here because it doesn't go through
1387       --  Activate_Tasks, which does it for all other tasks.
1388
1389       Known_Tasks (Known_Tasks'First) := Environment_Task;
1390       Environment_Task.Known_Tasks_Index := Known_Tasks'First;
1391
1392       Enter_Task (Environment_Task);
1393    end Initialize;
1394
1395 end System.Task_Primitives.Operations;