gcc/ada/s-stchop-vxworks.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --
   4 --                                                                          --
   5 --     S Y S T E M . S T A C K _ C H E C K I N G . O P E R A T I O N S      --
   6 --                                                                          --
   7 --                                  B o d y                                 --
   8 --                                                                          --
   9 --          Copyright (C) 1999-2009, 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 verson for VxWorks 5 and VxWorks MILS
  33
  34 --  This file should be kept synchronized with the general implementation
  35 --  provided by s-stchop.adb.
  36
  37 pragma Restrictions (No_Elaboration_Code);
  38 --  We want to guarantee the absence of elaboration code because the
  39 --  binder does not handle references to this package.
  40
  41 with System.Storage_Elements; use System.Storage_Elements;
  42 with System.Parameters; use System.Parameters;
  43 with Interfaces.C;
  44
  45 package body System.Stack_Checking.Operations is
  46
  47    --  In order to have stack checking working appropriately on VxWorks we need
  48    --  to extract the stack size information from the VxWorks kernel itself.
  49
  50    --  For VxWorks 5 the library for showing task-related information needs to
  51    --  be linked into the VxWorks system, when using stack checking. The
  52    --  taskShow library can be linked into the VxWorks system by either:
  53
  54    --    * defining INCLUDE_SHOW_ROUTINES in config.h when using
  55    --      configuration header files, or
  56
  57    --    * selecting INCLUDE_TASK_SHOW when using the Tornado project
  58    --      facility.
  59
  60    --  VxWorks MILS includes the necessary routine in taskLib, so nothing
  61    --  special needs to be done there.
  62
  63    Stack_Limit : Address :=
  64                    Boolean'Pos (Stack_Grows_Down) * Address'First
  65                    + Boolean'Pos (not Stack_Grows_Down) * Address'Last;
  66    pragma Export (C, Stack_Limit, "__gnat_stack_limit");
  67    --  Stack_Limit contains the limit of the stack. This variable is later made
  68    --  a task variable (by calling taskVarAdd) and then correctly set to the
  69    --  stack limit of the task. Before being so initialized its value must be
  70    --  valid so that any subprogram with stack checking enabled will run. We
  71    --  use extreme values according to the direction of the stack.
  72
  73    type Set_Stack_Limit_Proc_Acc is access procedure;
  74    pragma Convention (C, Set_Stack_Limit_Proc_Acc);
  75
  76    Set_Stack_Limit_Hook : Set_Stack_Limit_Proc_Acc;
  77    pragma Import (C, Set_Stack_Limit_Hook, "__gnat_set_stack_limit_hook");
  78    --  Procedure to be called when a task is created to set stack
  79    --  limit.
  80
  81    procedure Set_Stack_Limit_For_Current_Task;
  82    pragma Convention (C, Set_Stack_Limit_For_Current_Task);
  83    --  Register Initial_SP as the initial stack pointer value for the current
  84    --  task when it starts and Size as the associated stack area size. This
  85    --  should be called once, after the soft-links have been initialized?
  86
  87    -----------------------------
  88    --  Initialize_Stack_Limit --
  89    -----------------------------
  90
  91    procedure Initialize_Stack_Limit is
  92    begin
  93       --  For the environment task
  94
  95       Set_Stack_Limit_For_Current_Task;
  96
  97       --  Will be called by every created task
  98
  99       Set_Stack_Limit_Hook := Set_Stack_Limit_For_Current_Task'Access;
 100    end Initialize_Stack_Limit;
 101
 102    --------------------------------------
 103    -- Set_Stack_Limit_For_Current_Task --
 104    --------------------------------------
 105
 106    procedure Set_Stack_Limit_For_Current_Task is
 107       use Interfaces.C;
 108
 109       function Task_Var_Add (Tid : Interfaces.C.int; Var : Address)
 110                             return Interfaces.C.int;
 111       pragma Import (C, Task_Var_Add, "taskVarAdd");
 112       --  Import from VxWorks
 113
 114       type OS_Stack_Info is record
 115          Size  : Interfaces.C.int;
 116          Base  : System.Address;
 117          Limit : System.Address;
 118       end record;
 119       pragma Convention (C, OS_Stack_Info);
 120       --  Type representing the information that we want to extract from the
 121       --  underlying kernel.
 122
 123       procedure Get_Stack_Info (Stack : not null access OS_Stack_Info);
 124       pragma Import (C, Get_Stack_Info, "__gnat_get_stack_info");
 125       --  Procedure that fills the stack information associated to the
 126       --  currently executing task.
 127
 128       Stack_Info : aliased OS_Stack_Info;
 129
 130       Limit : System.Address;
 131
 132    begin
 133       --  Get stack bounds from VxWorks
 134
 135       Get_Stack_Info (Stack_Info'Access);
 136
 137       --  In s-stchop.adb, we check for overflow in the following operations,
 138       --  but we have no such check in this vxworks version. Why not ???
 139
 140       if Stack_Grows_Down then
 141          Limit := Stack_Info.Base - Storage_Offset (Stack_Info.Size);
 142       else
 143          Limit := Stack_Info.Base + Storage_Offset (Stack_Info.Size);
 144       end if;
 145
 146       --  Note: taskVarAdd implicitly calls taskVarInit if required
 147
 148       if Task_Var_Add (0, Stack_Limit'Address) = 0 then
 149          Stack_Limit := Limit;
 150       end if;
 151    end Set_Stack_Limit_For_Current_Task;
 152
 153 end System.Stack_Checking.Operations;