| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS -- |
| -- -- |
| -- S Y S T E M . S T A C K _ C H E C K I N G -- |
| -- -- |
| -- S p e c -- |
| -- -- |
| -- $Revision: 1.6 $ |
| -- -- |
| -- Copyright (C) 1999-2001 Free Software Foundation, Inc. -- |
| -- -- |
| -- GNARL is free software; you can redistribute it and/or modify it under -- |
| -- terms of the GNU General Public License as published by the Free Soft- -- |
| -- ware Foundation; either version 2, or (at your option) any later ver- -- |
| -- sion. GNARL is distributed in the hope that it will be useful, but WITH- -- |
| -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- |
| -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- |
| -- for more details. You should have received a copy of the GNU General -- |
| -- Public License distributed with GNARL; see file COPYING. If not, write -- |
| -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- |
| -- MA 02111-1307, USA. -- |
| -- -- |
| -- As a special exception, if other files instantiate generics from this -- |
| -- unit, or you link this unit with other files to produce an executable, -- |
| -- this unit does not by itself cause the resulting executable to be -- |
| -- covered by the GNU General Public License. This exception does not -- |
| -- however invalidate any other reasons why the executable file might be -- |
| -- covered by the GNU Public License. -- |
| -- -- |
| -- GNARL was developed by the GNARL team at Florida State University. It is -- |
| -- now maintained by Ada Core Technologies Inc. in cooperation with Florida -- |
| -- State University (http://www.gnat.com). -- |
| -- -- |
| ------------------------------------------------------------------------------ |
| |
| -- This package provides a system-independent implementation of stack |
| -- checking using comparison with stack base and limit. |
| |
| with System.Storage_Elements; |
| |
| pragma Polling (Off); |
| -- Turn off polling, we do not want polling to take place during stack |
| -- checking operations. It causes infinite loops and other problems. |
| |
| package System.Stack_Checking is |
| type Stack_Info is record |
| Limit : System.Address := System.Null_Address; |
| Base : System.Address := System.Null_Address; |
| Size : System.Storage_Elements.Storage_Offset := 0; |
| end record; |
| -- This record may be part of a larger data structure like the |
| -- task control block in the tasking case. |
| -- This specific layout has the advantage of being compatible with the |
| -- Intel x86 BOUNDS instruction. |
| |
| type Stack_Access is access all Stack_Info; |
| -- Unique local storage associated with a specific task. This storage is |
| -- used for the stack base and limit, and is returned by Checked_Self. |
| -- Only self may write this information, it may be read by any task. |
| -- At no time the address range Limit .. Base (or Base .. Limit for |
| -- upgrowing stack) may contain any address that is part of another stack. |
| -- The Stack_Access may be part of a larger data structure. |
| |
| Multi_Processor : constant Boolean := False; -- Not supported yet |
| |
| ---------------------- |
| -- Client Interface -- |
| ---------------------- |
| |
| procedure Set_Stack_Size |
| (Stack_Size : System.Storage_Elements.Storage_Offset); |
| -- Specify the stack size for the current task. |
| |
| procedure Update_Stack_Cache (Stack : Stack_Access); |
| -- Set the stack cache for the current task. Note that this is only |
| -- for optimization purposes, nothing can be assumed about the |
| -- contents of the cache at any time, see Set_Stack_Info. |
| |
| procedure Invalidate_Stack_Cache (Any_Stack : Stack_Access); |
| -- Invalidate cache entries for the task T that owns Any_Stack. |
| -- This causes the Set_Stack_Info function to be called during |
| -- the next stack check done by T. This can be used to interrupt |
| -- task T asynchronously. |
| -- Stack_Check should be called in loops for this to work reliably. |
| |
| function Stack_Check (Stack_Address : System.Address) return Stack_Access; |
| -- This version of Stack_Check should not be inlined. |
| |
| private |
| |
| Null_Stack_Info : aliased Stack_Info := |
| (Limit => System.Null_Address, |
| Base => System.Null_Address, |
| Size => 0); |
| -- Use explicit assignment to avoid elaboration code (call to _init_proc). |
| |
| Null_Stack : constant Stack_Access := Null_Stack_Info'Access; |
| -- Stack_Access value that will return a Stack_Base and Stack_Limit |
| -- that fail any stack check. |
| |
| Cache : aliased Stack_Access := Null_Stack; |
| |
| pragma Export (C, Cache, "_gnat_stack_cache"); |
| pragma Export (C, Stack_Check, "_gnat_stack_check"); |
| |
| end System.Stack_Checking; |
