------------------------------------------------------------------------------ -- -- -- 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 -- -- -- -- -- -- 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. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ -- 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;