| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT 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) 1999-2013, 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 3, or (at your option) any later ver- -- |
| -- sion. GNAT 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. -- |
| -- -- |
| -- As a special exception under Section 7 of GPL version 3, you are granted -- |
| -- additional permissions described in the GCC Runtime Library Exception, -- |
| -- version 3.1, as published by the Free Software Foundation. -- |
| -- -- |
| -- You should have received a copy of the GNU General Public License and -- |
| -- a copy of the GCC Runtime Library Exception along with this program; -- |
| -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- |
| -- <http://www.gnu.org/licenses/>. -- |
| -- -- |
| -- 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. |
| |
| -- This package defines basic types and objects. Operations related to |
| -- stack checking can be found in package System.Stack_Checking.Operations. |
| |
| pragma Compiler_Unit_Warning; |
| |
| with System.Storage_Elements; |
| |
| package System.Stack_Checking is |
| pragma Preelaborate; |
| pragma Elaborate_Body; |
| -- This unit has a junk null body. The reason is that historically we |
| -- used to have a real body, and it causes bootstrapping path problems |
| -- to eliminate it, since the old body may still be present in the |
| -- compilation environment for a build. |
| |
| 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 |
| |
| 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. |
| |
| end System.Stack_Checking; |
