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Diffstat (limited to 'gcc/ada/s-stache.adb')
| -rw-r--r-- | gcc/ada/s-stache.adb | 282 |
1 files changed, 282 insertions, 0 deletions
diff --git a/gcc/ada/s-stache.adb b/gcc/ada/s-stache.adb new file mode 100644 index 00000000000..3a5e5b3176a --- /dev/null +++ b/gcc/ada/s-stache.adb @@ -0,0 +1,282 @@ +------------------------------------------------------------------------------ +-- -- +-- 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 -- +-- -- +-- B o d y -- +-- -- +-- $Revision: 1.10 $ +-- -- +-- 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). -- +-- -- +------------------------------------------------------------------------------ + +with Ada.Exceptions; + +with System.Storage_Elements; use System.Storage_Elements; +with System.Parameters; use System.Parameters; +with System.Soft_Links; + +package body System.Stack_Checking is + + Kilobyte : constant Storage_Offset := 1024; + Default_Env_Stack_Size : constant Storage_Offset := 8000 * Kilobyte; + -- This size is assumed for the environment stack when no size has been + -- set by the runtime, and no GNAT_STACK_LIMIT environment variable was + -- present. The value is chosen to be just under 8 MB whic is the actual + -- default size on some systems including LinuxThreads, so we will get + -- correct storage errors on those systems without setting environment + -- variables. + + function Set_Stack_Info (Stack : access Stack_Access) return Stack_Access; + + -- The function Set_Stack_Info is the actual function that updates + -- the cache containing a pointer to the Stack_Info. It may also + -- be used for detecting asynchronous abort in combination with + -- Invalidate_Self_Cache. + + -- Set_Stack_Info should do the following things in order: + -- 1) Get the Stack_Access value for the current task + -- 2) Set Stack.all to the value obtained in 1) + -- 3) Optionally Poll to check for asynchronous abort + + -- This order is important because if at any time a write to + -- the stack cache is pending, that write should be followed + -- by a Poll to prevent loosing signals. + + -- Note: This function must be compiled with Polling turned off + + -- Note: on systems like VxWorks and OS/2 with real thread-local storage, + -- Set_Stack_Info should return an access value for such local + -- storage. In those cases the cache will always be up-to-date. + + -- The following constants should be imported from some system-specific + -- constants package. The constants must be static for performance reasons. + + ---------------------------- + -- Invalidate_Stack_Cache -- + ---------------------------- + + procedure Invalidate_Stack_Cache (Any_Stack : Stack_Access) is + begin + Cache := Null_Stack; + end Invalidate_Stack_Cache; + + -------------------- + -- Set_Stack_Info -- + -------------------- + + function Set_Stack_Info + (Stack : access Stack_Access) + return Stack_Access + is + type Frame_Mark is null record; + Frame_Location : Frame_Mark; + Frame_Address : Address := Frame_Location'Address; + + My_Stack : Stack_Access; + Limit_Chars : System.Address; + Limit : Integer; + + function getenv (S : String) return System.Address; + pragma Import (C, getenv, External_Name => "getenv"); + + function atoi (A : System.Address) return Integer; + pragma Import (C, atoi); + + begin + -- The order of steps 1 .. 3 is important, see specification. + + -- 1) Get the Stack_Access value for the current task + + My_Stack := Soft_Links.Get_Stack_Info.all; + + if My_Stack.Base = Null_Address then + + -- First invocation, initialize based on the assumption that + -- there are Environment_Stack_Size bytes available beyond + -- the current frame address. + + if My_Stack.Size = 0 then + + My_Stack.Size := Default_Env_Stack_Size; + + -- When the environment variable GNAT_STACK_LIMIT is set, + -- set Environment_Stack_Size to that number of kB. + + Limit_Chars := getenv ("GNAT_STACK_LIMIT" & ASCII.NUL); + + if Limit_Chars /= Null_Address then + Limit := atoi (Limit_Chars); + if Limit >= 0 then + My_Stack.Size := Storage_Offset (Limit) * Kilobyte; + end if; + end if; + end if; + + My_Stack.Base := Frame_Address; + + if Stack_Grows_Down then + + -- Prevent wrap-around on too big stack sizes + + My_Stack.Limit := My_Stack.Base - My_Stack.Size; + + if My_Stack.Limit > My_Stack.Base then + My_Stack.Limit := Address'First; + end if; + + else + My_Stack.Limit := My_Stack.Base + My_Stack.Size; + + -- Prevent wrap-around on too big stack sizes + + if My_Stack.Limit < My_Stack.Base then + My_Stack.Limit := Address'Last; + end if; + end if; + end if; + + -- 2) Set Stack.all to the value obtained in 1) + + Stack.all := My_Stack; + + -- 3) Optionally Poll to check for asynchronous abort + + if Soft_Links.Check_Abort_Status.all /= 0 then + raise Standard'Abort_Signal; + end if; + + return My_Stack; -- Never trust the cached value, but return local copy! + end Set_Stack_Info; + + -------------------- + -- Set_Stack_Size -- + -------------------- + + -- Specify the stack size for the current frame. + + procedure Set_Stack_Size + (Stack_Size : System.Storage_Elements.Storage_Offset) + is + My_Stack : Stack_Access; + Frame_Address : constant System.Address := My_Stack'Address; + + begin + My_Stack := Stack_Check (Frame_Address); + + if Stack_Grows_Down then + My_Stack.Limit := My_Stack.Base - Stack_Size; + else + My_Stack.Limit := My_Stack.Base + Stack_Size; + end if; + end Set_Stack_Size; + + ----------------- + -- Stack_Check -- + ----------------- + + function Stack_Check + (Stack_Address : System.Address) + return Stack_Access + is + type Frame_Marker is null record; + Marker : Frame_Marker; + Cached_Stack : constant Stack_Access := Cache; + Frame_Address : constant System.Address := Marker'Address; + + begin + -- This function first does a "cheap" check which is correct + -- if it succeeds. In case of failure, the full check is done. + -- Ideally the cheap check should be done in an optimized manner, + -- or be inlined. + + if (Stack_Grows_Down and then + (Frame_Address <= Cached_Stack.Base + and + Stack_Address > Cached_Stack.Limit)) + or else + (not Stack_Grows_Down and then + (Frame_Address >= Cached_Stack.Base + and + Stack_Address < Cached_Stack.Limit)) + then + -- Cached_Stack is valid as it passed the stack check + return Cached_Stack; + end if; + + Full_Check : + declare + My_Stack : Stack_Access := Set_Stack_Info (Cache'Access); + -- At this point Stack.all might already be invalid, so + -- it is essential to use our local copy of Stack! + + begin + + if (Stack_Grows_Down and then + (not (Frame_Address <= My_Stack.Base))) + or else + (not Stack_Grows_Down and then + (not (Frame_Address >= My_Stack.Base))) + then + -- The returned Base is lower than the stored one, + -- so assume that the original one wasn't right and use the + -- current Frame_Address as new one. This allows initializing + -- Base with the Frame_Address as approximation. + -- During initialization the Frame_Address will be close to + -- the stack base anyway: the difference should be compensated + -- for in the stack reserve. + + My_Stack.Base := Frame_Address; + end if; + + if (Stack_Grows_Down and then + Stack_Address < My_Stack.Limit) + or else + (not Stack_Grows_Down and then + Stack_Address > My_Stack.Limit) + then + Ada.Exceptions.Raise_Exception + (E => Storage_Error'Identity, + Message => "stack overflow detected"); + end if; + + return My_Stack; + end Full_Check; + end Stack_Check; + + ------------------------ + -- Update_Stack_Cache -- + ------------------------ + + procedure Update_Stack_Cache (Stack : Stack_Access) is + begin + if not Multi_Processor then + Cache := Stack; + end if; + end Update_Stack_Cache; + +end System.Stack_Checking; |