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Diffstat (limited to 'gcc-4.8.3/gcc/ada/s-stchop.adb')
| -rw-r--r-- | gcc-4.8.3/gcc/ada/s-stchop.adb | 279 |
1 files changed, 279 insertions, 0 deletions
diff --git a/gcc-4.8.3/gcc/ada/s-stchop.adb b/gcc-4.8.3/gcc/ada/s-stchop.adb new file mode 100644 index 000000000..b757c5653 --- /dev/null +++ b/gcc-4.8.3/gcc/ada/s-stchop.adb @@ -0,0 +1,279 @@ +------------------------------------------------------------------------------ +-- -- +-- 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 . O P E R A T I O N S -- +-- -- +-- B o d y -- +-- -- +-- Copyright (C) 1999-2010, 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 is the general implementation of this package. There is a VxWorks +-- specific version of this package (s-stchop-vxworks.adb). This file should +-- be kept synchronized with it. + +pragma Restrictions (No_Elaboration_Code); +-- We want to guarantee the absence of elaboration code because the +-- binder does not handle references to this package. + +with System.Storage_Elements; use System.Storage_Elements; +with System.Parameters; use System.Parameters; +with System.Soft_Links; +with System.CRTL; + +package body System.Stack_Checking.Operations is + + Kilobyte : constant := 1024; + + function Set_Stack_Info + (Stack : not null 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 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. + + ---------------------------- + -- Invalidate_Stack_Cache -- + ---------------------------- + + procedure Invalidate_Stack_Cache (Any_Stack : Stack_Access) is + pragma Warnings (Off, Any_Stack); + begin + Cache := Null_Stack; + end Invalidate_Stack_Cache; + + ----------------------------- + -- Notify_Stack_Attributes -- + ----------------------------- + + procedure Notify_Stack_Attributes + (Initial_SP : System.Address; + Size : System.Storage_Elements.Storage_Offset) + is + My_Stack : constant Stack_Access := Soft_Links.Get_Stack_Info.all; + + -- We piggyback on the 'Limit' field to store what will be used as the + -- 'Base' and leave the 'Size' alone to not interfere with the logic in + -- Set_Stack_Info below. + + pragma Unreferenced (Size); + + begin + My_Stack.Limit := Initial_SP; + end Notify_Stack_Attributes; + + -------------------- + -- Set_Stack_Info -- + -------------------- + + function Set_Stack_Info + (Stack : not null access Stack_Access) return Stack_Access + is + type Frame_Mark is null record; + Frame_Location : Frame_Mark; + Frame_Address : constant Address := Frame_Location'Address; + + My_Stack : Stack_Access; + Limit_Chars : System.Address; + Limit : Integer; + + 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 := Storage_Offset (Default_Env_Stack_Size); + + -- When the environment variable GNAT_STACK_LIMIT is set, set + -- Environment_Stack_Size to that number of kB. + + Limit_Chars := System.CRTL.getenv ("GNAT_STACK_LIMIT" & ASCII.NUL); + + if Limit_Chars /= Null_Address then + Limit := System.CRTL.atoi (Limit_Chars); + + if Limit >= 0 then + My_Stack.Size := Storage_Offset (Limit) * Kilobyte; + end if; + end if; + end if; + + -- If a stack base address has been registered, honor it. Fallback to + -- the address of a local object otherwise. + + My_Stack.Base := + (if My_Stack.Limit /= System.Null_Address + then My_Stack.Limit else 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; + + -- Never trust the cached value, but return local copy! + + return My_Stack; + end Set_Stack_Info; + + ----------------- + -- 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 + -- The parameter may have wrapped around in System.Address arithmetics. + -- In that case, we have no other choices than raising the exception. + + if (Stack_Grows_Down and then + Stack_Address > Frame_Address) + or else + (not Stack_Grows_Down and then + Stack_Address < Frame_Address) + then + raise Storage_Error with "stack overflow detected"; + end if; + + -- 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 then + Stack_Address > Cached_Stack.Limit)) + or else + (not Stack_Grows_Down and then + (Frame_Address >= Cached_Stack.Base + and then + 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 : constant 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 Base to be initialized 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 + raise Storage_Error with "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.Operations; |