| ------------------------------------------------------------------------------ |
| -- -- |
| -- 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) 1999-2014, 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 |
| -- losing 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; |
