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Rename the "protection mutator context" module to "mutator context" (this module handles mutator context decoding for both the protection module and the thread module).

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Rename functions Prot{Can,}StepInstruction to MutatorContext{Can,}StepInstruction so that they follow the naming convention in guide.implc.naming.prefix.program.
Move mutator context declarations out of prot.h into new header prmc.h.
Correct .assume.null in a couple of places -- it's not safe for MutatorContextStepInstruction to return ResUNIMPL, instead MutatorContextCanStepInstruction should return FALSE.

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 Change: 192528
 ServerID: perforce.ravenbrook.com
This commit is contained in:
Gareth Rees 2016-10-13 15:06:14 +01:00
parent 437bf9c6a4
commit b4a3d0824b
30 changed files with 151 additions and 107 deletions
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1
mps/code/mpm.h
View file

@ -18,6 +18,7 @@
#include "event.h"
#include "lock.h"
#include "prmc.h"
#include "prot.h"
#include "sp.h"
#include "th.h"

2
mps/code/mps.c
View file

@ -106,7 +106,7 @@
#include "than.c" /* generic threads manager */
#include "vman.c" /* malloc-based pseudo memory mapping */
#include "protan.c" /* generic memory protection */
#include "prmcan.c" /* generic protection mutator context */
#include "prmcan.c" /* generic mutator context */
#include "span.c" /* generic stack probe */
#include "ssan.c" /* generic stack scanner */

4
mps/code/poolabs.c
View file

@ -494,7 +494,7 @@ Res PoolSingleAccess(Pool pool, Seg seg, Addr addr,
arena = PoolArena(pool);
if(ProtCanStepInstruction(context)) {
if (MutatorContextCanStepInstruction(context)) {
Ref ref;
Res res;
@ -517,7 +517,7 @@ Res PoolSingleAccess(Pool pool, Seg seg, Addr addr,
seg, (Ref *)addr);
}
}
res = ProtStepInstruction(context);
res = MutatorContextStepInstruction(context);
AVER(res == ResOK);
/* Update SegSummary according to the possibly changed reference. */

68
mps/code/prmc.h Normal file
View file

@ -0,0 +1,68 @@
/* prmc.h: MUTATOR CONTEXT INTERFACE
*
* $Id$
* Copyright (c) 2016 Ravenbrook Limited. See end of file for license.
*
* See <design/prmc/> for the design of the generic interface including
* the contracts for these functions.
*
* This interface has several different implementations, typically one
* per platform, see <code/prmc*.c> for the various implementations.
*/
#ifndef prmc_h
#define prmc_h
#include "mpmtypes.h"
extern Bool MutatorContextCanStepInstruction(MutatorContext context);
extern Res MutatorContextStepInstruction(MutatorContext context);
extern Addr MutatorContextSP(MutatorContext context);
extern Res MutatorContextScan(ScanState ss, MutatorContext context,
mps_area_scan_t scan, void *closure);
#endif /* prmc_h */
/* C. COPYRIGHT AND LICENSE
*
* Copyright (C) 2016 Ravenbrook Limited <http://www.ravenbrook.com/>.
* All rights reserved. This is an open source license. Contact
* Ravenbrook for commercial licensing options.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. Redistributions in any form must be accompanied by information on how
* to obtain complete source code for this software and any accompanying
* software that uses this software. The source code must either be
* included in the distribution or be available for no more than the cost
* of distribution plus a nominal fee, and must be freely redistributable
* under reasonable conditions. For an executable file, complete source
* code means the source code for all modules it contains. It does not
* include source code for modules or files that typically accompany the
* major components of the operating system on which the executable file
* runs.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
* PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

16
mps/code/prmcan.c
View file

@ -1,4 +1,4 @@
/* prmcan.c: PROTECTION MUTATOR CONTEXT (ANSI)
/* prmcan.c: MUTATOR CONTEXT (ANSI)
*
* $Id$
* Copyright (c) 2001-2016 Ravenbrook Limited. See end of file for license.
@ -7,9 +7,9 @@
* which is implemented in this module including the contracts for the
* functions.
*
* .purpose: This module implements the part of the protection module
* that implements the MutatorContext type. In this ANSI version
* none of the functions have a useful implementation.
* .purpose: Implement the mutator context module. See <design/prmc/>.
* In this ANSI version none of the functions have a useful
* implementation.
*/
#include "mpm.h"
@ -17,9 +17,7 @@
SRCID(prmcan, "$Id$");
/* ProtCanStepInstruction -- can the current instruction be single-stepped */
Bool ProtCanStepInstruction(MutatorContext context)
Bool MutatorContextCanStepInstruction(MutatorContext context)
{
UNUSED(context);
@ -27,9 +25,7 @@ Bool ProtCanStepInstruction(MutatorContext context)
}
/* ProtStepInstruction -- step over instruction by modifying context */
Res ProtStepInstruction(MutatorContext context)
Res MutatorContextStepInstruction(MutatorContext context)
{
UNUSED(context);

5
mps/code/prmcfri3.c
View file

@ -1,10 +1,9 @@
/* prmcfri3.c: PROTECTION MUTATOR CONTEXT INTEL 386 (FREEBSD)
/* prmcfri3.c: MUTATOR CONTEXT INTEL 386 (FREEBSD)
*
* $Id$
* Copyright (c) 2001-2016 Ravenbrook Limited. See end of file for license.
*
* .purpose: This module implements the part of the protection module
* that decodes the MutatorContext.
* .purpose: Implement the mutator context module. See <design/prmc/>.
*
*
* SOURCES

5
mps/code/prmcfri6.c
View file

@ -1,10 +1,9 @@
/* prmcfri6.c: PROTECTION MUTATOR CONTEXT x64 (FREEBSD)
/* prmcfri6.c: MUTATOR CONTEXT x64 (FREEBSD)
*
* $Id$
* Copyright (c) 2001-2016 Ravenbrook Limited. See end of file for license.
*
* .purpose: This module implements the part of the protection module
* that decodes the MutatorContext.
* .purpose: Implement the mutator context module. See <design/prmc/>.
*
*
* ASSUMPTIONS

17
mps/code/prmci3.c
View file

@ -1,14 +1,13 @@
/* prmci3.c: PROTECTION MUTATOR CONTEXT (INTEL 386)
/* prmci3.c: MUTATOR CONTEXT (INTEL 386)
*
* $Id$
* Copyright (c) 2001-2016 Ravenbrook Limited. See end of file for license.
*
* .design: See <design/prot/> for the generic design of the interface
* .design: See <design/prmc/> for the generic design of the interface
* which is implemented in this module, including the contracts for the
* functions.
*
* .purpose: This module implements the part of the protection module
* that implements the MutatorContext type.
* .purpose: Implement the mutator context module. See <design/prmc/>.
*
* .requirements: Current requirements are for limited support only, for
* stepping the sorts of instructions that the Dylan compiler might
@ -31,9 +30,9 @@
*
* ASSUMPTIONS
*
* .assume.null: It's always safe for Prot*StepInstruction to return
* ResUNIMPL. A null implementation of this module would be overly
* conservative but otherwise correct.
* .assume.null: It's always safe for MutatorContextCanStepInstruction
* to return FALSE. A null implementation of this module would be
* overly conservative but otherwise correct.
*
* .assume.want: The Dylan implementation is likely to access a
* weak table vector using either MOV r/m32,r32 or MOV r32,r/m32
@ -211,7 +210,7 @@ static Bool IsSimpleMov(Size *inslenReturn,
}
Bool ProtCanStepInstruction(MutatorContext context)
Bool MutatorContextCanStepInstruction(MutatorContext context)
{
Size inslen;
MRef src;
@ -227,7 +226,7 @@ Bool ProtCanStepInstruction(MutatorContext context)
}
Res ProtStepInstruction(MutatorContext context)
Res MutatorContextStepInstruction(MutatorContext context)
{
Size inslen;
MRef src;

2
mps/code/prmci3.h
View file

@ -1,4 +1,4 @@
/* prmci3.h: PROTECTION MUTATOR CONTEXT (Intel 386)
/* prmci3.h: MUTATOR CONTEXT (Intel 386)
*
* $Id$
* Copyright (c) 2001-2016 Ravenbrook Limited. See end of file for license.

17
mps/code/prmci6.c
View file

@ -1,14 +1,13 @@
/* prmci6.c: PROTECTION MUTATOR CONTEXT (x64)
/* prmci6.c: MUTATOR CONTEXT (x64)
*
* $Id$
* Copyright (c) 2001-2016 Ravenbrook Limited. See end of file for license.
*
* .design: See <design/prot/> for the generic design of the interface
* .design: See <design/prmc/> for the generic design of the interface
* which is implemented in this module, including the contracts for the
* functions.
*
* .purpose: This module implements the part of the protection module
* that implements the MutatorContext type.
* .purpose: Implement the mutator context module. See <design/prmc/>.
*
*
* SOURCES
@ -20,9 +19,9 @@
*
* ASSUMPTIONS
*
* .assume.null: It's always safe for Prot*StepInstruction to return
* ResUNIMPL. A null implementation of this module would be overly
* conservative but otherwise correct.
* .assume.null: It's always safe for MutatorContextCanStepInstruction
* to return FALSE. A null implementation of this module would be
* overly conservative but otherwise correct.
*
*/
@ -54,7 +53,7 @@ static Bool IsSimpleMov(Size *inslenReturn,
}
Bool ProtCanStepInstruction(MutatorContext context)
Bool MutatorContextCanStepInstruction(MutatorContext context)
{
Size inslen;
MRef src;
@ -69,7 +68,7 @@ Bool ProtCanStepInstruction(MutatorContext context)
}
Res ProtStepInstruction(MutatorContext context)
Res MutatorContextStepInstruction(MutatorContext context)
{
Size inslen;
MRef src;

2
mps/code/prmci6.h
View file

@ -1,4 +1,4 @@
/* prmci6.h: PROTECTION MUTATOR CONTEXT (x64)
/* prmci6.h: MUTATOR CONTEXT (x64)
*
* $Id$
* Copyright (c) 2001-2016 Ravenbrook Limited. See end of file for license.

2
mps/code/prmcix.h
View file

@ -1,4 +1,4 @@
/* prmcix.h: PROTECTION MUTATOR CONTEXT (UNIX)
/* prmcix.h: MUTATOR CONTEXT (UNIX)
*
* $Id$
* Copyright (c) 2001-2016 Ravenbrook Limited. See end of file for license.

5
mps/code/prmclii3.c
View file

@ -1,10 +1,9 @@
/* prmclii3.c: PROTECTION MUTATOR CONTEXT INTEL 386 (LINUX)
/* prmclii3.c: MUTATOR CONTEXT INTEL 386 (LINUX)
*
* $Id$
* Copyright (c) 2001-2016 Ravenbrook Limited. See end of file for license.
*
* .purpose: This module implements the part of the protection module
* that decodes the MutatorContext.
* .purpose: Implement the mutator context module. See <design/prmc/>.
*
*
* SOURCES

5
mps/code/prmclii6.c
View file

@ -1,10 +1,9 @@
/* prmclii6.c: PROTECTION MUTATOR CONTEXT x64 (LINUX)
/* prmclii6.c: MUTATOR CONTEXT x64 (LINUX)
*
* $Id$
* Copyright (c) 2001-2016 Ravenbrook Limited. See end of file for license.
*
* .purpose: This module implements the part of the protection module
* that decodes the MutatorContext.
* .purpose: Implement the mutator context module. See <design/prmc/>.
*
*
* SOURCES

5
mps/code/prmcw3i3.c
View file

@ -1,12 +1,11 @@
/* prmcw3i3.c: PROTECTION MUTATOR CONTEXT INTEL 386 (Windows)
/* prmcw3i3.c: MUTATOR CONTEXT INTEL 386 (Windows)
*
* $Id$
* Copyright (c) 2001-2016 Ravenbrook Limited. See end of file for license.
*
* PURPOSE
*
* .purpose: This module implements the part of the protection module
* that decodes the MutatorContext.
* .purpose: Implement the mutator context module. See <design/prmc/>.
*
* SOURCES
*

5
mps/code/prmcw3i6.c
View file

@ -1,12 +1,11 @@
/* prmcw3i6.c: PROTECTION MUTATOR CONTEXT INTEL x64 (Windows)
/* prmcw3i6.c: MUTATOR CONTEXT INTEL x64 (Windows)
*
* $Id$
* Copyright (c) 2001-2016 Ravenbrook Limited. See end of file for license.
*
* PURPOSE
*
* .purpose: This module implements the part of the protection module
* that decodes the MutatorContext.
* .purpose: Implement the mutator context module. See <design/prmc/>.
*
* SOURCES
*

2
mps/code/prmcxc.h
View file

@ -1,4 +1,4 @@
/* prmcxc.h: PROTECTION MUTATOR CONTEXT FOR OS X MACH
/* prmcxc.h: MUTATOR CONTEXT FOR OS X MACH
*
* $Id$
* Copyright (c) 2001-2016 Ravenbrook Limited. See end of file for license.

5
mps/code/prmcxci3.c
View file

@ -1,10 +1,9 @@
/* prmcxci3.c: PROTECTION MUTATOR CONTEXT INTEL 386 (MAC OS X)
/* prmcxci3.c: MUTATOR CONTEXT INTEL 386 (MAC OS X)
*
* $Id$
* Copyright (c) 2001-2016 Ravenbrook Limited. See end of file for license.
*
* .purpose: This module implements the part of the protection module
* that decodes the MutatorContext.
* .purpose: Implement the mutator context module. See <design/prmc/>.
*
*
* SOURCES

5
mps/code/prmcxci6.c
View file

@ -1,10 +1,9 @@
/* prmcxci6.c: PROTECTION MUTATOR CONTEXT x64 (OS X)
/* prmcxci6.c: MUTATOR CONTEXT x64 (OS X)
*
* $Id$
* Copyright (c) 2001-2016 Ravenbrook Limited. See end of file for license.
*
* .purpose: This module implements the part of the protection module
* that decodes the MutatorContext.
* .purpose: Implement the mutator context module. See <design/prmc/>.
*
*
* SOURCES

9
mps/code/prot.h
View file

@ -25,15 +25,6 @@ extern void ProtSet(Addr base, Addr limit, AccessSet mode);
extern void ProtSync(Arena arena);
/* Mutator Fault Context */
extern Bool ProtCanStepInstruction(MutatorContext context);
extern Res ProtStepInstruction(MutatorContext context);
extern Addr MutatorContextSP(MutatorContext context);
extern Res MutatorContextScan(ScanState ss, MutatorContext context,
mps_area_scan_t scan, void *closure);
#endif /* prot_h */

2
mps/code/pthrdext.c
View file

@ -55,8 +55,6 @@ static RingStruct suspendedRing; /* PThreadext suspend ring */
*
* See <design/pthreadext/#impl.suspend-handler>
*
* The interface for determining the MFC might be platform specific.
*
* Handle PTHREADEXT_SIGSUSPEND in the target thread, to suspend it until
* receiving PTHREADEXT_SIGRESUME (resume). Note that this is run with both
* PTHREADEXT_SIGSUSPEND and PTHREADEXT_SIGRESUME blocked. Having

2
mps/code/thix.c
View file

@ -276,7 +276,7 @@ Res ThreadScan(ScanState ss, Thread thread, Word *stackCold,
if(res != ResOK)
return res;
/* scan the registers in the mutator fault context */
/* scan the registers in the mutator context */
res = MutatorContextScan(ss, context, scan_area, closure);
if(res != ResOK)
return res;

2
mps/code/thxc.c
View file

@ -263,7 +263,7 @@ Res ThreadScan(ScanState ss, Thread thread, Word *stackCold,
if(res != ResOK)
return res;
/* scan the registers in the mutator fault context */
/* scan the registers in the mutator context */
res = MutatorContextScan(ss, &context, scan_area, closure);
if(res != ResOK)
return res;

6
mps/design/an.txt
View file

@ -100,7 +100,7 @@ _`.mod`: This section lists the functional modules in the MPS.
_`.mod.lock`: Locks. See design.mps.lock_.
_`.mod.prmc`: Protection mutator context. See design.mps.prmc_.
_`.mod.prmc`: Mutator context. See design.mps.prmc_.
_`.mod.prot`: Memory protection. See design.mps.prot_.
@ -136,7 +136,7 @@ design.mps.prmc.impl.an.fault_) and requires a single-threaded mutator
_`.lim.prot`: Does not support incremental collection (see
design.mps.prot.impl.an.sync_) and is not compatible with
implementations of the protection mutator context module that support
implementations of the mutator context module that support
single-stepping of accesses (see design.mps.prot.impl.an.sync.issue_).
_`.lim.sp`: Only suitable for use with programs that do not handle
@ -176,7 +176,7 @@ Document History
Copyright and License
---------------------
Copyright © 2014 Ravenbrook Limited <http://www.ravenbrook.com/>.
Copyright © 2014-2016 Ravenbrook Limited <http://www.ravenbrook.com/>.
All rights reserved. This is an open source license. Contact
Ravenbrook for commercial licensing options.

8
mps/design/exec-env.txt
View file

@ -112,10 +112,10 @@ The core must be freestanding.
_`.arch.platform`: The *platform* provides the core with interfaces to
features of the operating system and processor (locks, memory
protection, protection mutator context, stack probing, stack and
register scanning, thread management, and virtual memory). The
platform is specialized to a particular environment and so can safely
use whatever features are available in that environment.
protection, mutator context, stack probing, stack and register
scanning, thread management, and virtual memory). The platform is
specialized to a particular environment and so can safely use whatever
features are available in that environment.
_`.arch.plinth`: The *plinth* provides the core with interfaces to
features of the user environment (time, assertions, and logging). See

2
mps/design/index.txt
View file

@ -85,7 +85,7 @@ poolmrg_ Manual Rank Guardian pool class
poolmv_ Manual Variable pool class
poolmvt_ Manual Variable Temporal pool class
poolmvff_ Manual Variable First-Fit pool class
prmc_ Protection mutator context
prmc_ Mutator context
prot_ Memory protection
protli_ Linux implementation of protection module
protocol_ Protocol inheritance

37
mps/design/prmc.txt
View file

@ -1,7 +1,7 @@
.. mode: -*- rst -*-
Protection mutator context
==========================
Mutator context
===============
:Tag: design.mps.prmc
:Author: Gareth Rees
@ -9,31 +9,30 @@ Protection mutator context
:Status: complete design
:Revision: $Id$
:Copyright: See `Copyright and License`_.
:Index terms: pair: protection mutator context; design
:Index terms: pair: mutator context; design
Introduction
------------
_`.intro`: This is the design of the protection mutator context
module.
_`.intro`: This is the design of the mutator context module.
_`.readership`: Any MPS developer; anyone porting the MPS to a new
platform.
_`.overview`: The protection mutator context module decodes the
*context* of a mutator thread at the point when it caused a protection
fault, so that access to a protected region of memory can be handled,
or when it was suspended by the thread manager, so that its registers
and control stack can be scanned.
_`.overview`: The mutator context module decodes the *context* of a
mutator thread at the point when it caused a protection fault, so that
access to a protected region of memory can be handled, or when it was
suspended by the thread manager, so that its registers and control
stack can be scanned.
_`.def.context`: The *context* of a thread (also called its
*continuation*) is an abstract representation of the control state of
the thread at a point in time, including enough information to
continue the thread from that point.
_`.status`: The protection mutator context module does not currently
present a clean interface to the rest of the MPS: source files are
_`.status`: The mutator context module does not currently present a
clean interface to the rest of the MPS: source files are
inconsistently named, and the implementation is (necessarily) mixed up
with the implementation of the memory protection module
(design.mps.prot_) and the thread manager
@ -64,7 +63,7 @@ weak hash tables. See request.dylan.160044_.)
.. _request.dylan.160044: https://info.ravenbrook.com/project/mps/import/2001-11-05/mmprevol/request/dylan/160044/
_`.req.suspend.scan`: Must capature enough information to ambiguously
_`.req.suspend.scan`: Must capture enough information to ambiguously
scan all roots in the context of a thread that has been suspended by
the thread manager. (This is necessary for conservative garbage
collection to work. See design.mps.thread-manager.if.scan_.)
@ -85,14 +84,14 @@ See design.mps.thread-manager.if.thread_.
.. _design.mps.thread-manager.if.thread: thread-manager#if.thread
``Bool ProtCanStepInstruction(MutatorContext context)``
``Bool MutatorContextCanStepInstruction(MutatorContext context)``
_`.if.canstep`: Examine the context to determine whether the
protection module can single-step the instruction which is causing the
fault. Return ``TRUE`` if ``ProtStepInstruction()`` is capable of
single-stepping the instruction, or ``FALSE`` if not.
fault. Return ``TRUE`` if ``MutatorContextStepInstruction()`` is
capable of single-stepping the instruction, or ``FALSE`` if not.
``Bool Res ProtStepInstruction(MutatorContext context)``
``Bool Res MutatorContextStepInstruction(MutatorContext context)``
_`.if.step`: Single-step the instruction which is causing the fault.
Update the mutator context according to the emulation or execution of
@ -101,8 +100,8 @@ instruction which was caused the fault to be re-executed. Return
``ResOK`` if the instruction was single-stepped successfully, or
``ResUNIMPL`` if the instruction cannot be single-stepped.
This function is only called if ``ProtCanStepInstruction(context)``
returned ``TRUE``.
This function is only called if
``MutatorContextCanStepInstruction(context)`` returned ``TRUE``.
``Res MutatorContextScan(ScanState ss, MutatorContext context, mps_area_scan_t scan, void *closure)``

4
mps/design/prot.txt
View file

@ -153,8 +153,8 @@ Document History
- 2013-05-23 GDR_ Converted to reStructuredText.
- 2014-10-23 GDR_ Move protection mutator context interface to
design.mps.prmc_. Bring design up to date.
- 2014-10-23 GDR_ Move mutator context interface to design.mps.prmc_.
Bring design up to date.
.. _design.mps.prmc: prmc

1
mps/manual/source/code-index.rst
View file

@ -163,6 +163,7 @@ lock.h Lock interface. See design.mps.lock_.
lockan.c Lock implementation for standard C.
lockix.c Lock implementation for POSIX.
lockw3.c Lock implementation for Windows.
prmc.h Mutator context interface. See design.mps.prmc_.
prmcan.c Mutator context implementation for standard C.
prmcfri3.c Mutator context implementation for FreeBSD, IA-32.
prmcfri6.c Mutator context implementation for FreeBSD, x86-64.

12
mps/manual/source/topic/porting.rst
View file

@ -69,13 +69,13 @@ usable.
there is no further need to protect it. This means it can't support
incremental collection, and has no control over pause times.
#. The **protection mutator context** module figures out what the
:term:`mutator` was doing when it caused a :term:`protection
fault`, so that access to a protected region of memory can be
handled, or when a thread was suspended, so that its
:term:`registers` and :term:`control stack` can be scanned.
#. The **mutator context** module figures out what the :term:`mutator`
was doing when it caused a :term:`protection fault`, so that access
to a protected region of memory can be handled, or when a thread
was suspended, so that its :term:`registers` and :term:`control
stack` can be scanned.
See :ref:`design-prmc` for the design, and ``prot.h`` for the
See :ref:`design-prmc` for the design, and ``prmc.h`` for the
interface. There are implementations on Unix, Windows, and OS X for
IA-32 and x86-64.