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Correcting design documentation relating to stacks. Referencing hot and cold end concepts from glossary entry for control stacks. Copied from Perforce Change: 189320 ServerID: perforce.ravenbrook.com
205 lines
6.8 KiB
C
205 lines
6.8 KiB
C
/* sc.h: STACK CONTEXT
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*
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* $Id$
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* Copyright (c) 2012 Ravenbrook Limited. See end of file for license.
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*
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* Provides a context to hold the registers and stack pointer
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*
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* This file provide wrappers for using setjmp or some similar mechanism
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* to save the current callee-saves on the stack.
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*
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* See http://info.ravenbrook.com/mail/2012/08/03/14-36-35/0/ and the rest of
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* the thread for the origin of the idea.
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*
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* TODO: Make StackScan take a StackContext
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*/
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#ifndef sc_h
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#define sc_h
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#include "mpm.h"
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/* StackContext -- holds the registers including a stack pointer
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*
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* This contains the callee-save registers and the stack pointer.
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*
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* This is used to save the registers after or on entry to the arena so that
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* they can be scanned.
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*/
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/* STACK_CONTEXT_SAVE - save the callee-saves and stack pointer
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*
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* This macro saves the callee-saves and stack pointer for the
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* current function into the passed StackContext. The StackContext
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* is no longer valid after the function returns.
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*
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* This needs to be a macro because the compiler may need to do
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* setjmp magic.
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*/
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/* StackContextStackHot - return the stack hot end from the stack context.
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*
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* We assume the stack is full. In other words the stack top points at
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* a word that contains a potential Ref.
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*/
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/* Mac OS X on 32-bit Intel built with Clang or GCC */
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#if defined(MPS_PF_XCI3LL) || defined(MPS_PF_XCI3GC)
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#include <setjmp.h>
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typedef struct StackContextStruct {
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jmp_buf jumpBuffer;
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} StackContextStruct;
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/* See the implementation of _setjmp in
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* <http://www.opensource.apple.com/source/Libc/Libc-825.24/i386/sys/_setjmp.s> */
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#define JB_ESP 36 /* offset into the jmp_buf in bytes as defined in _setjmp.s */
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#define STACK_CONTEXT_SAVE(sc) ((void)_setjmp((sc)->jumpBuffer))
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#define StackContextSP(sc) ((Addr *)(sc)->jumpBuffer[JB_ESP/sizeof(int)])
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/* On MacOS X the stackPointer can end up pointing above the StackContext
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* which we assume to be stored on the stack because it is no longer
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* needed once we have _longjmp()ed back. So take the minimum of the
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* SP and the base of the StackContext structure. */
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#define StackContextStackHot(sc) \
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(StackContextSP(sc) < (Addr*)(sc) ? StackContextSP(sc) : (Addr*)(sc))
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/* Mac OS X on 64-bit Intel build with Clang or GCC */
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#elif defined(MPS_PF_XCI6LL) || defined(MPS_PF_XCI6GC)
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#include <setjmp.h>
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/* We could use getcontext() from libunwind but that produces
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* deprecation warnings. See
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* <http://stackoverflow.com/questions/3592914/how-can-i-implement-cooperative-lightweight-threading-with-c-on-mac-os-x>
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*/
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typedef struct StackContextStruct {
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jmp_buf jumpBuffer;
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} StackContextStruct;
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/* See the implementation of _setjmp in
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* <http://www.opensource.apple.com/source/Libc/Libc-825.24/x86_64/sys/_setjmp.s> */
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#define STACK_CONTEXT_SAVE(sc) ((void)_setjmp((sc)->jumpBuffer))
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#define JB_RSP 16 /* offset into the jmp_buf in bytes as defined in _setjmp.s */
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/* jmp_buf is an int[] but the stack pointer is 8 bytes so we need a cast */
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/* FIXME: possible aliasing problem */
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#define StackContextSP(sc) \
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(*(Addr **)((char *)(sc)->jumpBuffer+JB_RSP))
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/* On MacOS X the stackPointer can end up pointing above the StackContext
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* which we assume to be stored on the stack because it is no longer
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* needed once we have _longjmp()ed back. So take the minimum of the
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* SP and the base of the StackContext structure. */
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#define StackContextStackHot(sc) \
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(StackContextSP(sc) < (Addr*)(sc) ? StackContextSP(sc) : (Addr*)(sc))
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/* Windows on 32-bit Intel with Microsoft Visual Studio */
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#elif defined(MPS_PF_W3I3MV)
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#include <setjmp.h>
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typedef struct StackContextStruct {
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jmp_buf jumpBuffer;
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} StackContextStruct;
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#define STACK_CONTEXT_SAVE(sc) ((void)setjmp((sc)->jumpBuffer))
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#define StackContextStackHot(sc) \
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((Addr *)((_JUMP_BUFFER *)(sc)->jumpBuffer)->Esp)
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/* Windows on 64-bit Intel with Microsoft Visual Studio */
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#elif defined(MPS_PF_W3I6MV)
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#include <setjmp.h>
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typedef struct StackContextStruct {
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jmp_buf jumpBuffer;
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} StackContextStruct;
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#define STACK_CONTEXT_SAVE(sc) ((void)setjmp((sc)->jumpBuffer))
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#define StackContextStackHot(sc) \
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((Addr *)((_JUMP_BUFFER *)(sc)->jumpBuffer)->Rsp)
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#else
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/* TODO: implement this on other platforms in a safer way.
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* Potentially the callee saves from the calling function could be spilled
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* underneath the jmp_buf so returning the address of the jmp_buf for the
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* stack top is not completely safe.
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*/
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#include <setjmp.h>
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typedef struct StackContextStruct {
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jmp_buf jumpBuffer;
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} StackContextStruct;
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#define STACK_CONTEXT_SAVE(sc) ((void)setjmp((sc)->jumpBuffer))
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#define StackContextStackHot(sc) ((Addr *)(sc)->jumpBuffer)
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#endif /* platform defines */
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#endif /* sc_h */
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/* C. COPYRIGHT AND LICENSE
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*
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* Copyright (C) 2001-2012 Ravenbrook Limited <http://www.ravenbrook.com/>.
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* All rights reserved. This is an open source license. Contact
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* Ravenbrook for commercial licensing options.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Redistributions in any form must be accompanied by information on how
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* to obtain complete source code for this software and any accompanying
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* software that uses this software. The source code must either be
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* included in the distribution or be available for no more than the cost
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* of distribution plus a nominal fee, and must be freely redistributable
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* under reasonable conditions. For an executable file, complete source
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* code means the source code for all modules it contains. It does not
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* include source code for modules or files that typically accompany the
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* major components of the operating system on which the executable file
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* runs.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
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* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
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* PURPOSE, OR NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDERS AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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