/* sc.h: STACK CONTEXT * * $Id$ * Copyright (c) 2012 Ravenbrook Limited. See end of file for license. * * Provides a context to hold the registers and stack pointer * * This file provide wrappers for using setjmp or some similar mechanism * to save the current callee-saves on the stack. * * See http://info.ravenbrook.com/mail/2012/08/03/14-36-35/0/ and the rest of * the thread for the origin of the idea. * * TODO: Make StackScan take a StackContext */ #ifndef sc_h #define sc_h #include "mpm.h" /* StackContext -- holds the registers including a stack pointer * * This contains the callee-save registers and the stack pointer. * * This is used to save the registers after or on entry to the arena so that * they can be scanned. */ /* STACK_CONTEXT_SAVE - save the callee-saves and stack pointer * * This macro saves the callee-saves and stack pointer for the * current function into the passed StackContext. The StackContext * is no longer valid after the function returns. * * This needs to be a macro because the compiler may need to do * setjmp magic. */ /* StackContextStackTop - return the stack top from the stack context. * * We assume the stack is full. In other words the stack top points at * a word that contains a potential Ref. */ /* Mac OS X on 32-bit Intel built with Clang or GCC */ #if defined(MPS_PF_XCI3LL) || defined(MPS_PF_XCI3GC) #include typedef struct StackContextStruct { jmp_buf jumpBuffer; } StackContextStruct; /* See the implementation of _setjmp in * */ #define JB_ESP 36 /* offset into the jmp_buf in bytes as defined in _setjmp.s */ #define STACK_CONTEXT_SAVE(sc) ((void)_setjmp((sc)->jumpBuffer)) #define StackContextSP(sc) ((Addr *)(sc)->jumpBuffer[JB_ESP/sizeof(int)]) /* On MacOS X the stackPointer can end up pointing above the StackContext * which we assume to be stored on the stack because it is no longer * needed once we have _longjmp()ed back. So take the minimum of the * SP and the base of the StackContext structure. */ #define StackContextStackTop(sc) \ (StackContextSP(sc) < (Addr*)(sc) ? StackContextSP(sc) : (Addr*)(sc)) /* Mac OS X on 64-bit Intel build with Clang or GCC */ #elif defined(MPS_PF_XCI6LL) || defined(MPS_PF_XCI6GC) #include /* We could use getcontext() from libunwind but that produces * deprecation warnings. See * */ typedef struct StackContextStruct { jmp_buf jumpBuffer; } StackContextStruct; /* See the implementation of _setjmp in * */ #define STACK_CONTEXT_SAVE(sc) ((void)_setjmp((sc)->jumpBuffer)) #define JB_RSP 16 /* offset into the jmp_buf in bytes as defined in _setjmp.s */ /* jmp_buf is an int[] but the stack pointer is 8 bytes so we need a cast */ /* FIXME: possible aliasing problem */ #define StackContextSP(sc) \ (*(Addr **)((char *)(sc)->jumpBuffer+JB_RSP)) /* On MacOS X the stackPointer can end up pointing above the StackContext * which we assume to be stored on the stack because it is no longer * needed once we have _longjmp()ed back. So take the minimum of the * SP and the base of the StackContext structure. */ #define StackContextStackTop(sc) \ (StackContextSP(sc) < (Addr*)(sc) ? StackContextSP(sc) : (Addr*)(sc)) /* Windows on 32-bit Intel with Microsoft Visual Studio */ #elif defined(MPS_PF_W3I3MV) #include typedef struct StackContextStruct { jmp_buf jumpBuffer; } StackContextStruct; #define STACK_CONTEXT_SAVE(sc) ((void)setjmp((sc)->jumpBuffer)) #define StackContextStackTop(sc) \ ((Addr *)((_JUMP_BUFFER *)(sc)->jumpBuffer)->Esp) /* Windows on 64-bit Intel with Microsoft Visual Studio */ #elif defined(MPS_PF_W3I6MV) #include typedef struct StackContextStruct { jmp_buf jumpBuffer; } StackContextStruct; #define STACK_CONTEXT_SAVE(sc) ((void)setjmp((sc)->jumpBuffer)) #define StackContextStackTop(sc) \ ((Addr *)((_JUMP_BUFFER *)(sc)->jumpBuffer)->Rsp) #else /* TODO: implement this on other platforms in a safer way. * Potentially the callee saves from the calling function could be spilled * underneath the jmp_buf so returning the address of the jmp_buf for the * stack top is not completely safe. */ #include typedef struct StackContextStruct { jmp_buf jumpBuffer; } StackContextStruct; #define STACK_CONTEXT_SAVE(sc) ((void)setjmp((sc)->jumpBuffer)) #define StackContextStackTop(sc) ((Addr *)(sc)->jumpBuffer) #endif /* platform defines */ #endif /* sc_h */ /* C. COPYRIGHT AND LICENSE * * Copyright (C) 2001-2012 Ravenbrook Limited . * 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. */