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Current File : //sys/ia64/include/ucontext.h |
/*- * Copyright (c) 1999, 2003 Marcel Moolenaar * All rights reserved. * * 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 * in this position and unchanged. * 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. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR 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. * * $FreeBSD: release/9.1.0/sys/ia64/include/ucontext.h 177091 2008-03-12 10:12:01Z jeff $ */ #ifndef _MACHINE_UCONTEXT_H_ #define _MACHINE_UCONTEXT_H_ #include <machine/_regset.h> /* * The mc_flags field provides the necessary clues when dealing with the gory * details of ia64 specific contexts. A comprehensive explanation is added for * everybody's sanity, including the author's. * * The first and foremost variation in the context is synchronous contexts * (= synctx) versus asynchronous contexts (= asynctx). A synctx is created * synchronously WRT program execution and has the advantage that none of the * scratch registers have to be saved. They are assumed to be clobbered by the * call to the function that creates the context. An asynctx needs to have the * scratch registers preserved because it can describe any point in a thread's * (or process') execution. * The second variation is for synchronous contexts. When the kernel creates * a synchronous context if needs to preserve the scratch registers, because * the syscall argument and return values are stored there in the trapframe * and they need to be preserved in order to restart a syscall or return the * proper return values. Also, the IIP and CFM fields need to be preserved * as they point to the syscall stub, which the kernel saves as a favor to * userland (it keeps the stubs small and simple). * * Below a description of the flags and their meaning: * * _MC_FLAGS_ASYNC_CONTEXT * If set, indicates that mc_scratch and mc_scratch_fp are both * valid. IFF not set, _MC_FLAGS_SYSCALL_CONTEXT indicates if the * synchronous context is one corresponding to a syscall or not. * Only the kernel is expected to create such a context and it's * probably wise to let the kernel restore it. * _MC_FLAGS_HIGHFP_VALID * If set, indicates that the high FP registers (f32-f127) are * valid. This flag is very likely not going to be set for any * sensible synctx, but is not explicitly disallowed. Any synctx * that has this flag may or may not have the high FP registers * restored. In short: don't do it. * _MC_FLAGS_SYSCALL_CONTEXT * If set (hence _MC_FLAGS_ASYNC_CONTEXT is not set) indicates * that the scratch registers contain syscall arguments and * return values and that additionally IIP and CFM are valid. * Only the kernel is expected to create such a context. It's * probably wise to let the kernel restore it. */ typedef struct __mcontext { unsigned long mc_flags; #define _MC_FLAGS_ASYNC_CONTEXT 0x0001 #define _MC_FLAGS_HIGHFP_VALID 0x0002 #define _MC_FLAGS_SYSCALL_CONTEXT 0x0008 unsigned long _reserved_; struct _special mc_special; struct _callee_saved mc_preserved; struct _callee_saved_fp mc_preserved_fp; struct _caller_saved mc_scratch; struct _caller_saved_fp mc_scratch_fp; struct _high_fp mc_high_fp; } mcontext_t; #endif /* !_MACHINE_UCONTEXT_H_ */