85 lines
2.8 KiB
C
85 lines
2.8 KiB
C
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/* $NetBSD: makecontext.c,v 1.4 2008/04/28 20:22:57 martin Exp $ */
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/*-
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* Copyright (c) 2001 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Klaus Klein.
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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
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* are met:
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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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* 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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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#if defined(LIBC_SCCS) && !defined(lint)
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__RCSID("$NetBSD: makecontext.c,v 1.4 2008/04/28 20:22:57 martin Exp $");
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#endif
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#include <inttypes.h>
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#include <stddef.h>
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#include <ucontext.h>
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#include "extern.h"
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#if __STDC__
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#include <stdarg.h>
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#else
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#include <varargs.h>
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#endif
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void
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makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
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{
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__greg_t *gr = ucp->uc_mcontext.__gregs;
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int *sp;
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int i;
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va_list ap;
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/* LINTED uintptr_t is safe */
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sp = (int *)
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((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
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/* LINTED uintptr_t is safe */
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sp -= 2 + (argc > 8 ? argc - 8: 0); /* Make room for call frame. */
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sp = (int *)
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((uintptr_t)sp & ~0xf); /* Align on quad-word boundary. */
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/*
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* Start executing at <func> -- when <func> completes, return to
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* <_resumecontext>.
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*/
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gr[_REG_R1] = (__greg_t)sp;
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gr[_REG_LR] = (__greg_t)_resumecontext;
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gr[_REG_PC] = (__greg_t)func;
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/* Wipe out stack frame backchain pointer. */
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*sp = 0;
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/* Construct argument list. */
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va_start(ap, argc);
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/* Up to the first eight arguments are passed in r3-10. */
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for (i = 0; i < argc && i < 8; i++)
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gr[_REG_R3 + i] = va_arg(ap, int);
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/* Pass remaining arguments on the stack above the backchain/lr gap. */
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for (sp += 2; i < argc; i++)
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*sp++ = va_arg(ap, int);
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va_end(ap);
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}
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