98 lines
3 KiB
C
98 lines
3 KiB
C
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/* $NetBSD: makecontext.c,v 1.4 2009/07/30 20:57:17 dsl Exp $ */
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/*-
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* Copyright (c) 1999 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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* Modified from the i386 version for x86_64 by fvdl@wasabisystems.com.
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*
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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 2009/07/30 20:57:17 dsl 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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#include <stdarg.h>
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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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uintptr_t *sp;
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va_list ap;
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int stackargs, i;
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stackargs = argc - 6;
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/* LINTED __greg_t is safe */
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gr[_REG_RIP] = (__greg_t)func;
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/* LINTED uintptr_t is safe */
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sp = (uintptr_t *)
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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 = (uintptr_t *)(((uintptr_t)sp & ~15));
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sp--;
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if (stackargs > 0)
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sp -= stackargs;
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/* LINTED __greg_t is safe */
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gr[_REG_RSP] = (__greg_t)sp;
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gr[_REG_RBP] = (__greg_t)0; /* Wipe out frame pointer. */
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/* Put return address on top of stack. */
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/* LINTED uintptr_t is safe */
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*sp++ = (uintptr_t)_resumecontext;
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/*
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* Construct argument list.
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* The registers used to pass the first 6 arguments
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* (rdi, rsi, rdx, rcx, r8, r9) are the first 6 in gregs,
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* in that order, so those arguments can just be copied to
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* the gregs array.
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*/
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va_start(ap, argc);
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for (i = 0; i < 6 && argc > 0; i++) {
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argc--;
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/* LINTED __greg_t is safe */
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gr[i] = va_arg(ap, __greg_t);
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}
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while (stackargs-- > 0) {
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/* LINTED uintptr_t is safe */
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*sp++ = va_arg(ap, uintptr_t);
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}
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va_end(ap);
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}
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