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100 lines
3.0 KiB
C
100 lines
3.0 KiB
C
/* Create new context.
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Copyright (C) 2008-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Helge Deller <deller@gmx.de>, 2008.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<http://www.gnu.org/licenses/>. */
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#include <libintl.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sysdep.h>
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#include <ucontext.h>
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/* POSIX only supports integer arguments. */
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/* Stack must be 64-byte aligned at all times. */
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#define STACK_ALIGN 64
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/* Size of frame marker in unsigned long words. */
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#define FRAME_SIZE_UL 8
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/* Size of frame marker in bytes. */
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#define FRAME_SIZE_BYTES (8 * sizeof(unsigned long))
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/* Size of X arguments in bytes. */
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#define ARGS(x) (x * sizeof(unsigned long))
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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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unsigned long *sp, *osp;
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va_list ap;
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int i;
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/* Create a 64-byte aligned frame to store args. Use ss_sp if
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it is available, otherwise be robust and use the currently
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saved stack pointer. */
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if (ucp->uc_stack.ss_sp && ucp->uc_stack.ss_size)
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osp = (unsigned long *)ucp->uc_stack.ss_sp;
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else
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osp = (unsigned long *)ucp->uc_mcontext.sc_gr[30];
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sp = (unsigned long *)((((unsigned long) osp)
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+ FRAME_SIZE_BYTES + ARGS(argc) + STACK_ALIGN)
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& ~(STACK_ALIGN - 1));
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/* Use new frame. */
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ucp->uc_mcontext.sc_gr[30] = ((unsigned long) sp);
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/* Finish frame setup. */
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if (ucp->uc_link)
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{
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/* Returning to the next context and next frame. */
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sp[-4/sizeof(unsigned long)] = ucp->uc_link->uc_mcontext.sc_gr[30];
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sp[-20/sizeof(unsigned long)] = ucp->uc_link->uc_mcontext.sc_gr[2];
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}
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else
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{
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/* This is the main context. No frame marker, and no return address. */
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sp[-4/sizeof(unsigned long)] = 0x0;
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sp[-20/sizeof(unsigned long)] = 0x0;
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}
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/* Store address to jump to. */
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ucp->uc_mcontext.sc_gr[2] = (unsigned long) func;
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/* Process arguments. */
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va_start (ap, argc);
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for (i = 0; i < argc; ++i)
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{
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if (i < 4)
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{
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ucp->uc_mcontext.sc_gr[26-i] = va_arg (ap, int);
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continue;
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}
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if ((i < 8) && (sizeof(unsigned long) == 8))
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{
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/* 64bit: r19-r22 are arg7-arg4. */
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ucp->uc_mcontext.sc_gr[22+4-i] = va_arg (ap, int);
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continue;
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}
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/* All other arguments go on the stack. */
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sp[-1 * (FRAME_SIZE_UL + 1 + i)] = va_arg (ap, int);
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}
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va_end (ap);
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}
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weak_alias(__makecontext, makecontext)
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