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/* Create new context.
Copyright (C) 2008-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library. If not, see
<https://www.gnu.org/licenses/>. */
#include <libintl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <sysdep.h>
#include <ucontext.h>
/* POSIX only supports integer arguments. */
/* Stack must be 64-byte aligned at all times. */
#define STACK_ALIGN 64
/* Size of frame marker in unsigned long words. */
#define FRAME_SIZE_UL 8
/* Size of frame marker in bytes. */
#define FRAME_SIZE_BYTES (8 * sizeof (unsigned long))
/* Size of X arguments in bytes. */
#define ARGS(x) (x * sizeof (unsigned long))
void
__makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
{
unsigned long *sp, *osp;
va_list ap;
int i;
/* Create a 64-byte aligned frame to store args. Use ss_sp if
it is available, otherwise be robust and use the currently
saved stack pointer. */
if (ucp->uc_stack.ss_sp && ucp->uc_stack.ss_size)
osp = (unsigned long *)ucp->uc_stack.ss_sp;
else
osp = (unsigned long *)ucp->uc_mcontext.sc_gr[30];
sp = (unsigned long *)((((unsigned long) osp)
+ FRAME_SIZE_BYTES + ARGS(argc) + STACK_ALIGN)
& ~(STACK_ALIGN - 1));
/* Use new frame. */
ucp->uc_mcontext.sc_gr[30] = ((unsigned long) sp);
/* Finish frame setup. */
if (ucp->uc_link)
{
/* Returning to the next context and next frame. */
sp[-4 / sizeof (unsigned long)] = ucp->uc_link->uc_mcontext.sc_gr[30];
sp[-20 / sizeof (unsigned long)] = ucp->uc_link->uc_mcontext.sc_gr[2];
}
else
{
/* This is the main context. No frame marker, and no return address. */
sp[-4 / sizeof (unsigned long)] = 0x0;
sp[-20 / sizeof (unsigned long)] = 0x0;
}
/* Store address to jump to. */
ucp->uc_mcontext.sc_gr[2] = (unsigned long) func;
/* Process arguments. */
va_start (ap, argc);
for (i = 0; i < argc; ++i)
{
if (i < 4)
{
ucp->uc_mcontext.sc_gr[26-i] = va_arg (ap, int);
continue;
}
if ((i < 8) && (sizeof (unsigned long) == 8))
{
/* 64bit: r19-r22 are arg7-arg4. */
ucp->uc_mcontext.sc_gr[22+4-i] = va_arg (ap, int);
continue;
}
/* All other arguments go on the stack. */
sp[-1 * (FRAME_SIZE_UL + 1 + i)] = va_arg (ap, int);
}
va_end (ap);
}
weak_alias(__makecontext, makecontext)
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