libucontext/arch/aarch64/makecontext.c

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/*
* Copyright (c) 2018 Ariadne Conill <ariadne@dereferenced.org>
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*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* This software is provided 'as is' and without any warranty, express or
* implied. In no event shall the authors be liable for any damages arising
* from the use of this software.
*/
#ifndef _GNU_SOURCE
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#define _GNU_SOURCE
#endif
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#include <stddef.h>
#include <stdarg.h>
#include <string.h>
#include <stdint.h>
#include <stdio.h>
#include "defs.h"
#include <libucontext/libucontext.h>
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extern void libucontext_trampoline(void);
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void
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libucontext_makecontext(libucontext_ucontext_t *ucp, void (*func)(void), int argc, ...)
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{
unsigned long *sp;
unsigned long *regp;
va_list va;
int i;
sp = (unsigned long *) ((uintptr_t) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
sp -= argc < 8 ? 0 : argc - 8;
sp = (unsigned long *) (((uintptr_t) sp & -16L));
ucp->uc_mcontext.sp = (uintptr_t) sp;
ucp->uc_mcontext.pc = (uintptr_t) func;
ucp->uc_mcontext.regs[19] = (uintptr_t) ucp->uc_link;
ucp->uc_mcontext.regs[30] = (uintptr_t) &libucontext_trampoline;
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va_start(va, argc);
regp = &(ucp->uc_mcontext.regs[0]);
for (i = 0; (i < argc && i < 8); i++)
*regp++ = va_arg (va, unsigned long);
for (; i < argc; i++)
*sp++ = va_arg (va, unsigned long);
va_end(va);
}
#ifdef EXPORT_UNPREFIXED
extern __typeof(libucontext_makecontext) makecontext __attribute__((weak, __alias__("libucontext_makecontext")));
#endif