libucontext/arch/m68k/makecontext.c

61 lines
1.5 KiB
C

/*
* Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
*
* 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.
*/
#define _GNU_SOURCE
#include <stddef.h>
#include <stdarg.h>
#include <ucontext.h>
#include <string.h>
#include <stdint.h>
#include <stdio.h>
#include "defs.h"
extern void __start_context(void);
void
libucontext_makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
{
greg_t *sp;
va_list va;
int i;
/* set up and align the stack. */
sp = (greg_t *) ((uintptr_t) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
sp -= (argc + 2);
sp = (greg_t *) (((uintptr_t) sp & ~0x3));
/* set up the ucontext structure */
ucp->uc_mcontext.gregs[REG_SP] = (greg_t) sp;
ucp->uc_mcontext.gregs[REG_A6] = 0;
ucp->uc_mcontext.gregs[REG_D7] = argc;
ucp->uc_mcontext.gregs[REG_PC] = (greg_t) func;
/* return address */
*sp++ = (greg_t) __start_context;
va_start(va, argc);
/* all arguments overflow into stack */
for (i = 0; i < argc; i++)
*sp++ = va_arg (va, greg_t);
va_end(va);
/* link pointer */
*sp++ = (greg_t) ucp->uc_link;
}
extern __typeof(libucontext_makecontext) makecontext __attribute__((weak, __alias__("libucontext_makecontext")));