libucontext/arch/s390x/makecontext.c

79 lines
1.7 KiB
C

/*
* Copyright (c) 2018 William Pitcock <nenolod@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 <signal.h>
#include <string.h>
#include <stdint.h>
#include "defs.h"
extern void __start_context(void);
extern int __setcontext(const ucontext_t *ucp);
void
__makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
{
greg_t *sp, *argp;
va_list va;
int i;
unsigned int stack_args;
stack_args = argc > 5 ? argc - 5 : 0;
sp = (greg_t *) ((uintptr_t) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
sp -= stack_args; // maybe +1
sp = (greg_t *) (((uintptr_t) sp & -16L));
ucp->uc_mcontext.gregs[7] = (uintptr_t) func;
ucp->uc_mcontext.gregs[8] = (uintptr_t) ucp->uc_link;
ucp->uc_mcontext.gregs[9] = (uintptr_t) &__setcontext;
ucp->uc_mcontext.gregs[14] = (uintptr_t) &__start_context;
argp = sp;
va_start(va, argc);
for (i = 0; i < argc; i++)
switch (i)
{
case 0:
case 1:
case 2:
case 3:
case 4:
case 5:
ucp->uc_mcontext.gregs[i + 2] = va_arg (va, greg_t);
break;
default:
*argp++ = va_arg (va, greg_t);
break;
}
va_end(va);
/* make room for backchain / register save area */
sp -= 20;
*sp = 0;
/* set up %r15 as sp */
ucp->uc_mcontext.gregs[15] = (uintptr_t) sp;
}
extern __typeof(__makecontext) makecontext __attribute__((weak, __alias__("__makecontext")));