forked from ariadne/libucontext
79 lines
1.7 KiB
C
79 lines
1.7 KiB
C
/*
|
|
* Copyright (c) 2018 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 <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")));
|