mirror of
https://github.com/autc04/Retro68.git
synced 2024-11-05 04:06:45 +00:00
80 lines
2.4 KiB
C
80 lines
2.4 KiB
C
/* Implement __enable_execute_stack using mprotect(2).
|
|
Copyright (C) 2011-2015 Free Software Foundation, Inc.
|
|
|
|
This file is part of GCC.
|
|
|
|
GCC is free software; you can redistribute it and/or modify it under
|
|
the terms of the GNU General Public License as published by the Free
|
|
Software Foundation; either version 3, or (at your option) any later
|
|
version.
|
|
|
|
GCC 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 General Public License
|
|
for more details.
|
|
|
|
Under Section 7 of GPL version 3, you are granted additional
|
|
permissions described in the GCC Runtime Library Exception, version
|
|
3.1, as published by the Free Software Foundation.
|
|
|
|
You should have received a copy of the GNU General Public License and
|
|
a copy of the GCC Runtime Library Exception along with this program;
|
|
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
#include <sys/mman.h>
|
|
#include <unistd.h>
|
|
#include <stdlib.h>
|
|
|
|
#define STACK_PROT_RWX (PROT_READ | PROT_WRITE | PROT_EXEC)
|
|
|
|
static int need_enable_exec_stack;
|
|
|
|
static void check_enabling (void) __attribute__ ((unused));
|
|
extern void __enable_execute_stack (void *);
|
|
|
|
#if defined __sun__ && defined __svr4__
|
|
static void __attribute__ ((constructor))
|
|
check_enabling (void)
|
|
{
|
|
int prot = (int) sysconf (_SC_STACK_PROT);
|
|
|
|
if (prot != STACK_PROT_RWX)
|
|
need_enable_exec_stack = 1;
|
|
}
|
|
#else
|
|
/* There is no way to query the execute permission of the stack, so
|
|
we always issue the mprotect() call. */
|
|
|
|
static int need_enable_exec_stack = 1;
|
|
#endif
|
|
|
|
/* Attempt to turn on access permissions for the stack. Unfortunately it
|
|
is not possible to make this namespace-clean.*/
|
|
|
|
void
|
|
__enable_execute_stack (void *addr)
|
|
{
|
|
if (!need_enable_exec_stack)
|
|
return;
|
|
else
|
|
{
|
|
static long size, mask;
|
|
|
|
if (size == 0) {
|
|
size = getpagesize ();
|
|
mask = ~(size - 1);
|
|
}
|
|
|
|
char *page = (char *) (((long) addr) & mask);
|
|
char *end = (char *)
|
|
((((long) (addr + __LIBGCC_TRAMPOLINE_SIZE__)) & mask) + size);
|
|
|
|
if (mprotect (page, end - page, STACK_PROT_RWX) < 0)
|
|
/* Note that no errors should be emitted by this code; it is
|
|
considered dangerous for library calls to send messages to
|
|
stdout/stderr. */
|
|
abort ();
|
|
}
|
|
}
|