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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgcc/] [enable-execute-stack-mprotect.c] - Rev 757
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/* Implement __enable_execute_stack using mprotect(2). Copyright (C) 2011, 2012 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 __FreeBSD__ #include <sys/sysctl.h> static void __attribute__ ((constructor)) check_enabling (void) { int prot = 0; size_t len = sizeof (prot); sysctlbyname ("kern.stackprot", &prot, &len, NULL, 0); if (prot != STACK_PROT_RWX) need_enable_exec_stack = 1; } #elif 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 (); } }
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