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Diffstat (limited to 'gcc/config/host-linux.c')
| -rw-r--r-- | gcc/config/host-linux.c | 137 |
1 files changed, 0 insertions, 137 deletions
diff --git a/gcc/config/host-linux.c b/gcc/config/host-linux.c deleted file mode 100644 index 7302d381dbe..00000000000 --- a/gcc/config/host-linux.c +++ /dev/null @@ -1,137 +0,0 @@ -/* Linux host-specific hook definitions. - Copyright (C) 2004 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 2, 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. - - You should have received a copy of the GNU General Public License - along with GCC; see the file COPYING. If not, write to the - Free Software Foundation, 59 Temple Place - Suite 330, Boston, - MA 02111-1307, USA. */ - -#include "config.h" -#include "system.h" -#include "coretypes.h" -#include <sys/mman.h> -#include "hosthooks.h" -#include "hosthooks-def.h" - - -/* Linux has a feature called exec-shield-randomize that perturbs the - address of non-fixed mapped segments by a (relatively) small amount. - The feature is intended to make it harder to attack the system with - buffer overflow attacks, since every invocation of a program will - have its libraries and data segments at slightly different addresses. - - This feature causes us problems with PCH because it makes it that - much harder to acquire a stable location at which to map our PCH - data file. - - [ The feature causes other points of non-determinism within the - compiler as well, so we'd *really* like to be able to have the - driver disable exec-shield-randomize for the process group, but - that isn't possible at present. ] - - We're going to try several things: - - * Select an architecture specific address as "likely" and see - if that's free. For our 64-bit hosts, we can easily choose - an address in Never Never Land. - - * If exec-shield-randomize is disabled, then just use the - address chosen by mmap in step one. - - * If exec-shield-randomize is enabled, then temporarily allocate - 32M of memory as a buffer, then allocate PCH memory, then - free the buffer. The theory here is that the perturbation is - no more than 16M, and so by allocating our buffer larger than - that we make it considerably more likely that the address will - be free when we want to load the data back. -*/ - -#undef HOST_HOOKS_GT_PCH_GET_ADDRESS -#define HOST_HOOKS_GT_PCH_GET_ADDRESS linux_gt_pch_get_address - -/* For various ports, try to guess a fixed spot in the vm space - that's probably free. */ -#if defined(__alpha) -# define TRY_EMPTY_VM_SPACE 0x10000000000 -#elif defined(__ia64) -# define TRY_EMPTY_VM_SPACE 0x2000000100000000 -#elif defined(__x86_64) -# define TRY_EMPTY_VM_SPACE 0x1000000000 -#elif defined(__i386) -# define TRY_EMPTY_VM_SPACE 0x60000000 -#else -# define TRY_EMPTY_VM_SPACE 0 -#endif - -/* Determine a location where we might be able to reliably allocate SIZE - bytes. FD is the PCH file, though we should return with the file - unmapped. */ - -static void * -linux_gt_pch_get_address (size_t size, int fd) -{ - size_t buffer_size = 32 * 1024 * 1024; - void *addr, *buffer; - FILE *f; - bool randomize_on; - - addr = mmap ((void *)TRY_EMPTY_VM_SPACE, size, PROT_READ | PROT_WRITE, - MAP_PRIVATE, fd, 0); - - /* If we failed the map, that means there's *no* free space. */ - if (addr == (void *) MAP_FAILED) - return NULL; - /* Unmap the area before returning. */ - munmap (addr, size); - - /* If we got the exact area we requested, then that's great. */ - if (TRY_EMPTY_VM_SPACE && addr == (void *) TRY_EMPTY_VM_SPACE) - return addr; - - /* If we didn't, then we need to look to see if randomization is on. */ - f = fopen ("/proc/sys/kernel/exec-shield-randomize", "r"); - randomize_on = false; - if (f != NULL) - { - char buf[100]; - size_t c; - - c = fread (buf, 1, sizeof buf - 1, f); - if (c > 0) - { - buf[c] = '\0'; - randomize_on = (atoi (buf) > 0); - } - fclose (f); - } - - /* If it isn't, then accept the address that mmap selected as fine. */ - if (!randomize_on) - return addr; - - /* Otherwise, we need to try again with buffer space. */ - buffer = mmap (0, buffer_size, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0); - addr = mmap (0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); - if (buffer != (void *) MAP_FAILED) - munmap (buffer, buffer_size); - if (addr == (void *) MAP_FAILED) - return NULL; - munmap (addr, size); - - return addr; -} - - -const struct host_hooks host_hooks = HOST_HOOKS_INITIALIZER; |