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author | Richard Henderson <rth@redhat.com> | 2004-03-10 19:19:04 -0800 |
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committer | Richard Henderson <rth@gcc.gnu.org> | 2004-03-10 19:19:04 -0800 |
commit | 4d0c31e68cc2a1c3d39c7d51d2af9cd3d5c1784f (patch) | |
tree | 1bfb02abe9d554906754df59966f7f6a0f7158fc /gcc/config/host-linux.c | |
parent | 20475e78e413a8a3327022a0b88da88b55819842 (diff) | |
download | gcc-4d0c31e68cc2a1c3d39c7d51d2af9cd3d5c1784f.tar.gz |
c-pch.c (c_common_no_more_pch): Update for gt_pch_use_address extra arguments.
* c-pch.c (c_common_no_more_pch): Update for gt_pch_use_address
extra arguments.
* config.host (*-*-solaris2*, *-*-linux*): Add out_host_hook_obj
and host_xmake_file fragments.
* ggc-common.c (gt_pch_save): Update for gt_pch_get_address change.
(gt_pch_restore): Similarly for gt_pch_use_address.
(default_gt_pch_get_address): New.
(mmap_gt_pch_get_address): Split out of gt_pch_save.
(default_gt_pch_use_address): Split out of gt_pch_restore.
(mmap_gt_pch_use_address): Likewise.
* hooks.c (hook_voidp_size_t_null): Remove.
(hook_bool_voidp_size_t_false): Remove.
* hooks.h: Likewise.
* hosthooks-def.h (HOST_HOOKS_GT_PCH_GET_ADDRESS): Use one of the
default_ or mmap_ definitions.
(HOST_HOOKS_GT_PCH_USE_ADDRESS): Likewise.
* hosthooks.h (struct host_hooks): Update gt_pch_get_address
and gt_pch_use_address.
* config/host-linux.c, config/host-solaris.c: New files.
* config/x-linux, config/x-solaris: New files.
* config/rs6000/host-darwin.c darwin_rs6000_gt_pch_get_address):
Update for changed definition.
(darwin_rs6000_gt_pch_use_address): Likewise.
* doc/hostconfig.texi: Update docs.
From-SVN: r79295
Diffstat (limited to 'gcc/config/host-linux.c')
-rw-r--r-- | gcc/config/host-linux.c | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/gcc/config/host-linux.c b/gcc/config/host-linux.c new file mode 100644 index 00000000000..7302d381dbe --- /dev/null +++ b/gcc/config/host-linux.c @@ -0,0 +1,137 @@ +/* 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; |