Mercurial > hg > CbC > CbC_gcc
annotate gcc/config/host-linux.c @ 88:f214c1d5b862
merge 89
| author | Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp> |
|---|---|
| date | Tue, 20 Dec 2011 18:53:46 +0900 |
| parents | f6334be47118 |
| children | 04ced10e8804 |
| rev | line source |
|---|---|
| 0 | 1 /* Linux host-specific hook definitions. |
|
67
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
2 Copyright (C) 2004, 2005, 2007, 2008, 2010 Free Software Foundation, Inc. |
| 0 | 3 |
| 4 This file is part of GCC. | |
| 5 | |
| 6 GCC is free software; you can redistribute it and/or modify it | |
| 7 under the terms of the GNU General Public License as published | |
| 8 by the Free Software Foundation; either version 3, or (at your | |
| 9 option) any later version. | |
| 10 | |
| 11 GCC is distributed in the hope that it will be useful, but WITHOUT | |
| 12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY | |
| 13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public | |
| 14 License for more details. | |
| 15 | |
| 16 You should have received a copy of the GNU General Public License | |
| 17 along with GCC; see the file COPYING3. If not see | |
| 18 <http://www.gnu.org/licenses/>. */ | |
| 19 | |
| 20 #include "config.h" | |
| 21 #include "system.h" | |
| 22 #include "coretypes.h" | |
| 23 #include "hosthooks.h" | |
| 24 #include "hosthooks-def.h" | |
| 25 | |
| 26 | |
| 27 /* Linux has a feature called exec-shield-randomize that perturbs the | |
| 28 address of non-fixed mapped segments by a (relatively) small amount. | |
| 29 The feature is intended to make it harder to attack the system with | |
| 30 buffer overflow attacks, since every invocation of a program will | |
| 31 have its libraries and data segments at slightly different addresses. | |
| 32 | |
| 33 This feature causes us problems with PCH because it makes it that | |
| 34 much harder to acquire a stable location at which to map our PCH | |
| 35 data file. | |
| 36 | |
| 37 [ The feature causes other points of non-determinism within the | |
| 38 compiler as well, so we'd *really* like to be able to have the | |
| 39 driver disable exec-shield-randomize for the process group, but | |
| 40 that isn't possible at present. ] | |
| 41 | |
| 42 We're going to try several things: | |
| 43 | |
| 44 * Select an architecture specific address as "likely" and see | |
| 45 if that's free. For our 64-bit hosts, we can easily choose | |
| 46 an address in Never Never Land. | |
| 47 | |
| 48 * If exec-shield-randomize is disabled, then just use the | |
| 49 address chosen by mmap in step one. | |
| 50 | |
| 51 * If exec-shield-randomize is enabled, then temporarily allocate | |
| 52 32M of memory as a buffer, then allocate PCH memory, then | |
| 53 free the buffer. The theory here is that the perturbation is | |
| 54 no more than 16M, and so by allocating our buffer larger than | |
| 55 that we make it considerably more likely that the address will | |
| 56 be free when we want to load the data back. | |
| 57 */ | |
| 58 | |
| 59 #undef HOST_HOOKS_GT_PCH_GET_ADDRESS | |
| 60 #define HOST_HOOKS_GT_PCH_GET_ADDRESS linux_gt_pch_get_address | |
| 61 | |
| 62 #undef HOST_HOOKS_GT_PCH_USE_ADDRESS | |
| 63 #define HOST_HOOKS_GT_PCH_USE_ADDRESS linux_gt_pch_use_address | |
| 64 | |
| 65 /* For various ports, try to guess a fixed spot in the vm space | |
| 66 that's probably free. */ | |
| 67 #if defined(__alpha) | |
| 68 # define TRY_EMPTY_VM_SPACE 0x10000000000 | |
| 69 #elif defined(__ia64) | |
| 70 # define TRY_EMPTY_VM_SPACE 0x2000000100000000 | |
| 71 #elif defined(__x86_64) | |
| 72 # define TRY_EMPTY_VM_SPACE 0x1000000000 | |
| 73 #elif defined(__i386) | |
| 74 # define TRY_EMPTY_VM_SPACE 0x60000000 | |
| 75 #elif defined(__powerpc__) | |
| 76 # define TRY_EMPTY_VM_SPACE 0x60000000 | |
| 77 #elif defined(__s390x__) | |
| 78 # define TRY_EMPTY_VM_SPACE 0x8000000000 | |
| 79 #elif defined(__s390__) | |
| 80 # define TRY_EMPTY_VM_SPACE 0x60000000 | |
| 81 #elif defined(__sparc__) && defined(__LP64__) | |
| 82 # define TRY_EMPTY_VM_SPACE 0x8000000000 | |
| 83 #elif defined(__sparc__) | |
| 84 # define TRY_EMPTY_VM_SPACE 0x60000000 | |
| 85 #elif defined(__mc68000__) | |
| 86 # define TRY_EMPTY_VM_SPACE 0x40000000 | |
| 87 #else | |
| 88 # define TRY_EMPTY_VM_SPACE 0 | |
| 89 #endif | |
| 90 | |
| 91 /* Determine a location where we might be able to reliably allocate SIZE | |
| 92 bytes. FD is the PCH file, though we should return with the file | |
| 93 unmapped. */ | |
| 94 | |
| 95 static void * | |
| 96 linux_gt_pch_get_address (size_t size, int fd) | |
| 97 { | |
| 98 size_t buffer_size = 32 * 1024 * 1024; | |
| 99 void *addr, *buffer; | |
| 100 FILE *f; | |
| 101 bool randomize_on; | |
| 102 | |
| 103 addr = mmap ((void *)TRY_EMPTY_VM_SPACE, size, PROT_READ | PROT_WRITE, | |
| 104 MAP_PRIVATE, fd, 0); | |
| 105 | |
| 106 /* If we failed the map, that means there's *no* free space. */ | |
| 107 if (addr == (void *) MAP_FAILED) | |
| 108 return NULL; | |
| 109 /* Unmap the area before returning. */ | |
| 110 munmap (addr, size); | |
| 111 | |
| 112 /* If we got the exact area we requested, then that's great. */ | |
| 113 if (TRY_EMPTY_VM_SPACE && addr == (void *) TRY_EMPTY_VM_SPACE) | |
| 114 return addr; | |
| 115 | |
| 116 /* If we didn't, then we need to look to see if virtual address | |
| 117 randomization is on. That is recorded in | |
| 118 kernel.randomize_va_space. An older implementation used | |
| 119 kernel.exec-shield-randomize. */ | |
| 120 f = fopen ("/proc/sys/kernel/randomize_va_space", "r"); | |
| 121 if (f == NULL) | |
| 122 f = fopen ("/proc/sys/kernel/exec-shield-randomize", "r"); | |
| 123 randomize_on = false; | |
| 124 if (f != NULL) | |
| 125 { | |
| 126 char buf[100]; | |
| 127 size_t c; | |
| 128 | |
| 129 c = fread (buf, 1, sizeof buf - 1, f); | |
| 130 if (c > 0) | |
| 131 { | |
| 132 buf[c] = '\0'; | |
| 133 randomize_on = (atoi (buf) > 0); | |
| 134 } | |
| 135 fclose (f); | |
| 136 } | |
| 137 | |
| 138 /* If it isn't, then accept the address that mmap selected as fine. */ | |
| 139 if (!randomize_on) | |
| 140 return addr; | |
| 141 | |
| 142 /* Otherwise, we need to try again with buffer space. */ | |
| 143 buffer = mmap (0, buffer_size, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0); | |
| 144 addr = mmap (0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); | |
| 145 if (buffer != (void *) MAP_FAILED) | |
| 146 munmap (buffer, buffer_size); | |
| 147 if (addr == (void *) MAP_FAILED) | |
| 148 return NULL; | |
| 149 munmap (addr, size); | |
| 150 | |
| 151 return addr; | |
| 152 } | |
| 153 | |
| 154 /* Map SIZE bytes of FD+OFFSET at BASE. Return 1 if we succeeded at | |
| 155 mapping the data at BASE, -1 if we couldn't. | |
| 156 | |
| 157 It's not possibly to reliably mmap a file using MAP_PRIVATE to | |
| 158 a specific START address on either hpux or linux. First we see | |
| 159 if mmap with MAP_PRIVATE works. If it does, we are off to the | |
| 160 races. If it doesn't, we try an anonymous private mmap since the | |
| 161 kernel is more likely to honor the BASE address in anonymous maps. | |
| 162 We then copy the data to the anonymous private map. This assumes | |
| 163 of course that we don't need to change the data in the PCH file | |
| 164 after it is created. | |
| 165 | |
| 166 This approach obviously causes a performance penalty but there is | |
| 167 little else we can do given the current PCH implementation. */ | |
| 168 | |
| 169 static int | |
| 170 linux_gt_pch_use_address (void *base, size_t size, int fd, size_t offset) | |
| 171 { | |
| 172 void *addr; | |
| 173 | |
| 174 /* We're called with size == 0 if we're not planning to load a PCH | |
| 175 file at all. This allows the hook to free any static space that | |
| 176 we might have allocated at link time. */ | |
| 177 if (size == 0) | |
| 178 return -1; | |
| 179 | |
| 180 /* Try to map the file with MAP_PRIVATE. */ | |
| 181 addr = mmap (base, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, offset); | |
| 182 | |
| 183 if (addr == base) | |
| 184 return 1; | |
| 185 | |
| 186 if (addr != (void *) MAP_FAILED) | |
| 187 munmap (addr, size); | |
| 188 | |
| 189 /* Try to make an anonymous private mmap at the desired location. */ | |
| 190 addr = mmap (base, size, PROT_READ | PROT_WRITE, | |
| 191 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); | |
| 192 | |
| 193 if (addr != base) | |
| 194 { | |
| 195 if (addr != (void *) MAP_FAILED) | |
| 196 munmap (addr, size); | |
| 197 return -1; | |
| 198 } | |
| 199 | |
| 200 if (lseek (fd, offset, SEEK_SET) == (off_t)-1) | |
| 201 return -1; | |
| 202 | |
| 203 while (size) | |
| 204 { | |
| 205 ssize_t nbytes; | |
| 206 | |
| 207 nbytes = read (fd, base, MIN (size, SSIZE_MAX)); | |
| 208 if (nbytes <= 0) | |
| 209 return -1; | |
| 210 base = (char *) base + nbytes; | |
| 211 size -= nbytes; | |
| 212 } | |
| 213 | |
| 214 return 1; | |
| 215 } | |
| 216 | |
| 217 | |
| 218 const struct host_hooks host_hooks = HOST_HOOKS_INITIALIZER; |