1 /*
2 * Copyright (C) 2013 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <stddef.h>
30 #include <sys/cdefs.h>
31 #include <sys/auxv.h>
32 #include <private/bionic_auxv.h>
33 #include <private/bionic_globals.h>
34 #include <private/bionic_ifuncs.h>
35 #include <elf.h>
36 #include <errno.h>
37
38 // This function needs to be safe to call before TLS is set up, so it can't
39 // access errno or the stack protector.
40 // Cannot use HWASan, as this is called during setup of the HWASan runtime to
41 // determine the page size.
__bionic_getauxval(unsigned long type,bool * exists)42 __LIBC_HIDDEN__ unsigned long __bionic_getauxval(unsigned long type, bool* exists) __attribute__((no_sanitize("hwaddress"))) {
43 for (ElfW(auxv_t)* v = __libc_shared_globals()->auxv; v->a_type != AT_NULL; ++v) {
44 if (v->a_type == type) {
45 *exists = true;
46 return v->a_un.a_val;
47 }
48 }
49 *exists = false;
50 return 0;
51 }
52
53 // Cannot use HWASan, as this is called during setup of the HWASan runtime to
54 // determine the page size.
getauxval(unsigned long type)55 extern "C" unsigned long getauxval(unsigned long type) __attribute__((no_sanitize("hwaddress"))) {
56 bool exists;
57 unsigned long result = __bionic_getauxval(type, &exists);
58 if (!exists) errno = ENOENT;
59 return result;
60 }
61