1 /* libc-internal interface for tagged (colored) memory support.
2 Copyright (C) 2020-2021 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
18
19 #ifndef _AARCH64_LIBC_MTAG_H
20 #define _AARCH64_LIBC_MTAG_H 1
21
22 #ifndef USE_MTAG
23 /* Generic bindings for systems that do not support memory tagging. */
24 #include_next "libc-mtag.h"
25 #else
26
27 /* Used to ensure additional alignment when objects need to have distinct
28 tags. */
29 #define __MTAG_GRANULE_SIZE 16
30
31 /* Non-zero if memory obtained via morecore (sbrk) is not tagged. */
32 #define __MTAG_SBRK_UNTAGGED 1
33
34 /* Extra flags to pass to mmap to get tagged pages. */
35 #define __MTAG_MMAP_FLAGS PROT_MTE
36
37 /* Set the tags for a region of memory, which must have size and alignment
38 that are multiples of __MTAG_GRANULE_SIZE. Size cannot be zero. */
39 void *__libc_mtag_tag_region (void *, size_t);
40
41 /* Optimized equivalent to __libc_mtag_tag_region followed by memset to 0. */
42 void *__libc_mtag_tag_zero_region (void *, size_t);
43
44 /* Convert address P to a pointer that is tagged correctly for that
45 location. */
46 static __always_inline void *
__libc_mtag_address_get_tag(void * p)47 __libc_mtag_address_get_tag (void *p)
48 {
49 register void *x0 asm ("x0") = p;
50 asm (".inst 0xd9600000 /* ldg x0, [x0] */" : "+r" (x0));
51 return x0;
52 }
53
54 /* Assign a new (random) tag to a pointer P (does not adjust the tag on
55 the memory addressed). */
56 static __always_inline void *
__libc_mtag_new_tag(void * p)57 __libc_mtag_new_tag (void *p)
58 {
59 register void *x0 asm ("x0") = p;
60 register unsigned long x1 asm ("x1");
61 /* Guarantee that the new tag is not the same as now. */
62 asm (".inst 0x9adf1401 /* gmi x1, x0, xzr */\n"
63 ".inst 0x9ac11000 /* irg x0, x0, x1 */" : "+r" (x0), "=r" (x1));
64 return x0;
65 }
66
67 #endif /* USE_MTAG */
68
69 #endif /* _AARCH64_LIBC_MTAG_H */
70