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de7b5723 AV |
1 | /* ARMv8-M Security Extensions routines. |
2 | Copyright (C) 2015-2016 Free Software Foundation, Inc. | |
3 | Contributed by ARM Ltd. | |
4 | ||
5 | This file is free software; you can redistribute it and/or modify it | |
6 | under the terms of the GNU General Public License as published by the | |
7 | Free Software Foundation; either version 3, or (at your option) any | |
8 | later version. | |
9 | ||
10 | This file is distributed in the hope that it will be useful, but | |
11 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | General Public License for more details. | |
14 | ||
15 | Under Section 7 of GPL version 3, you are granted additional | |
16 | permissions described in the GCC Runtime Library Exception, version | |
17 | 3.1, as published by the Free Software Foundation. | |
18 | ||
19 | You should have received a copy of the GNU General Public License and | |
20 | a copy of the GCC Runtime Library Exception along with this program; | |
21 | see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
22 | <http://www.gnu.org/licenses/>. */ | |
23 | ||
24 | ||
25 | #if __ARM_FEATURE_CMSE & 1 | |
26 | ||
27 | #include <arm_cmse.h> | |
28 | ||
29 | /* ARM intrinsic function to perform a permission check on a given | |
30 | address range. See ACLE changes for ARMv8-M. */ | |
31 | ||
32 | void * | |
33 | cmse_check_address_range (void *p, size_t size, int flags) | |
34 | { | |
35 | cmse_address_info_t permb, perme; | |
36 | char *pb = (char *) p, *pe; | |
37 | ||
38 | /* Check if the range wraps around. */ | |
39 | if (UINTPTR_MAX - (uintptr_t) p < size) | |
40 | return NULL; | |
41 | ||
42 | /* Check if an unknown flag is present. */ | |
43 | int known = CMSE_MPU_UNPRIV | CMSE_MPU_READWRITE | CMSE_MPU_READ; | |
44 | int known_secure_level = CMSE_MPU_UNPRIV; | |
45 | #if __ARM_FEATURE_CMSE & 2 | |
46 | known |= CMSE_AU_NONSECURE | CMSE_MPU_NONSECURE; | |
47 | known_secure_level |= CMSE_MPU_NONSECURE; | |
48 | #endif | |
49 | if (flags & (~known)) | |
50 | return NULL; | |
51 | ||
52 | /* Execute the right variant of the TT instructions. */ | |
53 | pe = pb + size - 1; | |
54 | const int singleCheck = (((uintptr_t) pb ^ (uintptr_t) pe) < 32); | |
55 | switch (flags & known_secure_level) | |
56 | { | |
57 | case 0: | |
58 | permb = cmse_TT (pb); | |
59 | perme = singleCheck ? permb : cmse_TT (pe); | |
60 | break; | |
61 | case CMSE_MPU_UNPRIV: | |
62 | permb = cmse_TTT (pb); | |
63 | perme = singleCheck ? permb : cmse_TTT (pe); | |
64 | break; | |
65 | #if __ARM_FEATURE_CMSE & 2 | |
66 | case CMSE_MPU_NONSECURE: | |
67 | permb = cmse_TTA (pb); | |
68 | perme = singleCheck ? permb : cmse_TTA (pe); | |
69 | break; | |
70 | case CMSE_MPU_UNPRIV | CMSE_MPU_NONSECURE: | |
71 | permb = cmse_TTAT (pb); | |
72 | perme = singleCheck ? permb : cmse_TTAT (pe); | |
73 | break; | |
74 | #endif | |
75 | default: | |
76 | /* Invalid flag, eg. CMSE_MPU_NONSECURE specified but | |
77 | __ARM_FEATURE_CMSE & 2 == 0. */ | |
78 | return NULL; | |
79 | } | |
80 | ||
81 | /* Check that the range does not cross MPU, SAU, or IDAU boundaries. */ | |
82 | if (permb.value != perme.value) | |
83 | return NULL; | |
84 | ||
85 | /* Check the permissions on the range. */ | |
86 | switch (flags & (~known_secure_level)) | |
87 | { | |
88 | #if __ARM_FEATURE_CMSE & 2 | |
89 | case CMSE_MPU_READ | CMSE_MPU_READWRITE | CMSE_AU_NONSECURE: | |
90 | case CMSE_MPU_READWRITE | CMSE_AU_NONSECURE: | |
91 | return permb.flags.nonsecure_readwrite_ok ? p : NULL; | |
92 | case CMSE_MPU_READ | CMSE_AU_NONSECURE: | |
93 | return permb.flags.nonsecure_read_ok ? p : NULL; | |
94 | case CMSE_AU_NONSECURE: | |
95 | return permb.flags.secure ? NULL : p; | |
96 | #endif | |
97 | case CMSE_MPU_READ | CMSE_MPU_READWRITE: | |
98 | case CMSE_MPU_READWRITE: | |
99 | return permb.flags.readwrite_ok ? p : NULL; | |
100 | case CMSE_MPU_READ: | |
101 | return permb.flags.read_ok ? p : NULL; | |
102 | default: | |
103 | return NULL; | |
104 | } | |
105 | } | |
106 | ||
107 | ||
108 | #endif /* __ARM_FEATURE_CMSE & 1. */ |