1 /*
2 * Copyright (c) 2022, Google, Inc. All rights reserved
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files
6 * (the "Software"), to deal in the Software without restriction,
7 * including without limitation the rights to use, copy, modify, merge,
8 * publish, distribute, sublicense, and/or sell copies of the Software,
9 * and to permit persons to whom the Software is furnished to do so,
10 * subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
18 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
19 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
20 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
21 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
22 */
23
24 #include <arch/ops.h>
25
26 /* FEAT_BTI is mandatory at ARM-A v8.5.
27 * Assume present at v9 (and above), otherwise probe ID registers.
28 */
29 #if __ARM_ARCH >= 9
arch_bti_supported(void)30 bool arch_bti_supported(void) {
31 return true;
32 }
33 #else
34
35 #include <arch/arm64/sregs.h>
36 #include <arch/arm64.h>
37
arm64_bti_support_level(void)38 static uint8_t arm64_bti_support_level(void) {
39 uint64_t v = ARM64_READ_SYSREG(id_aa64pfr1_el1);
40 return ((v >> ID_AA64PFR1_EL1_BTI_SHIFT) & ID_AA64PFR1_EL1_BIT_MASK);
41 }
42
arch_bti_supported(void)43 bool arch_bti_supported(void) {
44 return arm64_bti_support_level() != ID_AA64PFR1_EL1_BTI_NOT_SUPPORTED;
45 }
46 #endif
47