1 /*
2  * ARM MemTag convenience functions.
3  *
4  * This code is licensed under the GNU GPL v2 or later.
5  *
6  * SPDX-License-Identifier: LGPL-2.1-or-later
7  */
8 
9 #include "qemu/osdep.h"
10 #include "qemu.h"
11 #include "mte_user_helper.h"
12 
13 void arm_set_mte_tcf0(CPUArchState *env, abi_long value)
14 {
15     /*
16      * Write PR_MTE_TCF to SCTLR_EL1[TCF0].
17      *
18      * The kernel has a per-cpu configuration for the sysadmin,
19      * /sys/devices/system/cpu/cpu<N>/mte_tcf_preferred,
20      * which qemu does not implement.
21      *
22      * Because there is no performance difference between the modes, and
23      * because SYNC is most useful for debugging MTE errors, choose SYNC
24      * as the preferred mode.  With this preference, and the way the API
25      * uses only two bits, there is no way for the program to select
26      * ASYMM mode.
27      */
28     unsigned tcf = 0;
29     if (value & PR_MTE_TCF_SYNC) {
30         tcf = 1;
31     } else if (value & PR_MTE_TCF_ASYNC) {
32         tcf = 2;
33     }
34     env->cp15.sctlr_el[1] = deposit64(env->cp15.sctlr_el[1], 38, 2, tcf);
35 }
36