Disable processor Cycle Counting in Secure state
In a system with ARMv8.5-PMU implemented:
- If EL3 is using AArch32, setting MDCR_EL3.SCCD to 1 disables counting
in Secure state in PMCCNTR.
- If EL3 is using AArch64, setting SDCR.SCCD to 1 disables counting in
Secure state in PMCCNTR_EL0.
So far this effect has been achieved by setting PMCR_EL0.DP (in AArch64)
or PMCR.DP (in AArch32) to 1 instead, but this isn't considered secure
as any EL can change that value.
Change-Id: I82cbb3e48f2e5a55c44d9c4445683c5881ef1f6f
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/include/arch/aarch64/el3_common_macros.S b/include/arch/aarch64/el3_common_macros.S
index 410aeab..5f5e0c6 100644
--- a/include/arch/aarch64/el3_common_macros.S
+++ b/include/arch/aarch64/el3_common_macros.S
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2015-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2019, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@@ -101,10 +101,17 @@
*
* MDCR_EL3.TPM: Set to zero so that EL0, EL1, and EL2 System register
* accesses to all Performance Monitors registers do not trap to EL3.
+ *
+ * MDCR_EL3.SCCD: Set to one so that cycle counting by PMCCNTR_EL0 is
+ * prohibited in Secure state. This bit is RES0 in versions of the
+ * architecture earlier than ARMv8.5, setting it to 1 doesn't have any
+ * effect on them.
* ---------------------------------------------------------------------
*/
- mov_imm x0, ((MDCR_EL3_RESET_VAL | MDCR_SDD_BIT | MDCR_SPD32(MDCR_SPD32_DISABLE)) \
- & ~(MDCR_TDOSA_BIT | MDCR_TDA_BIT | MDCR_TPM_BIT))
+ mov_imm x0, ((MDCR_EL3_RESET_VAL | MDCR_SDD_BIT | \
+ MDCR_SPD32(MDCR_SPD32_DISABLE) | MDCR_SCCD_BIT) \
+ & ~(MDCR_TDOSA_BIT | MDCR_TDA_BIT | MDCR_TPM_BIT))
+
msr mdcr_el3, x0
/* ---------------------------------------------------------------------