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-rw-r--r--lib/el3_runtime/aarch32/context_mgmt.c14
-rw-r--r--lib/el3_runtime/aarch64/context_mgmt.c10
2 files changed, 23 insertions, 1 deletions
diff --git a/lib/el3_runtime/aarch32/context_mgmt.c b/lib/el3_runtime/aarch32/context_mgmt.c
index 02ae2a7e..29532e8c 100644
--- a/lib/el3_runtime/aarch32/context_mgmt.c
+++ b/lib/el3_runtime/aarch32/context_mgmt.c
@@ -200,7 +200,10 @@ void cm_prepare_el3_exit(uint32_t security_state)
isb();
} else if (read_id_pfr1() &
(ID_PFR1_VIRTEXT_MASK << ID_PFR1_VIRTEXT_SHIFT)) {
- /* Set the NS bit to access HCR, HCPTR, CNTHCTL, VPIDR, VMPIDR */
+ /*
+ * Set the NS bit to access NS copies of certain banked
+ * registers
+ */
write_scr(read_scr() | SCR_NS_BIT);
isb();
@@ -231,6 +234,15 @@ void cm_prepare_el3_exit(uint32_t security_state)
* translation are disabled.
*/
write64_vttbr(0);
+
+ /*
+ * Avoid unexpected debug traps in case where HDCR
+ * is not completely reset by the hardware - set
+ * HDCR.HPMN to PMCR.N and zero the remaining bits.
+ * The HDCR.HPMN and PMCR.N fields are the same size
+ * (5 bits) and HPMN is at offset zero within HDCR.
+ */
+ write_hdcr((read_pmcr() & PMCR_N_BITS) >> PMCR_N_SHIFT);
isb();
write_scr(read_scr() & ~SCR_NS_BIT);
diff --git a/lib/el3_runtime/aarch64/context_mgmt.c b/lib/el3_runtime/aarch64/context_mgmt.c
index 4b5d0ee5..fadc1dbf 100644
--- a/lib/el3_runtime/aarch64/context_mgmt.c
+++ b/lib/el3_runtime/aarch64/context_mgmt.c
@@ -259,6 +259,16 @@ void cm_prepare_el3_exit(uint32_t security_state)
* translation are disabled.
*/
write_vttbr_el2(0);
+ /*
+ * Avoid unexpected debug traps in case where MDCR_EL2
+ * is not completely reset by the hardware - set
+ * MDCR_EL2.HPMN to PMCR_EL0.N and zero the remaining
+ * bits.
+ * MDCR_EL2.HPMN and PMCR_EL0.N fields are the same size
+ * (5 bits) and HPMN is at offset zero within MDCR_EL2.
+ */
+ write_mdcr_el2((read_pmcr_el0() & PMCR_EL0_N_BITS)
+ >> PMCR_EL0_N_SHIFT);
}
}