feat(trf): enable trace filter control register access from lower NS EL
Introduced a build flag 'ENABLE_TRF_FOR_NS' to enable trace filter
control registers access in NS-EL2, or NS-EL1 (when NS-EL2 is
implemented but unused).
Change-Id: If3f53b8173a5573424b9a405a4bd8c206ffdeb8c
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
diff --git a/lib/extensions/trf/aarch64/trf.c b/lib/extensions/trf/aarch64/trf.c
new file mode 100644
index 0000000..1da5dce
--- /dev/null
+++ b/lib/extensions/trf/aarch64/trf.c
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2021, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdbool.h>
+
+#include <arch.h>
+#include <arch_helpers.h>
+#include <lib/extensions/trf.h>
+
+static bool trf_supported(void)
+{
+ uint64_t features;
+
+ features = read_id_aa64dfr0_el1() >> ID_AA64DFR0_TRACEFILT_SHIFT;
+ return ((features & ID_AA64DFR0_TRACEFILT_MASK) ==
+ ID_AA64DFR0_TRACEFILT_SUPPORTED);
+}
+
+void trf_enable(void)
+{
+ uint64_t val;
+
+ if (trf_supported()) {
+ /*
+ * MDCR_EL3.TTRF = b0
+ * Allow access of trace filter control registers from NS-EL2
+ * and NS-EL1 when NS-EL2 is implemented but not used
+ */
+ val = read_mdcr_el3();
+ val &= ~MDCR_TTRF_BIT;
+ write_mdcr_el3(val);
+ }
+}