Refactor Statistical Profiling Extensions implementation

Factor out SPE operations in a separate file.  Use the publish
subscribe framework to drain the SPE buffers before entering secure
world.  Additionally, enable SPE before entering normal world.

A side effect of this change is that the profiling buffers are now
only drained when a transition from normal world to secure world
happens.  Previously they were drained also on return from secure
world, which is unnecessary as SPE is not supported in S-EL1.

Change-Id: I17582c689b4b525770dbb6db098b3a0b5777b70a
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>

1 files changed, 85 insertions, 0 deletions

diff --git a/lib/extensions/spe/spe.c b/lib/extensions/spe/spe.c
new file mode 100644
index 00000000..3b297f21
--- /dev/null
+++ b/lib/extensions/spe/spe.c
@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch.h>
+#include <arch_helpers.h>
+#include <pubsub.h>
+
+/*
+ * The assembler does not yet understand the psb csync mnemonic
+ * so use the equivalent hint instruction.
+ */
+#define psb_csync()	asm volatile("hint #17")
+
+void spe_enable(int el2_unused)
+{
+	uint64_t features;
+
+	features = read_id_aa64dfr0_el1() >> ID_AA64DFR0_PMS_SHIFT;
+	if ((features & ID_AA64DFR0_PMS_MASK) == 1) {
+		uint64_t v;
+
+		if (el2_unused) {
+			/*
+			 * MDCR_EL2.TPMS (ARM v8.2): Do not trap statistical
+			 * profiling controls to EL2.
+			 *
+			 * MDCR_EL2.E2PB (ARM v8.2): SPE enabled in Non-secure
+			 * state. Accesses to profiling buffer controls at
+			 * Non-secure EL1 are not trapped to EL2.
+			 */
+			v = read_mdcr_el2();
+			v &= ~MDCR_EL2_TPMS;
+			v |= MDCR_EL2_E2PB(MDCR_EL2_E2PB_EL1);
+			write_mdcr_el2(v);
+		}
+
+		/*
+		 * MDCR_EL2.NSPB (ARM v8.2): SPE enabled in Non-secure state
+		 * and disabled in secure state. Accesses to SPE registers at
+		 * S-EL1 generate trap exceptions to EL3.
+		 */
+		v = read_mdcr_el3();
+		v |= MDCR_NSPB(MDCR_NSPB_EL1);
+		write_mdcr_el3(v);
+	}
+}
+
+void spe_disable(void)
+{
+	uint64_t features;
+
+	features = read_id_aa64dfr0_el1() >> ID_AA64DFR0_PMS_SHIFT;
+	if ((features & ID_AA64DFR0_PMS_MASK) == 1) {
+		uint64_t v;
+
+		/* Drain buffered data */
+		psb_csync();
+		dsbnsh();
+
+		/* Disable profiling buffer */
+		v = read_pmblimitr_el1();
+		v &= ~(1ULL << 0);
+		write_pmblimitr_el1(v);
+		isb();
+	}
+}
+
+static void *spe_drain_buffers_hook(const void *arg)
+{
+	uint64_t features;
+
+	features = read_id_aa64dfr0_el1() >> ID_AA64DFR0_PMS_SHIFT;
+	if ((features & ID_AA64DFR0_PMS_MASK) == 1) {
+		/* Drain buffered data */
+		psb_csync();
+		dsbnsh();
+	}
+
+	return 0;
+}
+
+SUBSCRIBE_TO_EVENT(cm_entering_secure_world, spe_drain_buffers_hook);