diff --git a/include/bl31/ehf.h b/include/bl31/ehf.h
new file mode 100644
index 0000000..142b4c0
--- /dev/null
+++ b/include/bl31/ehf.h
@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef __EHF_H__
+#define __EHF_H__
+
+#ifndef __ASSEMBLY__
+
+#include <stdint.h>
+#include <utils_def.h>
+
+/* Valid priorities set bit 0 of the priority handler. */
+#define _EHF_PRI_VALID	(((uintptr_t) 1) << 0)
+
+/* Marker for no handler registered for a valid priority */
+#define _EHF_NO_HANDLER	(0 | _EHF_PRI_VALID)
+
+/* Extract the specified number of top bits from 7 lower bits of priority */
+#define EHF_PRI_TO_IDX(pri, plat_bits) \
+	((pri & 0x7f) >> (7 - plat_bits))
+
+/* Install exception priority descriptor at a suitable index */
+#define EHF_PRI_DESC(plat_bits, priority) \
+	[EHF_PRI_TO_IDX(priority, plat_bits)] = { \
+		.ehf_handler = _EHF_NO_HANDLER, \
+	}
+
+/* Macro for platforms to regiter its exception priorities */
+#define EHF_REGISTER_PRIORITIES(priorities, num, bits) \
+	const ehf_priorities_t exception_data = { \
+		.num_priorities = num, \
+		.ehf_priorities = priorities, \
+		.pri_bits = bits, \
+	}
+
+/*
+ * Priority stack, managed as a bitmap.
+ *
+ * Currently only supports 32 priority levels, allowing platforms to use up to 5
+ * top bits of priority. But the type can be changed to uint64_t should need
+ * arise to support 64 priority levels, allowing platforms to use up to 6 top
+ * bits of priority.
+ */
+typedef uint32_t ehf_pri_bits_t;
+
+/*
+ * Per-PE exception data. The data for each PE is kept as a per-CPU data field.
+ * See cpu_data.h.
+ */
+typedef struct {
+	ehf_pri_bits_t active_pri_bits;
+
+	/* Priority mask value before any priority levels were active */
+	uint8_t init_pri_mask;
+} __aligned(sizeof(uint64_t)) pe_exc_data_t;
+
+typedef int (*ehf_handler_t)(uint32_t intr_raw, uint32_t flags, void *handle,
+		void *cookie);
+
+typedef struct ehf_pri_desc {
+	/*
+	 * 4-byte-aligned exception handler. Bit 0 indicates the corresponding
+	 * priority level is valid. This is effectively of ehf_handler_t type,
+	 * but left as uintptr_t in order to make pointer arithmetic convenient.
+	 */
+	uintptr_t ehf_handler;
+} ehf_pri_desc_t;
+
+typedef struct ehf_priorities {
+	ehf_pri_desc_t *ehf_priorities;
+	unsigned int num_priorities;
+	int pri_bits;
+} ehf_priorities_t;
+
+void ehf_init(void);
+void ehf_activate_priority(unsigned int priority);
+void ehf_deactivate_priority(unsigned int priority);
+void ehf_register_priority_handler(unsigned int pri, ehf_handler_t handler);
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __EHF_H__ */