Implement support for SMCCC v1.1

SMCCC v1.1 comes with a relaxed calling convention for AArch64
callers.  The caller only needs to save x0-x3 before doing an SMC
call.

This patch adds support for SMCCC_VERSION and SMCCC_ARCH_FEATURES.

Refer to "Firmware Interfaces for mitigating CVE_2017_5715 System
Software on Arm Systems"[0] for more information.

[0] https://developer.arm.com/-/media/developer/pdf/ARM%20DEN%200070A%20Firmware%20interfaces%20for%20mitigating%20CVE-2017-5715_V1.0.pdf

Change-Id: If5b1c55c17d6c5c7cb9c2c3ed355d3a91cdad0a9
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>

bl31/bl31.mk

@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.
+# Copyright (c) 2013-2018, ARM Limited and Contributors. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
@@ -23,6 +23,7 @@ BL31_SOURCES		+=	bl31/bl31_main.c				\
 				bl31/bl31_context_mgmt.c			\
 				common/runtime_svc.c				\
 				plat/common/aarch64/platform_mp_stack.S		\
+				services/arm_arch_svc/arm_arch_svc_setup.c	\
 				services/std_svc/std_svc_setup.c		\
 				${PSCI_LIB_SOURCES}				\
 				${SPM_SOURCES}					\

include/lib/smcc.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -67,6 +67,11 @@
 #include <cassert.h>
 #include <stdint.h>
 
+#define SMCCC_MAJOR_VERSION U(1)
+#define SMCCC_MINOR_VERSION U(1)
+
+#define MAKE_SMCCC_VERSION(_major, _minor) (((_major) << 16) | (_minor))
+
 /* Various flags passed to SMC handlers */
 #define SMC_FROM_SECURE		(U(0) << 0)
 #define SMC_FROM_NON_SECURE	(U(1) << 0)
@@ -78,6 +83,10 @@
 #define is_std_svc_call(_fid)		((((_fid) >> FUNCID_OEN_SHIFT) & \
 					   FUNCID_OEN_MASK) == OEN_STD_START)
 
+/* The macro below is used to identify a Arm Architectural Service SMC call */
+#define is_arm_arch_svc_call(_fid)	((((_fid) >> FUNCID_OEN_SHIFT) & \
+					   FUNCID_OEN_MASK) == OEN_ARM_START)
+
 /* The macro below is used to identify a valid Fast SMC call */
 #define is_valid_fast_smc(_fid)		((!(((_fid) >> 16) & U(0xff))) && \
 					   (GET_SMC_TYPE(_fid) == SMC_TYPE_FAST))

include/services/arm_arch_svc.h

@@ -0,0 +1,14 @@
+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef __ARM_ARCH_SVC_H__
+#define __ARM_ARCH_SVC_H__
+
+#define SMCCC_VERSION			U(0x80000000)
+#define SMCCC_ARCH_FEATURES		U(0x80000001)
+#define SMCCC_ARCH_WORKAROUND_1		U(0x80008000)
+
+#endif /* __ARM_ARCH_SVC_H__ */

services/arm_arch_svc/arm_arch_svc_setup.c

@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arm_arch_svc.h>
+#include <debug.h>
+#include <runtime_svc.h>
+#include <smcc.h>
+#include <smcc_helpers.h>
+
+static int32_t smccc_version(void)
+{
+	return MAKE_SMCCC_VERSION(SMCCC_MAJOR_VERSION, SMCCC_MINOR_VERSION);
+}
+
+static int32_t smccc_arch_features(u_register_t arg)
+{
+	switch (arg) {
+	case SMCCC_VERSION:
+	case SMCCC_ARCH_FEATURES:
+		return SMC_OK;
+#if WORKAROUND_CVE_2017_5715
+	case SMCCC_ARCH_WORKAROUND_1:
+		return SMC_OK;
+#endif
+	default:
+		return SMC_UNK;
+	}
+}
+
+/*
+ * Top-level Arm Architectural Service SMC handler.
+ */
+uintptr_t arm_arch_svc_smc_handler(uint32_t smc_fid,
+	u_register_t x1,
+	u_register_t x2,
+	u_register_t x3,
+	u_register_t x4,
+	void *cookie,
+	void *handle,
+	u_register_t flags)
+{
+	switch (smc_fid) {
+	case SMCCC_VERSION:
+		SMC_RET1(handle, smccc_version());
+	case SMCCC_ARCH_FEATURES:
+		SMC_RET1(handle, smccc_arch_features(x1));
+#if WORKAROUND_CVE_2017_5715
+	case SMCCC_ARCH_WORKAROUND_1:
+		/*
+		 * The workaround has already been applied on affected PEs
+		 * during entry to EL3.  On unaffected PEs, this function
+		 * has no effect.
+		 */
+		SMC_RET0(handle);
+#endif
+	default:
+		WARN("Unimplemented Arm Architecture Service Call: 0x%x \n",
+			smc_fid);
+		SMC_RET1(handle, SMC_UNK);
+	}
+}
+
+/* Register Standard Service Calls as runtime service */
+DECLARE_RT_SVC(
+		arm_arch_svc,
+		OEN_ARM_START,
+		OEN_ARM_END,
+		SMC_TYPE_FAST,
+		NULL,
+		arm_arch_svc_smc_handler
+);