SiP: Don't validate entrypoint if state switch is impossible

Switching execution states is only possible if EL3 is AArch64.
As such there is no need to validate the entrypoint on AArch32 builds.
Signed-off-by: Bence Szépkúti <bence.szepkuti@arm.com>
Change-Id: I3c1eb25b5df296a492870641d274bf65213c6608

plat/arm/common/execution_state_switch.c → plat/arm/common/aarch64/execution_state_switch.c

@@ -39,8 +39,6 @@ int arm_execution_state_switch(unsigned int smc_fid,
 		uint32_t cookie_lo,
 		void *handle)
 {
-	/* Execution state can be switched only if EL3 is AArch64 */
-#ifdef __aarch64__
 	bool caller_64, thumb = false, from_el2;
 	unsigned int el, endianness;
 	u_register_t spsr, pc, scr, sctlr;
@@ -48,6 +46,11 @@ int arm_execution_state_switch(unsigned int smc_fid,
 	cpu_context_t *ctx = (cpu_context_t *) handle;
 	el3_state_t *el3_ctx = get_el3state_ctx(ctx);
 
+	/* Validate supplied entry point */
+	pc = (u_register_t) (((uint64_t) pc_hi << 32) | pc_lo);
+	if (arm_validate_ns_entrypoint(pc) != 0)
+		goto invalid_param;
+
 	/* That the SMC originated from NS is already validated by the caller */
 
 	/*
@@ -173,7 +176,6 @@ invalid_param:
 	SMC_RET1(handle, STATE_SW_E_PARAM);
 
 exec_denied:
-#endif /* __aarch64__ */
 	/* State switch denied */
 	SMC_RET1(handle, STATE_SW_E_DENIED);
 }

plat/arm/common/arm_common.mk

@@ -215,13 +215,15 @@ BL2U_SOURCES		+=	drivers/delay_timer/delay_timer.c		\
 BL31_SOURCES		+=	plat/arm/common/arm_bl31_setup.c		\
 				plat/arm/common/arm_pm.c			\
 				plat/arm/common/arm_topology.c			\
-				plat/arm/common/execution_state_switch.c	\
 				plat/common/plat_psci_common.c
 
 ifeq (${ENABLE_PMF}, 1)
-BL31_SOURCES		+=	plat/arm/common/arm_sip_svc.c			\
+ifeq (${ARCH}, aarch64)
+BL31_SOURCES		+=	plat/arm/common/aarch64/execution_state_switch.c\
+				plat/arm/common/arm_sip_svc.c			\
 				lib/pmf/pmf_smc.c
 endif
+endif
 
 ifeq (${EL3_EXCEPTION_HANDLING},1)
 BL31_SOURCES		+=	plat/arm/common/aarch64/arm_ehf.c

plat/arm/common/arm_sip_svc.c

 /*
- * Copyright (c) 2016-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -50,23 +50,22 @@ static uintptr_t arm_sip_handler(unsigned int smc_fid,
 
 	switch (smc_fid) {
 	case ARM_SIP_SVC_EXE_STATE_SWITCH: {
-		u_register_t pc;
-
+		/* Execution state can be switched only if EL3 is AArch64 */
+#ifdef __aarch64__
 		/* Allow calls from non-secure only */
 		if (!is_caller_non_secure(flags))
 			SMC_RET1(handle, STATE_SW_E_DENIED);
 
-		/* Validate supplied entry point */
-		pc = (u_register_t) ((x1 << 32) | (uint32_t) x2);
-		if (arm_validate_ns_entrypoint(pc) != 0)
-			SMC_RET1(handle, STATE_SW_E_PARAM);
-
 		/*
 		 * Pointers used in execution state switch are all 32 bits wide
 		 */
 		return (uintptr_t) arm_execution_state_switch(smc_fid,
 				(uint32_t) x1, (uint32_t) x2, (uint32_t) x3,
 				(uint32_t) x4, handle);
+#else
+		/* State switch denied */
+		SMC_RET1(handle, STATE_SW_E_DENIED);
+#endif /* __aarch64__ */
 		}
 
 	case ARM_SIP_SVC_CALL_COUNT: