Changes to support updated register usage in SMCCC v1.2

From AArch64 state, arguments are passed in registers W0-W7(X0-X7)
and results are returned in W0-W7(X0-X7) for SMC32(SMC64) calls.
From AArch32 state, arguments are passed in registers R0-R7 and
results are returned in registers R0-R7 for SMC32 calls.

Most of the functions and macros already existed to support using
upto 8 registers for passing/returning parameters/results. Added
few helper macros for SMC calls from AArch32 state.

Link to the specification:
https://developer.arm.com/docs/den0028/c



Change-Id: I87976b42454dc3fc45c8343e9640aa78210e9741
Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>

docs/design/firmware-design.rst

@@ -978,8 +978,8 @@ manipulation; and with ``flags`` indicating the security state of the caller. Th
 framework finally sets up the execution stack for the handler, and invokes the
 services ``handle()`` function.
 
-On return from the handler the result registers are populated in X0-X3 before
-restoring the stack and CPU state and returning from the original SMC.
+On return from the handler the result registers are populated in X0-X7 as needed
+before restoring the stack and CPU state and returning from the original SMC.
 
 Exception Handling Framework
 ----------------------------

docs/getting_started/rt-svc-writers-guide.rst

@@ -244,17 +244,35 @@ The handler is responsible for:
 
    TF-A expects owning entities to follow this recommendation.
 
-#. Returning the result to the caller. The `SMCCC`_ allows for up to 256 bits
-   of return value in SMC64 using X0-X3 and 128 bits in SMC32 using W0-W3. The
-   framework provides a family of macros to set the multi-register return
-   value and complete the handler:
+#. Returning the result to the caller. Based on `SMCCC`_ spec, results are
+   returned in W0-W7(X0-X7) registers for SMC32(SMC64) calls from AArch64
+   state. Results are returned in R0-R7 registers for SMC32 calls from AArch32
+   state. The framework provides a family of macros to set the multi-register
+   return value and complete the handler:
 
    .. code:: c
 
+       AArch64 state:
+
        SMC_RET1(handle, x0);
        SMC_RET2(handle, x0, x1);
        SMC_RET3(handle, x0, x1, x2);
        SMC_RET4(handle, x0, x1, x2, x3);
+       SMC_RET5(handle, x0, x1, x2, x3, x4);
+       SMC_RET6(handle, x0, x1, x2, x3, x4, x5);
+       SMC_RET7(handle, x0, x1, x2, x3, x4, x5, x6);
+       SMC_RET8(handle, x0, x1, x2, x3, x4, x5, x6, x7);
+
+       AArch32 state:
+
+       SMC_RET1(handle, r0);
+       SMC_RET2(handle, r0, r1);
+       SMC_RET3(handle, r0, r1, r2);
+       SMC_RET4(handle, r0, r1, r2, r3);
+       SMC_RET5(handle, r0, r1, r2, r3, r4);
+       SMC_RET6(handle, r0, r1, r2, r3, r4, r5);
+       SMC_RET7(handle, r0, r1, r2, r3, r4, r5, r6);
+       SMC_RET8(handle, r0, r1, r2, r3, r4, r5, r6, r7);
 
 The ``cookie`` parameter to the handler is reserved for future use and can be
 ignored. The ``handle`` is returned by the SMC handler - completion of the

include/arch/aarch32/smccc_helpers.h

 /*
- * 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
  */
@@ -130,6 +130,22 @@ CASSERT(SMC_CTX_SIZE == sizeof(smc_ctx_t), assert_smc_ctx_size_mismatch);
 	((smc_ctx_t *)(_h))->r3 = (_r3);	\
 	SMC_RET3(_h, (_r0), (_r1), (_r2));	\
 }
+#define SMC_RET5(_h, _r0, _r1, _r2, _r3, _r4) {	\
+	((smc_ctx_t *)(_h))->r4 = (_r4);	\
+	SMC_RET4(_h, (_r0), (_r1), (_r2), (_r3));	\
+}
+#define SMC_RET6(_h, _r0, _r1, _r2, _r3, _r4, _r5) {	\
+	((smc_ctx_t *)(_h))->r5 = (_r5);	\
+	SMC_RET5(_h, (_r0), (_r1), (_r2), (_r3), (_r4));	\
+}
+#define SMC_RET7(_h, _r0, _r1, _r2, _r3, _r4, _r5, _r6) {	\
+	((smc_ctx_t *)(_h))->r6 = (_r6);	\
+	SMC_RET6(_h, (_r0), (_r1), (_r2), (_r3), (_r4), (_r5));	\
+}
+#define SMC_RET8(_h, _r0, _r1, _r2, _r3, _r4, _r5, _r6, _r7) {	\
+	((smc_ctx_t *)(_h))->r7 = (_r7);	\
+	SMC_RET7(_h, (_r0), (_r1), (_r2), (_r3), (_r4), (_r5), (_r6));	\
+}
 
 /*
  * Helper macro to retrieve the SMC parameters from smc_ctx_t.

include/lib/smccc.h

@@ -20,7 +20,7 @@
 						SMCCC_VERSION_MINOR_SHIFT))
 
 #define SMCCC_MAJOR_VERSION U(1)
-#define SMCCC_MINOR_VERSION U(1)
+#define SMCCC_MINOR_VERSION U(2)
 
 /*******************************************************************************
  * Bit definitions inside the function id as per the SMC calling convention
@@ -83,6 +83,12 @@
 #define SMC_UNK				-1
 #define SMC_PREEMPTED			-2	/* Not defined by the SMCCC */
 
+/* Return codes for Arm Architecture Service SMC calls */
+#define SMC_ARCH_CALL_SUCCESS		0
+#define SMC_ARCH_CALL_NOT_SUPPORTED	-1
+#define SMC_ARCH_CALL_NOT_REQUIRED	-2
+#define SMC_ARCH_CALL_INVAL_PARAM	-3
+
 /* Various flags passed to SMC handlers */
 #define SMC_FROM_SECURE		(U(0) << 0)
 #define SMC_FROM_NON_SECURE	(U(1) << 0)