Rework arithmetic operations in Test Secure Payload

This patch reworks the service provided by the TSP to perform common
arithmetic operations on a set of arguments provided by the non-secure
world. For a addition, division, subtraction & multiplication operation
requested on two arguments in x0 and x1 the steps are:

1. TSPD saves the non-secure context and passes the operation and its
   arguments to the TSP.

2. TSP asks the TSPD to return the same arguments once again. This
   exercises an additional SMC path.

3. TSP now has two copies of both x0 and x1. It performs the operation
   on the corresponding copies i.e. in case of addition it returns x0+x0
   and x1+x1.

4. TSPD receives the result, saves the secure context, restores the
   non-secure context and passes the result back to the non-secure
   client.

Change-Id: I6eebfa2ae0a6f28b1d2e11a31f575c7a4b96724b
Co-authored-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

2 files changed, 15 insertions, 19 deletions

diff --git a/bl32/tsp/aarch64/tsp_request.S b/bl32/tsp/aarch64/tsp_request.S
index 763e8fce..13e5931e 100644
--- a/bl32/tsp/aarch64/tsp_request.S
+++ b/bl32/tsp/aarch64/tsp_request.S
@@ -55,7 +55,6 @@ tsp_get_magic:
 
 	/* Store returned arguments to the array */
 	stp	x0, x1, [x4, #0]
-	stp	x2, x3, [x4, #16]
 
 	ret
 
diff --git a/bl32/tsp/tsp_main.c b/bl32/tsp/tsp_main.c
index f6640edd..05907f5c 100644
--- a/bl32/tsp/tsp_main.c
+++ b/bl32/tsp/tsp_main.c
@@ -288,17 +288,24 @@ tsp_args *tsp_fast_smc_handler(uint64_t func,
 			       uint64_t arg6,
 			       uint64_t arg7)
 {
-	uint64_t results[4];
-	uint64_t service_args[4];
+	uint64_t results[2];
+	uint64_t service_args[2];
+	uint64_t mpidr = read_mpidr();
+	uint32_t linear_id = platform_get_core_pos(mpidr);
 
-	INFO("Received fast smc 0x%x on cpu 0x%x\n", func, read_mpidr());
+	/* Update this cpu's statistics */
+	tsp_stats[linear_id].smc_count++;
+	tsp_stats[linear_id].eret_count++;
+
+	printf("SP: cpu 0x%x received fast smc 0x%x\n", read_mpidr(), func);
+	INFO("cpu 0x%x: %d smcs, %d erets\n", mpidr,
+	     tsp_stats[linear_id].smc_count,
+	     tsp_stats[linear_id].eret_count);
 
-	/* Render sercure services and obtain results here */
+	/* Render secure services and obtain results here */
 
 	results[0] = arg1;
 	results[1] = arg2;
-	results[2] = arg3;
-	results[3] = arg4;
 
 	/*
 	 * Request a service back from dispatcher/secure monitor. This call
@@ -311,36 +318,26 @@ tsp_args *tsp_fast_smc_handler(uint64_t func,
 	case TSP_FID_ADD:
 		results[0] += service_args[0];
 		results[1] += service_args[1];
-		results[2] += service_args[2];
-		results[3] += service_args[3];
 		break;
 	case TSP_FID_SUB:
 		results[0] -= service_args[0];
 		results[1] -= service_args[1];
-		results[2] -= service_args[2];
-		results[3] -= service_args[3];
 		break;
 	case TSP_FID_MUL:
 		results[0] *= service_args[0];
 		results[1] *= service_args[1];
-		results[2] *= service_args[2];
-		results[3] *= service_args[3];
 		break;
 	case TSP_FID_DIV:
 		results[0] /= service_args[0] ? service_args[0] : 1;
 		results[1] /= service_args[1] ? service_args[1] : 1;
-		results[2] /= service_args[2] ? service_args[2] : 1;
-		results[3] /= service_args[3] ? service_args[3] : 1;
 		break;
 	default:
 		break;
 	}
 
-	return set_smc_args(TSP_WORK_DONE,
+	return set_smc_args(func,
 			    results[0],
 			    results[1],
-			    results[2],
-			    results[3],
-			    0, 0, 0);
+			    0, 0, 0, 0, 0);
 }