[PATCH v4 2/6] ArmPkg: Correct return value of "SMCCC_ARCH_SOC_ID" Function ID call

["Nhi Pham" <nhi@os.amperecomputing.com>]

From: Minh Nguyen <minhn@amperecomputing.com>

According to "SMC Calling Convention" specification, section 7.4,
return value of Arm Architecture Calls is stored at first argument of
SMC aguments (ARM_SMC_ARGS). This value can be negative values indicating
error or positive values (including zero) indicating success. Positive
value would contain information of respective Function ID (Section 7.3.4
and 7.4.4).

For that reason, "SMCCC_VERSION" and "SMCCC_ARCH_FEATURES"
Function ID calls read return value from "SmcCallStatus" variable
(Args.Arg0 - first argument of SMC call). But "SMCCC_ARCH_SOC_ID"
Function ID call is reading return value from "SmcParam" variable
(Args.Arg1 - second argument of SMC call) so it leads to unexpected
results of "Jep106Code" and "SocRevision". This patch is to correct it.

Signed-off-by: Nhi Pham <nhi@os.amperecomputing.com>
Reviewed-by: Rebecca Cran <rebecca@quicinc.com>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Leif Lindholm <quic_llindhol@quicinc.com>
---
 ArmPkg/Universal/Smbios/ProcessorSubClassDxe/SmbiosProcessorArmCommon.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/ArmPkg/Universal/Smbios/ProcessorSubClassDxe/SmbiosProcessorArmCommon.c b/ArmPkg/Universal/Smbios/ProcessorSubClassDxe/SmbiosProcessorArmCommon.c
index e0010a40e489..b961be213358 100644
--- a/ArmPkg/Universal/Smbios/ProcessorSubClassDxe/SmbiosProcessorArmCommon.c
+++ b/ArmPkg/Universal/Smbios/ProcessorSubClassDxe/SmbiosProcessorArmCommon.c
@@ -2,7 +2,7 @@
   Functions for processor information common to ARM and AARCH64.
 
   Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>
-  Copyright (c) 2021, Ampere Computing LLC. All rights reserved.<BR>
+  Copyright (c) 2021 - 2022, Ampere Computing LLC. All rights reserved.<BR>
 
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
@@ -131,7 +131,7 @@ SmbiosGetSmcArm64SocId (
   SmcCallStatus = ArmCallSmc1 (SMCCC_ARCH_SOC_ID, &SmcParam, NULL, NULL);
 
   if (SmcCallStatus >= 0) {
-    *Jep106Code = (INT32)SmcParam;
+    *Jep106Code = SmcCallStatus;
   } else {
     Status = EFI_UNSUPPORTED;
   }
@@ -140,7 +140,7 @@ SmbiosGetSmcArm64SocId (
   SmcCallStatus = ArmCallSmc1 (SMCCC_ARCH_SOC_ID, &SmcParam, NULL, NULL);
 
   if (SmcCallStatus >= 0) {
-    *SocRevision = (INT32)SmcParam;
+    *SocRevision = SmcCallStatus;
   } else {
     Status = EFI_UNSUPPORTED;
   }
-- 
2.25.1