From 6952d1fa901a9053abe46c317ee820fc28a2835d Mon Sep 17 00:00:00 2001
From: Leif Lindholm <leif.lindholm@oss.qualcomm.com>
Date: Tue, 8 Apr 2025 18:18:08 +0100
Subject: [PATCH] ArmPlatformPkg/Sec: clean up FP enabling code

UEFI defines that FP support is required on AArch64, whereas many
platforms enable it anyway on Arm. But when it's enabled, C code can
generate instructions targeting FP registers, so:

- move ArmEnableVFP call to asm
- make it unconditional on AArch64

Signed-off-by: Leif Lindholm <leif.lindholm@oss.qualcomm.com>
---
 ArmPlatformPkg/PeilessSec/AArch64/ArchPeilessSec.c   | 5 -----
 ArmPlatformPkg/PeilessSec/AArch64/ModuleEntryPoint.S | 4 ++++
 ArmPlatformPkg/PeilessSec/Arm/ArchPeilessSec.c       | 4 ----
 ArmPlatformPkg/PeilessSec/Arm/ModuleEntryPoint.S     | 6 ++++++
 ArmPlatformPkg/PeilessSec/PeilessSec.inf             | 4 +++-
 ArmPlatformPkg/Sec/Arm/ModuleEntryPoint.S            | 6 ++++++
 ArmPlatformPkg/Sec/Sec.c                             | 5 -----
 ArmPlatformPkg/Sec/Sec.inf                           | 4 +++-
 8 files changed, 22 insertions(+), 16 deletions(-)

diff --git a/ArmPlatformPkg/PeilessSec/AArch64/ArchPeilessSec.c b/ArmPlatformPkg/PeilessSec/AArch64/ArchPeilessSec.c
index ccc9cde6d1..22148f0e20 100644
--- a/ArmPlatformPkg/PeilessSec/AArch64/ArchPeilessSec.c
+++ b/ArmPlatformPkg/PeilessSec/AArch64/ArchPeilessSec.c
@@ -18,11 +18,6 @@ ArchInitialize (
   VOID
   )
 {
-  // Enable Floating Point
-  if (FixedPcdGet32 (PcdVFPEnabled)) {
-    ArmEnableVFP ();
-  }
-
   if (ArmReadCurrentEL () == AARCH64_EL2) {
     // Trap General Exceptions. All exceptions that would be routed to EL1 are routed to EL2
     ArmWriteHcr (ARM_HCR_TGE);
diff --git a/ArmPlatformPkg/PeilessSec/AArch64/ModuleEntryPoint.S b/ArmPlatformPkg/PeilessSec/AArch64/ModuleEntryPoint.S
index c6b7093adb..5f285f3f13 100644
--- a/ArmPlatformPkg/PeilessSec/AArch64/ModuleEntryPoint.S
+++ b/ArmPlatformPkg/PeilessSec/AArch64/ModuleEntryPoint.S
@@ -11,6 +11,10 @@ ASM_FUNC(_ModuleEntryPoint)
   // Do early platform specific actions
   bl    ASM_PFX(ArmPlatformPeiBootAction)
 
+  // Enable Floating Point. This needs to be done before entering C code, which
+  // may use FP/SIMD registers.
+  bl    ArmEnableVFP
+
 // Check if we can install the stack at the top of the System Memory or if we need
 // to install the stacks at the bottom of the Firmware Device (case the FD is located
 // at the top of the DRAM)
diff --git a/ArmPlatformPkg/PeilessSec/Arm/ArchPeilessSec.c b/ArmPlatformPkg/PeilessSec/Arm/ArchPeilessSec.c
index 3c3cef6925..e2f6f67904 100644
--- a/ArmPlatformPkg/PeilessSec/Arm/ArchPeilessSec.c
+++ b/ArmPlatformPkg/PeilessSec/Arm/ArchPeilessSec.c
@@ -18,8 +18,4 @@ ArchInitialize (
 {
   // Enable program flow prediction, if supported.
   ArmEnableBranchPrediction ();
-
-  if (FixedPcdGet32 (PcdVFPEnabled)) {
-    ArmEnableVFP ();
-  }
 }
diff --git a/ArmPlatformPkg/PeilessSec/Arm/ModuleEntryPoint.S b/ArmPlatformPkg/PeilessSec/Arm/ModuleEntryPoint.S
index 6b38b86e01..9043d8679a 100644
--- a/ArmPlatformPkg/PeilessSec/Arm/ModuleEntryPoint.S
+++ b/ArmPlatformPkg/PeilessSec/Arm/ModuleEntryPoint.S
@@ -13,6 +13,12 @@ ASM_FUNC(_ModuleEntryPoint)
   // Do early platform specific actions
   bl    ASM_PFX(ArmPlatformPeiBootAction)
 
+#if (FixedPcdGet32 (PcdVFPEnabled))
+  // Enable Floating Point. This needs to be done before entering C code, which
+  // may use FP/SIMD registers.
+  bl    ArmEnableVFP
+#endif
+
 // Check if we can install the stack at the top of the System Memory or if we need
 // to install the stacks at the bottom of the Firmware Device (case the FD is located
 // at the top of the DRAM)
diff --git a/ArmPlatformPkg/PeilessSec/PeilessSec.inf b/ArmPlatformPkg/PeilessSec/PeilessSec.inf
index 7f67adfa71..e210d016da 100644
--- a/ArmPlatformPkg/PeilessSec/PeilessSec.inf
+++ b/ArmPlatformPkg/PeilessSec/PeilessSec.inf
@@ -70,9 +70,11 @@
   gArmTokenSpaceGuid.PcdFdSize
   gArmTokenSpaceGuid.PcdFvBaseAddress
   gArmTokenSpaceGuid.PcdFvSize
-  gArmTokenSpaceGuid.PcdVFPEnabled
   gEmbeddedTokenSpaceGuid.PcdPrePiCpuIoSize
 
+[FixedPcd.ARM]
+  gArmTokenSpaceGuid.PcdVFPEnabled
+
 [Pcd]
   gArmTokenSpaceGuid.PcdSystemMemoryBase
   gArmTokenSpaceGuid.PcdSystemMemorySize
diff --git a/ArmPlatformPkg/Sec/Arm/ModuleEntryPoint.S b/ArmPlatformPkg/Sec/Arm/ModuleEntryPoint.S
index 1207497dc7..7cb3de7d35 100644
--- a/ArmPlatformPkg/Sec/Arm/ModuleEntryPoint.S
+++ b/ArmPlatformPkg/Sec/Arm/ModuleEntryPoint.S
@@ -11,6 +11,12 @@ ASM_FUNC(_ModuleEntryPoint)
   // Do early platform specific actions
   bl    ASM_PFX(ArmPlatformPeiBootAction)
 
+#if (FixedPcdGet32 (PcdVFPEnabled))
+  // Enable Floating Point. This needs to be done before entering C code, which
+  // may use FP/SIMD registers.
+  bl    ArmEnableVFP
+#endif
+
   // Get the top of the primary stacks (and the base of the secondary stacks)
   MOV32 (r1, FixedPcdGet64(PcdCPUCoresStackBase) + FixedPcdGet32(PcdCPUCorePrimaryStackSize))
 
diff --git a/ArmPlatformPkg/Sec/Sec.c b/ArmPlatformPkg/Sec/Sec.c
index 9a700e5ef2..4535ae7e78 100644
--- a/ArmPlatformPkg/Sec/Sec.c
+++ b/ArmPlatformPkg/Sec/Sec.c
@@ -223,11 +223,6 @@ CEntryPoint (
   ASSERT (((UINTN)PeiVectorTable & ARM_VECTOR_TABLE_ALIGNMENT) == 0);
   ArmWriteVBar ((UINTN)PeiVectorTable);
 
-  // Enable Floating Point
-  if (FixedPcdGet32 (PcdVFPEnabled)) {
-    ArmEnableVFP ();
-  }
-
   // Invoke "ProcessLibraryConstructorList" to have all library constructors
   // called.
   ProcessLibraryConstructorList ();
diff --git a/ArmPlatformPkg/Sec/Sec.inf b/ArmPlatformPkg/Sec/Sec.inf
index b5af19e7a4..a75ce8d5ec 100644
--- a/ArmPlatformPkg/Sec/Sec.inf
+++ b/ArmPlatformPkg/Sec/Sec.inf
@@ -58,9 +58,11 @@
 [FixedPcd]
   gArmTokenSpaceGuid.PcdFvBaseAddress
   gArmTokenSpaceGuid.PcdFvSize
-  gArmTokenSpaceGuid.PcdVFPEnabled
 
   gArmPlatformTokenSpaceGuid.PcdCPUCoresStackBase
   gArmPlatformTokenSpaceGuid.PcdCPUCorePrimaryStackSize
 
   gEfiMdeModulePkgTokenSpaceGuid.PcdInitValueInTempStack
+
+[FixedPcd.ARM]
+  gArmTokenSpaceGuid.PcdVFPEnabled