From afdae789cd0d33c6f7debce2fc41f1af4946d869 Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ardb@kernel.org>
Date: Wed, 29 Jan 2025 11:29:54 +0100
Subject: ArmPkg/CpuDxe: Fix error handling in driver initialization

Failure to install the CPU arch protocol is a fatal error, so treat it
as such, rather than ignore it, even though we won't get very far if
this driver fails to dispatch - at least, we will get an error in a
DEBUG build rather than a mysterious failure due to unsatisfied DEPEXes.

Failure to install the idle loop event handler is not a fatal error, and
it should not cause the driver to exit with an error, as this will
unload the driver and keep the installed CPU arch protocol pointer
dangling. So keep the ASSERT() on the return value, but return
EFI_SUCCESS once we're past the point where the CPU arch protocol has
been installed.

Since the protocol is never uninstalled, make the CPU handle function
local, as there is no point in keeping its value around.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 ArmPkg/Drivers/CpuDxe/CpuDxe.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/ArmPkg/Drivers/CpuDxe/CpuDxe.c b/ArmPkg/Drivers/CpuDxe/CpuDxe.c
index fc63e52784..9bb2b4a600 100644
--- a/ArmPkg/Drivers/CpuDxe/CpuDxe.c
+++ b/ArmPkg/Drivers/CpuDxe/CpuDxe.c
@@ -206,8 +206,7 @@ IdleLoopEventCallback (
 //
 // Globals used to initialize the protocol
 //
-EFI_HANDLE             mCpuHandle = NULL;
-EFI_CPU_ARCH_PROTOCOL  mCpu       = {
+EFI_CPU_ARCH_PROTOCOL  mCpu = {
   CpuFlushCpuDataCache,
   CpuEnableInterrupt,
   CpuDisableInterrupt,
@@ -308,6 +307,7 @@ CpuDxeInitialize (
 {
   EFI_STATUS  Status;
   EFI_EVENT   IdleLoopEvent;
+  EFI_HANDLE  CpuHandle;
 
   InitializeExceptions (&mCpu);
 
@@ -327,14 +327,20 @@ CpuDxeInitialize (
     RemapUnusedMemoryNx ();
   }
 
+  CpuHandle = NULL;
+
   Status = gBS->InstallMultipleProtocolInterfaces (
-                  &mCpuHandle,
+                  &CpuHandle,
                   &gEfiCpuArchProtocolGuid,
                   &mCpu,
                   &gEfiMemoryAttributeProtocolGuid,
                   &mMemoryAttribute,
                   NULL
                   );
+  if (EFI_ERROR (Status)) {
+    ASSERT_EFI_ERROR (Status);
+    return Status;
+  }
 
   //
   // Make sure GCD and MMU settings match. This API calls gDS->SetMemorySpaceAttributes ()
@@ -358,5 +364,5 @@ CpuDxeInitialize (
                   );
   ASSERT_EFI_ERROR (Status);
 
-  return Status;
+  return EFI_SUCCESS;
 }
-- 
cgit