[edk2-devel] [PATCH v3 5/5] MdeModulePkg: Extend NestedInterruptTplLib to support Arm CPUs

["Michael Brown" <mcb30@ipxe.org>]

The only architecture-specific portion of NestedInterruptTplLib is in
Iret.c, which must manipulate the interrupt stack frame such that the
return-from-interrupt instruction will not re-enable interrupts.  The
remaining logic in Tpl.c is architecture-agnostic.

Add implementations of DisableInterruptsOnIret() for MDE_CPU_ARM and
MDE_CPU_AARCH64.  In both cases, the saved IRQs-disabled and
FIQs-disabled flags are set in the stored processor status register
(matching the behaviour of DisableInterrupts(), which also sets both
flags).

Tested by patching ArmPkg's TimerDxe to use NestedInterruptTplLib and
verifying that ArmVirtQemu passes the NestedInterruptTplLib self-tests
for both ARM and AARCH64.

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
---
 MdeModulePkg/MdeModulePkg.dsc                  |  2 +-
 .../NestedInterruptTplLib.inf                  |  3 +++
 .../Library/NestedInterruptTplLib/Iret.c       | 18 ++++++++++++++++++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/MdeModulePkg/MdeModulePkg.dsc b/MdeModulePkg/MdeModulePkg.dsc
index 5b9ddfd26e75..4565b8e1b6e7 100644
--- a/MdeModulePkg/MdeModulePkg.dsc
+++ b/MdeModulePkg/MdeModulePkg.dsc
@@ -462,6 +462,7 @@ [Components.IA32, Components.X64, Components.AARCH64]
 
 [Components.IA32, Components.X64, Components.ARM, Components.AARCH64]
   MdeModulePkg/Library/BrotliCustomDecompressLib/BrotliCustomDecompressLib.inf
+  MdeModulePkg/Library/NestedInterruptTplLib/NestedInterruptTplLib.inf
   MdeModulePkg/Library/LzmaCustomDecompressLib/LzmaCustomDecompressLib.inf
   MdeModulePkg/Library/VarCheckUefiLib/VarCheckUefiLib.inf
   MdeModulePkg/Core/Dxe/DxeMain.inf {
@@ -526,7 +527,6 @@ [Components.IA32, Components.X64]
   MdeModulePkg/Library/TraceHubDebugSysTLib/BaseTraceHubDebugSysTLib.inf
   MdeModulePkg/Library/TraceHubDebugSysTLib/PeiTraceHubDebugSysTLib.inf
   MdeModulePkg/Library/TraceHubDebugSysTLib/DxeSmmTraceHubDebugSysTLib.inf
-  MdeModulePkg/Library/NestedInterruptTplLib/NestedInterruptTplLib.inf
 
 [Components.X64]
   MdeModulePkg/Universal/CapsulePei/CapsuleX64.inf
diff --git a/MdeModulePkg/Library/NestedInterruptTplLib/NestedInterruptTplLib.inf b/MdeModulePkg/Library/NestedInterruptTplLib/NestedInterruptTplLib.inf
index e67d899b9446..1501f067d77f 100644
--- a/MdeModulePkg/Library/NestedInterruptTplLib/NestedInterruptTplLib.inf
+++ b/MdeModulePkg/Library/NestedInterruptTplLib/NestedInterruptTplLib.inf
@@ -27,6 +27,9 @@ [Packages]
   MdePkg/MdePkg.dec
   MdeModulePkg/MdeModulePkg.dec
 
+[Packages.ARM, Packages.AARCH64]
+  ArmPkg/ArmPkg.dec
+
 [LibraryClasses]
   BaseLib
   DebugLib
diff --git a/MdeModulePkg/Library/NestedInterruptTplLib/Iret.c b/MdeModulePkg/Library/NestedInterruptTplLib/Iret.c
index f6b2c51b6cc1..87cb74566730 100644
--- a/MdeModulePkg/Library/NestedInterruptTplLib/Iret.c
+++ b/MdeModulePkg/Library/NestedInterruptTplLib/Iret.c
@@ -9,6 +9,10 @@
 #include <Library/BaseLib.h>
 #include <Library/DebugLib.h>
 
+#if defined (MDE_CPU_AARCH64) || defined (MDE_CPU_ARM)
+#include <Library/ArmLib.h>
+#endif
+
 #include "Iret.h"
 
 /**
@@ -54,6 +58,20 @@ DisableInterruptsOnIret (
   Eflags.Bits.IF                          = 0;
   SystemContext.SystemContextIa32->Eflags = Eflags.UintN;
 
+ #elif defined (MDE_CPU_AARCH64)
+
+  //
+  // Set IRQ-disabled and FIQ-disabled flags.
+  //
+  SystemContext.SystemContextAArch64->SPSR |= (SPSR_I | SPSR_F);
+
+ #elif defined (MDE_CPU_ARM)
+
+  //
+  // Set IRQ-disabled and FIQ-disabled flags.
+  //
+  SystemContext.SystemContextArm->CPSR |= (CPSR_IRQ | CPSR_FIQ);
+
  #else
 
   #error "Unsupported CPU"
-- 
2.43.0



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