[edk2-devel] [PATCH] UefiCpuPkg/CpuExceptionHandlerLib: Code optimization to allow bigger stack

[duntan]

This commit is a code optimization to allow bigger seperate stack size in
ArchSetupExceptionStack. In previous code logic, CPU_STACK_ALIGNMENT bytes
will be wasted if StackTop is already CPU_STACK_ALIGNMENT aligned.

Signed-off-by: Dun Tan <dun.tan at intel.com>
Cc: Eric Dong <eric.dong at intel.com>
Cc: Ray Ni <ray.ni at intel.com>
Cc: Rahul Kumar <rahul1.kumar at intel.com>
---
 UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.c | 2 +-
 UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.c b/UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.c
index 8c398ebc5b..c8fa30a32f 100644
--- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.c
+++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.c
@@ -215,7 +215,7 @@ ArchSetupExceptionStack (
   // Fixup exception task descriptor and task-state segment
   //
   AsmGetTssTemplateMap (&TemplateMap);
-  StackTop = StackTop - CPU_STACK_ALIGNMENT;
+  StackTop = StackTop - CPU_STACK_ALIGNMENT + 1;
   StackTop = (UINTN)ALIGN_POINTER (StackTop, CPU_STACK_ALIGNMENT);
   IdtTable = (IA32_IDT_GATE_DESCRIPTOR  *)Idtr.Base;
   for (Index = 0; Index < CPU_STACK_SWITCH_EXCEPTION_NUMBER; ++Index) {
diff --git a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c
index 80e9f08e5b..74b2193cb0 100644
--- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c
+++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c
@@ -223,7 +223,7 @@ ArchSetupExceptionStack (
   // Fixup exception task descriptor and task-state segment
   //
   ZeroMem (Tss, sizeof (*Tss));
-  StackTop = StackTop - CPU_STACK_ALIGNMENT;
+  StackTop = StackTop - CPU_STACK_ALIGNMENT + 1;
   StackTop = (UINTN)ALIGN_POINTER (StackTop, CPU_STACK_ALIGNMENT);
   IdtTable = (IA32_IDT_GATE_DESCRIPTOR  *)Idtr.Base;
   for (Index = 0; Index < CPU_STACK_SWITCH_EXCEPTION_NUMBER; ++Index) {
-- 
2.31.1.windows.1



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