Reviewed-by: Ray Ni <ray...@intel.com>
> -----Original Message-----
> From: Tan, Dun <dun....@intel.com>
> Sent: Thursday, September 29, 2022 5:07 PM
> To: devel@edk2.groups.io
> Cc: Dong, Eric <eric.d...@intel.com>; Ni, Ray <ray...@intel.com>; Kumar,
> Rahul R <rahul.r.ku...@intel.com>
> Subject: [Patch V2] UefiCpuPkg/CpuExceptionHandlerLib: Code optimization
> to allow bigger stack
>
> 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....@intel.com>
> Cc: Eric Dong <eric.d...@intel.com>
> Reviewed-by: Ray Ni <ray...@intel.com>
> Cc: Rahul Kumar <rahul1.ku...@intel.com>
> ---
> UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.c |
> 5 ++++-
> UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c |
> 5 ++++-
> 2 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git
> a/UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.c
> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.
> c
> index 8c398ebc5b..c30ece1dc9 100644
> ---
> a/UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.c
> +++
> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.
> c
> @@ -215,7 +215,10 @@ ArchSetupExceptionStack (
> // Fixup exception task descriptor and task-state segment
> //
> AsmGetTssTemplateMap (&TemplateMap);
> - StackTop = StackTop - CPU_STACK_ALIGNMENT;
> + //
> + // Plus 1 byte is for compact stack layout in case StackTop is already
> aligned.
> + //
> + 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..4e85880ed4 100644
> ---
> a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c
> +++
> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c
> @@ -223,7 +223,10 @@ ArchSetupExceptionStack (
> // Fixup exception task descriptor and task-state segment
> //
> ZeroMem (Tss, sizeof (*Tss));
> - StackTop = StackTop - CPU_STACK_ALIGNMENT;
> + //
> + // Plus 1 byte is for compact stack layout in case StackTop is already
> aligned.
> + //
> + 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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