From a670f12a741a9511d9cedc7257d3693567f8fc43 Mon Sep 17 00:00:00 2001 From: "Tan, Dun" Date: Thu, 29 Sep 2022 17:06:51 +0800 Subject: [PATCH] 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 Cc: Eric Dong Reviewed-by: Ray Ni Cc: Rahul Kumar Reviewed-by: Abner Chang --- .../CpuExceptionHandlerLib/Ia32/ArchExceptionHandler.c | 5 ++++- .../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) { -- 2.39.5