Re: [PATCH] UefiCpuPkg/ExceptionHandlerAsm.S: Fix code length issue with GCC 5.4

["Gao, Liming" <liming.gao@intel.com>]

Reviewed-by: Liming Gao <liming.gao@intel.com>

>-----Original Message-----
>From: Fan, Jeff
>Sent: Tuesday, February 21, 2017 11:32 AM
>To: edk2-devel@ml01.01.org
>Cc: Gao, Liming <liming.gao@intel.com>; Tian, Feng <feng.tian@intel.com>;
>Kinney, Michael D <michael.d.kinney@intel.com>
>Subject: [PATCH] UefiCpuPkg/ExceptionHandlerAsm.S: Fix code length issue
>with GCC 5.4
>
>X64\ExceptionHandlerAsm.S define MARCO to set up 32 IDT entries header.
>It assume GCC compiler will generate the same code length on the following
>instrction for each IDT entry.
>  jmp    ASM_PFX(CommonInterruptEntry)
>
>It works with GCC 4.x. However, GCC 5.4 will generate different code size of
>IDT
>entry code per the offset value from CommonInterruptEntry address. We
>should use
>DB to make sure each IDT entry header has the same size whatever compiler
>version.
>
>.ASM and .nasm used the different solution and do not have this issue.
>
>https://bugzilla.tianocore.org/show_bug.cgi?id=389
>
>Cc: Liming Gao <liming.gao@intel.com>
>Cc: Feng Tian <feng.tian@intel.com>
>Cc: Michael D Kinney <michael.d.kinney@intel.com>
>Contributed-under: TianoCore Contribution Agreement 1.0
>Signed-off-by: Jeff Fan <jeff.fan@intel.com>
>---
> UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ExceptionHandlerAsm.S |
>5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
>diff --git
>a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ExceptionHandlerAsm.S
>b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ExceptionHandlerAsm.S
>index 6b62f09..975adaa 100644
>---
>a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ExceptionHandlerAsm.S
>+++
>b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ExceptionHandlerAsm.S
>@@ -1,5 +1,5 @@
> #------------------------------------------------------------------------------ ;
>-# Copyright (c) 2012 - 2014, Intel Corporation. All rights reserved.<BR>
>+# Copyright (c) 2012 - 2017, Intel Corporation. All rights reserved.<BR>
> # This program and the accompanying materials
> # are licensed and made available under the terms and conditions of the BSD
>License
> # which accompanies this distribution.  The full text of the license may be
>found at
>@@ -36,7 +36,8 @@ ASM_GLOBAL ASM_PFX(CommonExceptionHandler)
> .macro IDT_MACRO arg
>   push    \arg
> #endif
>-  jmp    ASM_PFX(CommonInterruptEntry)
>+  .byte   0xe9      # jmp     ASM_PFX(CommonInterruptEntry)
>+  .long   ASM_PFX(CommonInterruptEntry) - . - 4
> .endm
>
> AsmIdtVectorBegin:
>--
>2.9.3.windows.2