Re: [Patch 4/7] UefiCpuPkg: Update CpuExceptionHandlerLib pass XCODE5 tool chain

["Kinney, Michael D" <michael.d.kinney@intel.com>]

Liming,

Can we use NASM syntax for instructions instead of db bytes?

If you put the label for the fixup after the instruction, you
can patch by subtracting the size of the patch value from the
label.

For example, instead of:

> +    db      0x48, 0xB8
> +JmpAbsoluteAddress:
> +    dq      0 ;     mov     rax, HookAfterStubHeaderEnd

Use:

	movq	rax, 0
JmpAbsoluteAddress:

And in the patch loop:

    mov    qword [rcx + (JmpAbsoluteAddress - 8 - HookAfterStubHeaderBegin)], rax


If this works, then please use this technique to remove
use of db for instructions throughout this series.

Mike

> -----Original Message-----
> From: Gao, Liming
> Sent: Wednesday, January 10, 2018 7:24 AM
> To: edk2-devel@lists.01.org
> Cc: Andrew Fish <afish@apple.com>; Yao, Jiewen
> <jiewen.yao@intel.com>; Dong, Eric <eric.dong@intel.com>;
> Laszlo Ersek <lersek@redhat.com>; Kinney, Michael D
> <michael.d.kinney@intel.com>
> Subject: [Patch 4/7] UefiCpuPkg: Update
> CpuExceptionHandlerLib pass XCODE5 tool chain
> 
> Use the dummy address as jmp destination, and add the
> logic to fix up
> the address to the absolute address at boot time.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Liming Gao <liming.gao@intel.com>
> Cc: Andrew Fish <afish@apple.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Michael Kinney <michael.d.kinney@intel.com>
> ---
>  .../X64/ExceptionHandlerAsm.nasm                   | 29
> ++++++++++++++++------
>  1 file changed, 22 insertions(+), 7 deletions(-)
> 
> diff --git
> a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/Exception
> HandlerAsm.nasm
> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/Exception
> HandlerAsm.nasm
> index ba8993d84b..a5fde0a875 100644
> ---
> a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/Exception
> HandlerAsm.nasm
> +++
> b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/Exception
> HandlerAsm.nasm
> @@ -1,5 +1,5 @@
>  ;-------------------------------------------------------
> ----------------------- ;
> -; Copyright (c) 2012 - 2014, Intel Corporation. All
> rights reserved.<BR>
> +; Copyright (c) 2012 - 2018, 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
> @@ -40,7 +40,8 @@ AsmIdtVectorBegin:
>      db      0x6a        ; push  #VectorNum
>      db      ($ - AsmIdtVectorBegin) / ((AsmIdtVectorEnd
> - AsmIdtVectorBegin) / 32) ; VectorNum
>      push    rax
> -    mov     rax, ASM_PFX(CommonInterruptEntry)
> +    db      0x48, 0xB8
> +    dq      0 ;     mov     rax,
> ASM_PFX(CommonInterruptEntry)
>      jmp     rax
>  %endrep
>  AsmIdtVectorEnd:
> @@ -50,7 +51,9 @@ HookAfterStubHeaderBegin:
>  @VectorNum:
>      db      0          ; 0 will be fixed
>      push    rax
> -    mov     rax, HookAfterStubHeaderEnd
> +    db      0x48, 0xB8
> +JmpAbsoluteAddress:
> +    dq      0 ;     mov     rax, HookAfterStubHeaderEnd
>      jmp     rax
>  HookAfterStubHeaderEnd:
>      mov     rax, rsp
> @@ -260,8 +263,7 @@ HasErrorCode:
>      ; and make sure RSP is 16-byte aligned
>      ;
>      sub     rsp, 4 * 8 + 8
> -    mov     rax, ASM_PFX(CommonExceptionHandler)
> -    call    rax
> +    call    ASM_PFX(CommonExceptionHandler)
>      add     rsp, 4 * 8 + 8
> 
>      cli
> @@ -369,11 +371,24 @@ DoIret:
>  ; comments here for definition of address map
>  global ASM_PFX(AsmGetTemplateAddressMap)
>  ASM_PFX(AsmGetTemplateAddressMap):
> -    mov     rax, AsmIdtVectorBegin
> +    lea     rax, [AsmIdtVectorBegin]
>      mov     qword [rcx], rax
>      mov     qword [rcx + 0x8],  (AsmIdtVectorEnd -
> AsmIdtVectorBegin) / 32
> -    mov     rax, HookAfterStubHeaderBegin
> +    lea     rax, [HookAfterStubHeaderBegin]
>      mov     qword [rcx + 0x10], rax
> +
> +; Fix up CommonInterruptEntry address
> +    lea    rax, [ASM_PFX(CommonInterruptEntry)]
> +    lea    rcx, [AsmIdtVectorBegin]
> +%rep  32
> +    mov    qword [rcx + (JmpAbsoluteAddress -
> HookAfterStubHeaderBegin)], rax
> +    add    rcx, (AsmIdtVectorEnd - AsmIdtVectorBegin) /
> 32
> +%endrep
> +; Fix up HookAfterStubHeaderEnd
> +    lea    rax, [HookAfterStubHeaderEnd]
> +    lea    rcx, [JmpAbsoluteAddress]
> +    mov    qword [rcx], rax
> +
>      ret
> 
>  ;-------------------------------------------------------
> ------------------------------
> --
> 2.11.0.windows.1