From f45f2d4ad4d803eb33c608bca8242992f1841fec Mon Sep 17 00:00:00 2001
From: "Yao, Jiewen" <jiewen.yao@intel.com>
Date: Wed, 25 Nov 2015 08:51:15 +0000
Subject: Move SmmDebug feature from ASM to C.

SmmDebug feature is implemented in ASM, which is not easy to maintain.
So we move it to C function.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: "Yao, Jiewen" <jiewen.yao@intel.com>
Reviewed-by: "Kinney, Michael D" <michael.d.kinney@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18946 6f19259b-4bc3-4df7-8a09-765794883524
---
 UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.S   | 39 +++++++++----------------
 UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.asm | 47 ++++++++++--------------------
 2 files changed, 28 insertions(+), 58 deletions(-)

(limited to 'UefiCpuPkg/PiSmmCpuDxeSmm/X64')

diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.S b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.S
index 95e6dfa814..b488b74b70 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.S
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.S
@@ -24,7 +24,6 @@ ASM_GLOBAL  ASM_PFX(gcSmiHandlerSize)
 ASM_GLOBAL  ASM_PFX(gSmiCr3)
 ASM_GLOBAL  ASM_PFX(gSmiStack)
 ASM_GLOBAL  ASM_PFX(gSmbase)
-ASM_GLOBAL  ASM_PFX(FeaturePcdGet (PcdCpuSmmDebug))
 ASM_GLOBAL  ASM_PFX(gSmiHandlerIdtr)
 
 #
@@ -163,20 +162,7 @@ LongMode:                               # long mode (64-bit code) starts here
 #   jmp     _SmiHandler                 ; instruction is not needed
 
 _SmiHandler:
-    movabsq $ASM_PFX(FeaturePcdGet (PcdCpuSmmDebug)), %rax
-    cmpb    $0, (%rax)
-    jz      L1
-
-    .byte   0x48, 0x8b, 0x0d            # mov rcx, [rip + disp32]
-    .long   SSM_DR6 - (. + 4 - _SmiEntryPoint + 0x8000)
-    .byte   0x48, 0x8b, 0x15            # mov rdx, [rip + disp32]
-    .long   SSM_DR7 - (. + 4 - _SmiEntryPoint + 0x8000)
-    movq    %rcx, %dr6
-    movq    %rdx, %dr7
-L1:
-
-    movabsq $ASM_PFX(SmiRendezvous), %rax
-    movq    (%rsp), %rcx
+    movq    (%rsp), %rbx
     # Save FP registers
 
     subq    $0x208, %rsp
@@ -184,7 +170,19 @@ L1:
     fxsave  (%rsp)
 
     addq    $-0x20, %rsp
+
+    movq    %rbx, %rcx
+    movabsq $ASM_PFX(CpuSmmDebugEntry), %rax
     call    *%rax
+
+    movq    %rbx, %rcx
+    movabsq $ASM_PFX(SmiRendezvous), %rax
+    call    *%rax
+
+    movq    %rbx, %rcx
+    movabsq $ASM_PFX(CpuSmmDebugExit), %rax
+    call    *%rax
+
     addq    $0x20, %rsp
 
     #
@@ -193,17 +191,6 @@ L1:
     .byte   0x48                        # FXRSTOR64
     fxrstor (%rsp)
 
-    movabsq $ASM_PFX(FeaturePcdGet (PcdCpuSmmDebug)), %rax
-    cmpb    $0, (%rax)
-    jz      L2
-
-    movq    %dr7, %rdx
-    movq    %dr6, %rcx
-    .byte   0x48, 0x89, 0x15            # mov [rip + disp32], rdx
-    .long   SSM_DR7 - (. + 4 - _SmiEntryPoint + 0x8000)
-    .byte   0x48, 0x89, 0x0d            # mov [rip + disp32], rcx
-    .long   SSM_DR6 - (. + 4 - _SmiEntryPoint + 0x8000)
-L2:
     rsm
 
 ASM_PFX(gcSmiHandlerSize):    .word      . - _SmiEntryPoint
diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.asm b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.asm
index 4d53db5b00..4f5c03c5cf 100644
--- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.asm
+++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.asm
@@ -22,12 +22,13 @@
 ; Variables referenced by C code
 ;
 EXTERNDEF   SmiRendezvous:PROC
+EXTERNDEF   CpuSmmDebugEntry:PROC
+EXTERNDEF   CpuSmmDebugExit:PROC
 EXTERNDEF   gcSmiHandlerTemplate:BYTE
 EXTERNDEF   gcSmiHandlerSize:WORD
 EXTERNDEF   gSmiCr3:DWORD
 EXTERNDEF   gSmiStack:DWORD
 EXTERNDEF   gSmbase:DWORD
-EXTERNDEF   FeaturePcdGet (PcdCpuSmmDebug):BYTE
 EXTERNDEF   gSmiHandlerIdtr:FWORD
 
 
@@ -157,26 +158,7 @@ Base:
 ;   jmp     _SmiHandler                 ; instruction is not needed
 
 _SmiHandler:
-;
-; The following lines restore DR6 & DR7 before running C code. They are useful
-; when you want to enable hardware breakpoints in SMM.
-;
-; NOTE: These lines might not be appreciated in runtime since they might
-;       conflict with OS debugging facilities. Turn them off in RELEASE.
-;
-    mov     rax, offset FeaturePcdGet (PcdCpuSmmDebug) ;Get absolute address. Avoid RIP relative addressing
-    cmp     byte ptr [rax], 0
-    jz      @1
-
-    DB      48h, 8bh, 0dh               ; mov rcx, [rip + disp32]
-    DD      SSM_DR6 - ($ + 4 - _SmiEntryPoint + 8000h)
-    DB      48h, 8bh, 15h               ; mov rdx, [rip + disp32]
-    DD      SSM_DR7 - ($ + 4 - _SmiEntryPoint + 8000h)
-    mov     dr6, rcx
-    mov     dr7, rdx
-@1:
-    mov     rcx, [rsp]                  ; rcx <- CpuIndex
-    mov     rax, SmiRendezvous          ; rax <- absolute addr of SmiRedezvous
+    mov     rbx, [rsp]                  ; rbx <- CpuIndex
 
     ;
     ; Save FP registers
@@ -186,7 +168,19 @@ _SmiHandler:
     fxsave  [rsp]
 
     add     rsp, -20h
+
+    mov     rcx, rbx
+    mov     rax, CpuSmmDebugEntry
+    call    rax
+    
+    mov     rcx, rbx
+    mov     rax, SmiRendezvous          ; rax <- absolute addr of SmiRedezvous
+    call    rax
+    
+    mov     rcx, rbx
+    mov     rax, CpuSmmDebugExit
     call    rax
+    
     add     rsp, 20h
 
     ;
@@ -195,17 +189,6 @@ _SmiHandler:
     DB      48h                         ; FXRSTOR64
     fxrstor [rsp]
 
-    mov     rax, offset FeaturePcdGet (PcdCpuSmmDebug) ;Get absolute address. Avoid RIP relative addressing
-    cmp     byte ptr [rax], 0
-    jz      @2
-
-    mov     rdx, dr7
-    mov     rcx, dr6
-    DB      48h, 89h, 15h               ; mov [rip + disp32], rdx
-    DD      SSM_DR7 - ($ + 4 - _SmiEntryPoint + 8000h)
-    DB      48h, 89h, 0dh               ; mov [rip + disp32], rcx
-    DD      SSM_DR6 - ($ + 4 - _SmiEntryPoint + 8000h)
-@2:
     rsm
 
 gcSmiHandlerSize    DW      $ - _SmiEntryPoint
-- 
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