BaseUefiCpuLib: Preserve EBX register in InitializeFloatingPointUnits

The EBX register should be preserved for the IA32 C calling convention.
The use of the CPUID instruction was modifying the EBX register, so
we push and pop EBX.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@9573 6f19259b-4bc3-4df7-8a09-765794883524

2 files changed, 49 insertions, 40 deletions

diff --git a/UefiCpuPkg/Library/BaseUefiCpuLib/Ia32/InitializeFpu.S b/UefiCpuPkg/Library/BaseUefiCpuLib/Ia32/InitializeFpu.S
index c4a2f6fb83..4c74957f04 100644
--- a/UefiCpuPkg/Library/BaseUefiCpuLib/Ia32/InitializeFpu.S
+++ b/UefiCpuPkg/Library/BaseUefiCpuLib/Ia32/InitializeFpu.S
@@ -1,19 +1,19 @@
-#------------------------------------------------------------------------------
-#*
-#*   Copyright 2009, Intel Corporation
-#*   All rights reserved. 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
-#*   http://opensource.org/licenses/bsd-license.php
-#*
-#*   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
-#*   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
-#*
-#*
-#------------------------------------------------------------------------------
-
-
-
+#------------------------------------------------------------------------------

+#*

+#*   Copyright 2009, Intel Corporation

+#*   All rights reserved. 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

+#*   http://opensource.org/licenses/bsd-license.php

+#*

+#*   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,

+#*   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

+#*

+#*

+#------------------------------------------------------------------------------

+

+

+

 #

 # Float control word initial value: 

 # all exceptions masked, double-precision, round-to-nearest

@@ -23,18 +23,21 @@ ASM_PFX(mFpuControlWord): .word     0x027F
 # Multimedia-extensions control word:

 # all exceptions masked, round-to-nearest, flush to zero for masked underflow

 #

-ASM_PFX(mMmxControlWord): .long     0x01F80
-
-#
+ASM_PFX(mMmxControlWord): .long     0x01F80

+

+#

 # Initializes floating point units for requirement of UEFI specification.

 #

 # This function initializes floating-point control word to 0x027F (all exceptions

 # masked,double-precision, round-to-nearest) and multimedia-extensions control word

 # (if supported) to 0x1F80 (all exceptions masked, round-to-nearest, flush to zero

-# for masked underflow).
-#
-ASM_GLOBAL ASM_PFX(InitializeFloatingPointUnits)
-ASM_PFX(InitializeFloatingPointUnits):
+# for masked underflow).

+#

+ASM_GLOBAL ASM_PFX(InitializeFloatingPointUnits)

+ASM_PFX(InitializeFloatingPointUnits):

+

+    pushl   %ebx

+

     #

     # Initialize floating point units

     #

@@ -49,22 +52,24 @@ ASM_PFX(InitializeFloatingPointUnits):
     cpuid

     btl     $25, %edx

     jnc     Done

-    
-    #
-    # Set OSFXSR bit 9 in CR4
-    #
-    movl    %cr4, %eax 
-    or      $200, %eax
-    movl    %eax, %cr4
-    
+    

+    #

+    # Set OSFXSR bit 9 in CR4

+    #

+    movl    %cr4, %eax 

+    or      $200, %eax

+    movl    %eax, %cr4

+    

     #

     # The processor should support SSE instruction and we can use

     # ldmxcsr instruction

     #

-    ldmxcsr ASM_PFX(mMmxControlWord)
-
-Done:
-    ret
-
-#END
-
+    ldmxcsr ASM_PFX(mMmxControlWord)

+

+Done:

+    popl    %ebx

+

+    ret

+

+#END

+

diff --git a/UefiCpuPkg/Library/BaseUefiCpuLib/Ia32/InitializeFpu.asm b/UefiCpuPkg/Library/BaseUefiCpuLib/Ia32/InitializeFpu.asm
index 55244c72a9..083473311e 100644
--- a/UefiCpuPkg/Library/BaseUefiCpuLib/Ia32/InitializeFpu.asm
+++ b/UefiCpuPkg/Library/BaseUefiCpuLib/Ia32/InitializeFpu.asm
@@ -30,15 +30,18 @@ mMmxControlWord       DD      01F80h
     .xmm

     .code

 

-;
+;

 ; Initializes floating point units for requirement of UEFI specification.

 ;

 ; This function initializes floating-point control word to 0x027F (all exceptions

 ; masked,double-precision, round-to-nearest) and multimedia-extensions control word

 ; (if supported) to 0x1F80 (all exceptions masked, round-to-nearest, flush to zero

-; for masked underflow).
+; for masked underflow).

 ;

 InitializeFloatingPointUnits PROC PUBLIC

+

+    push    ebx

+

     ;

     ; Initialize floating point units

     ;

@@ -67,6 +70,7 @@ InitializeFloatingPointUnits PROC PUBLIC
     ;

     ldmxcsr mMmxControlWord

 Done:

+    pop     ebx

 

     ret