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OvmfPkg: QemuFwCfgLib: extract stateful implementation 

The current implementation of QemuFwCfgLib is:
- stateful
- implicitly initialized in the library constructor.

OVMF's SEC runs from read-only memory/flash. When the library is linked
into a SEC binary (which currently never happens), the
"mQemuFwCfgSupported" global variable becomes read-only, making the
library non-functional.

Extract the stateful, implicitly initialized library implementation into a
separate file, making room for a stateless, explicitly queried
implementation that's usable in SEC. Restrict the stateful implementation
to the current, non-SEC clients.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15045 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
Laszlo Ersek 2014-01-03 19:57:26 +00:00 committed by jljusten
parent 0dc231c9bd
commit 2ce7e221e7
3 changed files with 97 additions and 75 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

74
OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
View File

@ -22,8 +22,6 @@
#include <Library/MemoryAllocationLib.h>
#include <Library/UefiBootServicesTableLib.h>
STATIC BOOLEAN mQemuFwCfgSupported = FALSE;
/**
Reads an 8-bit I/O port fifo into a block of memory.
@ -78,26 +76,6 @@ IoWriteFifo8 (
);
/**
Returns a boolean indicating if the firmware configuration interface
is available or not.
This function may change fw_cfg state.
@retval TRUE The interface is available
@retval FALSE The interface is not available
**/
BOOLEAN
EFIAPI
QemuFwCfgIsAvailable (
VOID
)
{
return InternalQemuFwCfgIsAvailable ();
}
/**
Selects a firmware configuration item for reading.
@ -265,39 +243,6 @@ QemuFwCfgRead64 (
}
RETURN_STATUS
EFIAPI
QemuFwCfgInitialize (
VOID
)
{
UINT32 Signature;
UINT32 Revision;
//
// Enable the access routines while probing to see if it is supported.
//
mQemuFwCfgSupported = TRUE;
QemuFwCfgSelectItem (QemuFwCfgItemSignature);
Signature = QemuFwCfgRead32 ();
DEBUG ((EFI_D_INFO, "FW CFG Signature: 0x%x\n", Signature));
QemuFwCfgSelectItem (QemuFwCfgItemInterfaceVersion);
Revision = QemuFwCfgRead32 ();
DEBUG ((EFI_D_INFO, "FW CFG Revision: 0x%x\n", Revision));
if ((Signature != SIGNATURE_32 ('Q', 'E', 'M', 'U')) ||
(Revision < 1)
) {
DEBUG ((EFI_D_INFO, "QemuFwCfg interface not supported.\n"));
mQemuFwCfgSupported = FALSE;
return RETURN_SUCCESS;
}
DEBUG ((EFI_D_INFO, "QemuFwCfg interface is supported.\n"));
return RETURN_SUCCESS;
}
/**
Find the configuration item corresponding to the firmware configuration file.
@ -349,22 +294,3 @@ QemuFwCfgFindFile (
return RETURN_NOT_FOUND;
}
/**
Returns a boolean indicating if the firmware configuration interface is
available for library-internal purposes.
This function never changes fw_cfg state.
@retval TRUE The interface is available internally.
@retval FALSE The interface is not available internally.
**/
BOOLEAN
EFIAPI
InternalQemuFwCfgIsAvailable (
VOID
)
{
return mQemuFwCfgSupported;
}

6
OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.inf
View File

@ -1,5 +1,8 @@
## @file
#
# Stateful, implicitly initialized fw_cfg library.
#
# Copyright (C) 2013, Red Hat, Inc.
# Copyright (c) 2008 - 2012, Intel Corporation. All rights reserved.<BR>
#
# This program and the accompanying materials
@ -18,7 +21,7 @@
FILE_GUID = fdd53716-31e1-4acc-9007-8bd5d877c96f
MODULE_TYPE = BASE
VERSION_STRING = 1.0
LIBRARY_CLASS = QemuFwCfgLib
LIBRARY_CLASS = QemuFwCfgLib|PEIM DXE_DRIVER DXE_RUNTIME_DRIVER DXE_SMM_DRIVER
CONSTRUCTOR = QemuFwCfgInitialize
@ -30,6 +33,7 @@
[Sources]
QemuFwCfgLib.c
QemuFwCfgPeiDxe.c
[Sources.IA32]
Ia32/IoLibExAsm.asm

92
OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgPeiDxe.c Normal file
View File

@ -0,0 +1,92 @@
/** @file
Stateful and implicitly initialized fw_cfg library implementation.
Copyright (C) 2013, Red Hat, Inc.
Copyright (c) 2011 - 2013, 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
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.
**/
#include <Library/DebugLib.h>
#include <Library/QemuFwCfgLib.h>
STATIC BOOLEAN mQemuFwCfgSupported = FALSE;
/**
Returns a boolean indicating if the firmware configuration interface
is available or not.
This function may change fw_cfg state.
@retval TRUE The interface is available
@retval FALSE The interface is not available
**/
BOOLEAN
EFIAPI
QemuFwCfgIsAvailable (
VOID
)
{
return InternalQemuFwCfgIsAvailable ();
}
RETURN_STATUS
EFIAPI
QemuFwCfgInitialize (
VOID
)
{
UINT32 Signature;
UINT32 Revision;
//
// Enable the access routines while probing to see if it is supported.
//
mQemuFwCfgSupported = TRUE;
QemuFwCfgSelectItem (QemuFwCfgItemSignature);
Signature = QemuFwCfgRead32 ();
DEBUG ((EFI_D_INFO, "FW CFG Signature: 0x%x\n", Signature));
QemuFwCfgSelectItem (QemuFwCfgItemInterfaceVersion);
Revision = QemuFwCfgRead32 ();
DEBUG ((EFI_D_INFO, "FW CFG Revision: 0x%x\n", Revision));
if ((Signature != SIGNATURE_32 ('Q', 'E', 'M', 'U')) ||
(Revision < 1)
) {
DEBUG ((EFI_D_INFO, "QemuFwCfg interface not supported.\n"));
mQemuFwCfgSupported = FALSE;
return RETURN_SUCCESS;
}
DEBUG ((EFI_D_INFO, "QemuFwCfg interface is supported.\n"));
return RETURN_SUCCESS;
}
/**
Returns a boolean indicating if the firmware configuration interface is
available for library-internal purposes.
This function never changes fw_cfg state.
@retval TRUE The interface is available internally.
@retval FALSE The interface is not available internally.
**/
BOOLEAN
EFIAPI
InternalQemuFwCfgIsAvailable (
VOID
)
{
return mQemuFwCfgSupported;
}