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/*
* Copyright (C) 2025 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
* You can also choose to distribute this program under the terms of
* the Unmodified Binary Distribution Licence (as given in the file
* COPYING.UBDL), provided that you have satisfied its requirements.
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
FILE_SECBOOT ( PERMITTED );
#include <assert.h>
#include <errno.h>
#include <string.h>
#include <ipxe/efi/efi.h>
#include <ipxe/efi/efi_table.h>
/** @file
*
* EFI configuration tables
*
*/
/**
* Look up EFI configuration table
*
* @v guid Configuration table GUID
* @ret table Configuration table, or NULL
*/
void * efi_find_table ( EFI_GUID *guid ) {
void *table;
unsigned int i;
/* Scan for installed table */
for ( i = 0 ; i < efi_systab->NumberOfTableEntries ; i++ ) {
if ( memcmp ( &efi_systab->ConfigurationTable[i].VendorGuid,
guid, sizeof ( *guid ) ) == 0 ) {
table = efi_systab->ConfigurationTable[i].VendorTable;
DBGC ( guid, "EFITAB %s is at %p\n",
efi_guid_ntoa ( guid ), table );
return table;
}
}
return NULL;
}
/**
* Install EFI configuration table
*
* @v table Configuration table type
* @v data Configuration table data, or NULL to uninstall
* @v backup Table backup, or NULL to not back up old table
* @ret rc Return status code
*/
int efi_install_table ( struct efi_table *table, const void *data,
void **backup ) {
EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
EFI_GUID *guid = table->guid;
void *copy;
void *new;
void *old;
size_t old_len;
size_t new_len;
EFI_STATUS efirc;
int rc;
/* Get currently installed table, if any */
old = efi_find_table ( guid );
old_len = ( old ? table->len ( old ) : 0 );
/* Create backup copy, if applicable */
if ( old_len && backup ) {
if ( ( efirc = bs->AllocatePool ( EfiBootServicesData, old_len,
© ) ) != 0 ) {
rc = -EEFI ( efirc );
goto err_backup;
}
memcpy ( copy, old, old_len );
DBGC ( table, "EFITAB %s %p+%#zx backed up\n",
efi_guid_ntoa ( guid ), old, old_len );
} else {
copy = NULL;
}
/* Create installable runtime services data copy, if applicable */
new_len = ( data ? table->len ( data ) : 0 );
if ( new_len ) {
if ( ( efirc = bs->AllocatePool ( EfiRuntimeServicesData,
new_len, &new ) ) != 0 ) {
rc = -EEFI ( efirc );
goto err_allocate;
}
memcpy ( new, data, new_len );
} else {
new = NULL;
}
/* (Un)install configuration table, if applicable */
if ( new || old ) {
if ( ( efirc = bs->InstallConfigurationTable ( guid,
new ) ) != 0 ) {
rc = -EEFI ( efirc );
DBGC ( table, "EFITAB %s could not install: %s\n",
efi_guid_ntoa ( guid ), strerror ( rc ) );
goto err_install;
}
if ( old ) {
DBGC ( table, "EFITAB %s %p+%#zx uninstalled\n",
efi_guid_ntoa ( guid ), old, old_len );
}
if ( new ) {
DBGC ( table, "EFITAB %s %p+%#zx installed\n",
efi_guid_ntoa ( guid ), new, new_len );
}
}
/* Record backup copy, if applicable */
if ( backup ) {
if ( *backup )
bs->FreePool ( *backup );
*backup = copy;
}
/* Sanity check */
assert ( efi_find_table ( guid ) == new );
return 0;
err_install:
if ( new )
bs->FreePool ( new );
err_allocate:
if ( copy )
bs->FreePool ( copy );
err_backup:
return rc;
}
/**
* Uninstall EFI configuration table
*
* @v table Configuration table type
* @v backup Table backup (or NULL to not restore old table)
* @ret rc Return status code
*/
int efi_uninstall_table ( struct efi_table *table, void **backup ) {
EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
void *old;
int rc;
/* Uninstall or reinstall as applicable */
old = ( backup ? *backup : NULL );
if ( ( rc = efi_install_table ( table, old, NULL ) ) != 0 )
return rc;
/* Free backup copy, if applicable */
if ( backup && *backup ) {
bs->FreePool ( *backup );
*backup = NULL;
}
return 0;
}
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