diff options
Diffstat (limited to 'src/interface/efi/efi_table.c')
| -rw-r--r-- | src/interface/efi/efi_table.c | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/src/interface/efi/efi_table.c b/src/interface/efi/efi_table.c new file mode 100644 index 000000000..da5966a13 --- /dev/null +++ b/src/interface/efi/efi_table.c @@ -0,0 +1,179 @@ +/* + * 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; +} |