[efi] Open device path protocol only at point of use

Some EFI 1.10 systems (observed on an Apple iMac) do not allow us to
open the device path protocol with an attribute of
EFI_OPEN_PROTOCOL_BY_DRIVER and so we cannot maintain a safe,
long-lived pointer to the device path.  Work around this by instead
opening the device path protocol with an attribute of
EFI_OPEN_PROTOCOL_GET_PROTOCOL whenever we need to use it.

Debugged-by: Curtis Larsen <larsen@dixie.edu>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/efi/snpnet.c

  */
 static int snpnet_pci_info ( struct efi_device *efidev, struct device *dev ) {
 	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
-	EFI_DEVICE_PATH_PROTOCOL *devpath = efidev->path;
 	EFI_HANDLE device = efidev->device;
+	union {
+		EFI_DEVICE_PATH_PROTOCOL *path;
+		void *interface;
+	} path;
+	EFI_DEVICE_PATH_PROTOCOL *devpath;
 	struct pci_device pci;
 	EFI_HANDLE pci_device;
 	EFI_STATUS efirc;
 	int rc;
 
+	/* Get device path */
+	if ( ( efirc = bs->OpenProtocol ( device,
+					  &efi_device_path_protocol_guid,
+					  &path.interface,
+					  efi_image_handle, device,
+					  EFI_OPEN_PROTOCOL_GET_PROTOCOL ))!=0){
+		rc = -EEFI ( efirc );
+		DBGC ( device, "SNP %p %s cannot open device path: %s\n",
+		       device, efi_handle_name ( device ), strerror ( rc ) );
+		goto err_open_device_path;
+	}
+	devpath = path.path;
+
 	/* Check for presence of PCI I/O protocol */
 	if ( ( efirc = bs->LocateDevicePath ( &efi_pci_io_protocol_guid,
 					      &devpath, &pci_device ) ) != 0 ) {
+		rc = -EEFI ( efirc );
 		DBGC ( device, "SNP %p %s is not a PCI device\n",
 		       device, efi_handle_name ( device ) );
-		return -EEFI ( efirc );
+		goto err_locate_pci_io;
 	}
 
 	/* Get PCI device information */
 	if ( ( rc = efipci_info ( pci_device, &pci ) ) != 0 ) {
 		DBGC ( device, "SNP %p %s could not get PCI information: %s\n",
 		       device, efi_handle_name ( device ), strerror ( rc ) );
-		return rc;
+		goto err_efipci_info;
 	}
 
 	/* Populate SNP device information */
 	memcpy ( &dev->desc, &pci.dev.desc, sizeof ( dev->desc ) );
 	snprintf ( dev->name, sizeof ( dev->name ), "SNP-%s", pci.dev.name );
 
-	return 0;
+ err_efipci_info:
+ err_locate_pci_io:
+	bs->CloseProtocol ( device, &efi_device_path_protocol_guid,
+			    efi_image_handle, device );
+ err_open_device_path:
+	return rc;
 }
 
 /**

src/image/efi_image.c

 	}
 
 	/* Create device path for image */
-	path = efi_image_path ( image, &snpdev->path );
+	path = efi_image_path ( image, snpdev->path );
 	if ( ! path ) {
 		DBGC ( image, "EFIIMAGE %p could not create device path\n",
 		       image );

src/include/ipxe/efi/efi_driver.h

 	struct device dev;
 	/** EFI device handle */
 	EFI_HANDLE device;
-	/** Device path */
-	EFI_DEVICE_PATH_PROTOCOL *path;
 	/** Driver for this device */
 	struct efi_driver *driver;
 	/** Driver-private data */

src/include/ipxe/efi/efi_snp.h

 	wchar_t driver_name[16];
 	/** Controller name */
 	wchar_t controller_name[64];
-	/** The device path
-	 *
-	 * This field is variable in size and must appear at the end
-	 * of the structure.
-	 */
-	EFI_DEVICE_PATH_PROTOCOL path;
+	/** The device path */
+	EFI_DEVICE_PATH_PROTOCOL *path;
 };
 
 extern int efi_snp_hii_install ( struct efi_snp_device *snpdev );

src/interface/efi/efi_driver.c

 static EFI_STATUS EFIAPI
 efi_driver_start ( EFI_DRIVER_BINDING_PROTOCOL *driver __unused,
 		   EFI_HANDLE device, EFI_DEVICE_PATH_PROTOCOL *child ) {
-	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
 	struct efi_driver *efidrv;
 	struct efi_device *efidev;
-	union {
-		EFI_DEVICE_PATH_PROTOCOL *devpath;
-		void *interface;
-	} devpath;
 	EFI_STATUS efirc;
 	int rc;
 
 	INIT_LIST_HEAD ( &efidev->dev.children );
 	list_add ( &efidev->dev.siblings, &efi_devices );
 
-	/* Open device path protocol */
-	if ( ( efirc = bs->OpenProtocol ( device,
-					  &efi_device_path_protocol_guid,
-					  &devpath.interface,
-					  efi_image_handle, device,
-					  EFI_OPEN_PROTOCOL_BY_DRIVER ) ) != 0){
-		rc = -EEFI ( efirc );
-		DBGC ( device, "EFIDRV %p %s could not open device path: %s\n",
-		       device, efi_handle_name ( device ),
-		       strerror ( rc ) );
-		DBGC_EFI_OPENERS ( device, device,
-				   &efi_device_path_protocol_guid );
-		goto err_no_device_path;
-	}
-	efidev->path = devpath.devpath;
-
 	/* Try to start this device */
 	for_each_table_entry ( efidrv, EFI_DRIVERS ) {
 		if ( ( rc = efidrv->supported ( device ) ) != 0 ) {
 	}
 	efirc = EFI_UNSUPPORTED;
 
-	bs->CloseProtocol ( device, &efi_device_path_protocol_guid,
-			    efi_image_handle, device );
- err_no_device_path:
 	list_del ( &efidev->dev.siblings );
 	free ( efidev );
  err_alloc:
 efi_driver_stop ( EFI_DRIVER_BINDING_PROTOCOL *driver __unused,
 		  EFI_HANDLE device, UINTN num_children,
 		  EFI_HANDLE *children ) {
-	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
 	struct efi_driver *efidrv;
 	struct efi_device *efidev;
 	UINTN i;
 	efidrv = efidev->driver;
 	assert ( efidrv != NULL );
 	efidrv->stop ( efidev );
-	bs->CloseProtocol ( efidev->device, &efi_device_path_protocol_guid,
-			    efi_image_handle, efidev->device );
 	list_del ( &efidev->dev.siblings );
 	free ( efidev );
 

src/interface/efi/efi_snp.c

 	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
 	struct efi_device *efidev;
 	struct efi_snp_device *snpdev;
+	union {
+		EFI_DEVICE_PATH_PROTOCOL *path;
+		void *interface;
+	} path;
 	EFI_DEVICE_PATH_PROTOCOL *path_end;
 	MAC_ADDR_DEVICE_PATH *macpath;
 	size_t path_prefix_len = 0;
 		goto err_no_efidev;
 	}
 
-	/* Calculate device path prefix length */
-	path_end = efi_devpath_end ( efidev->path );
-	path_prefix_len = ( ( ( void * ) path_end ) -
-			    ( ( void * ) efidev->path ) );
-
 	/* Allocate the SNP device */
-	snpdev = zalloc ( sizeof ( *snpdev ) + path_prefix_len +
-			  sizeof ( *macpath ) );
+	snpdev = zalloc ( sizeof ( *snpdev ) );
 	if ( ! snpdev ) {
 		rc = -ENOMEM;
 		goto err_alloc_snp;
 				       sizeof ( snpdev->name[0] ) ),
 		       "%s", netdev->name );
 
+	/* Get the parent device path */
+	if ( ( efirc = bs->OpenProtocol ( efidev->device,
+					  &efi_device_path_protocol_guid,
+					  &path.interface, efi_image_handle,
+					  efidev->device,
+					  EFI_OPEN_PROTOCOL_GET_PROTOCOL ))!=0){
+		rc = -EEFI ( efirc );
+		DBGC ( snpdev, "SNPDEV %p cannot get %p %s device path: %s\n",
+		       snpdev, efidev->device,
+		       efi_handle_name ( efidev->device ), strerror ( rc ) );
+		goto err_open_device_path;
+	}
+
+	/* Allocate the new device path */
+	path_end = efi_devpath_end ( path.path );
+	path_prefix_len = ( ( ( void * ) path_end ) - ( ( void * ) path.path ));
+	snpdev->path = zalloc ( path_prefix_len + sizeof ( *macpath ) +
+				sizeof ( *path_end ) );
+	if ( ! snpdev->path ) {
+		rc = -ENOMEM;
+		goto err_alloc_device_path;
+	}
+
 	/* Populate the device path */
-	memcpy ( &snpdev->path, efidev->path, path_prefix_len );
-	macpath = ( ( ( void * ) &snpdev->path ) + path_prefix_len );
+	memcpy ( snpdev->path, path.path, path_prefix_len );
+	macpath = ( ( ( void * ) snpdev->path ) + path_prefix_len );
 	path_end = ( ( void * ) ( macpath + 1 ) );
 	memset ( macpath, 0, sizeof ( *macpath ) );
 	macpath->Header.Type = MESSAGING_DEVICE_PATH;
 	if ( ( efirc = bs->InstallMultipleProtocolInterfaces (
 			&snpdev->handle,
 			&efi_simple_network_protocol_guid, &snpdev->snp,
-			&efi_device_path_protocol_guid, &snpdev->path,
+			&efi_device_path_protocol_guid, snpdev->path,
 			&efi_nii_protocol_guid, &snpdev->nii,
 			&efi_nii31_protocol_guid, &snpdev->nii,
 			&efi_component_name2_protocol_guid, &snpdev->name2,
 	/* Add to list of SNP devices */
 	list_add ( &snpdev->list, &efi_snp_devices );
 
+	/* Close device path */
+	bs->CloseProtocol ( efidev->device, &efi_device_path_protocol_guid,
+			    efi_image_handle, efidev->device );
+
 	DBGC ( snpdev, "SNPDEV %p installed for %s as device %p %s\n",
 	       snpdev, netdev->name, snpdev->handle,
 	       efi_handle_name ( snpdev->handle ) );
 	bs->UninstallMultipleProtocolInterfaces (
 			snpdev->handle,
 			&efi_simple_network_protocol_guid, &snpdev->snp,
-			&efi_device_path_protocol_guid, &snpdev->path,
+			&efi_device_path_protocol_guid, snpdev->path,
 			&efi_nii_protocol_guid, &snpdev->nii,
 			&efi_nii31_protocol_guid, &snpdev->nii,
 			&efi_component_name2_protocol_guid, &snpdev->name2,
 			&efi_load_file_protocol_guid, &snpdev->load_file,
 			NULL );
  err_install_protocol_interface:
+	free ( snpdev->path );
+ err_alloc_device_path:
+	bs->CloseProtocol ( efidev->device, &efi_device_path_protocol_guid,
+			    efi_image_handle, efidev->device );
+ err_open_device_path:
 	bs->CloseEvent ( snpdev->snp.WaitForPacket );
  err_create_event:
  err_ll_addr_len:
 	bs->UninstallMultipleProtocolInterfaces (
 			snpdev->handle,
 			&efi_simple_network_protocol_guid, &snpdev->snp,
-			&efi_device_path_protocol_guid, &snpdev->path,
+			&efi_device_path_protocol_guid, snpdev->path,
 			&efi_nii_protocol_guid, &snpdev->nii,
 			&efi_nii31_protocol_guid, &snpdev->nii,
 			&efi_component_name2_protocol_guid, &snpdev->name2,
 			&efi_load_file_protocol_guid, &snpdev->load_file,
 			NULL );
+	free ( snpdev->path );
 	bs->CloseEvent ( snpdev->snp.WaitForPacket );
 	netdev_put ( snpdev->netdev );
 	free ( snpdev );