efi_loader: add device-path utils

Helpers to construct device-paths from devices, partitions, files, and
for parsing and manipulating device-paths.

For non-legacy devices, this will use u-boot's device-model to construct
device-paths which include bus hierarchy to construct device-paths.  For
legacy devices we still fake it, but slightly more convincingly.

Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

include/efi_api.h

@@ -314,6 +314,7 @@ struct efi_device_path_acpi_path {
 #define DEVICE_PATH_TYPE_MESSAGING_DEVICE	0x03
 #  define DEVICE_PATH_SUB_TYPE_MSG_USB		0x05
 #  define DEVICE_PATH_SUB_TYPE_MSG_MAC_ADDR	0x0b
+#  define DEVICE_PATH_SUB_TYPE_MSG_USB_CLASS	0x0f
 #  define DEVICE_PATH_SUB_TYPE_MSG_SD		0x1a
 #  define DEVICE_PATH_SUB_TYPE_MSG_MMC		0x1d
 
@@ -329,6 +330,15 @@ struct efi_device_path_mac_addr {
 	u8 if_type;
 } __packed;
 
+struct efi_device_path_usb_class {
+	struct efi_device_path dp;
+	u16 vendor_id;
+	u16 product_id;
+	u8 device_class;
+	u8 device_subclass;
+	u8 device_protocol;
+} __packed;
+
 struct efi_device_path_sd_mmc_path {
 	struct efi_device_path dp;
 	u8 slot_number;

include/efi_loader.h

@@ -220,6 +220,32 @@ extern void *efi_bounce_buffer;
 #define EFI_LOADER_BOUNCE_BUFFER_SIZE (64 * 1024 * 1024)
 #endif
 
+
+struct efi_device_path *efi_dp_next(const struct efi_device_path *dp);
+int efi_dp_match(struct efi_device_path *a, struct efi_device_path *b);
+struct efi_object *efi_dp_find_obj(struct efi_device_path *dp,
+				   struct efi_device_path **rem);
+unsigned efi_dp_size(const struct efi_device_path *dp);
+struct efi_device_path *efi_dp_dup(const struct efi_device_path *dp);
+struct efi_device_path *efi_dp_append(const struct efi_device_path *dp1,
+				      const struct efi_device_path *dp2);
+struct efi_device_path *efi_dp_append_node(const struct efi_device_path *dp,
+					   const struct efi_device_path *node);
+
+
+struct efi_device_path *efi_dp_from_dev(struct udevice *dev);
+struct efi_device_path *efi_dp_from_part(struct blk_desc *desc, int part);
+struct efi_device_path *efi_dp_from_file(struct blk_desc *desc, int part,
+					 const char *path);
+struct efi_device_path *efi_dp_from_eth(void);
+void efi_dp_split_file_path(struct efi_device_path *full_path,
+			    struct efi_device_path **device_path,
+			    struct efi_device_path **file_path);
+
+#define EFI_DP_TYPE(_dp, _type, _subtype) \
+	(((_dp)->type == DEVICE_PATH_TYPE_##_type) && \
+	 ((_dp)->sub_type == DEVICE_PATH_SUB_TYPE_##_subtype))
+
 /* Convert strings from normal C strings to uEFI strings */
 static inline void ascii2unicode(u16 *unicode, const char *ascii)
 {

lib/efi_loader/Makefile

@@ -16,7 +16,7 @@ endif
 
 obj-$(CONFIG_CMD_BOOTEFI_HELLO) += helloworld_efi.o
 obj-y += efi_image_loader.o efi_boottime.o efi_runtime.o efi_console.o
-obj-y += efi_memory.o efi_device_path_to_text.o
+obj-y += efi_memory.o efi_device_path_to_text.o efi_device_path.o
 obj-$(CONFIG_LCD) += efi_gop.o
 obj-$(CONFIG_DM_VIDEO) += efi_gop.o
 obj-$(CONFIG_PARTITIONS) += efi_disk.o

lib/efi_loader/efi_boottime.c

@@ -716,8 +716,17 @@ static efi_status_t EFIAPI efi_locate_device_path(efi_guid_t *protocol,
 			struct efi_device_path **device_path,
 			efi_handle_t *device)
 {
-	EFI_ENTRY("%p, %p, %p", protocol, device_path, device);
-	return EFI_EXIT(EFI_NOT_FOUND);
+	struct efi_object *efiobj;
+
+	EFI_ENTRY("%pUl, %p, %p", protocol, device_path, device);
+
+	efiobj = efi_dp_find_obj(*device_path, device_path);
+	if (!efiobj)
+		return EFI_EXIT(EFI_NOT_FOUND);
+
+	*device = efiobj->handle;
+
+	return EFI_EXIT(EFI_SUCCESS);
 }
 
 /* Collapses configuration table entries, removing index i */

lib/efi_loader/efi_device_path.c

@@ -0,0 +1,563 @@
+/*
+ * EFI device path from u-boot device-model mapping
+ *
+ * (C) Copyright 2017 Rob Clark
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <blk.h>
+#include <dm.h>
+#include <usb.h>
+#include <mmc.h>
+#include <efi_loader.h>
+#include <inttypes.h>
+#include <part.h>
+
+/* template END node: */
+static const struct efi_device_path END = {
+	.type     = DEVICE_PATH_TYPE_END,
+	.sub_type = DEVICE_PATH_SUB_TYPE_END,
+	.length   = sizeof(END),
+};
+
+#define U_BOOT_GUID \
+	EFI_GUID(0xe61d73b9, 0xa384, 0x4acc, \
+		 0xae, 0xab, 0x82, 0xe8, 0x28, 0xf3, 0x62, 0x8b)
+
+/* template ROOT node: */
+static const struct efi_device_path_vendor ROOT = {
+	.dp = {
+		.type     = DEVICE_PATH_TYPE_HARDWARE_DEVICE,
+		.sub_type = DEVICE_PATH_SUB_TYPE_VENDOR,
+		.length   = sizeof(ROOT),
+	},
+	.guid = U_BOOT_GUID,
+};
+
+static void *dp_alloc(size_t sz)
+{
+	void *buf;
+
+	if (efi_allocate_pool(EFI_ALLOCATE_ANY_PAGES, sz, &buf) != EFI_SUCCESS)
+		return NULL;
+
+	return buf;
+}
+
+/*
+ * Iterate to next block in device-path, terminating (returning NULL)
+ * at /End* node.
+ */
+struct efi_device_path *efi_dp_next(const struct efi_device_path *dp)
+{
+	if (dp == NULL)
+		return NULL;
+	if (dp->type == DEVICE_PATH_TYPE_END)
+		return NULL;
+	dp = ((void *)dp) + dp->length;
+	if (dp->type == DEVICE_PATH_TYPE_END)
+		return NULL;
+	return (struct efi_device_path *)dp;
+}
+
+/*
+ * Compare two device-paths, stopping when the shorter of the two hits
+ * an End* node.  This is useful to, for example, compare a device-path
+ * representing a device with one representing a file on the device, or
+ * a device with a parent device.
+ */
+int efi_dp_match(struct efi_device_path *a, struct efi_device_path *b)
+{
+	while (1) {
+		int ret;
+
+		ret = memcmp(&a->length, &b->length, sizeof(a->length));
+		if (ret)
+			return ret;
+
+		ret = memcmp(a, b, a->length);
+		if (ret)
+			return ret;
+
+		a = efi_dp_next(a);
+		b = efi_dp_next(b);
+
+		if (!a || !b)
+			return 0;
+	}
+}
+
+
+/*
+ * See UEFI spec (section 3.1.2, about short-form device-paths..
+ * tl;dr: we can have a device-path that starts with a USB WWID
+ * or USB Class node, and a few other cases which don't encode
+ * the full device path with bus hierarchy:
+ *
+ *   - MESSAGING:USB_WWID
+ *   - MESSAGING:USB_CLASS
+ *   - MEDIA:FILE_PATH
+ *   - MEDIA:HARD_DRIVE
+ *   - MESSAGING:URI
+ */
+static struct efi_device_path *shorten_path(struct efi_device_path *dp)
+{
+	while (dp) {
+		/*
+		 * TODO: Add MESSAGING:USB_WWID and MESSAGING:URI..
+		 * in practice fallback.efi just uses MEDIA:HARD_DRIVE
+		 * so not sure when we would see these other cases.
+		 */
+		if (EFI_DP_TYPE(dp, MESSAGING_DEVICE, MSG_USB_CLASS) ||
+		    EFI_DP_TYPE(dp, MEDIA_DEVICE, HARD_DRIVE_PATH) ||
+		    EFI_DP_TYPE(dp, MEDIA_DEVICE, FILE_PATH))
+			return dp;
+
+		dp = efi_dp_next(dp);
+	}
+
+	return dp;
+}
+
+static struct efi_object *find_obj(struct efi_device_path *dp, bool short_path,
+				   struct efi_device_path **rem)
+{
+	struct efi_object *efiobj;
+
+	list_for_each_entry(efiobj, &efi_obj_list, link) {
+		int i;
+
+		for (i = 0; i < ARRAY_SIZE(efiobj->protocols); i++) {
+			struct efi_handler *handler = &efiobj->protocols[i];
+			struct efi_device_path *obj_dp;
+
+			if (!handler->guid)
+				break;
+
+			if (guidcmp(handler->guid, &efi_guid_device_path))
+				continue;
+
+			obj_dp = handler->protocol_interface;
+
+			do {
+				if (efi_dp_match(dp, obj_dp) == 0) {
+					if (rem) {
+						*rem = ((void *)dp) +
+							efi_dp_size(obj_dp);
+					}
+					return efiobj;
+				}
+
+				obj_dp = shorten_path(efi_dp_next(obj_dp));
+			} while (short_path && obj_dp);
+		}
+	}
+
+	return NULL;
+}
+
+
+/*
+ * Find an efiobj from device-path, if 'rem' is not NULL, returns the
+ * remaining part of the device path after the matched object.
+ */
+struct efi_object *efi_dp_find_obj(struct efi_device_path *dp,
+				   struct efi_device_path **rem)
+{
+	struct efi_object *efiobj;
+
+	efiobj = find_obj(dp, false, rem);
+
+	if (!efiobj)
+		efiobj = find_obj(dp, true, rem);
+
+	return efiobj;
+}
+
+/* return size not including End node: */
+unsigned efi_dp_size(const struct efi_device_path *dp)
+{
+	unsigned sz = 0;
+
+	while (dp) {
+		sz += dp->length;
+		dp = efi_dp_next(dp);
+	}
+
+	return sz;
+}
+
+struct efi_device_path *efi_dp_dup(const struct efi_device_path *dp)
+{
+	struct efi_device_path *ndp;
+	unsigned sz = efi_dp_size(dp) + sizeof(END);
+
+	if (!dp)
+		return NULL;
+
+	ndp = dp_alloc(sz);
+	memcpy(ndp, dp, sz);
+
+	return ndp;
+}
+
+struct efi_device_path *efi_dp_append(const struct efi_device_path *dp1,
+				      const struct efi_device_path *dp2)
+{
+	struct efi_device_path *ret;
+
+	if (!dp1) {
+		ret = efi_dp_dup(dp2);
+	} else if (!dp2) {
+		ret = efi_dp_dup(dp1);
+	} else {
+		/* both dp1 and dp2 are non-null */
+		unsigned sz1 = efi_dp_size(dp1);
+		unsigned sz2 = efi_dp_size(dp2);
+		void *p = dp_alloc(sz1 + sz2 + sizeof(END));
+		memcpy(p, dp1, sz1);
+		memcpy(p + sz1, dp2, sz2);
+		memcpy(p + sz1 + sz2, &END, sizeof(END));
+		ret = p;
+	}
+
+	return ret;
+}
+
+struct efi_device_path *efi_dp_append_node(const struct efi_device_path *dp,
+					   const struct efi_device_path *node)
+{
+	struct efi_device_path *ret;
+
+	if (!node && !dp) {
+		ret = efi_dp_dup(&END);
+	} else if (!node) {
+		ret = efi_dp_dup(dp);
+	} else if (!dp) {
+		unsigned sz = node->length;
+		void *p = dp_alloc(sz + sizeof(END));
+		memcpy(p, node, sz);
+		memcpy(p + sz, &END, sizeof(END));
+		ret = p;
+	} else {
+		/* both dp and node are non-null */
+		unsigned sz = efi_dp_size(dp);
+		void *p = dp_alloc(sz + node->length + sizeof(END));
+		memcpy(p, dp, sz);
+		memcpy(p + sz, node, node->length);
+		memcpy(p + sz + node->length, &END, sizeof(END));
+		ret = p;
+	}
+
+	return ret;
+}
+
+#ifdef CONFIG_DM
+/* size of device-path not including END node for device and all parents
+ * up to the root device.
+ */
+static unsigned dp_size(struct udevice *dev)
+{
+	if (!dev || !dev->driver)
+		return sizeof(ROOT);
+
+	switch (dev->driver->id) {
+	case UCLASS_ROOT:
+	case UCLASS_SIMPLE_BUS:
+		/* stop traversing parents at this point: */
+		return sizeof(ROOT);
+	case UCLASS_MMC:
+		return dp_size(dev->parent) +
+			sizeof(struct efi_device_path_sd_mmc_path);
+	case UCLASS_MASS_STORAGE:
+	case UCLASS_USB_HUB:
+		return dp_size(dev->parent) +
+			sizeof(struct efi_device_path_usb_class);
+	default:
+		/* just skip over unknown classes: */
+		return dp_size(dev->parent);
+	}
+}
+
+static void *dp_fill(void *buf, struct udevice *dev)
+{
+	if (!dev || !dev->driver)
+		return buf;
+
+	switch (dev->driver->id) {
+	case UCLASS_ROOT:
+	case UCLASS_SIMPLE_BUS: {
+		/* stop traversing parents at this point: */
+		struct efi_device_path_vendor *vdp = buf;
+		*vdp = ROOT;
+		return &vdp[1];
+	}
+#if defined(CONFIG_DM_MMC) && defined(CONFIG_MMC)
+	case UCLASS_MMC: {
+		struct efi_device_path_sd_mmc_path *sddp =
+			dp_fill(buf, dev->parent);
+		struct mmc *mmc = mmc_get_mmc_dev(dev);
+		struct blk_desc *desc = mmc_get_blk_desc(mmc);
+
+		sddp->dp.type     = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
+		sddp->dp.sub_type = (desc->if_type == IF_TYPE_MMC) ?
+			DEVICE_PATH_SUB_TYPE_MSG_MMC :
+			DEVICE_PATH_SUB_TYPE_MSG_SD;
+		sddp->dp.length   = sizeof(*sddp);
+		sddp->slot_number = dev->seq;
+
+		return &sddp[1];
+	}
+#endif
+	case UCLASS_MASS_STORAGE:
+	case UCLASS_USB_HUB: {
+		struct efi_device_path_usb_class *udp =
+			dp_fill(buf, dev->parent);
+		struct usb_device *udev = dev_get_parent_priv(dev);
+		struct usb_device_descriptor *desc = &udev->descriptor;
+
+		udp->dp.type     = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
+		udp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MSG_USB_CLASS;
+		udp->dp.length   = sizeof(*udp);
+		udp->vendor_id   = desc->idVendor;
+		udp->product_id  = desc->idProduct;
+		udp->device_class    = desc->bDeviceClass;
+		udp->device_subclass = desc->bDeviceSubClass;
+		udp->device_protocol = desc->bDeviceProtocol;
+
+		return &udp[1];
+	}
+	default:
+		debug("unhandled device class: %s (%u)\n",
+		      dev->name, dev->driver->id);
+		return dp_fill(buf, dev->parent);
+	}
+}
+
+/* Construct a device-path from a device: */
+struct efi_device_path *efi_dp_from_dev(struct udevice *dev)
+{
+	void *buf, *start;
+
+	start = buf = dp_alloc(dp_size(dev) + sizeof(END));
+	buf = dp_fill(buf, dev);
+	*((struct efi_device_path *)buf) = END;
+
+	return start;
+}
+#endif
+
+static unsigned dp_part_size(struct blk_desc *desc, int part)
+{
+	unsigned dpsize;
+
+#ifdef CONFIG_BLK
+	dpsize = dp_size(desc->bdev->parent);
+#else
+	dpsize = sizeof(ROOT) + sizeof(struct efi_device_path_usb);
+#endif
+
+	if (part == 0) /* the actual disk, not a partition */
+		return dpsize;
+
+	if (desc->part_type == PART_TYPE_ISO)
+		dpsize += sizeof(struct efi_device_path_cdrom_path);
+	else
+		dpsize += sizeof(struct efi_device_path_hard_drive_path);
+
+	return dpsize;
+}
+
+static void *dp_part_fill(void *buf, struct blk_desc *desc, int part)
+{
+	disk_partition_t info;
+
+#ifdef CONFIG_BLK
+	buf = dp_fill(buf, desc->bdev->parent);
+#else
+	/*
+	 * We *could* make a more accurate path, by looking at if_type
+	 * and handling all the different cases like we do for non-
+	 * legacy (ie CONFIG_BLK=y) case.  But most important thing
+	 * is just to have a unique device-path for if_type+devnum.
+	 * So map things to a fictional USB device:
+	 */
+	struct efi_device_path_usb *udp;
+
+	memcpy(buf, &ROOT, sizeof(ROOT));
+	buf += sizeof(ROOT);
+
+	udp = buf;
+	udp->dp.type = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
+	udp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MSG_USB;
+	udp->dp.length = sizeof(*udp);
+	udp->parent_port_number = desc->if_type;
+	udp->usb_interface = desc->devnum;
+	buf = &udp[1];
+#endif
+
+	if (part == 0) /* the actual disk, not a partition */
+		return buf;
+
+	part_get_info(desc, part, &info);
+
+	if (desc->part_type == PART_TYPE_ISO) {
+		struct efi_device_path_cdrom_path *cddp = buf;
+
+		cddp->boot_entry = part - 1;
+		cddp->dp.type = DEVICE_PATH_TYPE_MEDIA_DEVICE;
+		cddp->dp.sub_type = DEVICE_PATH_SUB_TYPE_CDROM_PATH;
+		cddp->dp.length = sizeof(*cddp);
+		cddp->partition_start = info.start;
+		cddp->partition_end = info.size;
+
+		buf = &cddp[1];
+	} else {
+		struct efi_device_path_hard_drive_path *hddp = buf;
+
+		hddp->dp.type = DEVICE_PATH_TYPE_MEDIA_DEVICE;
+		hddp->dp.sub_type = DEVICE_PATH_SUB_TYPE_HARD_DRIVE_PATH;
+		hddp->dp.length = sizeof(*hddp);
+		hddp->partition_number = part - 1;
+		hddp->partition_start = info.start;
+		hddp->partition_end = info.size;
+		if (desc->part_type == PART_TYPE_EFI)
+			hddp->partmap_type = 2;
+		else
+			hddp->partmap_type = 1;
+		hddp->signature_type = desc->sig_type;
+		if (hddp->signature_type != 0)
+			memcpy(hddp->partition_signature, &desc->guid_sig,
+			       sizeof(hddp->partition_signature));
+
+		buf = &hddp[1];
+	}
+
+	return buf;
+}
+
+
+/* Construct a device-path from a partition on a blk device: */
+struct efi_device_path *efi_dp_from_part(struct blk_desc *desc, int part)
+{
+	void *buf, *start;
+
+	start = buf = dp_alloc(dp_part_size(desc, part) + sizeof(END));
+
+	buf = dp_part_fill(buf, desc, part);
+
+	*((struct efi_device_path *)buf) = END;
+
+	return start;
+}
+
+/* convert path to an UEFI style path (ie. DOS style backslashes and utf16) */
+static void path_to_uefi(u16 *uefi, const char *path)
+{
+	while (*path) {
+		char c = *(path++);
+		if (c == '/')
+			c = '\\';
+		*(uefi++) = c;
+	}
+	*uefi = '\0';
+}
+
+/*
+ * If desc is NULL, this creates a path with only the file component,
+ * otherwise it creates a full path with both device and file components
+ */
+struct efi_device_path *efi_dp_from_file(struct blk_desc *desc, int part,
+		const char *path)
+{
+	struct efi_device_path_file_path *fp;
+	void *buf, *start;
+	unsigned dpsize = 0, fpsize;
+
+	if (desc)
+		dpsize = dp_part_size(desc, part);
+
+	fpsize = sizeof(struct efi_device_path) + 2 * (strlen(path) + 1);
+	dpsize += fpsize;
+
+	start = buf = dp_alloc(dpsize + sizeof(END));
+
+	if (desc)
+		buf = dp_part_fill(buf, desc, part);
+
+	/* add file-path: */
+	fp = buf;
+	fp->dp.type = DEVICE_PATH_TYPE_MEDIA_DEVICE;
+	fp->dp.sub_type = DEVICE_PATH_SUB_TYPE_FILE_PATH;
+	fp->dp.length = fpsize;
+	path_to_uefi(fp->str, path);
+	buf += fpsize;
+
+	*((struct efi_device_path *)buf) = END;
+
+	return start;
+}
+
+#ifdef CONFIG_NET
+struct efi_device_path *efi_dp_from_eth(void)
+{
+	struct efi_device_path_mac_addr *ndp;
+	void *buf, *start;
+	unsigned dpsize = 0;
+
+	assert(eth_get_dev());
+
+#ifdef CONFIG_DM_ETH
+	dpsize += dp_size(eth_get_dev());
+#else
+	dpsize += sizeof(ROOT);
+#endif
+	dpsize += sizeof(*ndp);
+
+	start = buf = dp_alloc(dpsize + sizeof(END));
+
+#ifdef CONFIG_DM_ETH
+	buf = dp_fill(buf, eth_get_dev());
+#else
+	memcpy(buf, &ROOT, sizeof(ROOT));
+	buf += sizeof(ROOT);
+#endif
+
+	ndp = buf;
+	ndp->dp.type = DEVICE_PATH_TYPE_MESSAGING_DEVICE;
+	ndp->dp.sub_type = DEVICE_PATH_SUB_TYPE_MSG_MAC_ADDR;
+	ndp->dp.length = sizeof(*ndp);
+	memcpy(ndp->mac.addr, eth_get_ethaddr(), ARP_HLEN);
+	buf = &ndp[1];
+
+	*((struct efi_device_path *)buf) = END;
+
+	return start;
+}
+#endif
+
+/*
+ * Helper to split a full device path (containing both device and file
+ * parts) into it's constituent parts.
+ */
+void efi_dp_split_file_path(struct efi_device_path *full_path,
+			    struct efi_device_path **device_path,
+			    struct efi_device_path **file_path)
+{
+	struct efi_device_path *p, *dp, *fp;
+
+	dp = efi_dp_dup(full_path);
+	p = dp;
+	while (!EFI_DP_TYPE(p, MEDIA_DEVICE, FILE_PATH))
+		p = efi_dp_next(p);
+	fp = efi_dp_dup(p);
+
+	p->type = DEVICE_PATH_TYPE_END;
+	p->sub_type = DEVICE_PATH_SUB_TYPE_END;
+	p->length = sizeof(*p);
+
+	*device_path = dp;
+	*file_path = fp;
+}