efi_loader: Pass proper device path in on boot

EFI payloads can query for the device they were booted from. Because
we have a disconnect between loading binaries and running binaries,
we passed in a dummy device path so far.

Unfortunately that breaks grub2's logic to find its configuration
file from the same device it was booted from.

This patch adds logic to have the "load" command call into our efi
code to set the device path to the one we last loaded a binary from.

With this grub2 properly detects where we got booted from and can
find its configuration file, even when searching by-partition.

Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 25 insertions, 9 deletions

diff --git a/cmd/bootefi.c b/cmd/bootefi.c
index 2b104d4908..2f0b90a9da 100644
--- a/cmd/bootefi.c
+++ b/cmd/bootefi.c
@@ -21,16 +21,16 @@
  * In addition to the originating device we also declare the file path
  * of "bootefi" based loads to be /bootefi.
  */
-static struct efi_device_path_file_path bootefi_dummy_path[] = {
+static struct efi_device_path_file_path bootefi_image_path[] = {
 	{
 		.dp.type = DEVICE_PATH_TYPE_MEDIA_DEVICE,
 		.dp.sub_type = DEVICE_PATH_SUB_TYPE_FILE_PATH,
-		.dp.length = sizeof(bootefi_dummy_path[0]),
+		.dp.length = sizeof(bootefi_image_path[0]),
 		.str = { 'b','o','o','t','e','f','i' },
 	}, {
 		.dp.type = DEVICE_PATH_TYPE_END,
 		.dp.sub_type = DEVICE_PATH_SUB_TYPE_END,
-		.dp.length = sizeof(bootefi_dummy_path[0]),
+		.dp.length = sizeof(bootefi_image_path[0]),
 	}
 };
 
@@ -38,14 +38,14 @@ static efi_status_t bootefi_open_dp(void *handle, efi_guid_t *protocol,
 			void **protocol_interface, void *agent_handle,
 			void *controller_handle, uint32_t attributes)
 {
-	*protocol_interface = bootefi_dummy_path;
+	*protocol_interface = bootefi_image_path;
 	return EFI_SUCCESS;
 }
 
 /* The EFI loaded_image interface for the image executed via "bootefi" */
 static struct efi_loaded_image loaded_image_info = {
-	.device_handle = bootefi_dummy_path,
-	.file_path = bootefi_dummy_path,
+	.device_handle = bootefi_image_path,
+	.file_path = bootefi_image_path,
 };
 
 /* The EFI object struct for the image executed via "bootefi" */
@@ -63,7 +63,7 @@ static struct efi_object loaded_image_info_obj = {
 		{
 			/*
 			 * When asking for the device path interface, return
-			 * bootefi_dummy_path
+			 * bootefi_image_path
 			 */
 			.guid = &efi_guid_device_path,
 			.open = &bootefi_open_dp,
@@ -73,11 +73,11 @@ static struct efi_object loaded_image_info_obj = {
 
 /* The EFI object struct for the device the "bootefi" image was loaded from */
 static struct efi_object bootefi_device_obj = {
-	.handle = bootefi_dummy_path,
+	.handle = bootefi_image_path,
 	.protocols = {
 		{
 			/* When asking for the device path interface, return
-			 * bootefi_dummy_path */
+			 * bootefi_image_path */
 			.guid = &efi_guid_device_path,
 			.open = &bootefi_open_dp,
 		}
@@ -188,3 +188,19 @@ U_BOOT_CMD(
 	"Boots an EFI payload from memory\n",
 	bootefi_help_text
 );
+
+void efi_set_bootdev(const char *dev, const char *devnr)
+{
+	char devname[16] = { 0 }; /* dp->str is u16[16] long */
+	char *colon;
+
+	/* Assemble the condensed device name we use in efi_disk.c */
+	snprintf(devname, sizeof(devname), "%s%s", dev, devnr);
+	colon = strchr(devname, ':');
+	if (colon)
+		*colon = '\0';
+
+	/* Patch the bootefi_image_path to the target device */
+	memset(bootefi_image_path[0].str, 0, sizeof(bootefi_image_path[0].str));
+	ascii2unicode(bootefi_image_path[0].str, devname);
+}