[RFC 10/14] efi_loader: load device-tree specified in boot option

[Heinrich Schuchardt]

We allow to specify the triple of binary, initrd, and device-tree in boot
options.

Add the code to actually load the specified device-tree.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
---
 lib/efi_loader/efi_bootmgr.c | 57 +++++++++++++++++++++++++++++++++++-
 1 file changed, 56 insertions(+), 1 deletion(-)

diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c
index d924810a94b..3d58a928b10 100644
--- a/lib/efi_loader/efi_bootmgr.c
+++ b/lib/efi_loader/efi_bootmgr.c
@@ -1185,6 +1185,55 @@ out:
 	return ret;
 }
 
+/**
+ * load_fdt_from_load_option - load device-tree from load option
+ *
+ * Return:	pointer to loaded device-tree or NULL
+ */
+static void *load_fdt_from_load_option(void)
+{
+	struct efi_device_path *dp = NULL;
+	struct efi_file_handle *f = NULL;
+	efi_uintn_t filesize;
+	void *buffer;
+	efi_status_t ret;
+
+	dp = efi_get_dp_from_boot(&efi_guid_fdt);
+	if (!dp)
+		return NULL;
+
+	/* Open file */
+	f = efi_file_from_path(dp);
+	if (!f) {
+		log_err("Can't find fdt specified in Boot####\n");
+		goto out;
+	}
+
+	/* Get file size */
+	ret = efi_file_size(f, &filesize);
+	if (ret != EFI_SUCCESS)
+		goto out;
+
+	buffer = malloc(filesize);
+	if (!buffer) {
+		log_err("Out of memory\n");
+		goto out;
+	}
+	ret = EFI_CALL(f->read(f, &filesize, (void *)buffer));
+	if (ret != EFI_SUCCESS) {
+		log_err("Can't read fdt\n");
+		free(buffer);
+		buffer = NULL;
+	}
+
+out:
+	efi_free_pool(dp);
+	if (f)
+		EFI_CALL(f->close(f));
+
+	return buffer;
+}
+
 /**
  * efi_bootmgr_run() - execute EFI boot manager
  * @fdt:	Flat device tree
@@ -1200,6 +1249,7 @@ efi_status_t efi_bootmgr_run(void *fdt)
 	efi_handle_t handle;
 	void *load_options;
 	efi_status_t ret;
+	void *fdt_lo;
 
 	/* Initialize EFI drivers */
 	ret = efi_init_obj_list();
@@ -1215,9 +1265,14 @@ efi_status_t efi_bootmgr_run(void *fdt)
 		return ret;
 	}
 
+	fdt_lo = load_fdt_from_load_option();
+	if (fdt_lo)
+		fdt = fdt_lo;
+
 	ret = efi_install_fdt(fdt);
+	free(fdt_lo);
 	if (ret != EFI_SUCCESS) {
-		if (EFI_CALL(efi_unload_image(*handle)) == EFI_SUCCESS)
+		if (EFI_CALL(efi_unload_image(handle)) == EFI_SUCCESS)
 			free(load_options);
 		else
 			log_err("Unloading image failed\n");
-- 
2.43.0