From bc9a638a1031a171f0b2dfa4438aa3903fa589ae Mon Sep 17 00:00:00 2001
From: Simon Glass <sjg@chromium.org>
Date: Mon, 18 Jun 2018 08:08:25 -0600
Subject: [PATCH] efi: Tidy up device-tree-size calculation in copy_fdt()

This is a bit confusing at present since it adds 4KB to the pointer, then
rounds it up. It looks like a bug, but is not.

Move the 4KB addition into a separate statement and expand the comment.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
---
 cmd/bootefi.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/cmd/bootefi.c b/cmd/bootefi.c
index a0fd1a3158..d0f2c032a2 100644
--- a/cmd/bootefi.c
+++ b/cmd/bootefi.c
@@ -148,8 +148,12 @@ static void *copy_fdt(void *fdt)
 			fdt_ram_start = ram_start;
 	}
 
-	/* Give us at least 4kb breathing room */
-	fdt_size = ALIGN(fdt_size + 4096, EFI_PAGE_SIZE);
+	/*
+	 * Give us at least 4KB of breathing room in case the device tree needs
+	 * to be expanded later. Round up to the nearest EFI page boundary.
+	 */
+	fdt_size += 4096;
+	fdt_size = ALIGN(fdt_size + EFI_PAGE_SIZE - 1, EFI_PAGE_SIZE);
 	fdt_pages = fdt_size >> EFI_PAGE_SHIFT;
 
 	/* Safe fdt location is at 128MB */
-- 
2.39.5