[U-Boot] [PATCH] arm: mach-keystone: Use appended original image size in image processing

[Andrew F. Davis]

When an image is signed/encrypted on K2 devices the image may get padded
to meet alignment requirements for the signature/encryption type. The
original size is appended as 4 bytes little-endian to the end of the
final image.

Normally the trailing extra bytes are ignored and so restoring the
exact original size is not important. In the case of initrd the
original size is important as the kernel uses it to look for
additional filesystem data and can do the wrong thing when the
size is not correct.

Read off the original size and report it back from the image post
processing stage.

Signed-off-by: Andrew F. Davis <afd at ti.com>
---
 arch/arm/mach-keystone/mon.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-keystone/mon.c b/arch/arm/mach-keystone/mon.c
index 51af028590..b7ffe277c1 100644
--- a/arch/arm/mach-keystone/mon.c
+++ b/arch/arm/mach-keystone/mon.c
@@ -105,6 +105,7 @@ void board_fit_image_post_process(void **p_image, size_t *p_size)
 {
 	int result = 0;
 	void *image = *p_image;
+	uint8_t *size_image = image + (*p_size - 4);
 
 	if (strncmp(image + KS2_HS_SEC_TAG_OFFSET, "KEYS", 4)) {
 		printf("No signature found in image!\n");
@@ -120,9 +121,12 @@ void board_fit_image_post_process(void **p_image, size_t *p_size)
 	/*
 	 * Overwrite the image headers after authentication
 	 * and decryption. Update size to reflect removal
-	 * of header.
+	 * of header and restore original file size.
 	 */
-	*p_size -= KS2_HS_SEC_HEADER_LEN;
+	*p_size = *(size_image+0) <<  0 |
+	          *(size_image+1) <<  8 |
+	          *(size_image+2) << 16 |
+	          *(size_image+3) << 24;
 	memcpy(image, image + KS2_HS_SEC_HEADER_LEN, *p_size);
 
 	/*
-- 
2.17.1