[coreboot-gerrit] Change in coreboot[master]: cbfs: store header offset as absolute value BE from fmap_top

[Marty E. Plummer (Code Review)]

Marty E. Plummer has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/36346 )

Change subject: cbfs: store header offset as absolute value BE from fmap_top
......................................................................

cbfs: store header offset as absolute value BE from fmap_top

Change-Id: Idc99b0c133faa2aa15d06f998e7371d332ffa490
Signed-off-by: Marty E. Plummer 
---
M src/lib/cbfs.c
M util/cbfstool/cbfstool.c
2 files changed, 9 insertions(+), 5 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/46/36346/1

diff --git a/src/lib/cbfs.c b/src/lib/cbfs.c
index 91368fb..8fb747f 100644
--- a/src/lib/cbfs.c
+++ b/src/lib/cbfs.c
@@ -296,13 +296,14 @@

size_t fmap_top = ___FMAP__COREBOOT_BASE + ___FMAP__COREBOOT_SIZE;

-	/* Find location of header using signed 32-bit offset from
+	/* Find location of header using unsigned 32-bit offset from
     * end of CBFS region. */
    offset = fmap_top - sizeof(int32_t);
    if (rdev_readat(bdev, &rel_offset, offset, sizeof(int32_t)) < 0)
    	return -1;

-	offset = fmap_top + rel_offset;
+	/* Subtract after converting to the native byte ordering */
+	offset = fmap_top - ntohl(rel_offset);
    if (rdev_readat(bdev, &header, offset, sizeof(header)) < 0)
    	return -1;

diff --git a/util/cbfstool/cbfstool.c b/util/cbfstool/cbfstool.c
index 65c5e08..c829005 100644
--- a/util/cbfstool/cbfstool.c
+++ b/util/cbfstool/cbfstool.c
@@ -285,8 +285,8 @@

static void fill_header_offset(void *location, uint32_t offset)
 {
-	// TODO: When we have a BE target, we'll need to store this as BE
-	write_le32(location, offset);
+	// Store as BE as all other cbfs data structures are
+	write_be32(location, offset);
 }

static int update_master_header_loc_topswap(struct cbfs_image *image,
@@ -380,7 +380,10 @@

uint32_t header_offset = CBFS_SUBHEADER(entry) -
    	buffer_get(&image.buffer);
-	header_offset = -(buffer_size(&image.buffer) - header_offset);
+	/* Store as absolute value (positive) and subtract
+	 * it in src/lib/cbfs.c:cbfs_master_header_props
+	 */
+	header_offset = buffer_size(&image.buffer) - header_offset;

h_loc = (void *)(buffer_get(&image.buffer) +
    			buffer_size(&image.buffer) - 4);