[MTD] Improve heuristic for detecting wrong-endian RedBoot partition table

Also limit the amount we scan to one eraseblock.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

diff --git a/drivers/mtd/redboot.c b/drivers/mtd/redboot.c
index a459ffa1e6766a1a1f414255573d8422c911e814..a61351f88ec046d894bf07bc042907e2a22bb364 100644 (file)
--- a/drivers/mtd/redboot.c
+++ b/drivers/mtd/redboot.c
@@ -94,7 +94,16 @@ static int parse_redboot_partitions(struct mtd_info *master,
                         * (NOTE: this is 'size' not 'data_length'; size is
                         * the full size of the entry.)
                         */
-                       if (swab32(buf[i].size) == master->erasesize) {
+
+                       /* RedBoot can combine the FIS directory and
+                          config partitions into a single eraseblock;
+                          we assume wrong-endian if either the swapped
+                          'size' matches the eraseblock size precisely,
+                          or if the swapped size actually fits in an
+                          eraseblock while the unswapped size doesn't. */
+                       if (swab32(buf[i].size) == master->erasesize ||
+                           (buf[i].size > master->erasesize
+                            && swab32(buf[i].size) < master->erasesize)) {
                                int j;
                                /* Update numslots based on actual FIS directory size */
                                numslots = swab32(buf[i].size) / sizeof (struct fis_image_desc);
@@ -122,7 +131,7 @@ static int parse_redboot_partitions(struct mtd_info *master,
                                        swab32s(&buf[j].desc_cksum);
                                        swab32s(&buf[j].file_cksum);
                                }
-                       } else {
+                       } else if (buf[i].size < master->erasesize) {
                                /* Update numslots based on actual FIS directory size */
                                numslots = buf[i].size / sizeof(struct fis_image_desc);
                        }