vboot: cgpt: fix my_lba of the secondary GPT

Previously, my_lba of the secondary GPT was recorded as if that
GPT was written at the end of the device. This patch tweaks
my_lba to report where it is in the random-access GPT address space,
namely at the end of that space.

TEST=Compiled it into the firmware and observed the firmware to update
the my_lba field of the secondary GPT.
BRANCH=none
BUG=chromium:425677

Signed-off-by: Dan Ehrenberg <dehrenberg@chromium.org>

Change-Id: I88791fb2cff1086351ca8a3adeef675c4a88cc9a
Reviewed-on: https://chromium-review.googlesource.com/228942
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
Commit-Queue: Daniel Ehrenberg <dehrenberg@chromium.org>
Tested-by: Daniel Ehrenberg <dehrenberg@chromium.org>

3 files changed, 12 insertions, 8 deletions

diff --git a/firmware/lib/cgptlib/cgptlib_internal.c b/firmware/lib/cgptlib/cgptlib_internal.c
index e9f27c96..48b527ac 100644
--- a/firmware/lib/cgptlib/cgptlib_internal.c
+++ b/firmware/lib/cgptlib/cgptlib_internal.c
@@ -54,7 +54,7 @@ uint32_t HeaderCrc(GptHeader *h)
 }
 
 int CheckHeader(GptHeader *h, int is_secondary, uint64_t drive_sectors,
-	uint8_t stored_on_device)
+		uint64_t gpt_drive_sectors, uint8_t stored_on_device)
 {
 	if (!h)
 		return 1;
@@ -101,7 +101,7 @@ int CheckHeader(GptHeader *h, int is_secondary, uint64_t drive_sectors,
 	 * secondary is at the end of the drive, preceded by its entries.
 	 */
 	if (is_secondary) {
-		if (h->my_lba != drive_sectors - GPT_HEADER_SECTORS)
+		if (h->my_lba != gpt_drive_sectors - GPT_HEADER_SECTORS)
 			return 1;
 		if (h->entries_lba != h->my_lba - GPT_ENTRIES_SECTORS)
 			return 1;
@@ -245,11 +245,13 @@ int GptSanityCheck(GptData *gpt)
 		return retval;
 
 	/* Check both headers; we need at least one valid header. */
-	if (0 == CheckHeader(header1, 0, gpt->drive_sectors, gpt->stored_on_device)) {
+	if (0 == CheckHeader(header1, 0, gpt->drive_sectors,
+			     gpt->gpt_drive_sectors, gpt->stored_on_device)) {
 		gpt->valid_headers |= MASK_PRIMARY;
 		goodhdr = header1;
 	}
-	if (0 == CheckHeader(header2, 1, gpt->drive_sectors, gpt->stored_on_device)) {
+	if (0 == CheckHeader(header2, 1, gpt->drive_sectors,
+			     gpt->gpt_drive_sectors, gpt->stored_on_device)) {
 		gpt->valid_headers |= MASK_SECONDARY;
 		if (!goodhdr)
 			goodhdr = header2;
@@ -320,7 +322,7 @@ void GptRepair(GptData *gpt)
 	if (MASK_PRIMARY == gpt->valid_headers) {
 		/* Primary is good, secondary is bad */
 		Memcpy(header2, header1, sizeof(GptHeader));
-		header2->my_lba = gpt->drive_sectors - GPT_HEADER_SECTORS;
+		header2->my_lba = gpt->gpt_drive_sectors - GPT_HEADER_SECTORS;
 		header2->alternate_lba = GPT_PMBR_SECTORS;  /* Second sector. */
 		header2->entries_lba = header2->my_lba - GPT_ENTRIES_SECTORS;
 		header2->header_crc32 = HeaderCrc(header2);
diff --git a/firmware/lib/cgptlib/include/cgptlib_internal.h b/firmware/lib/cgptlib/include/cgptlib_internal.h
index 4a52420c..825bbbb2 100644
--- a/firmware/lib/cgptlib/include/cgptlib_internal.h
+++ b/firmware/lib/cgptlib/include/cgptlib_internal.h
@@ -91,7 +91,7 @@ int CheckParameters(GptData* gpt);
  * Returns 0 if header is valid, 1 if invalid.
  */
 int CheckHeader(GptHeader *h, int is_secondary, uint64_t drive_sectors,
-                uint8_t stored_on_device);
+                uint64_t gpt_drive_sectors, uint8_t stored_on_device);
 
 /**
  * Calculate and return the header CRC.
diff --git a/firmware/lib/gpt_misc.c b/firmware/lib/gpt_misc.c
index 499cc9e7..dc15d915 100644
--- a/firmware/lib/gpt_misc.c
+++ b/firmware/lib/gpt_misc.c
@@ -48,7 +48,8 @@ int AllocAndReadGptData(VbExDiskHandle_t disk_handle, GptData *gptdata)
 
 	/* Only read primary GPT if the primary header is valid */
 	GptHeader* primary_header = (GptHeader*)gptdata->primary_header;
-	if (0 == CheckHeader(primary_header, 0, gptdata->gpt_drive_sectors,
+	if (0 == CheckHeader(primary_header, 0, gptdata->drive_sectors,
+			gptdata->gpt_drive_sectors,
 			gptdata->stored_on_device)) {
 		primary_valid = 1;
 		if (0 != VbExDiskRead(disk_handle,
@@ -67,7 +68,8 @@ int AllocAndReadGptData(VbExDiskHandle_t disk_handle, GptData *gptdata)
 
 	/* Only read secondary GPT if the secondary header is valid */
 	GptHeader* secondary_header = (GptHeader*)gptdata->secondary_header;
-	if (0 == CheckHeader(secondary_header, 1, gptdata->gpt_drive_sectors,
+	if (0 == CheckHeader(secondary_header, 1, gptdata->drive_sectors,
+			gptdata->gpt_drive_sectors,
 			gptdata->stored_on_device)) {
 		secondary_valid = 1;
 		if (0 != VbExDiskRead(disk_handle,