vboot: cgpt: Refer to partition entries by entries_lba.

This CL accesses the partition entry array through its header's
entries_lba value.

Previously, we assume the primary entry array lies on third sector, and
the secondary array lies (1 + 32) sectors from disk end. This assumption
was fine, even Wikipedia assumed the same.

But in order for us to support writing boot code to the third sector (as
required by some Freescale board), the primary entry array must be moved
to another location. Therefore, we must use "entries_lba" to locate the
arrays from now on.

BRANCH=none
BUG=chromium:406432
TEST=unittest
TEST=`cgpt create -p` and then `cgpt show`. Make sure the table
     header and entries are properly moved.

Change-Id: Ia9008b0bb204f290b1f6240df562ce7d3a9bbff2
Reviewed-on: https://chromium-review.googlesource.com/213861
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
Tested-by: Bill Richardson <wfrichar@chromium.org>
Commit-Queue: Nam Nguyen <namnguyen@chromium.org>
Tested-by: Nam Nguyen <namnguyen@chromium.org>

cgpt/cgpt_common.c

@@ -318,14 +318,15 @@ static int GptLoad(struct drive *drive, uint32_t sector_bytes) {
                       drive->gpt.sector_bytes, GPT_HEADER_SECTOR)) {
     return -1;
   }
+  GptHeader* primary_header = (GptHeader*)drive->gpt.primary_header;
   if (CGPT_OK != Load(drive, &drive->gpt.primary_entries,
-                      GPT_PMBR_SECTOR + GPT_HEADER_SECTOR,
+                      primary_header->entries_lba,
                       drive->gpt.sector_bytes, GPT_ENTRIES_SECTORS)) {
     return -1;
   }
+  GptHeader* secondary_header = (GptHeader*)drive->gpt.secondary_header;
   if (CGPT_OK != Load(drive, &drive->gpt.secondary_entries,
-                      drive->gpt.drive_sectors - GPT_HEADER_SECTOR
+                      secondary_header->entries_lba,
-                      - GPT_ENTRIES_SECTORS,
                       drive->gpt.sector_bytes, GPT_ENTRIES_SECTORS)) {
     return -1;
   }
@@ -351,18 +352,19 @@ static int GptSave(struct drive *drive) {
       Error("Cannot write secondary header: %s\n", strerror(errno));
     }
   }
+  GptHeader* primary_header = (GptHeader*)drive->gpt.primary_header;
   if (drive->gpt.modified & GPT_MODIFIED_ENTRIES1) {
     if (CGPT_OK != Save(drive, drive->gpt.primary_entries,
-                        GPT_PMBR_SECTOR + GPT_HEADER_SECTOR,
+                        primary_header->entries_lba,
                         drive->gpt.sector_bytes, GPT_ENTRIES_SECTORS)) {
       errors++;
       Error("Cannot write primary entries: %s\n", strerror(errno));
     }
   }
+  GptHeader* secondary_header = (GptHeader*)drive->gpt.secondary_header;
   if (drive->gpt.modified & GPT_MODIFIED_ENTRIES2) {
     if (CGPT_OK != Save(drive, drive->gpt.secondary_entries,
-                        drive->gpt.drive_sectors - GPT_HEADER_SECTOR
+                        secondary_header->entries_lba,
-                        - GPT_ENTRIES_SECTORS,
                         drive->gpt.sector_bytes, GPT_ENTRIES_SECTORS)) {
       errors++;
       Error("Cannot write secondary entries: %s\n", strerror(errno));
@@ -1155,6 +1157,7 @@ uint8_t RepairHeader(GptData *gpt, const uint32_t valid_headers) {
     memcpy(primary_header, secondary_header, sizeof(GptHeader));
     primary_header->my_lba = GPT_PMBR_SECTOR;  /* the second sector on drive */
     primary_header->alternate_lba = secondary_header->my_lba;
+    /* TODO (namnguyen): Preserve (header, entries) padding space. */
     primary_header->entries_lba = primary_header->my_lba + GPT_HEADER_SECTOR;
     return GPT_MODIFIED_HEADER1;
   }

cgpt/cgpt_create.c

@@ -29,15 +29,16 @@ static int GptCreate(struct drive *drive, CgptCreateParams *params) {
     memcpy(h->signature, GPT_HEADER_SIGNATURE, GPT_HEADER_SIGNATURE_SIZE);
     h->revision = GPT_HEADER_REVISION;
     h->size = sizeof(GptHeader);
-    h->my_lba = 1;
+    h->my_lba = GPT_PMBR_SECTOR;  /* The second sector on drive. */
-    h->alternate_lba = drive->gpt.drive_sectors - 1;
+    h->alternate_lba = drive->gpt.drive_sectors - GPT_HEADER_SECTOR;
-    h->first_usable_lba = 1 + 1 + GPT_ENTRIES_SECTORS;
+    h->entries_lba = h->my_lba + GPT_HEADER_SECTOR + params->padding;
-    h->last_usable_lba = drive->gpt.drive_sectors - 1 - GPT_ENTRIES_SECTORS - 1;
+    h->first_usable_lba = h->entries_lba + GPT_ENTRIES_SECTORS;
+    h->last_usable_lba = (drive->gpt.drive_sectors - GPT_HEADER_SECTOR -
+                          GPT_ENTRIES_SECTORS - 1);
     if (CGPT_OK != GenerateGuid(&h->disk_uuid)) {
       Error("Unable to generate new GUID.\n");
       return -1;
     }
-    h->entries_lba = 2;
     h->number_of_entries = 128;
     h->size_of_entry = sizeof(GptEntry);
 

cgpt/cgpt_show.c

@@ -415,7 +415,8 @@ static int GptShow(struct drive *drive, CgptShowParams *params) {
       HeaderDetails(header, entries, indent, params->numeric);
     }
 
-    printf(GPT_FMT, (int)(GPT_PMBR_SECTOR + GPT_HEADER_SECTOR),
+    GptHeader* primary_header = (GptHeader*)drive->gpt.primary_header;
+    printf(GPT_FMT, (int)primary_header->entries_lba,
            (int)GPT_ENTRIES_SECTORS,
            drive->gpt.valid_entries & MASK_PRIMARY ? "" : "INVALID",
            "Pri GPT table");
@@ -425,8 +426,8 @@ static int GptShow(struct drive *drive, CgptShowParams *params) {
       EntriesDetails(drive, PRIMARY, params->numeric);
 
     /****************************** Secondary *************************/
-    printf(GPT_FMT, (int)(drive->gpt.drive_sectors - GPT_HEADER_SECTOR -
+    GptHeader* secondary_header = (GptHeader*)drive->gpt.secondary_header;
-                          GPT_ENTRIES_SECTORS),
+    printf(GPT_FMT, (int)secondary_header->entries_lba,
            (int)GPT_ENTRIES_SECTORS,
            drive->gpt.valid_entries & MASK_SECONDARY ? "" : "INVALID",
            "Sec GPT table");

cgpt/cmd_create.c

@@ -17,6 +17,8 @@ static void Usage(void)
          "Options:\n"
          "  -z           Zero the sectors of the GPT table and entries\n"
          "  -s           Size (in byes) of the disk (MTD only)\n"
+         "  -p           Size (in blocks) of the disk to pad between the\n"
+         "               primary GPT header and its entries, default 0\n"
          "\n", progname);
 }
 
@@ -29,7 +31,7 @@ int cmd_create(int argc, char *argv[]) {
   char *e = 0;
 
   opterr = 0;                     // quiet, you
-  while ((c=getopt(argc, argv, ":hzs:")) != -1)
+  while ((c=getopt(argc, argv, ":hzsp:")) != -1)
   {
     switch (c)
     {
@@ -39,6 +41,9 @@ int cmd_create(int argc, char *argv[]) {
     case 's':
       params.size = strtoull(optarg, &e, 0);
       break;
+    case 'p':
+      params.padding = strtoull(optarg, &e, 0);
+      break;
 
     case 'h':
       Usage();

firmware/lib/cgptlib/cgptlib_internal.c

@@ -88,14 +88,14 @@ 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 - 1)
+		if (h->my_lba != drive_sectors - GPT_HEADER_SECTOR)
 			return 1;
 		if (h->entries_lba != h->my_lba - GPT_ENTRIES_SECTORS)
 			return 1;
 	} else {
-		if (h->my_lba != 1)
+		if (h->my_lba != GPT_PMBR_SECTOR)
 			return 1;
-		if (h->entries_lba != h->my_lba + 1)
+		if (h->entries_lba < h->my_lba + 1)
 			return 1;
 	}
 
@@ -104,6 +104,7 @@ int CheckHeader(GptHeader *h, int is_secondary, uint64_t drive_sectors)
 	 * LastUsableLBA must be before the start of the secondary GPT table
 	 * array.  FirstUsableLBA <= LastUsableLBA.
 	 */
+	/* TODO(namnguyen): Also check for padding between header & entries. */
 	if (h->first_usable_lba < 2 + GPT_ENTRIES_SECTORS)
 		return 1;
 	if (h->last_usable_lba >= drive_sectors - 1 - GPT_ENTRIES_SECTORS)
@@ -295,8 +296,8 @@ 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 - 1;
+		header2->my_lba = gpt->drive_sectors - GPT_HEADER_SECTOR;
-		header2->alternate_lba = 1;
+		header2->alternate_lba = GPT_PMBR_SECTOR;  /* Second sector. */
 		header2->entries_lba = header2->my_lba - GPT_ENTRIES_SECTORS;
 		header2->header_crc32 = HeaderCrc(header2);
 		gpt->modified |= GPT_MODIFIED_HEADER2;
@@ -304,8 +305,9 @@ void GptRepair(GptData *gpt)
 	else if (MASK_SECONDARY == gpt->valid_headers) {
 		/* Secondary is good, primary is bad */
 		Memcpy(header1, header2, sizeof(GptHeader));
-		header1->my_lba = 1;
+		header1->my_lba = GPT_PMBR_SECTOR;  /* Second sector. */
-		header1->alternate_lba = gpt->drive_sectors - 1;
+		header1->alternate_lba = gpt->drive_sectors - GPT_HEADER_SECTOR;
+		/* TODO (namnguyen): Preserve (header, entries) padding. */
 		header1->entries_lba = header1->my_lba + 1;
 		header1->header_crc32 = HeaderCrc(header1);
 		gpt->modified |= GPT_MODIFIED_HEADER1;

firmware/lib/vboot_kernel.c

@@ -59,16 +59,18 @@ int AllocAndReadGptData(VbExDiskHandle_t disk_handle, GptData *gptdata)
 	/* Read data from the drive, skipping the protective MBR */
 	if (0 != VbExDiskRead(disk_handle, 1, 1, gptdata->primary_header))
 		return 1;
-	if (0 != VbExDiskRead(disk_handle, 2, entries_sectors,
+	GptHeader* primary_header = (GptHeader*)gptdata->primary_header;
-			      gptdata->primary_entries))
+	if (0 != VbExDiskRead(disk_handle, primary_header->entries_lba,
-		return 1;
+			      entries_sectors, gptdata->primary_entries))
-	if (0 != VbExDiskRead(disk_handle,
-			      gptdata->drive_sectors - entries_sectors - 1,
-			      entries_sectors, gptdata->secondary_entries))
 		return 1;
+
 	if (0 != VbExDiskRead(disk_handle, gptdata->drive_sectors - 1, 1,
 			      gptdata->secondary_header))
 		return 1;
+	GptHeader* secondary_header = (GptHeader*)gptdata->secondary_header;
+	if (0 != VbExDiskRead(disk_handle, secondary_header->entries_lba,
+			      entries_sectors, gptdata->secondary_entries))
+		return 1;
 
 	return 0;
 }
@@ -84,8 +86,14 @@ int WriteAndFreeGptData(VbExDiskHandle_t disk_handle, GptData *gptdata)
 	uint64_t entries_sectors = TOTAL_ENTRIES_SIZE / gptdata->sector_bytes;
 	int ret = 1;
 
+	/*
+	 * TODO(namnguyen): Preserve padding between primary GPT header and
+	 * its entries.
+	 */
+	uint64_t entries_lba = GPT_PMBR_SECTOR + GPT_HEADER_SECTOR;
 	if (gptdata->primary_header) {
 		GptHeader *h = (GptHeader *)(gptdata->primary_header);
+		entries_lba = h->entries_lba;
 
 		/*
 		 * Avoid even looking at this data if we don't need to. We
@@ -116,7 +124,7 @@ int WriteAndFreeGptData(VbExDiskHandle_t disk_handle, GptData *gptdata)
 					 "legacy mode is enabled.\n"));
 			} else {
 				VBDEBUG(("Updating GPT entries 1\n"));
-				if (0 != VbExDiskWrite(disk_handle, 2,
+				if (0 != VbExDiskWrite(disk_handle, entries_lba,
 						entries_sectors,
 						gptdata->primary_entries))
 					goto fail;
@@ -124,17 +132,11 @@ int WriteAndFreeGptData(VbExDiskHandle_t disk_handle, GptData *gptdata)
 		}
 	}
 
-	if (gptdata->secondary_entries) {
+	entries_lba = (gptdata->drive_sectors - entries_sectors -
-		if (gptdata->modified & GPT_MODIFIED_ENTRIES2) {
+		GPT_HEADER_SECTOR);
-			VBDEBUG(("Updating GPT header 2\n"));
-			if (0 != VbExDiskWrite(disk_handle,
-				gptdata->drive_sectors - entries_sectors - 1,
-				entries_sectors, gptdata->secondary_entries))
-				goto fail;
-		}
-	}
-
 	if (gptdata->secondary_header) {
+		GptHeader *h = (GptHeader *)(gptdata->secondary_header);
+		entries_lba = h->entries_lba;
 		if (gptdata->modified & GPT_MODIFIED_HEADER2) {
 			VBDEBUG(("Updating GPT entries 2\n"));
 			if (0 != VbExDiskWrite(disk_handle,
@@ -144,6 +146,16 @@ int WriteAndFreeGptData(VbExDiskHandle_t disk_handle, GptData *gptdata)
 		}
 	}
 
+	if (gptdata->secondary_entries) {
+		if (gptdata->modified & GPT_MODIFIED_ENTRIES2) {
+			VBDEBUG(("Updating GPT header 2\n"));
+			if (0 != VbExDiskWrite(disk_handle,
+				entries_lba, entries_sectors,
+				gptdata->secondary_entries))
+				goto fail;
+		}
+	}
+
 	ret = 0;
 
 fail:

host/include/cgpt_params.h

@@ -17,6 +17,7 @@ typedef struct CgptCreateParams {
   char *drive_name;
   int zap;
   uint64_t size;
+  uint64_t padding;
 } CgptCreateParams;
 
 typedef struct CgptAddParams {

tests/cgptlib_test.c

@@ -699,7 +699,15 @@ static int MyLbaTest(void)
 	h1->entries_lba++;
 	h2->entries_lba++;
 	RefreshCrc32(gpt);
-	EXPECT(1 == CheckHeader(h1, 0, gpt->drive_sectors));
+	/*
+	 * We support a padding between primary GPT header and its entries. So
+	 * this still passes.
+	 */
+	EXPECT(0 == CheckHeader(h1, 0, gpt->drive_sectors));
+	/*
+	 * But the secondary table should fail because it would overlap the
+	 * header, which is now lying after its entry array.
+	 */
 	EXPECT(1 == CheckHeader(h2, 1, gpt->drive_sectors));
 
 	BuildTestGptData(gpt);

tests/vboot_kernel_tests.c

@@ -139,6 +139,14 @@ VbError_t VbExDiskRead(VbExDiskHandle_t handle, uint64_t lba_start,
 
 	/* Keep valgrind happy */
 	Memset(buffer, '\0', lba_count);
+	/* Fix up entries_lba in GPT header. */
+	if (lba_start == 1 || lba_start == 1024 - 1) {
+		GptHeader* h = (GptHeader*)buffer;
+		if (lba_start == 1)
+			h->entries_lba = 1 + 1;
+		else
+			h->entries_lba = (1024 - 1 - 32);
+	}
 	return VBERROR_SUCCESS;
 }
 
@@ -245,8 +253,8 @@ static void ReadWriteGptTest(void)
 	TEST_EQ(AllocAndReadGptData(handle, &g), 0, "AllocAndRead");
 	TEST_CALLS("VbExDiskRead(h, 1, 1)\n"
 		   "VbExDiskRead(h, 2, 32)\n"
-		   "VbExDiskRead(h, 991, 32)\n"
+		   "VbExDiskRead(h, 1023, 1)\n"
-		   "VbExDiskRead(h, 1023, 1)\n");
+		   "VbExDiskRead(h, 991, 32)\n");
 	ResetCallLog();
 	/*
 	 * Valgrind complains about access to uninitialized memory here, so
@@ -262,6 +270,8 @@ static void ReadWriteGptTest(void)
 	g.modified |= GPT_MODIFIED_HEADER1 | GPT_MODIFIED_ENTRIES1;
 	ResetCallLog();
 	Memset(g.primary_header, '\0', g.sector_bytes);
+	h = (GptHeader*)g.primary_header;
+	h->entries_lba = 2;
 	TEST_EQ(WriteAndFreeGptData(handle, &g), 0, "WriteAndFree mod 1");
 	TEST_CALLS("VbExDiskWrite(h, 1, 1)\n"
 		   "VbExDiskWrite(h, 2, 32)\n");
@@ -272,11 +282,15 @@ static void ReadWriteGptTest(void)
 	g.modified = -1;
 	ResetCallLog();
 	Memset(g.primary_header, '\0', g.sector_bytes);
+	h = (GptHeader*)g.primary_header;
+	h->entries_lba = 2;
+	h = (GptHeader*)g.secondary_header;
+	h->entries_lba = 991;
 	TEST_EQ(WriteAndFreeGptData(handle, &g), 0, "WriteAndFree mod all");
 	TEST_CALLS("VbExDiskWrite(h, 1, 1)\n"
 		   "VbExDiskWrite(h, 2, 32)\n"
-		   "VbExDiskWrite(h, 991, 32)\n"
+		   "VbExDiskWrite(h, 1023, 1)\n"
-		   "VbExDiskWrite(h, 1023, 1)\n");
+		   "VbExDiskWrite(h, 991, 32)\n");
 
 	/* If legacy signature, don't modify GPT header/entries 1 */
 	ResetMocks();
@@ -286,8 +300,8 @@ static void ReadWriteGptTest(void)
 	g.modified = -1;
 	ResetCallLog();
 	TEST_EQ(WriteAndFreeGptData(handle, &g), 0, "WriteAndFree mod all");
-	TEST_CALLS("VbExDiskWrite(h, 991, 32)\n"
+	TEST_CALLS("VbExDiskWrite(h, 1023, 1)\n"
-		   "VbExDiskWrite(h, 1023, 1)\n");
+		   "VbExDiskWrite(h, 991, 32)\n");
 
 	/* Error reading */
 	ResetMocks();
@@ -327,6 +341,8 @@ static void ReadWriteGptTest(void)
 	AllocAndReadGptData(handle, &g);
 	g.modified = -1;
 	Memset(g.primary_header, '\0', g.sector_bytes);
+	h = (GptHeader*)g.primary_header;
+	h->entries_lba = 2;
 	TEST_NEQ(WriteAndFreeGptData(handle, &g), 0, "WriteAndFree disk fail");
 
 	ResetMocks();