xref: /openbmc/u-boot/disk/part_efi.c (revision 70ad375e)
1 /*
2  * Copyright (C) 2008 RuggedCom, Inc.
3  * Richard Retanubun <RichardRetanubun@RuggedCom.com>
4  *
5  * SPDX-License-Identifier:	GPL-2.0+
6  */
7 
8 /*
9  * Problems with CONFIG_SYS_64BIT_LBA:
10  *
11  * struct disk_partition.start in include/part.h is sized as ulong.
12  * When CONFIG_SYS_64BIT_LBA is activated, lbaint_t changes from ulong to uint64_t.
13  * For now, it is cast back to ulong at assignment.
14  *
15  * This limits the maximum size of addressable storage to < 2 Terra Bytes
16  */
17 #include <asm/unaligned.h>
18 #include <common.h>
19 #include <command.h>
20 #include <ide.h>
21 #include <malloc.h>
22 #include <part_efi.h>
23 #include <linux/ctype.h>
24 
25 DECLARE_GLOBAL_DATA_PTR;
26 
27 #ifdef HAVE_BLOCK_DEVICE
28 /**
29  * efi_crc32() - EFI version of crc32 function
30  * @buf: buffer to calculate crc32 of
31  * @len - length of buf
32  *
33  * Description: Returns EFI-style CRC32 value for @buf
34  */
35 static inline u32 efi_crc32(const void *buf, u32 len)
36 {
37 	return crc32(0, buf, len);
38 }
39 
40 /*
41  * Private function prototypes
42  */
43 
44 static int pmbr_part_valid(struct partition *part);
45 static int is_pmbr_valid(legacy_mbr * mbr);
46 static int is_gpt_valid(block_dev_desc_t * dev_desc, unsigned long long lba,
47 				gpt_header * pgpt_head, gpt_entry ** pgpt_pte);
48 static gpt_entry *alloc_read_gpt_entries(block_dev_desc_t * dev_desc,
49 				gpt_header * pgpt_head);
50 static int is_pte_valid(gpt_entry * pte);
51 
52 static char *print_efiname(gpt_entry *pte)
53 {
54 	static char name[PARTNAME_SZ + 1];
55 	int i;
56 	for (i = 0; i < PARTNAME_SZ; i++) {
57 		u8 c;
58 		c = pte->partition_name[i] & 0xff;
59 		c = (c && !isprint(c)) ? '.' : c;
60 		name[i] = c;
61 	}
62 	name[PARTNAME_SZ] = 0;
63 	return name;
64 }
65 
66 static efi_guid_t system_guid = PARTITION_SYSTEM_GUID;
67 
68 static inline int is_bootable(gpt_entry *p)
69 {
70 	return p->attributes.fields.legacy_bios_bootable ||
71 		!memcmp(&(p->partition_type_guid), &system_guid,
72 			sizeof(efi_guid_t));
73 }
74 
75 #ifdef CONFIG_EFI_PARTITION
76 /*
77  * Public Functions (include/part.h)
78  */
79 
80 void print_part_efi(block_dev_desc_t * dev_desc)
81 {
82 	ALLOC_CACHE_ALIGN_BUFFER_PAD(gpt_header, gpt_head, 1, dev_desc->blksz);
83 	gpt_entry *gpt_pte = NULL;
84 	int i = 0;
85 	char uuid[37];
86 	unsigned char *uuid_bin;
87 
88 	if (!dev_desc) {
89 		printf("%s: Invalid Argument(s)\n", __func__);
90 		return;
91 	}
92 	/* This function validates AND fills in the GPT header and PTE */
93 	if (is_gpt_valid(dev_desc, GPT_PRIMARY_PARTITION_TABLE_LBA,
94 			 gpt_head, &gpt_pte) != 1) {
95 		printf("%s: *** ERROR: Invalid GPT ***\n", __func__);
96 		return;
97 	}
98 
99 	debug("%s: gpt-entry at %p\n", __func__, gpt_pte);
100 
101 	printf("Part\tStart LBA\tEnd LBA\t\tName\n");
102 	printf("\tAttributes\n");
103 	printf("\tType GUID\n");
104 	printf("\tPartition GUID\n");
105 
106 	for (i = 0; i < le32_to_cpu(gpt_head->num_partition_entries); i++) {
107 		/* Stop at the first non valid PTE */
108 		if (!is_pte_valid(&gpt_pte[i]))
109 			break;
110 
111 		printf("%3d\t0x%08llx\t0x%08llx\t\"%s\"\n", (i + 1),
112 			le64_to_cpu(gpt_pte[i].starting_lba),
113 			le64_to_cpu(gpt_pte[i].ending_lba),
114 			print_efiname(&gpt_pte[i]));
115 		printf("\tattrs:\t0x%016llx\n", gpt_pte[i].attributes.raw);
116 		uuid_bin = (unsigned char *)gpt_pte[i].partition_type_guid.b;
117 		uuid_bin_to_str(uuid_bin, uuid, UUID_STR_FORMAT_GUID);
118 		printf("\ttype:\t%s\n", uuid);
119 		uuid_bin = (unsigned char *)gpt_pte[i].unique_partition_guid.b;
120 		uuid_bin_to_str(uuid_bin, uuid, UUID_STR_FORMAT_GUID);
121 		printf("\tguid:\t%s\n", uuid);
122 	}
123 
124 	/* Remember to free pte */
125 	free(gpt_pte);
126 	return;
127 }
128 
129 int get_partition_info_efi(block_dev_desc_t * dev_desc, int part,
130 				disk_partition_t * info)
131 {
132 	ALLOC_CACHE_ALIGN_BUFFER_PAD(gpt_header, gpt_head, 1, dev_desc->blksz);
133 	gpt_entry *gpt_pte = NULL;
134 
135 	/* "part" argument must be at least 1 */
136 	if (!dev_desc || !info || part < 1) {
137 		printf("%s: Invalid Argument(s)\n", __func__);
138 		return -1;
139 	}
140 
141 	/* This function validates AND fills in the GPT header and PTE */
142 	if (is_gpt_valid(dev_desc, GPT_PRIMARY_PARTITION_TABLE_LBA,
143 			gpt_head, &gpt_pte) != 1) {
144 		printf("%s: *** ERROR: Invalid GPT ***\n", __func__);
145 		return -1;
146 	}
147 
148 	if (part > le32_to_cpu(gpt_head->num_partition_entries) ||
149 	    !is_pte_valid(&gpt_pte[part - 1])) {
150 		debug("%s: *** ERROR: Invalid partition number %d ***\n",
151 			__func__, part);
152 		free(gpt_pte);
153 		return -1;
154 	}
155 
156 	/* The ulong casting limits the maximum disk size to 2 TB */
157 	info->start = (u64)le64_to_cpu(gpt_pte[part - 1].starting_lba);
158 	/* The ending LBA is inclusive, to calculate size, add 1 to it */
159 	info->size = ((u64)le64_to_cpu(gpt_pte[part - 1].ending_lba) + 1)
160 		     - info->start;
161 	info->blksz = dev_desc->blksz;
162 
163 	sprintf((char *)info->name, "%s",
164 			print_efiname(&gpt_pte[part - 1]));
165 	sprintf((char *)info->type, "U-Boot");
166 	info->bootable = is_bootable(&gpt_pte[part - 1]);
167 #ifdef CONFIG_PARTITION_UUIDS
168 	uuid_bin_to_str(gpt_pte[part - 1].unique_partition_guid.b, info->uuid,
169 			UUID_STR_FORMAT_GUID);
170 #endif
171 
172 	debug("%s: start 0x" LBAF ", size 0x" LBAF ", name %s", __func__,
173 	      info->start, info->size, info->name);
174 
175 	/* Remember to free pte */
176 	free(gpt_pte);
177 	return 0;
178 }
179 
180 int test_part_efi(block_dev_desc_t * dev_desc)
181 {
182 	ALLOC_CACHE_ALIGN_BUFFER_PAD(legacy_mbr, legacymbr, 1, dev_desc->blksz);
183 
184 	/* Read legacy MBR from block 0 and validate it */
185 	if ((dev_desc->block_read(dev_desc->dev, 0, 1, (ulong *)legacymbr) != 1)
186 		|| (is_pmbr_valid(legacymbr) != 1)) {
187 		return -1;
188 	}
189 	return 0;
190 }
191 
192 /**
193  * set_protective_mbr(): Set the EFI protective MBR
194  * @param dev_desc - block device descriptor
195  *
196  * @return - zero on success, otherwise error
197  */
198 static int set_protective_mbr(block_dev_desc_t *dev_desc)
199 {
200 	/* Setup the Protective MBR */
201 	ALLOC_CACHE_ALIGN_BUFFER(legacy_mbr, p_mbr, 1);
202 	memset(p_mbr, 0, sizeof(*p_mbr));
203 
204 	if (p_mbr == NULL) {
205 		printf("%s: calloc failed!\n", __func__);
206 		return -1;
207 	}
208 	/* Append signature */
209 	p_mbr->signature = MSDOS_MBR_SIGNATURE;
210 	p_mbr->partition_record[0].sys_ind = EFI_PMBR_OSTYPE_EFI_GPT;
211 	p_mbr->partition_record[0].start_sect = 1;
212 	p_mbr->partition_record[0].nr_sects = (u32) dev_desc->lba;
213 
214 	/* Write MBR sector to the MMC device */
215 	if (dev_desc->block_write(dev_desc->dev, 0, 1, p_mbr) != 1) {
216 		printf("** Can't write to device %d **\n",
217 			dev_desc->dev);
218 		return -1;
219 	}
220 
221 	return 0;
222 }
223 
224 int write_gpt_table(block_dev_desc_t *dev_desc,
225 		gpt_header *gpt_h, gpt_entry *gpt_e)
226 {
227 	const int pte_blk_cnt = BLOCK_CNT((gpt_h->num_partition_entries
228 					   * sizeof(gpt_entry)), dev_desc);
229 	u32 calc_crc32;
230 	u64 val;
231 
232 	debug("max lba: %x\n", (u32) dev_desc->lba);
233 	/* Setup the Protective MBR */
234 	if (set_protective_mbr(dev_desc) < 0)
235 		goto err;
236 
237 	/* Generate CRC for the Primary GPT Header */
238 	calc_crc32 = efi_crc32((const unsigned char *)gpt_e,
239 			      le32_to_cpu(gpt_h->num_partition_entries) *
240 			      le32_to_cpu(gpt_h->sizeof_partition_entry));
241 	gpt_h->partition_entry_array_crc32 = cpu_to_le32(calc_crc32);
242 
243 	calc_crc32 = efi_crc32((const unsigned char *)gpt_h,
244 			      le32_to_cpu(gpt_h->header_size));
245 	gpt_h->header_crc32 = cpu_to_le32(calc_crc32);
246 
247 	/* Write the First GPT to the block right after the Legacy MBR */
248 	if (dev_desc->block_write(dev_desc->dev, 1, 1, gpt_h) != 1)
249 		goto err;
250 
251 	if (dev_desc->block_write(dev_desc->dev, 2, pte_blk_cnt, gpt_e)
252 	    != pte_blk_cnt)
253 		goto err;
254 
255 	/* recalculate the values for the Second GPT Header */
256 	val = le64_to_cpu(gpt_h->my_lba);
257 	gpt_h->my_lba = gpt_h->alternate_lba;
258 	gpt_h->alternate_lba = cpu_to_le64(val);
259 	gpt_h->header_crc32 = 0;
260 
261 	calc_crc32 = efi_crc32((const unsigned char *)gpt_h,
262 			      le32_to_cpu(gpt_h->header_size));
263 	gpt_h->header_crc32 = cpu_to_le32(calc_crc32);
264 
265 	if (dev_desc->block_write(dev_desc->dev,
266 				  le32_to_cpu(gpt_h->last_usable_lba + 1),
267 				  pte_blk_cnt, gpt_e) != pte_blk_cnt)
268 		goto err;
269 
270 	if (dev_desc->block_write(dev_desc->dev,
271 				  le32_to_cpu(gpt_h->my_lba), 1, gpt_h) != 1)
272 		goto err;
273 
274 	debug("GPT successfully written to block device!\n");
275 	return 0;
276 
277  err:
278 	printf("** Can't write to device %d **\n", dev_desc->dev);
279 	return -1;
280 }
281 
282 int gpt_fill_pte(gpt_header *gpt_h, gpt_entry *gpt_e,
283 		disk_partition_t *partitions, int parts)
284 {
285 	u32 offset = (u32)le32_to_cpu(gpt_h->first_usable_lba);
286 	ulong start;
287 	int i, k;
288 	size_t efiname_len, dosname_len;
289 #ifdef CONFIG_PARTITION_UUIDS
290 	char *str_uuid;
291 	unsigned char *bin_uuid;
292 #endif
293 
294 	for (i = 0; i < parts; i++) {
295 		/* partition starting lba */
296 		start = partitions[i].start;
297 		if (start && (start < offset)) {
298 			printf("Partition overlap\n");
299 			return -1;
300 		}
301 		if (start) {
302 			gpt_e[i].starting_lba = cpu_to_le64(start);
303 			offset = start + partitions[i].size;
304 		} else {
305 			gpt_e[i].starting_lba = cpu_to_le64(offset);
306 			offset += partitions[i].size;
307 		}
308 		if (offset >= gpt_h->last_usable_lba) {
309 			printf("Partitions layout exceds disk size\n");
310 			return -1;
311 		}
312 		/* partition ending lba */
313 		if ((i == parts - 1) && (partitions[i].size == 0))
314 			/* extend the last partition to maximuim */
315 			gpt_e[i].ending_lba = gpt_h->last_usable_lba;
316 		else
317 			gpt_e[i].ending_lba = cpu_to_le64(offset - 1);
318 
319 		/* partition type GUID */
320 		memcpy(gpt_e[i].partition_type_guid.b,
321 			&PARTITION_BASIC_DATA_GUID, 16);
322 
323 #ifdef CONFIG_PARTITION_UUIDS
324 		str_uuid = partitions[i].uuid;
325 		bin_uuid = gpt_e[i].unique_partition_guid.b;
326 
327 		if (uuid_str_to_bin(str_uuid, bin_uuid, UUID_STR_FORMAT_STD)) {
328 			printf("Partition no. %d: invalid guid: %s\n",
329 				i, str_uuid);
330 			return -1;
331 		}
332 #endif
333 
334 		/* partition attributes */
335 		memset(&gpt_e[i].attributes, 0,
336 		       sizeof(gpt_entry_attributes));
337 
338 		/* partition name */
339 		efiname_len = sizeof(gpt_e[i].partition_name)
340 			/ sizeof(efi_char16_t);
341 		dosname_len = sizeof(partitions[i].name);
342 
343 		memset(gpt_e[i].partition_name, 0,
344 		       sizeof(gpt_e[i].partition_name));
345 
346 		for (k = 0; k < min(dosname_len, efiname_len); k++)
347 			gpt_e[i].partition_name[k] =
348 				(efi_char16_t)(partitions[i].name[k]);
349 
350 		debug("%s: name: %s offset[%d]: 0x%x size[%d]: 0x" LBAF "\n",
351 		      __func__, partitions[i].name, i,
352 		      offset, i, partitions[i].size);
353 	}
354 
355 	return 0;
356 }
357 
358 int gpt_fill_header(block_dev_desc_t *dev_desc, gpt_header *gpt_h,
359 		char *str_guid, int parts_count)
360 {
361 	gpt_h->signature = cpu_to_le64(GPT_HEADER_SIGNATURE);
362 	gpt_h->revision = cpu_to_le32(GPT_HEADER_REVISION_V1);
363 	gpt_h->header_size = cpu_to_le32(sizeof(gpt_header));
364 	gpt_h->my_lba = cpu_to_le64(1);
365 	gpt_h->alternate_lba = cpu_to_le64(dev_desc->lba - 1);
366 	gpt_h->first_usable_lba = cpu_to_le64(34);
367 	gpt_h->last_usable_lba = cpu_to_le64(dev_desc->lba - 34);
368 	gpt_h->partition_entry_lba = cpu_to_le64(2);
369 	gpt_h->num_partition_entries = cpu_to_le32(GPT_ENTRY_NUMBERS);
370 	gpt_h->sizeof_partition_entry = cpu_to_le32(sizeof(gpt_entry));
371 	gpt_h->header_crc32 = 0;
372 	gpt_h->partition_entry_array_crc32 = 0;
373 
374 	if (uuid_str_to_bin(str_guid, gpt_h->disk_guid.b, UUID_STR_FORMAT_GUID))
375 		return -1;
376 
377 	return 0;
378 }
379 
380 int gpt_restore(block_dev_desc_t *dev_desc, char *str_disk_guid,
381 		disk_partition_t *partitions, int parts_count)
382 {
383 	int ret;
384 
385 	gpt_header *gpt_h = calloc(1, PAD_TO_BLOCKSIZE(sizeof(gpt_header),
386 						       dev_desc));
387 	gpt_entry *gpt_e;
388 
389 	if (gpt_h == NULL) {
390 		printf("%s: calloc failed!\n", __func__);
391 		return -1;
392 	}
393 
394 	gpt_e = calloc(1, PAD_TO_BLOCKSIZE(GPT_ENTRY_NUMBERS
395 					       * sizeof(gpt_entry),
396 					       dev_desc));
397 	if (gpt_e == NULL) {
398 		printf("%s: calloc failed!\n", __func__);
399 		free(gpt_h);
400 		return -1;
401 	}
402 
403 	/* Generate Primary GPT header (LBA1) */
404 	ret = gpt_fill_header(dev_desc, gpt_h, str_disk_guid, parts_count);
405 	if (ret)
406 		goto err;
407 
408 	/* Generate partition entries */
409 	ret = gpt_fill_pte(gpt_h, gpt_e, partitions, parts_count);
410 	if (ret)
411 		goto err;
412 
413 	/* Write GPT partition table */
414 	ret = write_gpt_table(dev_desc, gpt_h, gpt_e);
415 
416 err:
417 	free(gpt_e);
418 	free(gpt_h);
419 	return ret;
420 }
421 #endif
422 
423 /*
424  * Private functions
425  */
426 /*
427  * pmbr_part_valid(): Check for EFI partition signature
428  *
429  * Returns: 1 if EFI GPT partition type is found.
430  */
431 static int pmbr_part_valid(struct partition *part)
432 {
433 	if (part->sys_ind == EFI_PMBR_OSTYPE_EFI_GPT &&
434 		get_unaligned_le32(&part->start_sect) == 1UL) {
435 		return 1;
436 	}
437 
438 	return 0;
439 }
440 
441 /*
442  * is_pmbr_valid(): test Protective MBR for validity
443  *
444  * Returns: 1 if PMBR is valid, 0 otherwise.
445  * Validity depends on two things:
446  *  1) MSDOS signature is in the last two bytes of the MBR
447  *  2) One partition of type 0xEE is found, checked by pmbr_part_valid()
448  */
449 static int is_pmbr_valid(legacy_mbr * mbr)
450 {
451 	int i = 0;
452 
453 	if (!mbr || le16_to_cpu(mbr->signature) != MSDOS_MBR_SIGNATURE)
454 		return 0;
455 
456 	for (i = 0; i < 4; i++) {
457 		if (pmbr_part_valid(&mbr->partition_record[i])) {
458 			return 1;
459 		}
460 	}
461 	return 0;
462 }
463 
464 /**
465  * is_gpt_valid() - tests one GPT header and PTEs for validity
466  *
467  * lba is the logical block address of the GPT header to test
468  * gpt is a GPT header ptr, filled on return.
469  * ptes is a PTEs ptr, filled on return.
470  *
471  * Description: returns 1 if valid,  0 on error.
472  * If valid, returns pointers to PTEs.
473  */
474 static int is_gpt_valid(block_dev_desc_t * dev_desc, unsigned long long lba,
475 			gpt_header * pgpt_head, gpt_entry ** pgpt_pte)
476 {
477 	u32 crc32_backup = 0;
478 	u32 calc_crc32;
479 	unsigned long long lastlba;
480 
481 	if (!dev_desc || !pgpt_head) {
482 		printf("%s: Invalid Argument(s)\n", __func__);
483 		return 0;
484 	}
485 
486 	/* Read GPT Header from device */
487 	if (dev_desc->block_read(dev_desc->dev, lba, 1, pgpt_head) != 1) {
488 		printf("*** ERROR: Can't read GPT header ***\n");
489 		return 0;
490 	}
491 
492 	/* Check the GPT header signature */
493 	if (le64_to_cpu(pgpt_head->signature) != GPT_HEADER_SIGNATURE) {
494 		printf("GUID Partition Table Header signature is wrong:"
495 			"0x%llX != 0x%llX\n",
496 			le64_to_cpu(pgpt_head->signature),
497 			GPT_HEADER_SIGNATURE);
498 		return 0;
499 	}
500 
501 	/* Check the GUID Partition Table CRC */
502 	memcpy(&crc32_backup, &pgpt_head->header_crc32, sizeof(crc32_backup));
503 	memset(&pgpt_head->header_crc32, 0, sizeof(pgpt_head->header_crc32));
504 
505 	calc_crc32 = efi_crc32((const unsigned char *)pgpt_head,
506 		le32_to_cpu(pgpt_head->header_size));
507 
508 	memcpy(&pgpt_head->header_crc32, &crc32_backup, sizeof(crc32_backup));
509 
510 	if (calc_crc32 != le32_to_cpu(crc32_backup)) {
511 		printf("GUID Partition Table Header CRC is wrong:"
512 			"0x%x != 0x%x\n",
513 		       le32_to_cpu(crc32_backup), calc_crc32);
514 		return 0;
515 	}
516 
517 	/* Check that the my_lba entry points to the LBA that contains the GPT */
518 	if (le64_to_cpu(pgpt_head->my_lba) != lba) {
519 		printf("GPT: my_lba incorrect: %llX != %llX\n",
520 			le64_to_cpu(pgpt_head->my_lba),
521 			lba);
522 		return 0;
523 	}
524 
525 	/* Check the first_usable_lba and last_usable_lba are within the disk. */
526 	lastlba = (unsigned long long)dev_desc->lba;
527 	if (le64_to_cpu(pgpt_head->first_usable_lba) > lastlba) {
528 		printf("GPT: first_usable_lba incorrect: %llX > %llX\n",
529 			le64_to_cpu(pgpt_head->first_usable_lba), lastlba);
530 		return 0;
531 	}
532 	if (le64_to_cpu(pgpt_head->last_usable_lba) > lastlba) {
533 		printf("GPT: last_usable_lba incorrect: %llX > %llX\n",
534 			(u64) le64_to_cpu(pgpt_head->last_usable_lba), lastlba);
535 		return 0;
536 	}
537 
538 	debug("GPT: first_usable_lba: %llX last_usable_lba %llX last lba %llX\n",
539 		le64_to_cpu(pgpt_head->first_usable_lba),
540 		le64_to_cpu(pgpt_head->last_usable_lba), lastlba);
541 
542 	/* Read and allocate Partition Table Entries */
543 	*pgpt_pte = alloc_read_gpt_entries(dev_desc, pgpt_head);
544 	if (*pgpt_pte == NULL) {
545 		printf("GPT: Failed to allocate memory for PTE\n");
546 		return 0;
547 	}
548 
549 	/* Check the GUID Partition Table Entry Array CRC */
550 	calc_crc32 = efi_crc32((const unsigned char *)*pgpt_pte,
551 		le32_to_cpu(pgpt_head->num_partition_entries) *
552 		le32_to_cpu(pgpt_head->sizeof_partition_entry));
553 
554 	if (calc_crc32 != le32_to_cpu(pgpt_head->partition_entry_array_crc32)) {
555 		printf("GUID Partition Table Entry Array CRC is wrong:"
556 			"0x%x != 0x%x\n",
557 			le32_to_cpu(pgpt_head->partition_entry_array_crc32),
558 			calc_crc32);
559 
560 		free(*pgpt_pte);
561 		return 0;
562 	}
563 
564 	/* We're done, all's well */
565 	return 1;
566 }
567 
568 /**
569  * alloc_read_gpt_entries(): reads partition entries from disk
570  * @dev_desc
571  * @gpt - GPT header
572  *
573  * Description: Returns ptes on success,  NULL on error.
574  * Allocates space for PTEs based on information found in @gpt.
575  * Notes: remember to free pte when you're done!
576  */
577 static gpt_entry *alloc_read_gpt_entries(block_dev_desc_t * dev_desc,
578 					 gpt_header * pgpt_head)
579 {
580 	size_t count = 0, blk_cnt;
581 	gpt_entry *pte = NULL;
582 
583 	if (!dev_desc || !pgpt_head) {
584 		printf("%s: Invalid Argument(s)\n", __func__);
585 		return NULL;
586 	}
587 
588 	count = le32_to_cpu(pgpt_head->num_partition_entries) *
589 		le32_to_cpu(pgpt_head->sizeof_partition_entry);
590 
591 	debug("%s: count = %u * %u = %zu\n", __func__,
592 	      (u32) le32_to_cpu(pgpt_head->num_partition_entries),
593 	      (u32) le32_to_cpu(pgpt_head->sizeof_partition_entry), count);
594 
595 	/* Allocate memory for PTE, remember to FREE */
596 	if (count != 0) {
597 		pte = memalign(ARCH_DMA_MINALIGN,
598 			       PAD_TO_BLOCKSIZE(count, dev_desc));
599 	}
600 
601 	if (count == 0 || pte == NULL) {
602 		printf("%s: ERROR: Can't allocate 0x%zX "
603 		       "bytes for GPT Entries\n",
604 			__func__, count);
605 		return NULL;
606 	}
607 
608 	/* Read GPT Entries from device */
609 	blk_cnt = BLOCK_CNT(count, dev_desc);
610 	if (dev_desc->block_read (dev_desc->dev,
611 		le64_to_cpu(pgpt_head->partition_entry_lba),
612 		(lbaint_t) (blk_cnt), pte)
613 		!= blk_cnt) {
614 
615 		printf("*** ERROR: Can't read GPT Entries ***\n");
616 		free(pte);
617 		return NULL;
618 	}
619 	return pte;
620 }
621 
622 /**
623  * is_pte_valid(): validates a single Partition Table Entry
624  * @gpt_entry - Pointer to a single Partition Table Entry
625  *
626  * Description: returns 1 if valid,  0 on error.
627  */
628 static int is_pte_valid(gpt_entry * pte)
629 {
630 	efi_guid_t unused_guid;
631 
632 	if (!pte) {
633 		printf("%s: Invalid Argument(s)\n", __func__);
634 		return 0;
635 	}
636 
637 	/* Only one validation for now:
638 	 * The GUID Partition Type != Unused Entry (ALL-ZERO)
639 	 */
640 	memset(unused_guid.b, 0, sizeof(unused_guid.b));
641 
642 	if (memcmp(pte->partition_type_guid.b, unused_guid.b,
643 		sizeof(unused_guid.b)) == 0) {
644 
645 		debug("%s: Found an unused PTE GUID at 0x%08X\n", __func__,
646 		      (unsigned int)(uintptr_t)pte);
647 
648 		return 0;
649 	} else {
650 		return 1;
651 	}
652 }
653 #endif
654