[PATCH v2 2/3] part: efi: add GPT PTE cache used with part_get_info_cached() API
Neil Armstrong
neil.armstrong at linaro.org
Tue Apr 8 11:13:41 CEST 2025
Implement a simple cache for part_efi to be used by the newly
introduced part_get_info_cached() API.
The cache simply stores a successfully scanned GPT PTE if called
from the part_get_info_cached() ops, and will return the cached
data if the blk_desc and lba offset matches, invalidating the
cache if not.
The cache will only operate if called from the part_get_info_cached()
API, all the over calls will operate uncached, making sure we
can still update & re-scan the GPT partitions like before.
Signed-off-by: Neil Armstrong <neil.armstrong at linaro.org>
---
disk/part_efi.c | 114 +++++++++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 96 insertions(+), 18 deletions(-)
diff --git a/disk/part_efi.c b/disk/part_efi.c
index 932d058c184ce6946b7142e7c2d9637b28e4661e..949968fcd30fc18766a023e73f43ca1381dcef89 100644
--- a/disk/part_efi.c
+++ b/disk/part_efi.c
@@ -55,12 +55,58 @@ static inline u32 efi_crc32(const void *buf, u32 len)
static int pmbr_part_valid(struct partition *part);
static int is_pmbr_valid(legacy_mbr * mbr);
static int is_gpt_valid(struct blk_desc *desc, u64 lba, gpt_header *pgpt_head,
- gpt_entry **pgpt_pte);
+ gpt_entry **pgpt_pte, bool cache);
static gpt_entry *alloc_read_gpt_entries(struct blk_desc *desc,
gpt_header *pgpt_head);
static int is_pte_valid(gpt_entry * pte);
static int find_valid_gpt(struct blk_desc *desc, gpt_header *gpt_head,
- gpt_entry **pgpt_pte);
+ gpt_entry **pgpt_pte, bool cache);
+
+static struct gpt_pte_cache_data {
+ struct blk_desc *desc;
+ u64 lba;
+ gpt_entry *gpt_pte;
+ gpt_header gpt_head;
+} gpt_pte_cache;
+
+static void clear_gpt_pte_cache(void)
+{
+ if (gpt_pte_cache.desc) {
+ if (gpt_pte_cache.gpt_pte)
+ free(gpt_pte_cache.gpt_pte);
+
+ memset(&gpt_pte_cache, 0, sizeof(gpt_pte_cache));
+ }
+}
+
+static void cache_gpt_pte(struct blk_desc *desc, u64 lba,
+ gpt_entry *gpt_pte, gpt_header *pgpt_head)
+{
+ if (gpt_pte_cache.gpt_pte)
+ free(gpt_pte_cache.gpt_pte);
+
+ gpt_pte_cache.desc = desc;
+ gpt_pte_cache.lba = lba;
+ gpt_pte_cache.gpt_pte = gpt_pte;
+ if (pgpt_head)
+ memcpy(&gpt_pte_cache.gpt_head, pgpt_head, sizeof(gpt_header));
+}
+
+static gpt_entry *get_cached_gpt_pte(struct blk_desc *desc, u64 lba,
+ gpt_header *pgpt_head)
+{
+ if (gpt_pte_cache.desc && gpt_pte_cache.gpt_pte) {
+ if (gpt_pte_cache.desc == desc &&
+ gpt_pte_cache.lba == lba) {
+ memcpy(pgpt_head, &gpt_pte_cache.gpt_head, sizeof(gpt_header));
+ return gpt_pte_cache.gpt_pte;
+ }
+
+ clear_gpt_pte_cache();
+ }
+
+ return NULL;
+}
static char *print_efiname(gpt_entry *pte)
{
@@ -205,7 +251,7 @@ int get_disk_guid(struct blk_desc *desc, char *guid)
unsigned char *guid_bin;
/* This function validates AND fills in the GPT header and PTE */
- if (find_valid_gpt(desc, gpt_head, &gpt_pte) != 1)
+ if (find_valid_gpt(desc, gpt_head, &gpt_pte, false) != 1)
return -EINVAL;
guid_bin = gpt_head->disk_guid.b;
@@ -224,7 +270,7 @@ static void __maybe_unused part_print_efi(struct blk_desc *desc)
unsigned char *uuid;
/* This function validates AND fills in the GPT header and PTE */
- if (find_valid_gpt(desc, gpt_head, &gpt_pte) != 1)
+ if (find_valid_gpt(desc, gpt_head, &gpt_pte, false) != 1)
return;
debug("%s: gpt-entry at %p\n", __func__, gpt_pte);
@@ -258,8 +304,13 @@ static void __maybe_unused part_print_efi(struct blk_desc *desc)
return;
}
-static int __maybe_unused part_get_info_efi(struct blk_desc *desc, int part,
- struct disk_partition *info)
+static void __maybe_unused part_get_info_cache_free_efi(struct blk_desc *desc)
+{
+ clear_gpt_pte_cache();
+}
+
+static int _part_get_info_efi(struct blk_desc *desc, int part,
+ struct disk_partition *info, bool cache)
{
ALLOC_CACHE_ALIGN_BUFFER_PAD(gpt_header, gpt_head, 1, desc->blksz);
gpt_entry *gpt_pte = NULL;
@@ -271,13 +322,14 @@ static int __maybe_unused part_get_info_efi(struct blk_desc *desc, int part,
}
/* This function validates AND fills in the GPT header and PTE */
- if (find_valid_gpt(desc, gpt_head, &gpt_pte) != 1)
+ if (find_valid_gpt(desc, gpt_head, &gpt_pte, cache) != 1)
return -EINVAL;
if (part > le32_to_cpu(gpt_head->num_partition_entries) ||
!is_pte_valid(&gpt_pte[part - 1])) {
log_debug("Invalid partition number %d\n", part);
- free(gpt_pte);
+ if (!cache)
+ free(gpt_pte);
return -EPERM;
}
@@ -307,11 +359,23 @@ static int __maybe_unused part_get_info_efi(struct blk_desc *desc, int part,
log_debug("start 0x" LBAF ", size 0x" LBAF ", name %s\n", info->start,
info->size, info->name);
- /* Remember to free pte */
- free(gpt_pte);
+ if (!cache)
+ free(gpt_pte);
return 0;
}
+static int __maybe_unused part_get_info_cached_efi(struct blk_desc *desc, int part,
+ struct disk_partition *info)
+{
+ return _part_get_info_efi(desc, part, info, true);
+}
+
+static int __maybe_unused part_get_info_efi(struct blk_desc *desc, int part,
+ struct disk_partition *info)
+{
+ return _part_get_info_efi(desc, part, info, false);
+}
+
static int part_test_efi(struct blk_desc *desc)
{
ALLOC_CACHE_ALIGN_BUFFER_PAD(legacy_mbr, legacymbr, 1, desc->blksz);
@@ -689,7 +753,7 @@ int gpt_verify_headers(struct blk_desc *desc, gpt_header *gpt_head,
*/
if (is_gpt_valid(desc,
GPT_PRIMARY_PARTITION_TABLE_LBA,
- gpt_head, gpt_pte) != 1) {
+ gpt_head, gpt_pte, false) != 1) {
log_debug("Invalid GPT\n");
return -1;
}
@@ -706,7 +770,7 @@ int gpt_verify_headers(struct blk_desc *desc, gpt_header *gpt_head,
}
if (is_gpt_valid(desc, (desc->lba - 1),
- gpt_head, gpt_pte) != 1) {
+ gpt_head, gpt_pte, false) != 1) {
log_debug("Invalid Backup GPT\n");
return -1;
}
@@ -765,9 +829,9 @@ int gpt_repair_headers(struct blk_desc *desc)
int ret = -1;
is_gpt1_valid = is_gpt_valid(desc, GPT_PRIMARY_PARTITION_TABLE_LBA,
- gpt_h1, &gpt_e1);
+ gpt_h1, &gpt_e1, false);
is_gpt2_valid = is_gpt_valid(desc, desc->lba - 1,
- gpt_h2, &gpt_e2);
+ gpt_h2, &gpt_e2, false);
if (is_gpt1_valid && is_gpt2_valid) {
ret = 0;
@@ -1023,12 +1087,13 @@ static int is_pmbr_valid(legacy_mbr *mbr)
* lba is the logical block address of the GPT header to test
* gpt is a GPT header ptr, filled on return.
* ptes is a PTEs ptr, filled on return.
+ * cache is a bool, true to use the cached gpt_pte from previous call
*
* Description: returns 1 if valid, 0 on error, 2 if ignored header
* If valid, returns pointers to PTEs.
*/
static int is_gpt_valid(struct blk_desc *desc, u64 lba, gpt_header *pgpt_head,
- gpt_entry **pgpt_pte)
+ gpt_entry **pgpt_pte, bool cache)
{
/* Confirm valid arguments prior to allocation. */
if (!desc || !pgpt_head) {
@@ -1036,6 +1101,12 @@ static int is_gpt_valid(struct blk_desc *desc, u64 lba, gpt_header *pgpt_head,
return 0;
}
+ if (cache) {
+ *pgpt_pte = get_cached_gpt_pte(desc, lba, pgpt_head);
+ if (*pgpt_pte)
+ return 1;
+ }
+
ALLOC_CACHE_ALIGN_BUFFER_PAD(legacy_mbr, mbr, 1, desc->blksz);
/* Read MBR Header from device */
@@ -1081,6 +1152,9 @@ static int is_gpt_valid(struct blk_desc *desc, u64 lba, gpt_header *pgpt_head,
return 0;
}
+ if (cache)
+ cache_gpt_pte(desc, lba, *pgpt_pte, pgpt_head);
+
/* We're done, all's well */
return 1;
}
@@ -1090,23 +1164,25 @@ static int is_gpt_valid(struct blk_desc *desc, u64 lba, gpt_header *pgpt_head,
*
* gpt is a GPT header ptr, filled on return.
* ptes is a PTEs ptr, filled on return.
+ * cache if a bool, use cached GPT if available
*
* Description: returns 1 if found a valid gpt, 0 on error.
* If valid, returns pointers to PTEs.
*/
static int find_valid_gpt(struct blk_desc *desc, gpt_header *gpt_head,
- gpt_entry **pgpt_pte)
+ gpt_entry **pgpt_pte, bool cache)
{
int r;
r = is_gpt_valid(desc, GPT_PRIMARY_PARTITION_TABLE_LBA, gpt_head,
- pgpt_pte);
+ pgpt_pte, cache);
if (r != 1) {
if (r != 2)
log_debug("Invalid GPT\n");
- if (is_gpt_valid(desc, desc->lba - 1, gpt_head, pgpt_pte)
+ if (is_gpt_valid(desc, desc->lba - 1, gpt_head, pgpt_pte,
+ true)
!= 1) {
log_debug("Invalid Backup GPT\n");
return 0;
@@ -1210,6 +1286,8 @@ U_BOOT_PART_TYPE(a_efi) = {
.name = "EFI",
.part_type = PART_TYPE_EFI,
.max_entries = GPT_ENTRY_NUMBERS,
+ .get_info_cache_free = part_get_info_ptr(part_get_info_cache_free_efi),
+ .get_info_cached = part_get_info_ptr(part_get_info_cached_efi),
.get_info = part_get_info_ptr(part_get_info_efi),
.print = part_print_ptr(part_print_efi),
.test = part_test_efi,
--
2.34.1
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