| /* SPDX-License-Identifier: GPL-2.0-only */ |
| |
| #include <commonlib/helpers.h> |
| #include <console/console.h> |
| #include <region_file.h> |
| #include <string.h> |
| |
| /* |
| * A region file provides generic support for appending new data |
| * within a storage region. The book keeping is tracked in metadata |
| * blocks where an offset pointer points to the last byte of a newly |
| * allocated byte sequence. Thus, by taking 2 block offets one can |
| * determine start and size of the latest update. The data does not |
| * have to be the same consistent size, but the data size has be small |
| * enough to fit a metadata block and one data write within the region. |
| * |
| * The granularity of the block offsets are 16 bytes. By using 16-bit |
| * block offsets a region's total size can be no larger than 1MiB. |
| * However, the last 32 bytes cannot be used in the 1MiB maximum region |
| * because one needs to put a block offset indicating last byte written. |
| * An unused block offset is the value 0xffff or 0xffff0 bytes. The last |
| * block offset that can be written is 0xfffe or 0xfffe0 byte offset. |
| * |
| * The goal of this library is to provide a simple mechanism for |
| * allocating blocks of data for updates. The metadata is written first |
| * followed by the data. That means a power event between the block offset |
| * write and the data write results in blocks being allocated but not |
| * entirely written. It's up to the user of the library to sanity check |
| * data stored. |
| */ |
| |
| #define REGF_BLOCK_SHIFT 4 |
| #define REGF_BLOCK_GRANULARITY (1 << REGF_BLOCK_SHIFT) |
| #define REGF_METADATA_BLOCK_SIZE REGF_BLOCK_GRANULARITY |
| #define REGF_UNALLOCATED_BLOCK 0xffff |
| #define REGF_UPDATES_PER_METADATA_BLOCK \ |
| (REGF_METADATA_BLOCK_SIZE / sizeof(uint16_t)) |
| |
| enum { |
| RF_ONLY_METADATA = 0, |
| RF_EMPTY = -1, |
| RF_NEED_TO_EMPTY = -2, |
| RF_FATAL = -3, |
| }; |
| |
| struct metadata_block { |
| uint16_t blocks[REGF_UPDATES_PER_METADATA_BLOCK]; |
| }; |
| |
| static size_t block_to_bytes(uint16_t offset) |
| { |
| return (size_t)offset << REGF_BLOCK_SHIFT; |
| } |
| |
| static size_t bytes_to_block(size_t bytes) |
| { |
| return bytes >> REGF_BLOCK_SHIFT; |
| } |
| |
| static inline int block_offset_unallocated(uint16_t offset) |
| { |
| return offset == REGF_UNALLOCATED_BLOCK; |
| } |
| |
| static inline size_t region_file_data_begin(const struct region_file *f) |
| { |
| return f->data_blocks[0]; |
| } |
| |
| static inline size_t region_file_data_end(const struct region_file *f) |
| { |
| return f->data_blocks[1]; |
| } |
| |
| static int all_block_offsets_unallocated(const struct metadata_block *mb) |
| { |
| size_t i; |
| |
| for (i = 0; i < ARRAY_SIZE(mb->blocks); i++) { |
| if (!block_offset_unallocated(mb->blocks[i])) |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| /* Read metadata block at block i. */ |
| static int read_mb(size_t i, struct metadata_block *mb, |
| const struct region_file *f) |
| { |
| size_t offset = block_to_bytes(i); |
| |
| if (rdev_readat(&f->metadata, mb, offset, sizeof(*mb)) < 0) |
| return -1; |
| |
| return 0; |
| } |
| |
| /* Locate metadata block with the latest update */ |
| static int find_latest_mb(struct metadata_block *mb, size_t num_mb_blocks, |
| struct region_file *f) |
| { |
| size_t l = 0; |
| size_t r = num_mb_blocks; |
| |
| while (l + 1 < r) { |
| size_t mid = (l + r) / 2; |
| |
| if (read_mb(mid, mb, f) < 0) |
| return -1; |
| if (all_block_offsets_unallocated(mb)) |
| r = mid; |
| else |
| l = mid; |
| } |
| |
| /* Set the base block slot. */ |
| f->slot = l * REGF_UPDATES_PER_METADATA_BLOCK; |
| |
| /* Re-read metadata block with the latest update. */ |
| if (read_mb(l, mb, f) < 0) |
| return -1; |
| |
| return 0; |
| } |
| |
| static void find_latest_slot(struct metadata_block *mb, struct region_file *f) |
| { |
| size_t i; |
| |
| for (i = REGF_UPDATES_PER_METADATA_BLOCK - 1; i > 0; i--) { |
| if (!block_offset_unallocated(mb->blocks[i])) |
| break; |
| } |
| |
| f->slot += i; |
| } |
| |
| static int fill_data_boundaries(struct region_file *f) |
| { |
| struct region_device slots; |
| size_t offset; |
| size_t size = sizeof(f->data_blocks); |
| |
| if (f->slot == RF_ONLY_METADATA) { |
| size_t start = bytes_to_block(region_device_sz(&f->metadata)); |
| f->data_blocks[0] = start; |
| f->data_blocks[1] = start; |
| return 0; |
| } |
| |
| /* Sanity check the 2 slot sequence to read. If it's out of the |
| * metadata blocks' bounds then one needs to empty it. This is done |
| * to uniquely identify I/O vs data errors in the readat() below. */ |
| offset = (f->slot - 1) * sizeof(f->data_blocks[0]); |
| if (rdev_chain(&slots, &f->metadata, offset, size)) { |
| f->slot = RF_NEED_TO_EMPTY; |
| return 0; |
| } |
| |
| if (rdev_readat(&slots, &f->data_blocks, 0, size) < 0) { |
| printk(BIOS_ERR, "REGF failed to read data boundaries.\n"); |
| return -1; |
| } |
| |
| /* All used blocks should be incrementing from previous write. */ |
| if (region_file_data_begin(f) >= region_file_data_end(f)) { |
| printk(BIOS_ERR, "REGF data boundaries wrong. [%zd,%zd) Need to empty.\n", |
| region_file_data_begin(f), region_file_data_end(f)); |
| f->slot = RF_NEED_TO_EMPTY; |
| return 0; |
| } |
| |
| /* Ensure data doesn't exceed the region. */ |
| if (region_file_data_end(f) > |
| bytes_to_block(region_device_sz(&f->rdev))) { |
| printk(BIOS_ERR, "REGF data exceeds region %zd > %zd\n", |
| region_file_data_end(f), |
| bytes_to_block(region_device_sz(&f->rdev))); |
| f->slot = RF_NEED_TO_EMPTY; |
| } |
| |
| return 0; |
| } |
| |
| int region_file_init(struct region_file *f, const struct region_device *p) |
| { |
| struct metadata_block mb; |
| |
| /* Total number of metadata blocks is found by reading the first |
| * block offset as the metadata is allocated first. At least one |
| * metadata block is available. */ |
| |
| memset(f, 0, sizeof(*f)); |
| f->slot = RF_FATAL; |
| |
| /* Keep parent around for accessing data later. */ |
| if (rdev_chain_full(&f->rdev, p)) |
| return -1; |
| |
| if (rdev_readat(p, &mb, 0, sizeof(mb)) < 0) { |
| printk(BIOS_ERR, "REGF fail reading first metadata block.\n"); |
| return -1; |
| } |
| |
| /* No metadata has been allocated. Assume region is empty. */ |
| if (block_offset_unallocated(mb.blocks[0])) { |
| f->slot = RF_EMPTY; |
| return 0; |
| } |
| |
| /* If metadata block is 0 in size then need to empty. */ |
| if (mb.blocks[0] == 0) { |
| f->slot = RF_NEED_TO_EMPTY; |
| return 0; |
| } |
| |
| /* The region needs to be emptied as the metadata is broken. */ |
| if (rdev_chain(&f->metadata, p, 0, block_to_bytes(mb.blocks[0]))) { |
| f->slot = RF_NEED_TO_EMPTY; |
| return 0; |
| } |
| |
| /* Locate latest metadata block with latest update. */ |
| if (find_latest_mb(&mb, mb.blocks[0], f)) { |
| printk(BIOS_ERR, "REGF fail locating latest metadata block.\n"); |
| f->slot = RF_FATAL; |
| return -1; |
| } |
| |
| find_latest_slot(&mb, f); |
| |
| /* Fill in the data blocks marking the latest update. */ |
| if (fill_data_boundaries(f)) { |
| printk(BIOS_ERR, "REGF fail locating data boundaries.\n"); |
| f->slot = RF_FATAL; |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| int region_file_data(const struct region_file *f, struct region_device *rdev) |
| { |
| |
| size_t offset; |
| size_t size; |
| |
| /* Slot indicates if any data is available. */ |
| if (f->slot <= RF_ONLY_METADATA) |
| return -1; |
| |
| offset = block_to_bytes(region_file_data_begin(f)); |
| size = block_to_bytes(region_file_data_end(f)) - offset; |
| |
| return rdev_chain(rdev, &f->rdev, offset, size); |
| } |
| |
| /* |
| * Allocate enough metadata blocks to maximize data updates. Do this in |
| * terms of blocks. To solve the balance of metadata vs data, 2 linear |
| * equations are solved in terms of blocks where 'x' is number of |
| * data updates and 'y' is number of metadata blocks: |
| * |
| * x = number of data updates |
| * y = number of metadata blocks |
| * T = total blocks in region |
| * D = data size in blocks |
| * M = metadata size in blocks |
| * A = updates accounted for in each metadata block |
| * |
| * T = D * x + M * y |
| * y = x / A |
| * ----------------- |
| * T = D * x + M * x / A = x * (D + M / A) |
| * T * A = x * (D * A + M) |
| * x = T * A / (D * A + M) |
| */ |
| static int allocate_metadata(struct region_file *f, size_t data_blks) |
| { |
| size_t t, m; |
| size_t x, y; |
| uint16_t tot_metadata; |
| const size_t a = REGF_UPDATES_PER_METADATA_BLOCK; |
| const size_t d = data_blks; |
| |
| t = bytes_to_block(ALIGN_DOWN(region_device_sz(&f->rdev), |
| REGF_BLOCK_GRANULARITY)); |
| m = bytes_to_block(ALIGN_UP(REGF_METADATA_BLOCK_SIZE, |
| REGF_BLOCK_GRANULARITY)); |
| |
| /* Ensure at least one data update can fit with 1 metadata block |
| * within the region. */ |
| if (d > t - m) |
| return -1; |
| |
| /* Maximize number of updates by aligning up to the number updates in |
| * a metadata block. May not really be able to achieve the number of |
| * updates in practice, but it ensures enough metadata blocks are |
| * allocated. */ |
| x = ALIGN_UP(t * a / (d * a + m), a); |
| |
| /* One data block has to fit. */ |
| if (x == 0) |
| x = 1; |
| |
| /* Now calculate how many metadata blocks are needed. */ |
| y = ALIGN_UP(x, a) / a; |
| |
| /* Need to commit the metadata allocation. */ |
| tot_metadata = m * y; |
| if (rdev_writeat(&f->rdev, &tot_metadata, 0, sizeof(tot_metadata)) < 0) |
| return -1; |
| |
| if (rdev_chain(&f->metadata, &f->rdev, 0, |
| block_to_bytes(tot_metadata))) |
| return -1; |
| |
| /* Initialize a 0 data block to start appending from. */ |
| f->data_blocks[0] = tot_metadata; |
| f->data_blocks[1] = tot_metadata; |
| |
| return 0; |
| } |
| |
| static int update_can_fit(const struct region_file *f, size_t data_blks) |
| { |
| size_t metadata_slots; |
| size_t end_blk; |
| |
| metadata_slots = region_device_sz(&f->metadata) / sizeof(uint16_t); |
| |
| /* No more slots. */ |
| if ((size_t)f->slot + 1 >= metadata_slots) |
| return 0; |
| |
| /* See where the last block lies from the current one. */ |
| end_blk = data_blks + region_file_data_end(f); |
| |
| /* Update would have exceeded block addressing. */ |
| if (end_blk >= REGF_UNALLOCATED_BLOCK) |
| return 0; |
| |
| /* End block exceeds size of region. */ |
| if (end_blk > bytes_to_block(region_device_sz(&f->rdev))) |
| return 0; |
| |
| return 1; |
| } |
| |
| static int commit_data_allocation(struct region_file *f, size_t data_blks) |
| { |
| size_t offset; |
| |
| f->slot++; |
| |
| offset = f->slot * sizeof(uint16_t); |
| f->data_blocks[0] = region_file_data_end(f); |
| f->data_blocks[1] = region_file_data_begin(f) + data_blks; |
| |
| if (rdev_writeat(&f->metadata, &f->data_blocks[1], offset, |
| sizeof(f->data_blocks[1])) < 0) |
| return -1; |
| |
| return 0; |
| } |
| |
| static int commit_data(const struct region_file *f, |
| const struct update_region_file_entry *entries, |
| size_t num_entries) |
| { |
| size_t offset = block_to_bytes(region_file_data_begin(f)); |
| for (int i = 0; i < num_entries; i++) { |
| if (rdev_writeat(&f->rdev, entries[i].data, offset, entries[i].size) < 0) |
| return -1; |
| offset += entries[i].size; |
| } |
| return 0; |
| } |
| |
| static int handle_empty(struct region_file *f, size_t data_blks) |
| { |
| if (allocate_metadata(f, data_blks)) { |
| printk(BIOS_ERR, "REGF metadata allocation failed: %zd data blocks %zd total blocks\n", |
| data_blks, bytes_to_block(region_device_sz(&f->rdev))); |
| return -1; |
| } |
| |
| f->slot = RF_ONLY_METADATA; |
| |
| return 0; |
| } |
| |
| static int handle_need_to_empty(struct region_file *f) |
| { |
| if (rdev_eraseat(&f->rdev, 0, region_device_sz(&f->rdev)) < 0) { |
| printk(BIOS_ERR, "REGF empty failed.\n"); |
| return -1; |
| } |
| |
| f->slot = RF_EMPTY; |
| |
| return 0; |
| } |
| |
| static int handle_update(struct region_file *f, size_t blocks, |
| const struct update_region_file_entry *entries, |
| size_t num_entries) |
| { |
| if (!update_can_fit(f, blocks)) { |
| printk(BIOS_INFO, "REGF update can't fit. Will empty.\n"); |
| f->slot = RF_NEED_TO_EMPTY; |
| return 0; |
| } |
| |
| if (commit_data_allocation(f, blocks)) { |
| printk(BIOS_ERR, "REGF failed to commit data allocation.\n"); |
| return -1; |
| } |
| |
| if (commit_data(f, entries, num_entries)) { |
| printk(BIOS_ERR, "REGF failed to commit data.\n"); |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| int region_file_update_data_arr(struct region_file *f, |
| const struct update_region_file_entry *entries, |
| size_t num_entries) |
| { |
| int ret; |
| size_t blocks; |
| size_t size = 0; |
| |
| for (int i = 0; i < num_entries; i++) |
| size += entries[i].size; |
| blocks = bytes_to_block(ALIGN_UP(size, REGF_BLOCK_GRANULARITY)); |
| |
| while (1) { |
| int prev_slot = f->slot; |
| |
| switch (f->slot) { |
| case RF_EMPTY: |
| ret = handle_empty(f, blocks); |
| break; |
| case RF_NEED_TO_EMPTY: |
| ret = handle_need_to_empty(f); |
| break; |
| case RF_FATAL: |
| ret = -1; |
| break; |
| default: |
| ret = handle_update(f, blocks, entries, num_entries); |
| break; |
| } |
| |
| /* Failing case. No more updates allowed to be attempted. */ |
| if (ret) { |
| f->slot = RF_FATAL; |
| break; |
| } |
| |
| /* No more state changes and data committed. */ |
| if (f->slot > RF_ONLY_METADATA && prev_slot != f->slot) |
| break; |
| } |
| |
| return ret; |
| } |
| |
| int region_file_update_data(struct region_file *f, const void *buf, size_t size) |
| { |
| struct update_region_file_entry entry = { |
| .size = size, |
| .data = buf, |
| }; |
| return region_file_update_data_arr(f, &entry, 1); |
| } |