/* * This file is part of the coreboot project. * * Copyright 2016 Google Inc. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; version 2 of the License. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. */ #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(&f->rdev, p, 0, region_device_sz(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 void *buf, size_t size) { size_t offset = block_to_bytes(region_file_data_begin(f)); if (rdev_writeat(&f->rdev, buf, offset, size) < 0) return -1; 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 void *buf, size_t size) { 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, buf, size)) { printk(BIOS_ERR, "REGF failed to commit data.\n"); return -1; } return 0; } int region_file_update_data(struct region_file *f, const void *buf, size_t size) { int ret; size_t blocks; 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, buf, size); break; } /* Failing case. No more updates allowed to be attempted. */ if (ret) { f->slot = RF_FATAL; break; } /* No more state changes and data commited. */ if (f->slot > RF_ONLY_METADATA && prev_slot != f->slot) break; } return ret; }