1 /* 2 * Copyright (c) 2020-2021 Apple Inc. All rights reserved. 3 * 4 * @APPLE_LICENSE_HEADER_START@ 5 * 6 * This file contains Original Code and/or Modifications of Original Code 7 * as defined in and that are subject to the Apple Public Source License 8 * Version 2.0 (the 'License'). You may not use this file except in 9 * compliance with the License. Please obtain a copy of the License at 10 * http://www.opensource.apple.com/apsl/ and read it before using this 11 * file. 12 * 13 * The Original Code and all software distributed under the License are 14 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 15 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 16 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 17 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 18 * Please see the License for the specific language governing rights and 19 * limitations under the License. 20 * 21 * @APPLE_LICENSE_HEADER_END@ 22 */ 23 24 #ifndef log_mem_h 25 #define log_mem_h 26 27 #include <stddef.h> 28 #include <stdint.h> 29 #include <sys/param.h> 30 31 /* 32 * A simple allocator on a top of a plain byte array. Primarily intended to 33 * support OS kernel logging in order to avoid dependency to VM. 34 */ 35 typedef struct logmem_s { 36 lck_spin_t lm_lock; 37 uint8_t *lm_mem; 38 uint8_t *lm_mem_map; 39 size_t lm_mem_size; 40 size_t lm_cap_order; 41 size_t lm_min_order; 42 size_t lm_max_order; 43 uint32_t lm_cnt_allocations; 44 uint32_t lm_cnt_failed_size; 45 uint32_t lm_cnt_failed_full; 46 uint32_t lm_cnt_failed_lmoff; 47 uint32_t lm_cnt_free; 48 } logmem_t; 49 50 /* 51 * Initializes dynamically allocated logmem. The caller is responsible for 52 * allocating and providing backing memory for both data and the bitmap. 53 * LOGMEM_SIZE and LOGMEM_MAP_SIZE provide a way to determine the right sizes. 54 */ 55 void logmem_init(logmem_t *, void *, size_t, size_t, size_t, size_t); 56 57 /* 58 * Returns true if the logmem is initialized, false otherwise. 59 */ 60 bool logmem_ready(const logmem_t *); 61 62 /* 63 * Allocates memory from a respective logmem. Returns a pointer to the beginning 64 * of the allocated block. The resulting size of the allocated block is equal or 65 * bigger than the size passed in during the call. The function comes in two 66 * flavours, locking and non-locking. The caller is responsible for choosing the 67 * right one based on where and how the logmem is used. 68 */ 69 void *logmem_alloc(logmem_t *, size_t *); 70 void *logmem_alloc_locked(logmem_t *, size_t *); 71 72 /* 73 * Frees memory previously allocated by logmem_alloc*(). The caller must call 74 * logmem_free*() with exact pointer and size value returned by logmem_alloc*(). 75 * The function comes in two flavours, locking and non-locking. The caller is 76 * responsible for choosing the right one based on where and how the logmem is 77 * used. 78 */ 79 void logmem_free(logmem_t *, void *, size_t); 80 void logmem_free_locked(logmem_t *, void *, size_t); 81 82 /* 83 * Returns the maximum memory size allocatable by the logmem. 84 */ 85 size_t logmem_max_size(const logmem_t *); 86 87 /* 88 * Returns true if logmem is empty, false otherwise. 89 */ 90 bool logmem_empty(const logmem_t *); 91 92 /* 93 * Returns an amount of memory the logmem needs to be initialized with in order 94 * to provide allocations and to maintain its internal state. The caller should 95 * use this function to get the right amount, allocate the memory accodingly and 96 * pass it to logmem_init(). 97 */ 98 size_t logmem_required_size(size_t, size_t); 99 100 #endif /* log_mem_h */ 101