1 // SPDX-License-Identifier: BSD-2-Clause 2 /* 3 * Copyright (c) 2014, STMicroelectronics International N.V. 4 * Copyright (c) 2018-2019, Linaro Limited 5 */ 6 7 8 #include <assert.h> 9 #include <compiler.h> 10 #include <malloc.h> 11 #include <mempool.h> 12 #include <string.h> 13 #include <util.h> 14 15 #if defined(__KERNEL__) 16 #include <kernel/mutex.h> 17 #include <kernel/panic.h> 18 #include <kernel/thread.h> 19 #include <kernel/refcount.h> 20 #endif 21 22 /* 23 * Allocation of temporary memory buffers which are used in a stack like 24 * fashion. One exmaple is when a Big Number is needed for a temporary 25 * variable in a Big Number computation: Big Number operations (add,...), 26 * crypto algorithms (rsa, ecc,,...). 27 * 28 * The allocation algorithm takes memory buffers from a pool, 29 * characterized by (cf. struct mempool): 30 * - the total size (in bytes) of the pool 31 * - the offset of the last item allocated in the pool (struct 32 * mempool_item). This offset is -1 is nothing is allocated yet. 33 * 34 * Each item consists of (struct mempool_item) 35 * - the size of the item 36 * - the offsets, in the pool, of the previous and next items 37 * 38 * The allocation allocates an item for a given size. 39 * The allocation is performed in the pool after the last 40 * allocated items. This means: 41 * - the heap is never used. 42 * - there is no assumption on the size of the allocated memory buffers. Only 43 * the size of the pool will limit the allocation. 44 * - a constant time allocation and free as there is no list scan 45 * - but a potentially fragmented memory as the allocation does not take into 46 * account "holes" in the pool (allocation is performed after the last 47 * allocated variable). Indeed, this interface is supposed to be used 48 * with stack like allocations to avoid this issue. This means that 49 * allocated items: 50 * - should have a short life cycle 51 * - if an item A is allocated before another item B, then A should be 52 * released after B. 53 * So the potential fragmentation is mitigated. 54 */ 55 56 57 struct mempool { 58 size_t size; /* size of the memory pool, in bytes */ 59 ssize_t last_offset; /* offset to the last one */ 60 vaddr_t data; 61 #ifdef CFG_MEMPOOL_REPORT_LAST_OFFSET 62 ssize_t max_last_offset; 63 #endif 64 #if defined(__KERNEL__) 65 void (*release_mem)(void *ptr, size_t size); 66 struct mutex mu; 67 struct condvar cv; 68 struct refcount refc; 69 int owner; 70 #endif 71 }; 72 73 static void get_pool(struct mempool *pool __maybe_unused) 74 { 75 #if defined(__KERNEL__) 76 /* 77 * Owner matches our thread it cannot be changed. If it doesn't 78 * match it can change any at time we're not holding the mutex to 79 * any value but our thread id. 80 */ 81 if (atomic_load_int(&pool->owner) == thread_get_id()) { 82 if (!refcount_inc(&pool->refc)) 83 panic(); 84 return; 85 } 86 87 mutex_lock(&pool->mu); 88 89 /* Wait until the pool is available */ 90 while (pool->owner != THREAD_ID_INVALID) 91 condvar_wait(&pool->cv, &pool->mu); 92 93 pool->owner = thread_get_id(); 94 refcount_set(&pool->refc, 1); 95 96 mutex_unlock(&pool->mu); 97 #endif 98 } 99 100 static void put_pool(struct mempool *pool __maybe_unused) 101 { 102 #if defined(__KERNEL__) 103 assert(atomic_load_int(&pool->owner) == thread_get_id()); 104 105 if (refcount_dec(&pool->refc)) { 106 mutex_lock(&pool->mu); 107 108 /* 109 * Do an atomic store to match the atomic load in 110 * get_pool() above. 111 */ 112 atomic_store_int(&pool->owner, THREAD_ID_INVALID); 113 condvar_signal(&pool->cv); 114 115 /* As the refcount is 0 there should be no items left */ 116 if (pool->last_offset >= 0) 117 panic(); 118 if (pool->release_mem) 119 pool->release_mem((void *)pool->data, pool->size); 120 121 mutex_unlock(&pool->mu); 122 } 123 #endif 124 } 125 126 struct mempool * 127 mempool_alloc_pool(void *data, size_t size, 128 void (*release_mem)(void *ptr, size_t size) __maybe_unused) 129 { 130 struct mempool *pool = calloc(1, sizeof(*pool)); 131 132 COMPILE_TIME_ASSERT(MEMPOOL_ALIGN >= __alignof__(struct mempool_item)); 133 assert(!((vaddr_t)data & (MEMPOOL_ALIGN - 1))); 134 135 if (pool) { 136 pool->size = size; 137 pool->data = (vaddr_t)data; 138 pool->last_offset = -1; 139 #if defined(__KERNEL__) 140 pool->release_mem = release_mem; 141 mutex_init(&pool->mu); 142 condvar_init(&pool->cv); 143 pool->owner = THREAD_ID_INVALID; 144 #endif 145 } 146 147 return pool; 148 } 149 150 void *mempool_alloc(struct mempool *pool, size_t size) 151 { 152 size_t offset; 153 struct mempool_item *new_item; 154 struct mempool_item *last_item = NULL; 155 156 get_pool(pool); 157 158 if (pool->last_offset < 0) { 159 offset = 0; 160 } else { 161 last_item = (struct mempool_item *)(pool->data + 162 pool->last_offset); 163 offset = pool->last_offset + last_item->size; 164 165 offset = ROUNDUP(offset, MEMPOOL_ALIGN); 166 if (offset > pool->size) 167 goto error; 168 } 169 170 size = sizeof(struct mempool_item) + size; 171 size = ROUNDUP(size, MEMPOOL_ALIGN); 172 if (offset + size > pool->size) 173 goto error; 174 175 new_item = (struct mempool_item *)(pool->data + offset); 176 new_item->size = size; 177 new_item->prev_item_offset = pool->last_offset; 178 if (last_item) 179 last_item->next_item_offset = offset; 180 new_item->next_item_offset = -1; 181 pool->last_offset = offset; 182 #ifdef CFG_MEMPOOL_REPORT_LAST_OFFSET 183 if (pool->last_offset > pool->max_last_offset) { 184 pool->max_last_offset = pool->last_offset; 185 DMSG("Max memory usage increased to %zu", 186 (size_t)pool->max_last_offset); 187 } 188 #endif 189 190 return new_item + 1; 191 192 error: 193 EMSG("Failed to allocate %zu bytes, please tune the pool size", size); 194 put_pool(pool); 195 return NULL; 196 } 197 198 void *mempool_calloc(struct mempool *pool, size_t nmemb, size_t size) 199 { 200 size_t sz; 201 void *p; 202 203 if (MUL_OVERFLOW(nmemb, size, &sz)) 204 return NULL; 205 206 p = mempool_alloc(pool, sz); 207 if (p) 208 memset(p, 0, sz); 209 210 return p; 211 } 212 213 void mempool_free(struct mempool *pool, void *ptr) 214 { 215 struct mempool_item *item; 216 struct mempool_item *prev_item; 217 struct mempool_item *next_item; 218 ssize_t last_offset = -1; 219 220 if (!ptr) 221 return; 222 223 item = (struct mempool_item *)((vaddr_t)ptr - 224 sizeof(struct mempool_item)); 225 if (item->prev_item_offset >= 0) { 226 prev_item = (struct mempool_item *)(pool->data + 227 item->prev_item_offset); 228 prev_item->next_item_offset = item->next_item_offset; 229 last_offset = item->prev_item_offset; 230 } 231 232 if (item->next_item_offset >= 0) { 233 next_item = (struct mempool_item *)(pool->data + 234 item->next_item_offset); 235 next_item->prev_item_offset = item->prev_item_offset; 236 last_offset = pool->last_offset; 237 } 238 239 pool->last_offset = last_offset; 240 put_pool(pool); 241 } 242