blob: c8f1642eb54cfc7863182286be03d03599dd4dae [file] [log] [blame]
/*
* simple memory allocator, backed by mmap() so that it hands out memory
* that can be shared across processes and threads
*/
#include <sys/mman.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include <unistd.h>
#include <inttypes.h>
#include <sys/types.h>
#include <limits.h>
#include <fcntl.h>
#include "mutex.h"
#include "arch/arch.h"
#include "os/os.h"
#include "smalloc.h"
#define SMALLOC_REDZONE /* define to detect memory corruption */
#define SMALLOC_BPB 32 /* block size, bytes-per-bit in bitmap */
#define SMALLOC_BPI (sizeof(unsigned int) * 8)
#define SMALLOC_BPL (SMALLOC_BPB * SMALLOC_BPI)
#define INITIAL_SIZE 8192*1024 /* new pool size */
#define MAX_POOLS 128 /* maximum number of pools to setup */
#define SMALLOC_PRE_RED 0xdeadbeefU
#define SMALLOC_POST_RED 0x5aa55aa5U
unsigned int smalloc_pool_size = INITIAL_SIZE;
static const int int_mask = sizeof(int) - 1;
struct pool {
struct fio_mutex *lock; /* protects this pool */
void *map; /* map of blocks */
unsigned int *bitmap; /* blocks free/busy map */
size_t free_blocks; /* free blocks */
size_t nr_blocks; /* total blocks */
size_t next_non_full;
size_t mmap_size;
};
struct block_hdr {
size_t size;
#ifdef SMALLOC_REDZONE
unsigned int prered;
#endif
};
static struct pool mp[MAX_POOLS];
static unsigned int nr_pools;
static unsigned int last_pool;
static struct fio_rwlock *lock;
static inline void pool_lock(struct pool *pool)
{
fio_mutex_down(pool->lock);
}
static inline void pool_unlock(struct pool *pool)
{
fio_mutex_up(pool->lock);
}
static inline void global_read_lock(void)
{
fio_rwlock_read(lock);
}
static inline void global_read_unlock(void)
{
fio_rwlock_unlock(lock);
}
static inline void global_write_lock(void)
{
fio_rwlock_write(lock);
}
static inline void global_write_unlock(void)
{
fio_rwlock_unlock(lock);
}
static inline int ptr_valid(struct pool *pool, void *ptr)
{
unsigned int pool_size = pool->nr_blocks * SMALLOC_BPL;
return (ptr >= pool->map) && (ptr < pool->map + pool_size);
}
static inline size_t size_to_blocks(size_t size)
{
return (size + SMALLOC_BPB - 1) / SMALLOC_BPB;
}
static int blocks_iter(struct pool *pool, unsigned int pool_idx,
unsigned int idx, size_t nr_blocks,
int (*func)(unsigned int *map, unsigned int mask))
{
while (nr_blocks) {
unsigned int this_blocks, mask;
unsigned int *map;
if (pool_idx >= pool->nr_blocks)
return 0;
map = &pool->bitmap[pool_idx];
this_blocks = nr_blocks;
if (this_blocks + idx > SMALLOC_BPI) {
this_blocks = SMALLOC_BPI - idx;
idx = SMALLOC_BPI - this_blocks;
}
if (this_blocks == SMALLOC_BPI)
mask = -1U;
else
mask = ((1U << this_blocks) - 1) << idx;
if (!func(map, mask))
return 0;
nr_blocks -= this_blocks;
idx = 0;
pool_idx++;
}
return 1;
}
static int mask_cmp(unsigned int *map, unsigned int mask)
{
return !(*map & mask);
}
static int mask_clear(unsigned int *map, unsigned int mask)
{
assert((*map & mask) == mask);
*map &= ~mask;
return 1;
}
static int mask_set(unsigned int *map, unsigned int mask)
{
assert(!(*map & mask));
*map |= mask;
return 1;
}
static int blocks_free(struct pool *pool, unsigned int pool_idx,
unsigned int idx, size_t nr_blocks)
{
return blocks_iter(pool, pool_idx, idx, nr_blocks, mask_cmp);
}
static void set_blocks(struct pool *pool, unsigned int pool_idx,
unsigned int idx, size_t nr_blocks)
{
blocks_iter(pool, pool_idx, idx, nr_blocks, mask_set);
}
static void clear_blocks(struct pool *pool, unsigned int pool_idx,
unsigned int idx, size_t nr_blocks)
{
blocks_iter(pool, pool_idx, idx, nr_blocks, mask_clear);
}
static int find_next_zero(int word, int start)
{
assert(word != -1U);
word >>= start;
return ffz(word) + start;
}
static int add_pool(struct pool *pool, unsigned int alloc_size)
{
int bitmap_blocks;
void *ptr;
#ifdef SMALLOC_REDZONE
alloc_size += sizeof(unsigned int);
#endif
alloc_size += sizeof(struct block_hdr);
if (alloc_size < INITIAL_SIZE)
alloc_size = INITIAL_SIZE;
/* round up to nearest full number of blocks */
alloc_size = (alloc_size + SMALLOC_BPL - 1) & ~(SMALLOC_BPL - 1);
bitmap_blocks = alloc_size / SMALLOC_BPL;
alloc_size += bitmap_blocks * sizeof(unsigned int);
pool->mmap_size = alloc_size;
pool->nr_blocks = bitmap_blocks;
pool->free_blocks = bitmap_blocks * SMALLOC_BPB;
ptr = mmap(NULL, alloc_size, PROT_READ|PROT_WRITE,
MAP_SHARED | OS_MAP_ANON, -1, 0);
if (ptr == MAP_FAILED)
goto out_fail;
memset(ptr, 0, alloc_size);
pool->map = ptr;
pool->bitmap = (void *) ptr + (pool->nr_blocks * SMALLOC_BPL);
pool->lock = fio_mutex_init(FIO_MUTEX_UNLOCKED);
if (!pool->lock)
goto out_fail;
nr_pools++;
return 0;
out_fail:
fprintf(stderr, "smalloc: failed adding pool\n");
if (pool->map)
munmap(pool->map, pool->mmap_size);
return 1;
}
void sinit(void)
{
int ret;
lock = fio_rwlock_init();
ret = add_pool(&mp[0], INITIAL_SIZE);
assert(!ret);
}
static void cleanup_pool(struct pool *pool)
{
/*
* This will also remove the temporary file we used as a backing
* store, it was already unlinked
*/
munmap(pool->map, pool->mmap_size);
if (pool->lock)
fio_mutex_remove(pool->lock);
}
void scleanup(void)
{
unsigned int i;
for (i = 0; i < nr_pools; i++)
cleanup_pool(&mp[i]);
if (lock)
fio_rwlock_remove(lock);
}
#ifdef SMALLOC_REDZONE
static void *postred_ptr(struct block_hdr *hdr)
{
uintptr_t ptr;
ptr = (uintptr_t) hdr + hdr->size - sizeof(unsigned int);
ptr = (ptr + int_mask) & ~int_mask;
return (void *) ptr;
}
static void fill_redzone(struct block_hdr *hdr)
{
unsigned int *postred = postred_ptr(hdr);
hdr->prered = SMALLOC_PRE_RED;
*postred = SMALLOC_POST_RED;
}
static void sfree_check_redzone(struct block_hdr *hdr)
{
unsigned int *postred = postred_ptr(hdr);
if (hdr->prered != SMALLOC_PRE_RED) {
fprintf(stderr, "smalloc pre redzone destroyed!\n");
fprintf(stderr, " ptr=%p, prered=%x, expected %x\n",
hdr, hdr->prered, SMALLOC_PRE_RED);
assert(0);
}
if (*postred != SMALLOC_POST_RED) {
fprintf(stderr, "smalloc post redzone destroyed!\n");
fprintf(stderr, " ptr=%p, postred=%x, expected %x\n",
hdr, *postred, SMALLOC_POST_RED);
assert(0);
}
}
#else
static void fill_redzone(struct block_hdr *hdr)
{
}
static void sfree_check_redzone(struct block_hdr *hdr)
{
}
#endif
static void sfree_pool(struct pool *pool, void *ptr)
{
struct block_hdr *hdr;
unsigned int i, idx;
unsigned long offset;
if (!ptr)
return;
ptr -= sizeof(*hdr);
hdr = ptr;
assert(ptr_valid(pool, ptr));
sfree_check_redzone(hdr);
offset = ptr - pool->map;
i = offset / SMALLOC_BPL;
idx = (offset % SMALLOC_BPL) / SMALLOC_BPB;
pool_lock(pool);
clear_blocks(pool, i, idx, size_to_blocks(hdr->size));
if (i < pool->next_non_full)
pool->next_non_full = i;
pool->free_blocks += size_to_blocks(hdr->size);
pool_unlock(pool);
}
void sfree(void *ptr)
{
struct pool *pool = NULL;
unsigned int i;
if (!ptr)
return;
global_read_lock();
for (i = 0; i < nr_pools; i++) {
if (ptr_valid(&mp[i], ptr)) {
pool = &mp[i];
break;
}
}
global_read_unlock();
assert(pool);
sfree_pool(pool, ptr);
}
static void *__smalloc_pool(struct pool *pool, size_t size)
{
size_t nr_blocks;
unsigned int i;
unsigned int offset;
unsigned int last_idx;
void *ret = NULL;
pool_lock(pool);
nr_blocks = size_to_blocks(size);
if (nr_blocks > pool->free_blocks)
goto fail;
i = pool->next_non_full;
last_idx = 0;
offset = -1U;
while (i < pool->nr_blocks) {
unsigned int idx;
if (pool->bitmap[i] == -1U) {
i++;
pool->next_non_full = i;
last_idx = 0;
continue;
}
idx = find_next_zero(pool->bitmap[i], last_idx);
if (!blocks_free(pool, i, idx, nr_blocks)) {
idx += nr_blocks;
if (idx < SMALLOC_BPI)
last_idx = idx;
else {
last_idx = 0;
while (idx >= SMALLOC_BPI) {
i++;
idx -= SMALLOC_BPI;
}
}
continue;
}
set_blocks(pool, i, idx, nr_blocks);
offset = i * SMALLOC_BPL + idx * SMALLOC_BPB;
break;
}
if (i < pool->nr_blocks) {
pool->free_blocks -= nr_blocks;
ret = pool->map + offset;
}
fail:
pool_unlock(pool);
return ret;
}
static void *smalloc_pool(struct pool *pool, size_t size)
{
size_t alloc_size = size + sizeof(struct block_hdr);
void *ptr;
/*
* Round to int alignment, so that the postred pointer will
* be naturally aligned as well.
*/
#ifdef SMALLOC_REDZONE
alloc_size += sizeof(unsigned int);
alloc_size = (alloc_size + int_mask) & ~int_mask;
#endif
ptr = __smalloc_pool(pool, alloc_size);
if (ptr) {
struct block_hdr *hdr = ptr;
hdr->size = alloc_size;
fill_redzone(hdr);
ptr += sizeof(*hdr);
memset(ptr, 0, size);
}
return ptr;
}
void *smalloc(size_t size)
{
unsigned int i;
if (size != (unsigned int) size)
return NULL;
global_write_lock();
i = last_pool;
do {
for (; i < nr_pools; i++) {
void *ptr = smalloc_pool(&mp[i], size);
if (ptr) {
last_pool = i;
global_write_unlock();
return ptr;
}
}
if (last_pool) {
last_pool = 0;
continue;
}
if (nr_pools + 1 > MAX_POOLS)
break;
else {
i = nr_pools;
if (add_pool(&mp[nr_pools], size))
goto out;
}
} while (1);
out:
global_write_unlock();
return NULL;
}
char *smalloc_strdup(const char *str)
{
char *ptr;
ptr = smalloc(strlen(str) + 1);
strcpy(ptr, str);
return ptr;
}