[librseq.git] / src / rseq-percpu-alloc.c

// SPDX-License-Identifier: MIT
// SPDX-FileCopyrightText: 2024 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

#include <rseq/percpu-alloc.h>
#include <sys/mman.h>
#include <assert.h>
#include <string.h>
#include <pthread.h>
#include <unistd.h>
#include <stdlib.h>
#include <rseq/compiler.h>
#include <errno.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>

#ifdef HAVE_LIBNUMA
# include <numa.h>
# include <numaif.h>
#endif

/*
 * rseq-percpu-alloc.c: rseq per-cpu memory allocator.
 *
 * The rseq per-cpu memory allocator allows the application the request
 * memory pools of per-cpu memory each of a given virtual address size
 * per-cpu, for a given maximum number of CPUs.
 */

/* Use lowest bits of per-cpu addresses to index the pool. */
#if RSEQ_BITS_PER_LONG == 64
# define OFFSET_SHIFT	16
#else
# define OFFSET_SHIFT	8
#endif
#define MAX_NR_POOLS	(1U << OFFSET_SHIFT)
#define POOL_MASK	(MAX_NR_POOLS - 1)

#define POOL_SET_NR_ENTRIES	(RSEQ_BITS_PER_LONG - OFFSET_SHIFT)
#define POOL_SET_MAX_ALLOC_LEN	(1U << POOL_SET_NR_ENTRIES)

#if RSEQ_BITS_PER_LONG == 64
# define POOL_SET_MIN_ENTRY	3	/* Smallest item_len=8 */
#else
# define POOL_SET_MIN_ENTRY	2	/* Smallest item_len=4 */
#endif

#define DEFAULT_PAGE_SIZE	4096

struct free_list_node;

struct free_list_node {
	struct free_list_node *next;
};

/* This lock protects pool create/destroy. */
static pthread_mutex_t pool_lock = PTHREAD_MUTEX_INITIALIZER;

struct rseq_percpu_pool {
	void *base;
	unsigned int index;
	size_t item_len;
	size_t percpu_len;
	int item_order;
	int max_nr_cpus;

	/*
	 * The free list chains freed items on the cpu 0 address range.
	 * We should rethink this decision if false sharing between
	 * malloc/free from other cpus and data accesses from cpu 0
	 * becomes an issue. This is a NULL-terminated singly-linked
	 * list.
	 */
	struct free_list_node *free_list_head;
	size_t next_unused;
	/* This lock protects allocation/free within the pool. */
	pthread_mutex_t lock;
};

//TODO: the array of pools should grow dynamically on create.
static struct rseq_percpu_pool rseq_percpu_pool[MAX_NR_POOLS];

/*
 * Pool set entries are indexed by item_len rounded to the next power of
 * 2. A pool set can contain NULL pool entries, in which case the next
 * large enough entry will be used for allocation.
 */
struct rseq_percpu_pool_set {
	/* This lock protects add vs malloc/zmalloc within the pool set. */
	pthread_mutex_t lock;
	struct rseq_percpu_pool *entries[POOL_SET_NR_ENTRIES];
};

#define __rseq_align_mask(v, mask)	(((v) + (mask)) & ~(mask))
#define rseq_align(v, align)		__rseq_align_mask(v, (__typeof__(v)) (align) - 1)

static __attribute__((unused))
unsigned int fls_u64(uint64_t x)
{
	unsigned int r = 64;

	if (!x)
		return 0;

	if (!(x & 0xFFFFFFFF00000000ULL)) {
		x <<= 32;
		r -= 32;
	}
	if (!(x & 0xFFFF000000000000ULL)) {
		x <<= 16;
		r -= 16;
	}
	if (!(x & 0xFF00000000000000ULL)) {
		x <<= 8;
		r -= 8;
	}
	if (!(x & 0xF000000000000000ULL)) {
		x <<= 4;
		r -= 4;
	}
	if (!(x & 0xC000000000000000ULL)) {
		x <<= 2;
		r -= 2;
	}
	if (!(x & 0x8000000000000000ULL)) {
		x <<= 1;
		r -= 1;
	}
	return r;
}

static __attribute__((unused))
unsigned int fls_u32(uint32_t x)
{
	unsigned int r = 32;

	if (!x)
		return 0;
	if (!(x & 0xFFFF0000U)) {
		x <<= 16;
		r -= 16;
	}
	if (!(x & 0xFF000000U)) {
		x <<= 8;
		r -= 8;
	}
	if (!(x & 0xF0000000U)) {
		x <<= 4;
		r -= 4;
	}
	if (!(x & 0xC0000000U)) {
		x <<= 2;
		r -= 2;
	}
	if (!(x & 0x80000000U)) {
		x <<= 1;
		r -= 1;
	}
	return r;
}

static
unsigned int fls_ulong(unsigned long x)
{
#if RSEQ_BITS_PER_LONG == 32
	return fls_u32(x);
#else
	return fls_u64(x);
#endif
}

/*
 * Return the minimum order for which x <= (1UL << order).
 * Return -1 if x is 0.
 */
static
int get_count_order_ulong(unsigned long x)
{
	if (!x)
		return -1;

	return fls_ulong(x - 1);
}

static
long rseq_get_page_len(void)
{
	long page_len = sysconf(_SC_PAGE_SIZE);

	if (page_len < 0)
		page_len = DEFAULT_PAGE_SIZE;
	return page_len;
}

static
void *__rseq_pool_percpu_ptr(struct rseq_percpu_pool *pool, int cpu, uintptr_t item_offset)
{
	return pool->base + (pool->percpu_len * cpu) + item_offset;
}

void *__rseq_percpu_ptr(void *_ptr, int cpu)
{
	uintptr_t ptr = (uintptr_t) _ptr;
	uintptr_t item_offset = ptr >> OFFSET_SHIFT;
	uintptr_t pool_index = ptr & POOL_MASK;
	struct rseq_percpu_pool *pool = &rseq_percpu_pool[pool_index];

	assert(cpu >= 0);
	return __rseq_pool_percpu_ptr(pool, cpu, item_offset);
}

static
void rseq_percpu_zero_item(struct rseq_percpu_pool *pool, uintptr_t item_offset)
{
	int i;

	for (i = 0; i < pool->max_nr_cpus; i++) {
		char *p = __rseq_pool_percpu_ptr(pool, i, item_offset);
		memset(p, 0, pool->item_len);
	}
}

#ifdef HAVE_LIBNUMA
static
void rseq_percpu_pool_init_numa(struct rseq_percpu_pool *pool,
		int numa_flags)
{
	unsigned long nr_pages, page;
	long ret, page_len;
	int cpu;

	if (!numa_flags)
		return;
	page_len = rseq_get_page_len();
	nr_pages = pool->percpu_len >> get_count_order_ulong(page_len);
	for (cpu = 0; cpu < pool->max_nr_cpus; cpu++) {
		int node = numa_node_of_cpu(cpu);

		/* TODO: batch move_pages() call with an array of pages. */
		for (page = 0; page < nr_pages; page++) {
			void *pageptr = __rseq_pool_percpu_ptr(pool, cpu, page * page_len);
			int status = -EPERM;

			ret = move_pages(0, 1, &pageptr, &node, &status, numa_flags);
			if (ret) {
				perror("move_pages");
				abort();
			}
		}
	}
}
#else
static
void rseq_percpu_pool_init_numa(struct rseq_percpu_pool *pool __attribute__((unused)),
		int numa_flags __attribute__((unused)))
{
}
#endif

/*
 * Expected numa_flags:
 *   0:                do not move pages to specific numa nodes (use for e.g. mm_cid indexing).
 *   MPOL_MF_MOVE:     move process-private pages to cpu-specific numa nodes.
 *   MPOL_MF_MOVE_ALL: move shared pages to cpu-specific numa nodes (requires CAP_SYS_NICE).
 */
struct rseq_percpu_pool *rseq_percpu_pool_create(size_t item_len,
		size_t percpu_len, int max_nr_cpus,
		int mmap_prot, int mmap_flags, int mmap_fd,
		off_t mmap_offset, int numa_flags)
{
	struct rseq_percpu_pool *pool;
	void *base;
	unsigned int i;
	int order;

	/* Make sure each item is large enough to contain free list pointers. */
	if (item_len < sizeof(void *))
		item_len = sizeof(void *);

	/* Align item_len on next power of two. */
	order = get_count_order_ulong(item_len);
	if (order < 0) {
		errno = EINVAL;
		return NULL;
	}
	item_len = 1UL << order;

	/* Align percpu_len on page size. */
	percpu_len = rseq_align(percpu_len, rseq_get_page_len());

	if (max_nr_cpus < 0 || item_len > percpu_len ||
			percpu_len > (UINTPTR_MAX >> OFFSET_SHIFT)) {
		errno = EINVAL;
		return NULL;
	}

	pthread_mutex_lock(&pool_lock);
	/* Linear scan in array of pools to find empty spot. */
	for (i = 0; i < MAX_NR_POOLS; i++) {
		pool = &rseq_percpu_pool[i];
		if (!pool->base)
			goto found_empty;
	}
	errno = ENOMEM;
	pool = NULL;
	goto end;

found_empty:
	base = mmap(NULL, percpu_len * max_nr_cpus, mmap_prot,
			mmap_flags, mmap_fd, mmap_offset);
	if (base == MAP_FAILED) {
		pool = NULL;
		goto end;
	}
	rseq_percpu_pool_init_numa(pool, numa_flags);
	pthread_mutex_init(&pool->lock, NULL);
	pool->base = base;
	pool->percpu_len = percpu_len;
	pool->max_nr_cpus = max_nr_cpus;
	pool->index = i;
	pool->item_len = item_len;
	pool->item_order = order;
end:
	pthread_mutex_unlock(&pool_lock);
	return pool;
}

int rseq_percpu_pool_destroy(struct rseq_percpu_pool *pool)
{
	int ret;

	pthread_mutex_lock(&pool_lock);
	if (!pool->base) {
		errno = ENOENT;
		ret = -1;
		goto end;
	}
	ret = munmap(pool->base, pool->percpu_len * pool->max_nr_cpus);
	if (ret)
		goto end;
	pthread_mutex_destroy(&pool->lock);
	memset(pool, 0, sizeof(*pool));
end:
	pthread_mutex_unlock(&pool_lock);
	return 0;
}

static
void *__rseq_percpu_malloc(struct rseq_percpu_pool *pool, bool zeroed)
{
	struct free_list_node *node;
	uintptr_t item_offset;
	void *addr;

	pthread_mutex_lock(&pool->lock);
	/* Get first entry from free list. */
	node = pool->free_list_head;
	if (node != NULL) {
		/* Remove node from free list (update head). */
		pool->free_list_head = node->next;
		item_offset = (uintptr_t) ((void *) node - pool->base);
		addr = (void *) ((item_offset << OFFSET_SHIFT) | pool->index);
		goto end;
	}
	if (pool->next_unused + pool->item_len > pool->percpu_len) {
		addr = NULL;
		goto end;
	}
	item_offset = pool->next_unused;
	addr = (void *) ((item_offset << OFFSET_SHIFT) | pool->index);
	pool->next_unused += pool->item_len;
end:
	pthread_mutex_unlock(&pool->lock);
	if (zeroed && addr)
		rseq_percpu_zero_item(pool, item_offset);
	return addr;
}

void *rseq_percpu_malloc(struct rseq_percpu_pool *pool)
{
	return __rseq_percpu_malloc(pool, false);
}

void *rseq_percpu_zmalloc(struct rseq_percpu_pool *pool)
{
	return __rseq_percpu_malloc(pool, true);
}

void rseq_percpu_free(void *_ptr)
{
	uintptr_t ptr = (uintptr_t) _ptr;
	uintptr_t item_offset = ptr >> OFFSET_SHIFT;
	uintptr_t pool_index = ptr & POOL_MASK;
	struct rseq_percpu_pool *pool = &rseq_percpu_pool[pool_index];
	struct free_list_node *head, *item;

	pthread_mutex_lock(&pool->lock);
	/* Add ptr to head of free list */
	head = pool->free_list_head;
	/* Free-list is in cpu 0 range. */
	item = (struct free_list_node *)__rseq_pool_percpu_ptr(pool, 0, item_offset);
	item->next = head;
	pool->free_list_head = item;
	pthread_mutex_unlock(&pool->lock);
}

struct rseq_percpu_pool_set *rseq_percpu_pool_set_create(void)
{
	struct rseq_percpu_pool_set *pool_set;

	pool_set = calloc(1, sizeof(struct rseq_percpu_pool_set));
	if (!pool_set)
		return NULL;
	pthread_mutex_init(&pool_set->lock, NULL);
	return pool_set;
}

int rseq_percpu_pool_set_destroy(struct rseq_percpu_pool_set *pool_set)
{
	int order, ret;

	for (order = POOL_SET_MIN_ENTRY; order < POOL_SET_NR_ENTRIES; order++) {
		struct rseq_percpu_pool *pool = pool_set->entries[order];

		if (!pool)
			continue;
		ret = rseq_percpu_pool_destroy(pool);
		if (ret)
			return ret;
		pool_set->entries[order] = NULL;
	}
	pthread_mutex_destroy(&pool_set->lock);
	free(pool_set);
	return 0;
}

/* Ownership of pool is handed over to pool set on success. */
int rseq_percpu_pool_set_add_pool(struct rseq_percpu_pool_set *pool_set, struct rseq_percpu_pool *pool)
{
	size_t item_order = pool->item_order;
	int ret = 0;

	pthread_mutex_lock(&pool_set->lock);
	if (pool_set->entries[item_order]) {
		errno = EBUSY;
		ret = -1;
		goto end;
	}
	pool_set->entries[pool->item_order] = pool;
end:
	pthread_mutex_unlock(&pool_set->lock);
	return ret;
}

static
void *__rseq_percpu_pool_set_malloc(struct rseq_percpu_pool_set *pool_set, size_t len, bool zeroed)
{
	int order, min_order = POOL_SET_MIN_ENTRY;
	struct rseq_percpu_pool *pool;
	void *addr;

again:
	pthread_mutex_lock(&pool_set->lock);
	/* First smallest present pool where @len fits. */
	for (order = min_order; order < POOL_SET_NR_ENTRIES; order++) {
		pool = pool_set->entries[order];

		if (!pool)
			continue;
		if (pool->item_len >= len)
			goto found;
	}
	pool = NULL;
found:
	pthread_mutex_unlock(&pool_set->lock);
	if (pool) {
		addr = __rseq_percpu_malloc(pool, zeroed);
		if (addr == NULL && errno == ENOMEM) {
			/*
			 * If the allocation failed, try again with a
			 * larger pool.
			 */
			min_order = order + 1;
			goto again;
		}
	} else {
		/* Not found. */
		errno = ENOMEM;
		addr = NULL;
	}
	return addr;
}

void *rseq_percpu_pool_set_malloc(struct rseq_percpu_pool_set *pool_set, size_t len)
{
	return __rseq_percpu_pool_set_malloc(pool_set, len, false);
}

void *rseq_percpu_pool_set_zmalloc(struct rseq_percpu_pool_set *pool_set, size_t len)
{
	return __rseq_percpu_pool_set_malloc(pool_set, len, true);
}
Commit	Line	Data
ef6695f1 MD	1	// SPDX-License-Identifier: MIT
	2	// SPDX-FileCopyrightText: 2024 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	3
	4	#include <rseq/percpu-alloc.h>
	5	#include <sys/mman.h>
	6	#include <assert.h>
	7	#include <string.h>
	8	#include <pthread.h>
	9	#include <unistd.h>
	10	#include <stdlib.h>
	11	#include <rseq/compiler.h>
	12	#include <errno.h>
	13	#include <stdint.h>
	14	#include <stdbool.h>
367e559c MD	15	#include <stdio.h>
	16
	17	#ifdef HAVE_LIBNUMA
	18	# include <numa.h>
	19	# include <numaif.h>
	20	#endif
ef6695f1 MD	21
	22	/*
	23	* rseq-percpu-alloc.c: rseq per-cpu memory allocator.
	24	*
	25	* The rseq per-cpu memory allocator allows the application the request
	26	* memory pools of per-cpu memory each of a given virtual address size
	27	* per-cpu, for a given maximum number of CPUs.
	28	*/
	29
	30	/* Use lowest bits of per-cpu addresses to index the pool. */
	31	#if RSEQ_BITS_PER_LONG == 64
	32	# define OFFSET_SHIFT 16
	33	#else
	34	# define OFFSET_SHIFT 8
	35	#endif
	36	#define MAX_NR_POOLS (1U << OFFSET_SHIFT)
	37	#define POOL_MASK (MAX_NR_POOLS - 1)
	38
	39	#define POOL_SET_NR_ENTRIES (RSEQ_BITS_PER_LONG - OFFSET_SHIFT)
	40	#define POOL_SET_MAX_ALLOC_LEN (1U << POOL_SET_NR_ENTRIES)
	41
	42	#if RSEQ_BITS_PER_LONG == 64
	43	# define POOL_SET_MIN_ENTRY 3 /* Smallest item_len=8 */
	44	#else
	45	# define POOL_SET_MIN_ENTRY 2 /* Smallest item_len=4 */
	46	#endif
	47
	48	#define DEFAULT_PAGE_SIZE 4096
	49
	50	struct free_list_node;
	51
	52	struct free_list_node {
	53	struct free_list_node *next;
	54	};
	55
	56	/* This lock protects pool create/destroy. */
	57	static pthread_mutex_t pool_lock = PTHREAD_MUTEX_INITIALIZER;
	58
	59	struct rseq_percpu_pool {
	60	void *base;
	61	unsigned int index;
	62	size_t item_len;
	63	size_t percpu_len;
	64	int item_order;
	65	int max_nr_cpus;
	66
	67	/*
	68	* The free list chains freed items on the cpu 0 address range.
	69	* We should rethink this decision if false sharing between
	70	* malloc/free from other cpus and data accesses from cpu 0
	71	* becomes an issue. This is a NULL-terminated singly-linked
	72	* list.
	73	*/
	74	struct free_list_node *free_list_head;
	75	size_t next_unused;
	76	/* This lock protects allocation/free within the pool. */
	77	pthread_mutex_t lock;
	78	};
	79
	80	//TODO: the array of pools should grow dynamically on create.
	81	static struct rseq_percpu_pool rseq_percpu_pool[MAX_NR_POOLS];
	82
	83	/*
	84	* Pool set entries are indexed by item_len rounded to the next power of
85	* 2. A pool set can contain NULL pool entries, in which case the next
86	* large enough entry will be used for allocation.
87	*/
88	struct rseq_percpu_pool_set {
89	/* This lock protects add vs malloc/zmalloc within the pool set. */
90	pthread_mutex_t lock;
91	struct rseq_percpu_pool *entries[POOL_SET_NR_ENTRIES];
92	};
93
94	#define __rseq_align_mask(v, mask) (((v) + (mask)) & ~(mask))
95	#define rseq_align(v, align) __rseq_align_mask(v, (__typeof__(v)) (align) - 1)
96
97	static __attribute__((unused))
98	unsigned int fls_u64(uint64_t x)
99	{
100	unsigned int r = 64;
101
102	if (!x)
103	return 0;
104
105	if (!(x & 0xFFFFFFFF00000000ULL)) {
106	x <<= 32;
107	r -= 32;
108	}
109	if (!(x & 0xFFFF000000000000ULL)) {
110	x <<= 16;
111	r -= 16;
112	}
113	if (!(x & 0xFF00000000000000ULL)) {
114	x <<= 8;
115	r -= 8;
116	}
117	if (!(x & 0xF000000000000000ULL)) {
118	x <<= 4;
119	r -= 4;
120	}
121	if (!(x & 0xC000000000000000ULL)) {
122	x <<= 2;
123	r -= 2;
124	}
125	if (!(x & 0x8000000000000000ULL)) {
126	x <<= 1;
127	r -= 1;
128	}
129	return r;
130	}
131
132	static __attribute__((unused))
133	unsigned int fls_u32(uint32_t x)
134	{
135	unsigned int r = 32;
136
137	if (!x)
138	return 0;
139	if (!(x & 0xFFFF0000U)) {
140	x <<= 16;
141	r -= 16;
142	}
143	if (!(x & 0xFF000000U)) {
144	x <<= 8;
145	r -= 8;
146	}
147	if (!(x & 0xF0000000U)) {
148	x <<= 4;
149	r -= 4;
150	}
151	if (!(x & 0xC0000000U)) {
152	x <<= 2;
153	r -= 2;
154	}
155	if (!(x & 0x80000000U)) {
156	x <<= 1;
157	r -= 1;
158	}
159	return r;
160	}
161
162	static
163	unsigned int fls_ulong(unsigned long x)
164	{
165	#if RSEQ_BITS_PER_LONG == 32
166	return fls_u32(x);
167	#else
168	return fls_u64(x);
169	#endif
170	}
171
172	/*
173	* Return the minimum order for which x <= (1UL << order).
174	* Return -1 if x is 0.
175	*/
176	static
177	int get_count_order_ulong(unsigned long x)
178	{
179	if (!x)
180	return -1;
181
182	return fls_ulong(x - 1);
183	}
184
367e559c MD	185	static
	186	long rseq_get_page_len(void)
	187	{
	188	long page_len = sysconf(_SC_PAGE_SIZE);
	189
	190	if (page_len < 0)
	191	page_len = DEFAULT_PAGE_SIZE;
	192	return page_len;
	193	}
	194
	195	static
	196	void __rseq_pool_percpu_ptr(struct rseq_percpu_pool pool, int cpu, uintptr_t item_offset)
	197	{
	198	return pool->base + (pool->percpu_len * cpu) + item_offset;
	199	}
	200
	201	void __rseq_percpu_ptr(void _ptr, int cpu)
	202	{
	203	uintptr_t ptr = (uintptr_t) _ptr;
	204	uintptr_t item_offset = ptr >> OFFSET_SHIFT;
	205	uintptr_t pool_index = ptr & POOL_MASK;
	206	struct rseq_percpu_pool *pool = &rseq_percpu_pool[pool_index];
	207
	208	assert(cpu >= 0);
	209	return __rseq_pool_percpu_ptr(pool, cpu, item_offset);
	210	}
	211
	212	static
	213	void rseq_percpu_zero_item(struct rseq_percpu_pool *pool, uintptr_t item_offset)
	214	{
	215	int i;
	216
	217	for (i = 0; i < pool->max_nr_cpus; i++) {
	218	char *p = __rseq_pool_percpu_ptr(pool, i, item_offset);
	219	memset(p, 0, pool->item_len);
	220	}
	221	}
	222
	223	#ifdef HAVE_LIBNUMA
	224	static
	225	void rseq_percpu_pool_init_numa(struct rseq_percpu_pool *pool,
	226	int numa_flags)
	227	{
	228	unsigned long nr_pages, page;
	229	long ret, page_len;
	230	int cpu;
	231
	232	if (!numa_flags)
	233	return;
	234	page_len = rseq_get_page_len();
	235	nr_pages = pool->percpu_len >> get_count_order_ulong(page_len);
	236	for (cpu = 0; cpu < pool->max_nr_cpus; cpu++) {
	237	int node = numa_node_of_cpu(cpu);
	238
	239	/* TODO: batch move_pages() call with an array of pages. */
	240	for (page = 0; page < nr_pages; page++) {
	241	void pageptr = __rseq_pool_percpu_ptr(pool, cpu, page page_len);
	242	int status = -EPERM;
	243
	244	ret = move_pages(0, 1, &pageptr, &node, &status, numa_flags);
	245	if (ret) {
	246	perror("move_pages");
	247	abort();
	248	}
249	}
250	}
251	}
252	#else
253	static
254	void rseq_percpu_pool_init_numa(struct rseq_percpu_pool *pool __attribute__((unused)),
255	int numa_flags __attribute__((unused)))
256	{
257	}
258	#endif
259
260	/*
261	* Expected numa_flags:
262	* 0: do not move pages to specific numa nodes (use for e.g. mm_cid indexing).
263	* MPOL_MF_MOVE: move process-private pages to cpu-specific numa nodes.
264	* MPOL_MF_MOVE_ALL: move shared pages to cpu-specific numa nodes (requires CAP_SYS_NICE).
265	*/
ef6695f1 MD	266	struct rseq_percpu_pool *rseq_percpu_pool_create(size_t item_len,
ef6695f1 MD	267	size_t percpu_len, int max_nr_cpus,
367e559c MD	268	int mmap_prot, int mmap_flags, int mmap_fd,
367e559c MD	269	off_t mmap_offset, int numa_flags)
ef6695f1 MD	270	{
	271	struct rseq_percpu_pool *pool;
	272	void *base;
	273	unsigned int i;
	274	int order;
ef6695f1 MD	275
	276	/* Make sure each item is large enough to contain free list pointers. */
	277	if (item_len < sizeof(void *))
	278	item_len = sizeof(void *);
	279
	280	/* Align item_len on next power of two. */
	281	order = get_count_order_ulong(item_len);
	282	if (order < 0) {
	283	errno = EINVAL;
	284	return NULL;
	285	}
	286	item_len = 1UL << order;
	287
	288	/* Align percpu_len on page size. */
367e559c	289	percpu_len = rseq_align(percpu_len, rseq_get_page_len());
ef6695f1 MD	290
	291	if (max_nr_cpus < 0 \|\| item_len > percpu_len \|\|
	292	percpu_len > (UINTPTR_MAX >> OFFSET_SHIFT)) {
	293	errno = EINVAL;
	294	return NULL;
	295	}
	296
	297	pthread_mutex_lock(&pool_lock);
	298	/* Linear scan in array of pools to find empty spot. */
	299	for (i = 0; i < MAX_NR_POOLS; i++) {
	300	pool = &rseq_percpu_pool[i];
	301	if (!pool->base)
	302	goto found_empty;
	303	}
	304	errno = ENOMEM;
	305	pool = NULL;
	306	goto end;
	307
	308	found_empty:
367e559c MD	309	base = mmap(NULL, percpu_len * max_nr_cpus, mmap_prot,
367e559c MD	310	mmap_flags, mmap_fd, mmap_offset);
ef6695f1 MD	311	if (base == MAP_FAILED) {
	312	pool = NULL;
	313	goto end;
	314	}
367e559c	315	rseq_percpu_pool_init_numa(pool, numa_flags);
ef6695f1 MD	316	pthread_mutex_init(&pool->lock, NULL);
	317	pool->base = base;
	318	pool->percpu_len = percpu_len;
	319	pool->max_nr_cpus = max_nr_cpus;
	320	pool->index = i;
	321	pool->item_len = item_len;
	322	pool->item_order = order;
	323	end:
	324	pthread_mutex_unlock(&pool_lock);
	325	return pool;
	326	}
	327
	328	int rseq_percpu_pool_destroy(struct rseq_percpu_pool *pool)
	329	{
	330	int ret;
	331
	332	pthread_mutex_lock(&pool_lock);
	333	if (!pool->base) {
	334	errno = ENOENT;
	335	ret = -1;
	336	goto end;
	337	}
	338	ret = munmap(pool->base, pool->percpu_len * pool->max_nr_cpus);
	339	if (ret)
	340	goto end;
	341	pthread_mutex_destroy(&pool->lock);
	342	memset(pool, 0, sizeof(*pool));
	343	end:
	344	pthread_mutex_unlock(&pool_lock);
	345	return 0;
	346	}
	347
ef6695f1 MD	348	static
	349	void __rseq_percpu_malloc(struct rseq_percpu_pool pool, bool zeroed)
	350	{
	351	struct free_list_node *node;
	352	uintptr_t item_offset;
	353	void *addr;
	354
	355	pthread_mutex_lock(&pool->lock);
	356	/* Get first entry from free list. */
	357	node = pool->free_list_head;
	358	if (node != NULL) {
	359	/* Remove node from free list (update head). */
	360	pool->free_list_head = node->next;
	361	item_offset = (uintptr_t) ((void *) node - pool->base);
	362	addr = (void *) ((item_offset << OFFSET_SHIFT) \| pool->index);
	363	goto end;
	364	}
	365	if (pool->next_unused + pool->item_len > pool->percpu_len) {
	366	addr = NULL;
	367	goto end;
	368	}
	369	item_offset = pool->next_unused;
	370	addr = (void *) ((item_offset << OFFSET_SHIFT) \| pool->index);
	371	pool->next_unused += pool->item_len;
	372	end:
	373	pthread_mutex_unlock(&pool->lock);
	374	if (zeroed && addr)
	375	rseq_percpu_zero_item(pool, item_offset);
	376	return addr;
	377	}
	378
	379	void rseq_percpu_malloc(struct rseq_percpu_pool pool)
	380	{
	381	return __rseq_percpu_malloc(pool, false);
	382	}
	383
	384	void rseq_percpu_zmalloc(struct rseq_percpu_pool pool)
	385	{
	386	return __rseq_percpu_malloc(pool, true);
	387	}
	388
	389	void rseq_percpu_free(void *_ptr)
	390	{
	391	uintptr_t ptr = (uintptr_t) _ptr;
	392	uintptr_t item_offset = ptr >> OFFSET_SHIFT;
	393	uintptr_t pool_index = ptr & POOL_MASK;
	394	struct rseq_percpu_pool *pool = &rseq_percpu_pool[pool_index];
	395	struct free_list_node head, item;
	396
	397	pthread_mutex_lock(&pool->lock);
	398	/* Add ptr to head of free list */
	399	head = pool->free_list_head;
	400	/* Free-list is in cpu 0 range. */
	401	item = (struct free_list_node *)__rseq_pool_percpu_ptr(pool, 0, item_offset);
	402	item->next = head;
	403	pool->free_list_head = item;
	404	pthread_mutex_unlock(&pool->lock);
	405	}
	406
	407	struct rseq_percpu_pool_set *rseq_percpu_pool_set_create(void)
	408	{
	409	struct rseq_percpu_pool_set *pool_set;
	410
	411	pool_set = calloc(1, sizeof(struct rseq_percpu_pool_set));
412	if (!pool_set)
413	return NULL;
414	pthread_mutex_init(&pool_set->lock, NULL);
415	return pool_set;
416	}
417
418	int rseq_percpu_pool_set_destroy(struct rseq_percpu_pool_set *pool_set)
419	{
420	int order, ret;
421
422	for (order = POOL_SET_MIN_ENTRY; order < POOL_SET_NR_ENTRIES; order++) {
423	struct rseq_percpu_pool *pool = pool_set->entries[order];
424
425	if (!pool)
426	continue;
427	ret = rseq_percpu_pool_destroy(pool);
428	if (ret)
429	return ret;
430	pool_set->entries[order] = NULL;
431	}
432	pthread_mutex_destroy(&pool_set->lock);
433	free(pool_set);
434	return 0;
435	}
436
437	/* Ownership of pool is handed over to pool set on success. */
438	int rseq_percpu_pool_set_add_pool(struct rseq_percpu_pool_set pool_set, struct rseq_percpu_pool pool)
439	{
440	size_t item_order = pool->item_order;
441	int ret = 0;
442
443	pthread_mutex_lock(&pool_set->lock);
444	if (pool_set->entries[item_order]) {
445	errno = EBUSY;
446	ret = -1;
447	goto end;
448	}
449	pool_set->entries[pool->item_order] = pool;
450	end:
451	pthread_mutex_unlock(&pool_set->lock);
452	return ret;
453	}
454
455	static
456	void __rseq_percpu_pool_set_malloc(struct rseq_percpu_pool_set pool_set, size_t len, bool zeroed)
457	{
458	int order, min_order = POOL_SET_MIN_ENTRY;
459	struct rseq_percpu_pool *pool;
460	void *addr;
461
462	again:
463	pthread_mutex_lock(&pool_set->lock);
464	/* First smallest present pool where @len fits. */
465	for (order = min_order; order < POOL_SET_NR_ENTRIES; order++) {
466	pool = pool_set->entries[order];
467
468	if (!pool)
469	continue;
470	if (pool->item_len >= len)
471	goto found;
472	}
473	pool = NULL;
474	found:
475	pthread_mutex_unlock(&pool_set->lock);
476	if (pool) {
477	addr = __rseq_percpu_malloc(pool, zeroed);
478	if (addr == NULL && errno == ENOMEM) {
479	/*
480	* If the allocation failed, try again with a
481	* larger pool.
482	*/
483	min_order = order + 1;
484	goto again;
485	}
486	} else {
487	/* Not found. */
488	errno = ENOMEM;
489	addr = NULL;
490	}
491	return addr;
492	}
493
494	void rseq_percpu_pool_set_malloc(struct rseq_percpu_pool_set pool_set, size_t len)
495	{
496	return __rseq_percpu_pool_set_malloc(pool_set, len, false);
497	}
498
499	void rseq_percpu_pool_set_zmalloc(struct rseq_percpu_pool_set pool_set, size_t len)
500	{
501	return __rseq_percpu_pool_set_malloc(pool_set, len, true);
502	}