[mirror_ubuntu-hirsute-kernel.git] / kernel / bpf / ringbuf.c

#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/err.h>
#include <linux/irq_work.h>
#include <linux/slab.h>
#include <linux/filter.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/wait.h>
#include <linux/poll.h>
#include <uapi/linux/btf.h>

#define RINGBUF_CREATE_FLAG_MASK (BPF_F_NUMA_NODE)

/* non-mmap()'able part of bpf_ringbuf (everything up to consumer page) */
#define RINGBUF_PGOFF \
	(offsetof(struct bpf_ringbuf, consumer_pos) >> PAGE_SHIFT)
/* consumer page and producer page */
#define RINGBUF_POS_PAGES 2

#define RINGBUF_MAX_RECORD_SZ (UINT_MAX/4)

/* Maximum size of ring buffer area is limited by 32-bit page offset within
 * record header, counted in pages. Reserve 8 bits for extensibility, and take
 * into account few extra pages for consumer/producer pages and
 * non-mmap()'able parts. This gives 64GB limit, which seems plenty for single
 * ring buffer.
 */
#define RINGBUF_MAX_DATA_SZ \
	(((1ULL << 24) - RINGBUF_POS_PAGES - RINGBUF_PGOFF) * PAGE_SIZE)

struct bpf_ringbuf {
	wait_queue_head_t waitq;
	struct irq_work work;
	u64 mask;
	struct page **pages;
	int nr_pages;
	spinlock_t spinlock ____cacheline_aligned_in_smp;
	/* Consumer and producer counters are put into separate pages to allow
	 * mapping consumer page as r/w, but restrict producer page to r/o.
	 * This protects producer position from being modified by user-space
	 * application and ruining in-kernel position tracking.
	 */
	unsigned long consumer_pos __aligned(PAGE_SIZE);
	unsigned long producer_pos __aligned(PAGE_SIZE);
	char data[] __aligned(PAGE_SIZE);
};

struct bpf_ringbuf_map {
	struct bpf_map map;
	struct bpf_ringbuf *rb;
};

/* 8-byte ring buffer record header structure */
struct bpf_ringbuf_hdr {
	u32 len;
	u32 pg_off;
};

static struct bpf_ringbuf *bpf_ringbuf_area_alloc(size_t data_sz, int numa_node)
{
	const gfp_t flags = GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL |
			    __GFP_NOWARN | __GFP_ZERO;
	int nr_meta_pages = RINGBUF_PGOFF + RINGBUF_POS_PAGES;
	int nr_data_pages = data_sz >> PAGE_SHIFT;
	int nr_pages = nr_meta_pages + nr_data_pages;
	struct page **pages, *page;
	struct bpf_ringbuf *rb;
	size_t array_size;
	int i;

	/* Each data page is mapped twice to allow "virtual"
	 * continuous read of samples wrapping around the end of ring
	 * buffer area:
	 * ------------------------------------------------------
	 * | meta pages |  real data pages  |  same data pages  |
	 * ------------------------------------------------------
	 * |            | 1 2 3 4 5 6 7 8 9 | 1 2 3 4 5 6 7 8 9 |
	 * ------------------------------------------------------
	 * |            | TA             DA | TA             DA |
	 * ------------------------------------------------------
	 *                               ^^^^^^^
	 *                                  |
	 * Here, no need to worry about special handling of wrapped-around
	 * data due to double-mapped data pages. This works both in kernel and
	 * when mmap()'ed in user-space, simplifying both kernel and
	 * user-space implementations significantly.
	 */
	array_size = (nr_meta_pages + 2 * nr_data_pages) * sizeof(*pages);
	pages = bpf_map_area_alloc(array_size, numa_node);
	if (!pages)
		return NULL;

	for (i = 0; i < nr_pages; i++) {
		page = alloc_pages_node(numa_node, flags, 0);
		if (!page) {
			nr_pages = i;
			goto err_free_pages;
		}
		pages[i] = page;
		if (i >= nr_meta_pages)
			pages[nr_data_pages + i] = page;
	}

	rb = vmap(pages, nr_meta_pages + 2 * nr_data_pages,
		  VM_ALLOC | VM_USERMAP, PAGE_KERNEL);
	if (rb) {
		rb->pages = pages;
		rb->nr_pages = nr_pages;
		return rb;
	}

err_free_pages:
	for (i = 0; i < nr_pages; i++)
		__free_page(pages[i]);
	kvfree(pages);
	return NULL;
}

static void bpf_ringbuf_notify(struct irq_work *work)
{
	struct bpf_ringbuf *rb = container_of(work, struct bpf_ringbuf, work);

	wake_up_all(&rb->waitq);
}

static struct bpf_ringbuf *bpf_ringbuf_alloc(size_t data_sz, int numa_node)
{
	struct bpf_ringbuf *rb;

	rb = bpf_ringbuf_area_alloc(data_sz, numa_node);
	if (!rb)
		return NULL;

	spin_lock_init(&rb->spinlock);
	init_waitqueue_head(&rb->waitq);
	init_irq_work(&rb->work, bpf_ringbuf_notify);

	rb->mask = data_sz - 1;
	rb->consumer_pos = 0;
	rb->producer_pos = 0;

	return rb;
}

static struct bpf_map *ringbuf_map_alloc(union bpf_attr *attr)
{
	struct bpf_ringbuf_map *rb_map;

	if (attr->map_flags & ~RINGBUF_CREATE_FLAG_MASK)
		return ERR_PTR(-EINVAL);

	if (attr->key_size || attr->value_size ||
	    !is_power_of_2(attr->max_entries) ||
	    !PAGE_ALIGNED(attr->max_entries))
		return ERR_PTR(-EINVAL);

#ifdef CONFIG_64BIT
	/* on 32-bit arch, it's impossible to overflow record's hdr->pgoff */
	if (attr->max_entries > RINGBUF_MAX_DATA_SZ)
		return ERR_PTR(-E2BIG);
#endif

	rb_map = kzalloc(sizeof(*rb_map), GFP_USER | __GFP_ACCOUNT);
	if (!rb_map)
		return ERR_PTR(-ENOMEM);

	bpf_map_init_from_attr(&rb_map->map, attr);

	rb_map->rb = bpf_ringbuf_alloc(attr->max_entries, rb_map->map.numa_node);
	if (!rb_map->rb) {
		kfree(rb_map);
		return ERR_PTR(-ENOMEM);
	}

	return &rb_map->map;
}

static void bpf_ringbuf_free(struct bpf_ringbuf *rb)
{
	/* copy pages pointer and nr_pages to local variable, as we are going
	 * to unmap rb itself with vunmap() below
	 */
	struct page **pages = rb->pages;
	int i, nr_pages = rb->nr_pages;

	vunmap(rb);
	for (i = 0; i < nr_pages; i++)
		__free_page(pages[i]);
	kvfree(pages);
}

static void ringbuf_map_free(struct bpf_map *map)
{
	struct bpf_ringbuf_map *rb_map;

	rb_map = container_of(map, struct bpf_ringbuf_map, map);
	bpf_ringbuf_free(rb_map->rb);
	kfree(rb_map);
}

static void *ringbuf_map_lookup_elem(struct bpf_map *map, void *key)
{
	return ERR_PTR(-ENOTSUPP);
}

static int ringbuf_map_update_elem(struct bpf_map *map, void *key, void *value,
				   u64 flags)
{
	return -ENOTSUPP;
}

static int ringbuf_map_delete_elem(struct bpf_map *map, void *key)
{
	return -ENOTSUPP;
}

static int ringbuf_map_get_next_key(struct bpf_map *map, void *key,
				    void *next_key)
{
	return -ENOTSUPP;
}

static int ringbuf_map_mmap(struct bpf_map *map, struct vm_area_struct *vma)
{
	struct bpf_ringbuf_map *rb_map;

	rb_map = container_of(map, struct bpf_ringbuf_map, map);

	if (vma->vm_flags & VM_WRITE) {
		/* allow writable mapping for the consumer_pos only */
		if (vma->vm_pgoff != 0 || vma->vm_end - vma->vm_start != PAGE_SIZE)
			return -EPERM;
	} else {
		vma->vm_flags &= ~VM_MAYWRITE;
	}
	/* remap_vmalloc_range() checks size and offset constraints */
	return remap_vmalloc_range(vma, rb_map->rb,
				   vma->vm_pgoff + RINGBUF_PGOFF);
}

static unsigned long ringbuf_avail_data_sz(struct bpf_ringbuf *rb)
{
	unsigned long cons_pos, prod_pos;

	cons_pos = smp_load_acquire(&rb->consumer_pos);
	prod_pos = smp_load_acquire(&rb->producer_pos);
	return prod_pos - cons_pos;
}

static __poll_t ringbuf_map_poll(struct bpf_map *map, struct file *filp,
				 struct poll_table_struct *pts)
{
	struct bpf_ringbuf_map *rb_map;

	rb_map = container_of(map, struct bpf_ringbuf_map, map);
	poll_wait(filp, &rb_map->rb->waitq, pts);

	if (ringbuf_avail_data_sz(rb_map->rb))
		return EPOLLIN | EPOLLRDNORM;
	return 0;
}

static int ringbuf_map_btf_id;
const struct bpf_map_ops ringbuf_map_ops = {
	.map_meta_equal = bpf_map_meta_equal,
	.map_alloc = ringbuf_map_alloc,
	.map_free = ringbuf_map_free,
	.map_mmap = ringbuf_map_mmap,
	.map_poll = ringbuf_map_poll,
	.map_lookup_elem = ringbuf_map_lookup_elem,
	.map_update_elem = ringbuf_map_update_elem,
	.map_delete_elem = ringbuf_map_delete_elem,
	.map_get_next_key = ringbuf_map_get_next_key,
	.map_btf_name = "bpf_ringbuf_map",
	.map_btf_id = &ringbuf_map_btf_id,
};

/* Given pointer to ring buffer record metadata and struct bpf_ringbuf itself,
 * calculate offset from record metadata to ring buffer in pages, rounded
 * down. This page offset is stored as part of record metadata and allows to
 * restore struct bpf_ringbuf * from record pointer. This page offset is
 * stored at offset 4 of record metadata header.
 */
static size_t bpf_ringbuf_rec_pg_off(struct bpf_ringbuf *rb,
				     struct bpf_ringbuf_hdr *hdr)
{
	return ((void *)hdr - (void *)rb) >> PAGE_SHIFT;
}

/* Given pointer to ring buffer record header, restore pointer to struct
 * bpf_ringbuf itself by using page offset stored at offset 4
 */
static struct bpf_ringbuf *
bpf_ringbuf_restore_from_rec(struct bpf_ringbuf_hdr *hdr)
{
	unsigned long addr = (unsigned long)(void *)hdr;
	unsigned long off = (unsigned long)hdr->pg_off << PAGE_SHIFT;

	return (void*)((addr & PAGE_MASK) - off);
}

static void *__bpf_ringbuf_reserve(struct bpf_ringbuf *rb, u64 size)
{
	unsigned long cons_pos, prod_pos, new_prod_pos, flags;
	u32 len, pg_off;
	struct bpf_ringbuf_hdr *hdr;

	if (unlikely(size > RINGBUF_MAX_RECORD_SZ))
		return NULL;

	len = round_up(size + BPF_RINGBUF_HDR_SZ, 8);
	if (len > rb->mask + 1)
		return NULL;

	cons_pos = smp_load_acquire(&rb->consumer_pos);

	if (in_nmi()) {
		if (!spin_trylock_irqsave(&rb->spinlock, flags))
			return NULL;
	} else {
		spin_lock_irqsave(&rb->spinlock, flags);
	}

	prod_pos = rb->producer_pos;
	new_prod_pos = prod_pos + len;

	/* check for out of ringbuf space by ensuring producer position
	 * doesn't advance more than (ringbuf_size - 1) ahead
	 */
	if (new_prod_pos - cons_pos > rb->mask) {
		spin_unlock_irqrestore(&rb->spinlock, flags);
		return NULL;
	}

	hdr = (void *)rb->data + (prod_pos & rb->mask);
	pg_off = bpf_ringbuf_rec_pg_off(rb, hdr);
	hdr->len = size | BPF_RINGBUF_BUSY_BIT;
	hdr->pg_off = pg_off;

	/* pairs with consumer's smp_load_acquire() */
	smp_store_release(&rb->producer_pos, new_prod_pos);

	spin_unlock_irqrestore(&rb->spinlock, flags);

	return (void *)hdr + BPF_RINGBUF_HDR_SZ;
}

BPF_CALL_3(bpf_ringbuf_reserve, struct bpf_map *, map, u64, size, u64, flags)
{
	struct bpf_ringbuf_map *rb_map;

	if (unlikely(flags))
		return 0;

	rb_map = container_of(map, struct bpf_ringbuf_map, map);
	return (unsigned long)__bpf_ringbuf_reserve(rb_map->rb, size);
}

const struct bpf_func_proto bpf_ringbuf_reserve_proto = {
	.func		= bpf_ringbuf_reserve,
	.ret_type	= RET_PTR_TO_ALLOC_MEM_OR_NULL,
	.arg1_type	= ARG_CONST_MAP_PTR,
	.arg2_type	= ARG_CONST_ALLOC_SIZE_OR_ZERO,
	.arg3_type	= ARG_ANYTHING,
};

static void bpf_ringbuf_commit(void *sample, u64 flags, bool discard)
{
	unsigned long rec_pos, cons_pos;
	struct bpf_ringbuf_hdr *hdr;
	struct bpf_ringbuf *rb;
	u32 new_len;

	hdr = sample - BPF_RINGBUF_HDR_SZ;
	rb = bpf_ringbuf_restore_from_rec(hdr);
	new_len = hdr->len ^ BPF_RINGBUF_BUSY_BIT;
	if (discard)
		new_len |= BPF_RINGBUF_DISCARD_BIT;

	/* update record header with correct final size prefix */
	xchg(&hdr->len, new_len);

	/* if consumer caught up and is waiting for our record, notify about
	 * new data availability
	 */
	rec_pos = (void *)hdr - (void *)rb->data;
	cons_pos = smp_load_acquire(&rb->consumer_pos) & rb->mask;

	if (flags & BPF_RB_FORCE_WAKEUP)
		irq_work_queue(&rb->work);
	else if (cons_pos == rec_pos && !(flags & BPF_RB_NO_WAKEUP))
		irq_work_queue(&rb->work);
}

BPF_CALL_2(bpf_ringbuf_submit, void *, sample, u64, flags)
{
	bpf_ringbuf_commit(sample, flags, false /* discard */);
	return 0;
}

const struct bpf_func_proto bpf_ringbuf_submit_proto = {
	.func		= bpf_ringbuf_submit,
	.ret_type	= RET_VOID,
	.arg1_type	= ARG_PTR_TO_ALLOC_MEM,
	.arg2_type	= ARG_ANYTHING,
};

BPF_CALL_2(bpf_ringbuf_discard, void *, sample, u64, flags)
{
	bpf_ringbuf_commit(sample, flags, true /* discard */);
	return 0;
}

const struct bpf_func_proto bpf_ringbuf_discard_proto = {
	.func		= bpf_ringbuf_discard,
	.ret_type	= RET_VOID,
	.arg1_type	= ARG_PTR_TO_ALLOC_MEM,
	.arg2_type	= ARG_ANYTHING,
};

BPF_CALL_4(bpf_ringbuf_output, struct bpf_map *, map, void *, data, u64, size,
	   u64, flags)
{
	struct bpf_ringbuf_map *rb_map;
	void *rec;

	if (unlikely(flags & ~(BPF_RB_NO_WAKEUP | BPF_RB_FORCE_WAKEUP)))
		return -EINVAL;

	rb_map = container_of(map, struct bpf_ringbuf_map, map);
	rec = __bpf_ringbuf_reserve(rb_map->rb, size);
	if (!rec)
		return -EAGAIN;

	memcpy(rec, data, size);
	bpf_ringbuf_commit(rec, flags, false /* discard */);
	return 0;
}

const struct bpf_func_proto bpf_ringbuf_output_proto = {
	.func		= bpf_ringbuf_output,
	.ret_type	= RET_INTEGER,
	.arg1_type	= ARG_CONST_MAP_PTR,
	.arg2_type	= ARG_PTR_TO_MEM,
	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
	.arg4_type	= ARG_ANYTHING,
};

BPF_CALL_2(bpf_ringbuf_query, struct bpf_map *, map, u64, flags)
{
	struct bpf_ringbuf *rb;

	rb = container_of(map, struct bpf_ringbuf_map, map)->rb;

	switch (flags) {
	case BPF_RB_AVAIL_DATA:
		return ringbuf_avail_data_sz(rb);
	case BPF_RB_RING_SIZE:
		return rb->mask + 1;
	case BPF_RB_CONS_POS:
		return smp_load_acquire(&rb->consumer_pos);
	case BPF_RB_PROD_POS:
		return smp_load_acquire(&rb->producer_pos);
	default:
		return 0;
	}
}

const struct bpf_func_proto bpf_ringbuf_query_proto = {
	.func		= bpf_ringbuf_query,
	.ret_type	= RET_INTEGER,
	.arg1_type	= ARG_CONST_MAP_PTR,
	.arg2_type	= ARG_ANYTHING,
};
Commit	Line	Data
457f4436 AN	1	#include <linux/bpf.h>
	2	#include <linux/btf.h>
	3	#include <linux/err.h>
	4	#include <linux/irq_work.h>
	5	#include <linux/slab.h>
	6	#include <linux/filter.h>
	7	#include <linux/mm.h>
	8	#include <linux/vmalloc.h>
	9	#include <linux/wait.h>
	10	#include <linux/poll.h>
	11	#include <uapi/linux/btf.h>
	12
	13	#define RINGBUF_CREATE_FLAG_MASK (BPF_F_NUMA_NODE)
	14
	15	/* non-mmap()'able part of bpf_ringbuf (everything up to consumer page) */
	16	#define RINGBUF_PGOFF \
	17	(offsetof(struct bpf_ringbuf, consumer_pos) >> PAGE_SHIFT)
	18	/* consumer page and producer page */
	19	#define RINGBUF_POS_PAGES 2
	20
	21	#define RINGBUF_MAX_RECORD_SZ (UINT_MAX/4)
	22
	23	/* Maximum size of ring buffer area is limited by 32-bit page offset within
	24	* record header, counted in pages. Reserve 8 bits for extensibility, and take
	25	* into account few extra pages for consumer/producer pages and
	26	* non-mmap()'able parts. This gives 64GB limit, which seems plenty for single
	27	* ring buffer.
	28	*/
	29	#define RINGBUF_MAX_DATA_SZ \
	30	(((1ULL << 24) - RINGBUF_POS_PAGES - RINGBUF_PGOFF) * PAGE_SIZE)
	31
	32	struct bpf_ringbuf {
	33	wait_queue_head_t waitq;
	34	struct irq_work work;
	35	u64 mask;
	36	struct page **pages;
	37	int nr_pages;
	38	spinlock_t spinlock ____cacheline_aligned_in_smp;
	39	/* Consumer and producer counters are put into separate pages to allow
	40	* mapping consumer page as r/w, but restrict producer page to r/o.
	41	* This protects producer position from being modified by user-space
	42	* application and ruining in-kernel position tracking.
	43	*/
	44	unsigned long consumer_pos __aligned(PAGE_SIZE);
	45	unsigned long producer_pos __aligned(PAGE_SIZE);
	46	char data[] __aligned(PAGE_SIZE);
	47	};
	48
	49	struct bpf_ringbuf_map {
	50	struct bpf_map map;
457f4436 AN	51	struct bpf_ringbuf *rb;
	52	};
	53
	54	/* 8-byte ring buffer record header structure */
	55	struct bpf_ringbuf_hdr {
	56	u32 len;
	57	u32 pg_off;
	58	};
	59
	60	static struct bpf_ringbuf *bpf_ringbuf_area_alloc(size_t data_sz, int numa_node)
	61	{
be4035c7 RG	62	const gfp_t flags = GFP_KERNEL_ACCOUNT \| __GFP_RETRY_MAYFAIL \|
be4035c7 RG	63	__GFP_NOWARN \| __GFP_ZERO;
457f4436 AN	64	int nr_meta_pages = RINGBUF_PGOFF + RINGBUF_POS_PAGES;
	65	int nr_data_pages = data_sz >> PAGE_SHIFT;
	66	int nr_pages = nr_meta_pages + nr_data_pages;
	67	struct page *pages, page;
	68	struct bpf_ringbuf *rb;
	69	size_t array_size;
	70	int i;
	71
	72	/* Each data page is mapped twice to allow "virtual"
	73	* continuous read of samples wrapping around the end of ring
	74	* buffer area:
	75	* ------------------------------------------------------
	76	* \| meta pages \| real data pages \| same data pages \|
	77	* ------------------------------------------------------
	78	* \| \| 1 2 3 4 5 6 7 8 9 \| 1 2 3 4 5 6 7 8 9 \|
	79	* ------------------------------------------------------
	80	* \| \| TA DA \| TA DA \|
	81	* ------------------------------------------------------
	82	* ^^^^^^^
	83	* \|
	84	* Here, no need to worry about special handling of wrapped-around
	85	* data due to double-mapped data pages. This works both in kernel and
	86	* when mmap()'ed in user-space, simplifying both kernel and
	87	* user-space implementations significantly.
	88	*/
	89	array_size = (nr_meta_pages + 2 * nr_data_pages) * sizeof(*pages);
be4035c7	90	pages = bpf_map_area_alloc(array_size, numa_node);
457f4436 AN	91	if (!pages)
	92	return NULL;
	93
	94	for (i = 0; i < nr_pages; i++) {
	95	page = alloc_pages_node(numa_node, flags, 0);
	96	if (!page) {
	97	nr_pages = i;
	98	goto err_free_pages;
	99	}
	100	pages[i] = page;
	101	if (i >= nr_meta_pages)
	102	pages[nr_data_pages + i] = page;
	103	}
	104
	105	rb = vmap(pages, nr_meta_pages + 2 * nr_data_pages,
	106	VM_ALLOC \| VM_USERMAP, PAGE_KERNEL);
	107	if (rb) {
	108	rb->pages = pages;
	109	rb->nr_pages = nr_pages;
	110	return rb;
	111	}
	112
	113	err_free_pages:
	114	for (i = 0; i < nr_pages; i++)
	115	__free_page(pages[i]);
	116	kvfree(pages);
	117	return NULL;
	118	}
	119
	120	static void bpf_ringbuf_notify(struct irq_work *work)
	121	{
	122	struct bpf_ringbuf *rb = container_of(work, struct bpf_ringbuf, work);
	123
	124	wake_up_all(&rb->waitq);
	125	}
	126
	127	static struct bpf_ringbuf *bpf_ringbuf_alloc(size_t data_sz, int numa_node)
	128	{
	129	struct bpf_ringbuf *rb;
	130
457f4436 AN	131	rb = bpf_ringbuf_area_alloc(data_sz, numa_node);
457f4436 AN	132	if (!rb)
abbdd081	133	return NULL;
457f4436 AN	134
	135	spin_lock_init(&rb->spinlock);
	136	init_waitqueue_head(&rb->waitq);
	137	init_irq_work(&rb->work, bpf_ringbuf_notify);
	138
	139	rb->mask = data_sz - 1;
	140	rb->consumer_pos = 0;
	141	rb->producer_pos = 0;
	142
	143	return rb;
	144	}
	145
	146	static struct bpf_map ringbuf_map_alloc(union bpf_attr attr)
	147	{
	148	struct bpf_ringbuf_map *rb_map;
457f4436 AN	149
	150	if (attr->map_flags & ~RINGBUF_CREATE_FLAG_MASK)
	151	return ERR_PTR(-EINVAL);
	152
	153	if (attr->key_size \|\| attr->value_size \|\|
517bbe19 AN	154	!is_power_of_2(attr->max_entries) \|\|
517bbe19 AN	155	!PAGE_ALIGNED(attr->max_entries))
457f4436 AN	156	return ERR_PTR(-EINVAL);
457f4436 AN	157
517bbe19 AN	158	#ifdef CONFIG_64BIT
	159	/* on 32-bit arch, it's impossible to overflow record's hdr->pgoff */
	160	if (attr->max_entries > RINGBUF_MAX_DATA_SZ)
	161	return ERR_PTR(-E2BIG);
	162	#endif
	163
be4035c7	164	rb_map = kzalloc(sizeof(*rb_map), GFP_USER \| __GFP_ACCOUNT);
457f4436 AN	165	if (!rb_map)
	166	return ERR_PTR(-ENOMEM);
	167
	168	bpf_map_init_from_attr(&rb_map->map, attr);
	169
457f4436	170	rb_map->rb = bpf_ringbuf_alloc(attr->max_entries, rb_map->map.numa_node);
abbdd081 RG	171	if (!rb_map->rb) {
	172	kfree(rb_map);
	173	return ERR_PTR(-ENOMEM);
457f4436 AN	174	}
	175
	176	return &rb_map->map;
457f4436 AN	177	}
	178
	179	static void bpf_ringbuf_free(struct bpf_ringbuf *rb)
	180	{
	181	/* copy pages pointer and nr_pages to local variable, as we are going
	182	* to unmap rb itself with vunmap() below
	183	*/
	184	struct page **pages = rb->pages;
	185	int i, nr_pages = rb->nr_pages;
	186
	187	vunmap(rb);
	188	for (i = 0; i < nr_pages; i++)
	189	__free_page(pages[i]);
	190	kvfree(pages);
	191	}
	192
	193	static void ringbuf_map_free(struct bpf_map *map)
	194	{
	195	struct bpf_ringbuf_map *rb_map;
	196
457f4436 AN	197	rb_map = container_of(map, struct bpf_ringbuf_map, map);
	198	bpf_ringbuf_free(rb_map->rb);
	199	kfree(rb_map);
	200	}
	201
	202	static void ringbuf_map_lookup_elem(struct bpf_map map, void *key)
	203	{
	204	return ERR_PTR(-ENOTSUPP);
	205	}
	206
	207	static int ringbuf_map_update_elem(struct bpf_map map, void key, void *value,
	208	u64 flags)
	209	{
	210	return -ENOTSUPP;
	211	}
	212
	213	static int ringbuf_map_delete_elem(struct bpf_map map, void key)
	214	{
	215	return -ENOTSUPP;
	216	}
	217
	218	static int ringbuf_map_get_next_key(struct bpf_map map, void key,
	219	void *next_key)
	220	{
	221	return -ENOTSUPP;
	222	}
	223
457f4436 AN	224	static int ringbuf_map_mmap(struct bpf_map map, struct vm_area_struct vma)
	225	{
	226	struct bpf_ringbuf_map *rb_map;
457f4436 AN	227
457f4436 AN	228	rb_map = container_of(map, struct bpf_ringbuf_map, map);
457f4436	229
15735c6b AN	230	if (vma->vm_flags & VM_WRITE) {
	231	/* allow writable mapping for the consumer_pos only */
	232	if (vma->vm_pgoff != 0 \|\| vma->vm_end - vma->vm_start != PAGE_SIZE)
	233	return -EPERM;
	234	} else {
	235	vma->vm_flags &= ~VM_MAYWRITE;
	236	}
	237	/* remap_vmalloc_range() checks size and offset constraints */
457f4436 AN	238	return remap_vmalloc_range(vma, rb_map->rb,
	239	vma->vm_pgoff + RINGBUF_PGOFF);
	240	}
	241
	242	static unsigned long ringbuf_avail_data_sz(struct bpf_ringbuf *rb)
	243	{
	244	unsigned long cons_pos, prod_pos;
	245
	246	cons_pos = smp_load_acquire(&rb->consumer_pos);
	247	prod_pos = smp_load_acquire(&rb->producer_pos);
	248	return prod_pos - cons_pos;
	249	}
	250
	251	static __poll_t ringbuf_map_poll(struct bpf_map map, struct file filp,
	252	struct poll_table_struct *pts)
	253	{
	254	struct bpf_ringbuf_map *rb_map;
	255
	256	rb_map = container_of(map, struct bpf_ringbuf_map, map);
	257	poll_wait(filp, &rb_map->rb->waitq, pts);
	258
	259	if (ringbuf_avail_data_sz(rb_map->rb))
	260	return EPOLLIN \| EPOLLRDNORM;
	261	return 0;
	262	}
	263
2872e9ac	264	static int ringbuf_map_btf_id;
457f4436	265	const struct bpf_map_ops ringbuf_map_ops = {
f4d05259	266	.map_meta_equal = bpf_map_meta_equal,
457f4436 AN	267	.map_alloc = ringbuf_map_alloc,
	268	.map_free = ringbuf_map_free,
	269	.map_mmap = ringbuf_map_mmap,
	270	.map_poll = ringbuf_map_poll,
	271	.map_lookup_elem = ringbuf_map_lookup_elem,
	272	.map_update_elem = ringbuf_map_update_elem,
	273	.map_delete_elem = ringbuf_map_delete_elem,
	274	.map_get_next_key = ringbuf_map_get_next_key,
2872e9ac AI	275	.map_btf_name = "bpf_ringbuf_map",
2872e9ac AI	276	.map_btf_id = &ringbuf_map_btf_id,
457f4436 AN	277	};
	278
	279	/* Given pointer to ring buffer record metadata and struct bpf_ringbuf itself,
	280	* calculate offset from record metadata to ring buffer in pages, rounded
	281	* down. This page offset is stored as part of record metadata and allows to
	282	* restore struct bpf_ringbuf * from record pointer. This page offset is
	283	* stored at offset 4 of record metadata header.
	284	*/
	285	static size_t bpf_ringbuf_rec_pg_off(struct bpf_ringbuf *rb,
	286	struct bpf_ringbuf_hdr *hdr)
	287	{
	288	return ((void )hdr - (void )rb) >> PAGE_SHIFT;
	289	}
	290
	291	/* Given pointer to ring buffer record header, restore pointer to struct
	292	* bpf_ringbuf itself by using page offset stored at offset 4
	293	*/
	294	static struct bpf_ringbuf *
	295	bpf_ringbuf_restore_from_rec(struct bpf_ringbuf_hdr *hdr)
	296	{
	297	unsigned long addr = (unsigned long)(void *)hdr;
	298	unsigned long off = (unsigned long)hdr->pg_off << PAGE_SHIFT;
	299
	300	return (void*)((addr & PAGE_MASK) - off);
	301	}
	302
	303	static void __bpf_ringbuf_reserve(struct bpf_ringbuf rb, u64 size)
	304	{
	305	unsigned long cons_pos, prod_pos, new_prod_pos, flags;
	306	u32 len, pg_off;
	307	struct bpf_ringbuf_hdr *hdr;
	308
	309	if (unlikely(size > RINGBUF_MAX_RECORD_SZ))
	310	return NULL;
	311
	312	len = round_up(size + BPF_RINGBUF_HDR_SZ, 8);
ae6eef43 TLSC	313	if (len > rb->mask + 1)
	314	return NULL;
	315
457f4436 AN	316	cons_pos = smp_load_acquire(&rb->consumer_pos);
	317
	318	if (in_nmi()) {
	319	if (!spin_trylock_irqsave(&rb->spinlock, flags))
	320	return NULL;
	321	} else {
	322	spin_lock_irqsave(&rb->spinlock, flags);
	323	}
	324
	325	prod_pos = rb->producer_pos;
	326	new_prod_pos = prod_pos + len;
	327
	328	/* check for out of ringbuf space by ensuring producer position
	329	* doesn't advance more than (ringbuf_size - 1) ahead
	330	*/
	331	if (new_prod_pos - cons_pos > rb->mask) {
	332	spin_unlock_irqrestore(&rb->spinlock, flags);
	333	return NULL;
	334	}
	335
	336	hdr = (void *)rb->data + (prod_pos & rb->mask);
	337	pg_off = bpf_ringbuf_rec_pg_off(rb, hdr);
	338	hdr->len = size \| BPF_RINGBUF_BUSY_BIT;
	339	hdr->pg_off = pg_off;
	340
	341	/* pairs with consumer's smp_load_acquire() */
	342	smp_store_release(&rb->producer_pos, new_prod_pos);
	343
	344	spin_unlock_irqrestore(&rb->spinlock, flags);
	345
	346	return (void *)hdr + BPF_RINGBUF_HDR_SZ;
	347	}
	348
	349	BPF_CALL_3(bpf_ringbuf_reserve, struct bpf_map *, map, u64, size, u64, flags)
	350	{
	351	struct bpf_ringbuf_map *rb_map;
	352
	353	if (unlikely(flags))
	354	return 0;
	355
	356	rb_map = container_of(map, struct bpf_ringbuf_map, map);
	357	return (unsigned long)__bpf_ringbuf_reserve(rb_map->rb, size);
	358	}
	359
	360	const struct bpf_func_proto bpf_ringbuf_reserve_proto = {
	361	.func = bpf_ringbuf_reserve,
	362	.ret_type = RET_PTR_TO_ALLOC_MEM_OR_NULL,
	363	.arg1_type = ARG_CONST_MAP_PTR,
	364	.arg2_type = ARG_CONST_ALLOC_SIZE_OR_ZERO,
	365	.arg3_type = ARG_ANYTHING,
	366	};
	367
	368	static void bpf_ringbuf_commit(void *sample, u64 flags, bool discard)
	369	{
	370	unsigned long rec_pos, cons_pos;
	371	struct bpf_ringbuf_hdr *hdr;
	372	struct bpf_ringbuf *rb;
	373	u32 new_len;
	374
	375	hdr = sample - BPF_RINGBUF_HDR_SZ;
	376	rb = bpf_ringbuf_restore_from_rec(hdr);
	377	new_len = hdr->len ^ BPF_RINGBUF_BUSY_BIT;
	378	if (discard)
	379	new_len \|= BPF_RINGBUF_DISCARD_BIT;
380
381	/* update record header with correct final size prefix */
382	xchg(&hdr->len, new_len);
383
384	/* if consumer caught up and is waiting for our record, notify about
385	* new data availability
386	*/
387	rec_pos = (void )hdr - (void )rb->data;
388	cons_pos = smp_load_acquire(&rb->consumer_pos) & rb->mask;
389
390	if (flags & BPF_RB_FORCE_WAKEUP)
391	irq_work_queue(&rb->work);
392	else if (cons_pos == rec_pos && !(flags & BPF_RB_NO_WAKEUP))
393	irq_work_queue(&rb->work);
394	}
395
396	BPF_CALL_2(bpf_ringbuf_submit, void *, sample, u64, flags)
397	{
398	bpf_ringbuf_commit(sample, flags, false /* discard */);
399	return 0;
400	}
401
402	const struct bpf_func_proto bpf_ringbuf_submit_proto = {
403	.func = bpf_ringbuf_submit,
404	.ret_type = RET_VOID,
405	.arg1_type = ARG_PTR_TO_ALLOC_MEM,
406	.arg2_type = ARG_ANYTHING,
407	};
408
409	BPF_CALL_2(bpf_ringbuf_discard, void *, sample, u64, flags)
410	{
411	bpf_ringbuf_commit(sample, flags, true /* discard */);
412	return 0;
413	}
414
415	const struct bpf_func_proto bpf_ringbuf_discard_proto = {
416	.func = bpf_ringbuf_discard,
417	.ret_type = RET_VOID,
418	.arg1_type = ARG_PTR_TO_ALLOC_MEM,
419	.arg2_type = ARG_ANYTHING,
420	};
421
422	BPF_CALL_4(bpf_ringbuf_output, struct bpf_map , map, void , data, u64, size,
423	u64, flags)
424	{
425	struct bpf_ringbuf_map *rb_map;
426	void *rec;
427
428	if (unlikely(flags & ~(BPF_RB_NO_WAKEUP \| BPF_RB_FORCE_WAKEUP)))
429	return -EINVAL;
430
431	rb_map = container_of(map, struct bpf_ringbuf_map, map);
432	rec = __bpf_ringbuf_reserve(rb_map->rb, size);
433	if (!rec)
434	return -EAGAIN;
435
436	memcpy(rec, data, size);
437	bpf_ringbuf_commit(rec, flags, false /* discard */);
438	return 0;
439	}
440
441	const struct bpf_func_proto bpf_ringbuf_output_proto = {
442	.func = bpf_ringbuf_output,
443	.ret_type = RET_INTEGER,
444	.arg1_type = ARG_CONST_MAP_PTR,
445	.arg2_type = ARG_PTR_TO_MEM,
446	.arg3_type = ARG_CONST_SIZE_OR_ZERO,
447	.arg4_type = ARG_ANYTHING,
448	};
449
450	BPF_CALL_2(bpf_ringbuf_query, struct bpf_map *, map, u64, flags)
451	{
452	struct bpf_ringbuf *rb;
453
454	rb = container_of(map, struct bpf_ringbuf_map, map)->rb;
455
456	switch (flags) {
457	case BPF_RB_AVAIL_DATA:
458	return ringbuf_avail_data_sz(rb);
459	case BPF_RB_RING_SIZE:
460	return rb->mask + 1;
461	case BPF_RB_CONS_POS:
462	return smp_load_acquire(&rb->consumer_pos);
463	case BPF_RB_PROD_POS:
464	return smp_load_acquire(&rb->producer_pos);
465	default:
466	return 0;
467	}
468	}
469
470	const struct bpf_func_proto bpf_ringbuf_query_proto = {
471	.func = bpf_ringbuf_query,
472	.ret_type = RET_INTEGER,
473	.arg1_type = ARG_CONST_MAP_PTR,
474	.arg2_type = ARG_ANYTHING,
475	};