Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 790 insertions, 0 deletions

diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c
new file mode 100644
index 0000000000..f045fde632
--- /dev/null
+++ b/kernel/bpf/ringbuf.c
@@ -0,0 +1,790 @@
+#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 <linux/kmemleak.h>
+#include <uapi/linux/btf.h>
+#include <linux/btf_ids.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_NR_META_PAGES (RINGBUF_PGOFF + RINGBUF_POS_PAGES)
+
+#define RINGBUF_MAX_RECORD_SZ (UINT_MAX/4)
+
+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;
+	/* For user-space producer ring buffers, an atomic_t busy bit is used
+	 * to synchronize access to the ring buffers in the kernel, rather than
+	 * the spinlock that is used for kernel-producer ring buffers. This is
+	 * done because the ring buffer must hold a lock across a BPF program's
+	 * callback:
+	 *
+	 *    __bpf_user_ringbuf_peek() // lock acquired
+	 * -> program callback_fn()
+	 * -> __bpf_user_ringbuf_sample_release() // lock released
+	 *
+	 * It is unsafe and incorrect to hold an IRQ spinlock across what could
+	 * be a long execution window, so we instead simply disallow concurrent
+	 * access to the ring buffer by kernel consumers, and return -EBUSY from
+	 * __bpf_user_ringbuf_peek() if the busy bit is held by another task.
+	 */
+	atomic_t busy ____cacheline_aligned_in_smp;
+	/* Consumer and producer counters are put into separate pages to
+	 * allow each position to be mapped with different permissions.
+	 * This prevents a user-space application from modifying the
+	 * position and ruining in-kernel tracking. The permissions of the
+	 * pages depend on who is producing samples: user-space or the
+	 * kernel.
+	 *
+	 * Kernel-producer
+	 * ---------------
+	 * The producer position and data pages are mapped as r/o in
+	 * userspace. For this approach, bits in the header of samples are
+	 * used to signal to user-space, and to other producers, whether a
+	 * sample is currently being written.
+	 *
+	 * User-space producer
+	 * -------------------
+	 * Only the page containing the consumer position is mapped r/o in
+	 * user-space. User-space producers also use bits of the header to
+	 * communicate to the kernel, but the kernel must carefully check and
+	 * validate each sample to ensure that they're correctly formatted, and
+	 * fully contained within the ring buffer.
+	 */
+	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_NR_META_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_MAP | VM_USERMAP, PAGE_KERNEL);
+	if (rb) {
+		kmemleak_not_leak(pages);
+		rb->pages = pages;
+		rb->nr_pages = nr_pages;
+		return rb;
+	}
+
+err_free_pages:
+	for (i = 0; i < nr_pages; i++)
+		__free_page(pages[i]);
+	bpf_map_area_free(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);
+}
+
+/* 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, the current maximum size would be:
+ *
+ *     (((1ULL << 24) - RINGBUF_POS_PAGES - RINGBUF_PGOFF) * PAGE_SIZE)
+ *
+ * This gives 64GB limit, which seems plenty for single ring buffer. Now
+ * considering that the maximum value of data_sz is (4GB - 1), there
+ * will be no overflow, so just note the size limit in the comments.
+ */
+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);
+	atomic_set(&rb->busy, 0);
+	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);
+
+	rb_map = bpf_map_area_alloc(sizeof(*rb_map), NUMA_NO_NODE);
+	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) {
+		bpf_map_area_free(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]);
+	bpf_map_area_free(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);
+	bpf_map_area_free(rb_map);
+}
+
+static void *ringbuf_map_lookup_elem(struct bpf_map *map, void *key)
+{
+	return ERR_PTR(-ENOTSUPP);
+}
+
+static long ringbuf_map_update_elem(struct bpf_map *map, void *key, void *value,
+				    u64 flags)
+{
+	return -ENOTSUPP;
+}
+
+static long 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_kern(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 {
+		vm_flags_clear(vma, VM_MAYWRITE);
+	}
+	/* remap_vmalloc_range() checks size and offset constraints */
+	return remap_vmalloc_range(vma, rb_map->rb,
+				   vma->vm_pgoff + RINGBUF_PGOFF);
+}
+
+static int ringbuf_map_mmap_user(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) {
+		if (vma->vm_pgoff == 0)
+			/* Disallow writable mappings to the consumer pointer,
+			 * and allow writable mappings to both the producer
+			 * position, and the ring buffer data itself.
+			 */
+			return -EPERM;
+	} else {
+		vm_flags_clear(vma, 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 u32 ringbuf_total_data_sz(const struct bpf_ringbuf *rb)
+{
+	return rb->mask + 1;
+}
+
+static __poll_t ringbuf_map_poll_kern(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 __poll_t ringbuf_map_poll_user(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) < ringbuf_total_data_sz(rb_map->rb))
+		return EPOLLOUT | EPOLLWRNORM;
+	return 0;
+}
+
+static u64 ringbuf_map_mem_usage(const struct bpf_map *map)
+{
+	struct bpf_ringbuf *rb;
+	int nr_data_pages;
+	int nr_meta_pages;
+	u64 usage = sizeof(struct bpf_ringbuf_map);
+
+	rb = container_of(map, struct bpf_ringbuf_map, map)->rb;
+	usage += (u64)rb->nr_pages << PAGE_SHIFT;
+	nr_meta_pages = RINGBUF_NR_META_PAGES;
+	nr_data_pages = map->max_entries >> PAGE_SHIFT;
+	usage += (nr_meta_pages + 2 * nr_data_pages) * sizeof(struct page *);
+	return usage;
+}
+
+BTF_ID_LIST_SINGLE(ringbuf_map_btf_ids, struct, bpf_ringbuf_map)
+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_kern,
+	.map_poll = ringbuf_map_poll_kern,
+	.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_mem_usage = ringbuf_map_mem_usage,
+	.map_btf_id = &ringbuf_map_btf_ids[0],
+};
+
+BTF_ID_LIST_SINGLE(user_ringbuf_map_btf_ids, struct, bpf_ringbuf_map)
+const struct bpf_map_ops user_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_user,
+	.map_poll = ringbuf_map_poll_user,
+	.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_mem_usage = ringbuf_map_mem_usage,
+	.map_btf_id = &user_ringbuf_map_btf_ids[0],
+};
+
+/* 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 > ringbuf_total_data_sz(rb))
+		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_RINGBUF_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_RINGBUF_MEM | OBJ_RELEASE,
+	.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_RINGBUF_MEM | OBJ_RELEASE,
+	.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 | MEM_RDONLY,
+	.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 ringbuf_total_data_sz(rb);
+	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,
+};
+
+BPF_CALL_4(bpf_ringbuf_reserve_dynptr, struct bpf_map *, map, u32, size, u64, flags,
+	   struct bpf_dynptr_kern *, ptr)
+{
+	struct bpf_ringbuf_map *rb_map;
+	void *sample;
+	int err;
+
+	if (unlikely(flags)) {
+		bpf_dynptr_set_null(ptr);
+		return -EINVAL;
+	}
+
+	err = bpf_dynptr_check_size(size);
+	if (err) {
+		bpf_dynptr_set_null(ptr);
+		return err;
+	}
+
+	rb_map = container_of(map, struct bpf_ringbuf_map, map);
+
+	sample = __bpf_ringbuf_reserve(rb_map->rb, size);
+	if (!sample) {
+		bpf_dynptr_set_null(ptr);
+		return -EINVAL;
+	}
+
+	bpf_dynptr_init(ptr, sample, BPF_DYNPTR_TYPE_RINGBUF, 0, size);
+
+	return 0;
+}
+
+const struct bpf_func_proto bpf_ringbuf_reserve_dynptr_proto = {
+	.func		= bpf_ringbuf_reserve_dynptr,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_CONST_MAP_PTR,
+	.arg2_type	= ARG_ANYTHING,
+	.arg3_type	= ARG_ANYTHING,
+	.arg4_type	= ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_RINGBUF | MEM_UNINIT,
+};
+
+BPF_CALL_2(bpf_ringbuf_submit_dynptr, struct bpf_dynptr_kern *, ptr, u64, flags)
+{
+	if (!ptr->data)
+		return 0;
+
+	bpf_ringbuf_commit(ptr->data, flags, false /* discard */);
+
+	bpf_dynptr_set_null(ptr);
+
+	return 0;
+}
+
+const struct bpf_func_proto bpf_ringbuf_submit_dynptr_proto = {
+	.func		= bpf_ringbuf_submit_dynptr,
+	.ret_type	= RET_VOID,
+	.arg1_type	= ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_RINGBUF | OBJ_RELEASE,
+	.arg2_type	= ARG_ANYTHING,
+};
+
+BPF_CALL_2(bpf_ringbuf_discard_dynptr, struct bpf_dynptr_kern *, ptr, u64, flags)
+{
+	if (!ptr->data)
+		return 0;
+
+	bpf_ringbuf_commit(ptr->data, flags, true /* discard */);
+
+	bpf_dynptr_set_null(ptr);
+
+	return 0;
+}
+
+const struct bpf_func_proto bpf_ringbuf_discard_dynptr_proto = {
+	.func		= bpf_ringbuf_discard_dynptr,
+	.ret_type	= RET_VOID,
+	.arg1_type	= ARG_PTR_TO_DYNPTR | DYNPTR_TYPE_RINGBUF | OBJ_RELEASE,
+	.arg2_type	= ARG_ANYTHING,
+};
+
+static int __bpf_user_ringbuf_peek(struct bpf_ringbuf *rb, void **sample, u32 *size)
+{
+	int err;
+	u32 hdr_len, sample_len, total_len, flags, *hdr;
+	u64 cons_pos, prod_pos;
+
+	/* Synchronizes with smp_store_release() in user-space producer. */
+	prod_pos = smp_load_acquire(&rb->producer_pos);
+	if (prod_pos % 8)
+		return -EINVAL;
+
+	/* Synchronizes with smp_store_release() in __bpf_user_ringbuf_sample_release() */
+	cons_pos = smp_load_acquire(&rb->consumer_pos);
+	if (cons_pos >= prod_pos)
+		return -ENODATA;
+
+	hdr = (u32 *)((uintptr_t)rb->data + (uintptr_t)(cons_pos & rb->mask));
+	/* Synchronizes with smp_store_release() in user-space producer. */
+	hdr_len = smp_load_acquire(hdr);
+	flags = hdr_len & (BPF_RINGBUF_BUSY_BIT | BPF_RINGBUF_DISCARD_BIT);
+	sample_len = hdr_len & ~flags;
+	total_len = round_up(sample_len + BPF_RINGBUF_HDR_SZ, 8);
+
+	/* The sample must fit within the region advertised by the producer position. */
+	if (total_len > prod_pos - cons_pos)
+		return -EINVAL;
+
+	/* The sample must fit within the data region of the ring buffer. */
+	if (total_len > ringbuf_total_data_sz(rb))
+		return -E2BIG;
+
+	/* The sample must fit into a struct bpf_dynptr. */
+	err = bpf_dynptr_check_size(sample_len);
+	if (err)
+		return -E2BIG;
+
+	if (flags & BPF_RINGBUF_DISCARD_BIT) {
+		/* If the discard bit is set, the sample should be skipped.
+		 *
+		 * Update the consumer pos, and return -EAGAIN so the caller
+		 * knows to skip this sample and try to read the next one.
+		 */
+		smp_store_release(&rb->consumer_pos, cons_pos + total_len);
+		return -EAGAIN;
+	}
+
+	if (flags & BPF_RINGBUF_BUSY_BIT)
+		return -ENODATA;
+
+	*sample = (void *)((uintptr_t)rb->data +
+			   (uintptr_t)((cons_pos + BPF_RINGBUF_HDR_SZ) & rb->mask));
+	*size = sample_len;
+	return 0;
+}
+
+static void __bpf_user_ringbuf_sample_release(struct bpf_ringbuf *rb, size_t size, u64 flags)
+{
+	u64 consumer_pos;
+	u32 rounded_size = round_up(size + BPF_RINGBUF_HDR_SZ, 8);
+
+	/* Using smp_load_acquire() is unnecessary here, as the busy-bit
+	 * prevents another task from writing to consumer_pos after it was read
+	 * by this task with smp_load_acquire() in __bpf_user_ringbuf_peek().
+	 */
+	consumer_pos = rb->consumer_pos;
+	 /* Synchronizes with smp_load_acquire() in user-space producer. */
+	smp_store_release(&rb->consumer_pos, consumer_pos + rounded_size);
+}
+
+BPF_CALL_4(bpf_user_ringbuf_drain, struct bpf_map *, map,
+	   void *, callback_fn, void *, callback_ctx, u64, flags)
+{
+	struct bpf_ringbuf *rb;
+	long samples, discarded_samples = 0, ret = 0;
+	bpf_callback_t callback = (bpf_callback_t)callback_fn;
+	u64 wakeup_flags = BPF_RB_NO_WAKEUP | BPF_RB_FORCE_WAKEUP;
+	int busy = 0;
+
+	if (unlikely(flags & ~wakeup_flags))
+		return -EINVAL;
+
+	rb = container_of(map, struct bpf_ringbuf_map, map)->rb;
+
+	/* If another consumer is already consuming a sample, wait for them to finish. */
+	if (!atomic_try_cmpxchg(&rb->busy, &busy, 1))
+		return -EBUSY;
+
+	for (samples = 0; samples < BPF_MAX_USER_RINGBUF_SAMPLES && ret == 0; samples++) {
+		int err;
+		u32 size;
+		void *sample;
+		struct bpf_dynptr_kern dynptr;
+
+		err = __bpf_user_ringbuf_peek(rb, &sample, &size);
+		if (err) {
+			if (err == -ENODATA) {
+				break;
+			} else if (err == -EAGAIN) {
+				discarded_samples++;
+				continue;
+			} else {
+				ret = err;
+				goto schedule_work_return;
+			}
+		}
+
+		bpf_dynptr_init(&dynptr, sample, BPF_DYNPTR_TYPE_LOCAL, 0, size);
+		ret = callback((uintptr_t)&dynptr, (uintptr_t)callback_ctx, 0, 0, 0);
+		__bpf_user_ringbuf_sample_release(rb, size, flags);
+	}
+	ret = samples - discarded_samples;
+
+schedule_work_return:
+	/* Prevent the clearing of the busy-bit from being reordered before the
+	 * storing of any rb consumer or producer positions.
+	 */
+	smp_mb__before_atomic();
+	atomic_set(&rb->busy, 0);
+
+	if (flags & BPF_RB_FORCE_WAKEUP)
+		irq_work_queue(&rb->work);
+	else if (!(flags & BPF_RB_NO_WAKEUP) && samples > 0)
+		irq_work_queue(&rb->work);
+	return ret;
+}
+
+const struct bpf_func_proto bpf_user_ringbuf_drain_proto = {
+	.func		= bpf_user_ringbuf_drain,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_CONST_MAP_PTR,
+	.arg2_type	= ARG_PTR_TO_FUNC,
+	.arg3_type	= ARG_PTR_TO_STACK_OR_NULL,
+	.arg4_type	= ARG_ANYTHING,
+};