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![Suren Baghdasaryan](/assets/img/avatar_default.png)
Replace direct modifications to vma->vm_flags with calls to modifier functions to be able to track flag changes and to keep vma locking correctness. [akpm@linux-foundation.org: fix drivers/misc/open-dice.c, per Hyeonggon Yoo] Link: https://lkml.kernel.org/r/20230126193752.297968-5-surenb@google.com Signed-off-by: Suren Baghdasaryan <surenb@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Mike Rapoport (IBM) <rppt@kernel.org> Acked-by: Sebastian Reichel <sebastian.reichel@collabora.com> Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arjun Roy <arjunroy@google.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: David Rientjes <rientjes@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Greg Thelen <gthelen@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Joel Fernandes <joelaf@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Minchan Kim <minchan@google.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Oskolkov <posk@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Punit Agrawal <punit.agrawal@bytedance.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Shakeel Butt <shakeelb@google.com> Cc: Soheil Hassas Yeganeh <soheil@google.com> Cc: Song Liu <songliubraving@fb.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
776 lines
22 KiB
C
776 lines
22 KiB
C
#include <linux/bpf.h>
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#include <linux/btf.h>
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#include <linux/err.h>
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#include <linux/irq_work.h>
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#include <linux/slab.h>
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#include <linux/filter.h>
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#include <linux/mm.h>
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#include <linux/vmalloc.h>
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#include <linux/wait.h>
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#include <linux/poll.h>
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#include <linux/kmemleak.h>
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#include <uapi/linux/btf.h>
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#include <linux/btf_ids.h>
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#define RINGBUF_CREATE_FLAG_MASK (BPF_F_NUMA_NODE)
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/* non-mmap()'able part of bpf_ringbuf (everything up to consumer page) */
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#define RINGBUF_PGOFF \
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(offsetof(struct bpf_ringbuf, consumer_pos) >> PAGE_SHIFT)
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/* consumer page and producer page */
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#define RINGBUF_POS_PAGES 2
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#define RINGBUF_MAX_RECORD_SZ (UINT_MAX/4)
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/* Maximum size of ring buffer area is limited by 32-bit page offset within
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* record header, counted in pages. Reserve 8 bits for extensibility, and take
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* into account few extra pages for consumer/producer pages and
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* non-mmap()'able parts. This gives 64GB limit, which seems plenty for single
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* ring buffer.
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*/
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#define RINGBUF_MAX_DATA_SZ \
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(((1ULL << 24) - RINGBUF_POS_PAGES - RINGBUF_PGOFF) * PAGE_SIZE)
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struct bpf_ringbuf {
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wait_queue_head_t waitq;
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struct irq_work work;
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u64 mask;
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struct page **pages;
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int nr_pages;
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spinlock_t spinlock ____cacheline_aligned_in_smp;
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/* For user-space producer ring buffers, an atomic_t busy bit is used
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* to synchronize access to the ring buffers in the kernel, rather than
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* the spinlock that is used for kernel-producer ring buffers. This is
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* done because the ring buffer must hold a lock across a BPF program's
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* callback:
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*
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* __bpf_user_ringbuf_peek() // lock acquired
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* -> program callback_fn()
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* -> __bpf_user_ringbuf_sample_release() // lock released
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*
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* It is unsafe and incorrect to hold an IRQ spinlock across what could
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* be a long execution window, so we instead simply disallow concurrent
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* access to the ring buffer by kernel consumers, and return -EBUSY from
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* __bpf_user_ringbuf_peek() if the busy bit is held by another task.
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*/
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atomic_t busy ____cacheline_aligned_in_smp;
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/* Consumer and producer counters are put into separate pages to
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* allow each position to be mapped with different permissions.
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* This prevents a user-space application from modifying the
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* position and ruining in-kernel tracking. The permissions of the
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* pages depend on who is producing samples: user-space or the
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* kernel.
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*
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* Kernel-producer
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* ---------------
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* The producer position and data pages are mapped as r/o in
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* userspace. For this approach, bits in the header of samples are
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* used to signal to user-space, and to other producers, whether a
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* sample is currently being written.
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*
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* User-space producer
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* -------------------
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* Only the page containing the consumer position is mapped r/o in
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* user-space. User-space producers also use bits of the header to
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* communicate to the kernel, but the kernel must carefully check and
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* validate each sample to ensure that they're correctly formatted, and
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* fully contained within the ring buffer.
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*/
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unsigned long consumer_pos __aligned(PAGE_SIZE);
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unsigned long producer_pos __aligned(PAGE_SIZE);
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char data[] __aligned(PAGE_SIZE);
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};
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struct bpf_ringbuf_map {
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struct bpf_map map;
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struct bpf_ringbuf *rb;
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};
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/* 8-byte ring buffer record header structure */
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struct bpf_ringbuf_hdr {
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u32 len;
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u32 pg_off;
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};
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static struct bpf_ringbuf *bpf_ringbuf_area_alloc(size_t data_sz, int numa_node)
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{
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const gfp_t flags = GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL |
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__GFP_NOWARN | __GFP_ZERO;
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int nr_meta_pages = RINGBUF_PGOFF + RINGBUF_POS_PAGES;
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int nr_data_pages = data_sz >> PAGE_SHIFT;
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int nr_pages = nr_meta_pages + nr_data_pages;
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struct page **pages, *page;
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struct bpf_ringbuf *rb;
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size_t array_size;
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int i;
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/* Each data page is mapped twice to allow "virtual"
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* continuous read of samples wrapping around the end of ring
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* buffer area:
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* ------------------------------------------------------
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* | meta pages | real data pages | same data pages |
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* ------------------------------------------------------
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* | | 1 2 3 4 5 6 7 8 9 | 1 2 3 4 5 6 7 8 9 |
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* ------------------------------------------------------
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* | | TA DA | TA DA |
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* ------------------------------------------------------
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* ^^^^^^^
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* |
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* Here, no need to worry about special handling of wrapped-around
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* data due to double-mapped data pages. This works both in kernel and
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* when mmap()'ed in user-space, simplifying both kernel and
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* user-space implementations significantly.
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*/
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array_size = (nr_meta_pages + 2 * nr_data_pages) * sizeof(*pages);
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pages = bpf_map_area_alloc(array_size, numa_node);
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if (!pages)
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return NULL;
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for (i = 0; i < nr_pages; i++) {
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page = alloc_pages_node(numa_node, flags, 0);
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if (!page) {
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nr_pages = i;
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goto err_free_pages;
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}
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pages[i] = page;
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if (i >= nr_meta_pages)
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pages[nr_data_pages + i] = page;
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}
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rb = vmap(pages, nr_meta_pages + 2 * nr_data_pages,
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VM_MAP | VM_USERMAP, PAGE_KERNEL);
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if (rb) {
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kmemleak_not_leak(pages);
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rb->pages = pages;
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rb->nr_pages = nr_pages;
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return rb;
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}
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err_free_pages:
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for (i = 0; i < nr_pages; i++)
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__free_page(pages[i]);
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bpf_map_area_free(pages);
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return NULL;
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}
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static void bpf_ringbuf_notify(struct irq_work *work)
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{
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struct bpf_ringbuf *rb = container_of(work, struct bpf_ringbuf, work);
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wake_up_all(&rb->waitq);
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}
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static struct bpf_ringbuf *bpf_ringbuf_alloc(size_t data_sz, int numa_node)
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{
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struct bpf_ringbuf *rb;
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rb = bpf_ringbuf_area_alloc(data_sz, numa_node);
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if (!rb)
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return NULL;
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spin_lock_init(&rb->spinlock);
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atomic_set(&rb->busy, 0);
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init_waitqueue_head(&rb->waitq);
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init_irq_work(&rb->work, bpf_ringbuf_notify);
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rb->mask = data_sz - 1;
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rb->consumer_pos = 0;
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rb->producer_pos = 0;
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return rb;
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}
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static struct bpf_map *ringbuf_map_alloc(union bpf_attr *attr)
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{
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struct bpf_ringbuf_map *rb_map;
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if (attr->map_flags & ~RINGBUF_CREATE_FLAG_MASK)
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return ERR_PTR(-EINVAL);
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if (attr->key_size || attr->value_size ||
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!is_power_of_2(attr->max_entries) ||
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!PAGE_ALIGNED(attr->max_entries))
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return ERR_PTR(-EINVAL);
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#ifdef CONFIG_64BIT
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/* on 32-bit arch, it's impossible to overflow record's hdr->pgoff */
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if (attr->max_entries > RINGBUF_MAX_DATA_SZ)
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return ERR_PTR(-E2BIG);
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#endif
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rb_map = bpf_map_area_alloc(sizeof(*rb_map), NUMA_NO_NODE);
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if (!rb_map)
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return ERR_PTR(-ENOMEM);
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bpf_map_init_from_attr(&rb_map->map, attr);
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rb_map->rb = bpf_ringbuf_alloc(attr->max_entries, rb_map->map.numa_node);
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if (!rb_map->rb) {
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bpf_map_area_free(rb_map);
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return ERR_PTR(-ENOMEM);
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}
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return &rb_map->map;
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}
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static void bpf_ringbuf_free(struct bpf_ringbuf *rb)
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{
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/* copy pages pointer and nr_pages to local variable, as we are going
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* to unmap rb itself with vunmap() below
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*/
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struct page **pages = rb->pages;
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int i, nr_pages = rb->nr_pages;
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vunmap(rb);
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for (i = 0; i < nr_pages; i++)
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__free_page(pages[i]);
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bpf_map_area_free(pages);
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}
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static void ringbuf_map_free(struct bpf_map *map)
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{
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struct bpf_ringbuf_map *rb_map;
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rb_map = container_of(map, struct bpf_ringbuf_map, map);
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bpf_ringbuf_free(rb_map->rb);
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bpf_map_area_free(rb_map);
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}
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static void *ringbuf_map_lookup_elem(struct bpf_map *map, void *key)
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{
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return ERR_PTR(-ENOTSUPP);
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}
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static int ringbuf_map_update_elem(struct bpf_map *map, void *key, void *value,
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u64 flags)
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{
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return -ENOTSUPP;
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}
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static int ringbuf_map_delete_elem(struct bpf_map *map, void *key)
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{
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return -ENOTSUPP;
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}
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static int ringbuf_map_get_next_key(struct bpf_map *map, void *key,
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void *next_key)
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{
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return -ENOTSUPP;
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}
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static int ringbuf_map_mmap_kern(struct bpf_map *map, struct vm_area_struct *vma)
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{
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struct bpf_ringbuf_map *rb_map;
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rb_map = container_of(map, struct bpf_ringbuf_map, map);
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if (vma->vm_flags & VM_WRITE) {
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/* allow writable mapping for the consumer_pos only */
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if (vma->vm_pgoff != 0 || vma->vm_end - vma->vm_start != PAGE_SIZE)
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return -EPERM;
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} else {
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vm_flags_clear(vma, VM_MAYWRITE);
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}
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/* remap_vmalloc_range() checks size and offset constraints */
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return remap_vmalloc_range(vma, rb_map->rb,
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vma->vm_pgoff + RINGBUF_PGOFF);
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}
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static int ringbuf_map_mmap_user(struct bpf_map *map, struct vm_area_struct *vma)
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{
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struct bpf_ringbuf_map *rb_map;
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rb_map = container_of(map, struct bpf_ringbuf_map, map);
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if (vma->vm_flags & VM_WRITE) {
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if (vma->vm_pgoff == 0)
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/* Disallow writable mappings to the consumer pointer,
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* and allow writable mappings to both the producer
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* position, and the ring buffer data itself.
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*/
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return -EPERM;
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} else {
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vm_flags_clear(vma, VM_MAYWRITE);
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}
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/* remap_vmalloc_range() checks size and offset constraints */
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return remap_vmalloc_range(vma, rb_map->rb, vma->vm_pgoff + RINGBUF_PGOFF);
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}
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static unsigned long ringbuf_avail_data_sz(struct bpf_ringbuf *rb)
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{
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unsigned long cons_pos, prod_pos;
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cons_pos = smp_load_acquire(&rb->consumer_pos);
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prod_pos = smp_load_acquire(&rb->producer_pos);
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return prod_pos - cons_pos;
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}
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static u32 ringbuf_total_data_sz(const struct bpf_ringbuf *rb)
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{
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return rb->mask + 1;
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}
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static __poll_t ringbuf_map_poll_kern(struct bpf_map *map, struct file *filp,
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struct poll_table_struct *pts)
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{
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struct bpf_ringbuf_map *rb_map;
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rb_map = container_of(map, struct bpf_ringbuf_map, map);
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poll_wait(filp, &rb_map->rb->waitq, pts);
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if (ringbuf_avail_data_sz(rb_map->rb))
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return EPOLLIN | EPOLLRDNORM;
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return 0;
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}
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static __poll_t ringbuf_map_poll_user(struct bpf_map *map, struct file *filp,
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struct poll_table_struct *pts)
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{
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struct bpf_ringbuf_map *rb_map;
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rb_map = container_of(map, struct bpf_ringbuf_map, map);
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poll_wait(filp, &rb_map->rb->waitq, pts);
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if (ringbuf_avail_data_sz(rb_map->rb) < ringbuf_total_data_sz(rb_map->rb))
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return EPOLLOUT | EPOLLWRNORM;
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return 0;
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}
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BTF_ID_LIST_SINGLE(ringbuf_map_btf_ids, struct, bpf_ringbuf_map)
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const struct bpf_map_ops ringbuf_map_ops = {
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.map_meta_equal = bpf_map_meta_equal,
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.map_alloc = ringbuf_map_alloc,
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.map_free = ringbuf_map_free,
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.map_mmap = ringbuf_map_mmap_kern,
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.map_poll = ringbuf_map_poll_kern,
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.map_lookup_elem = ringbuf_map_lookup_elem,
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.map_update_elem = ringbuf_map_update_elem,
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.map_delete_elem = ringbuf_map_delete_elem,
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.map_get_next_key = ringbuf_map_get_next_key,
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.map_btf_id = &ringbuf_map_btf_ids[0],
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};
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BTF_ID_LIST_SINGLE(user_ringbuf_map_btf_ids, struct, bpf_ringbuf_map)
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const struct bpf_map_ops user_ringbuf_map_ops = {
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.map_meta_equal = bpf_map_meta_equal,
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.map_alloc = ringbuf_map_alloc,
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.map_free = ringbuf_map_free,
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.map_mmap = ringbuf_map_mmap_user,
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.map_poll = ringbuf_map_poll_user,
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.map_lookup_elem = ringbuf_map_lookup_elem,
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.map_update_elem = ringbuf_map_update_elem,
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.map_delete_elem = ringbuf_map_delete_elem,
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.map_get_next_key = ringbuf_map_get_next_key,
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.map_btf_id = &user_ringbuf_map_btf_ids[0],
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};
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/* Given pointer to ring buffer record metadata and struct bpf_ringbuf itself,
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* calculate offset from record metadata to ring buffer in pages, rounded
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* down. This page offset is stored as part of record metadata and allows to
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* restore struct bpf_ringbuf * from record pointer. This page offset is
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* stored at offset 4 of record metadata header.
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*/
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static size_t bpf_ringbuf_rec_pg_off(struct bpf_ringbuf *rb,
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struct bpf_ringbuf_hdr *hdr)
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{
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return ((void *)hdr - (void *)rb) >> PAGE_SHIFT;
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}
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/* Given pointer to ring buffer record header, restore pointer to struct
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* bpf_ringbuf itself by using page offset stored at offset 4
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*/
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static struct bpf_ringbuf *
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bpf_ringbuf_restore_from_rec(struct bpf_ringbuf_hdr *hdr)
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{
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unsigned long addr = (unsigned long)(void *)hdr;
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unsigned long off = (unsigned long)hdr->pg_off << PAGE_SHIFT;
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return (void*)((addr & PAGE_MASK) - off);
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}
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static void *__bpf_ringbuf_reserve(struct bpf_ringbuf *rb, u64 size)
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{
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unsigned long cons_pos, prod_pos, new_prod_pos, flags;
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u32 len, pg_off;
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struct bpf_ringbuf_hdr *hdr;
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if (unlikely(size > RINGBUF_MAX_RECORD_SZ))
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return NULL;
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len = round_up(size + BPF_RINGBUF_HDR_SZ, 8);
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if (len > ringbuf_total_data_sz(rb))
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return NULL;
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cons_pos = smp_load_acquire(&rb->consumer_pos);
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if (in_nmi()) {
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if (!spin_trylock_irqsave(&rb->spinlock, flags))
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return NULL;
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} else {
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spin_lock_irqsave(&rb->spinlock, flags);
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}
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prod_pos = rb->producer_pos;
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new_prod_pos = prod_pos + len;
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/* check for out of ringbuf space by ensuring producer position
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* doesn't advance more than (ringbuf_size - 1) ahead
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*/
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if (new_prod_pos - cons_pos > rb->mask) {
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spin_unlock_irqrestore(&rb->spinlock, flags);
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return NULL;
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}
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hdr = (void *)rb->data + (prod_pos & rb->mask);
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pg_off = bpf_ringbuf_rec_pg_off(rb, hdr);
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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,
|
|
};
|