OSCL-LXR linux-6.0.1/​kernel/​bpf/​ringbuf.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 #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_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_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]);
     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;
 }
 
 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,
     .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_id = &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 > 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 | 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_ALLOC_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 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,
 };
 
 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,
 };

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