diff options
| -rw-r--r-- | include/linux/bpf.h | 1 | ||||
| -rw-r--r-- | kernel/bpf/stackmap.c | 86 | ||||
| -rw-r--r-- | kernel/bpf/syscall.c | 2 |
3 files changed, 71 insertions, 18 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index efd1d4ca95c6..21ee41b92e8a 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -195,6 +195,7 @@ int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value, u64 flags); int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value, u64 flags); +int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value); /* memcpy that is used with 8-byte aligned pointers, power-of-8 size and * forced to use 'long' read/writes to try to atomically copy long counters. diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index f0a02c344358..499d9e933f8e 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -10,9 +10,10 @@ #include <linux/vmalloc.h> #include <linux/stacktrace.h> #include <linux/perf_event.h> +#include "percpu_freelist.h" struct stack_map_bucket { - struct rcu_head rcu; + struct pcpu_freelist_node fnode; u32 hash; u32 nr; u64 ip[]; @@ -20,10 +21,34 @@ struct stack_map_bucket { struct bpf_stack_map { struct bpf_map map; + void *elems; + struct pcpu_freelist freelist; u32 n_buckets; - struct stack_map_bucket __rcu *buckets[]; + struct stack_map_bucket *buckets[]; }; +static int prealloc_elems_and_freelist(struct bpf_stack_map *smap) +{ + u32 elem_size = sizeof(struct stack_map_bucket) + smap->map.value_size; + int err; + + smap->elems = vzalloc(elem_size * smap->map.max_entries); + if (!smap->elems) + return -ENOMEM; + + err = pcpu_freelist_init(&smap->freelist); + if (err) + goto free_elems; + + pcpu_freelist_populate(&smap->freelist, smap->elems, elem_size, + smap->map.max_entries); + return 0; + +free_elems: + vfree(smap->elems); + return err; +} + /* Called from syscall */ static struct bpf_map *stack_map_alloc(union bpf_attr *attr) { @@ -70,12 +95,22 @@ static struct bpf_map *stack_map_alloc(union bpf_attr *attr) smap->n_buckets = n_buckets; smap->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT; + err = bpf_map_precharge_memlock(smap->map.pages); + if (err) + goto free_smap; + err = get_callchain_buffers(); if (err) goto free_smap; + err = prealloc_elems_and_freelist(smap); + if (err) + goto put_buffers; + return &smap->map; +put_buffers: + put_callchain_buffers(); free_smap: kvfree(smap); return ERR_PTR(err); @@ -121,7 +156,7 @@ static u64 bpf_get_stackid(u64 r1, u64 r2, u64 flags, u64 r4, u64 r5) ips = trace->ip + skip + init_nr; hash = jhash2((u32 *)ips, trace_len / sizeof(u32), 0); id = hash & (smap->n_buckets - 1); - bucket = rcu_dereference(smap->buckets[id]); + bucket = READ_ONCE(smap->buckets[id]); if (bucket && bucket->hash == hash) { if (flags & BPF_F_FAST_STACK_CMP) @@ -135,19 +170,18 @@ static u64 bpf_get_stackid(u64 r1, u64 r2, u64 flags, u64 r4, u64 r5) if (bucket && !(flags & BPF_F_REUSE_STACKID)) return -EEXIST; - new_bucket = kmalloc(sizeof(struct stack_map_bucket) + map->value_size, - GFP_ATOMIC | __GFP_NOWARN); + new_bucket = (struct stack_map_bucket *) + pcpu_freelist_pop(&smap->freelist); if (unlikely(!new_bucket)) return -ENOMEM; memcpy(new_bucket->ip, ips, trace_len); - memset(new_bucket->ip + trace_len / 8, 0, map->value_size - trace_len); new_bucket->hash = hash; new_bucket->nr = trace_nr; old_bucket = xchg(&smap->buckets[id], new_bucket); if (old_bucket) - kfree_rcu(old_bucket, rcu); + pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); return id; } @@ -160,17 +194,34 @@ const struct bpf_func_proto bpf_get_stackid_proto = { .arg3_type = ARG_ANYTHING, }; -/* Called from syscall or from eBPF program */ +/* Called from eBPF program */ static void *stack_map_lookup_elem(struct bpf_map *map, void *key) { + return NULL; +} + +/* Called from syscall */ +int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value) +{ struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); - struct stack_map_bucket *bucket; - u32 id = *(u32 *)key; + struct stack_map_bucket *bucket, *old_bucket; + u32 id = *(u32 *)key, trace_len; if (unlikely(id >= smap->n_buckets)) - return NULL; - bucket = rcu_dereference(smap->buckets[id]); - return bucket ? bucket->ip : NULL; + return -ENOENT; + + bucket = xchg(&smap->buckets[id], NULL); + if (!bucket) + return -ENOENT; + + trace_len = bucket->nr * sizeof(u64); + memcpy(value, bucket->ip, trace_len); + memset(value + trace_len, 0, map->value_size - trace_len); + + old_bucket = xchg(&smap->buckets[id], bucket); + if (old_bucket) + pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); + return 0; } static int stack_map_get_next_key(struct bpf_map *map, void *key, void *next_key) @@ -196,7 +247,7 @@ static int stack_map_delete_elem(struct bpf_map *map, void *key) old_bucket = xchg(&smap->buckets[id], NULL); if (old_bucket) { - kfree_rcu(old_bucket, rcu); + pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); return 0; } else { return -ENOENT; @@ -207,13 +258,12 @@ static int stack_map_delete_elem(struct bpf_map *map, void *key) static void stack_map_free(struct bpf_map *map) { struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); - int i; + /* wait for bpf programs to complete before freeing stack map */ synchronize_rcu(); - for (i = 0; i < smap->n_buckets; i++) - if (smap->buckets[i]) - kfree_rcu(smap->buckets[i], rcu); + vfree(smap->elems); + pcpu_freelist_destroy(&smap->freelist); kvfree(smap); put_callchain_buffers(); } diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index cbd94b2144ff..2978d0d08869 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -290,6 +290,8 @@ static int map_lookup_elem(union bpf_attr *attr) err = bpf_percpu_hash_copy(map, key, value); } else if (map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY) { err = bpf_percpu_array_copy(map, key, value); + } else if (map->map_type == BPF_MAP_TYPE_STACK_TRACE) { + err = bpf_stackmap_copy(map, key, value); } else { rcu_read_lock(); ptr = map->ops->map_lookup_elem(map, key); |