From 824bd0ce6c7c43a9e1e210abf124958e54d88342 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 1 Feb 2016 22:39:53 -0800 Subject: [PATCH 1/6] bpf: introduce BPF_MAP_TYPE_PERCPU_HASH map Introduce BPF_MAP_TYPE_PERCPU_HASH map type which is used to do accurate counters without need to use BPF_XADD instruction which turned out to be too costly for high-performance network monitoring. In the typical use case the 'key' is the flow tuple or other long living object that sees a lot of events per second. bpf_map_lookup_elem() returns per-cpu area. Example: struct { u32 packets; u32 bytes; } * ptr = bpf_map_lookup_elem(&map, &key); /* ptr points to this_cpu area of the value, so the following * increments will not collide with other cpus */ ptr->packets ++; ptr->bytes += skb->len; bpf_update_elem() atomically creates a new element where all per-cpu values are zero initialized and this_cpu value is populated with given 'value'. Note that non-per-cpu hash map always allocates new element and then deletes old after rcu grace period to maintain atomicity of update. Per-cpu hash map updates element values in-place. Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller --- include/uapi/linux/bpf.h | 1 + kernel/bpf/hashtab.c | 275 ++++++++++++++++++++++++++++++++------- 2 files changed, 229 insertions(+), 47 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index aa6f8571de13..43ae40c8763e 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -81,6 +81,7 @@ enum bpf_map_type { BPF_MAP_TYPE_ARRAY, BPF_MAP_TYPE_PROG_ARRAY, BPF_MAP_TYPE_PERF_EVENT_ARRAY, + BPF_MAP_TYPE_PERCPU_HASH, }; enum bpf_prog_type { diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index c5b30fd8a315..2be5f6e8bb04 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -31,21 +31,27 @@ struct bpf_htab { struct htab_elem { struct hlist_node hash_node; struct rcu_head rcu; - u32 hash; + union { + u32 hash; + u32 key_size; + }; char key[0] __aligned(8); }; /* Called from syscall */ static struct bpf_map *htab_map_alloc(union bpf_attr *attr) { + bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_HASH; struct bpf_htab *htab; int err, i; + u64 cost; htab = kzalloc(sizeof(*htab), GFP_USER); if (!htab) return ERR_PTR(-ENOMEM); /* mandatory map attributes */ + htab->map.map_type = attr->map_type; htab->map.key_size = attr->key_size; htab->map.value_size = attr->value_size; htab->map.max_entries = attr->max_entries; @@ -77,24 +83,34 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr) */ goto free_htab; + if (percpu && round_up(htab->map.value_size, 8) > PCPU_MIN_UNIT_SIZE) + /* make sure the size for pcpu_alloc() is reasonable */ + goto free_htab; + htab->elem_size = sizeof(struct htab_elem) + - round_up(htab->map.key_size, 8) + - htab->map.value_size; + round_up(htab->map.key_size, 8); + if (percpu) + htab->elem_size += sizeof(void *); + else + htab->elem_size += htab->map.value_size; /* prevent zero size kmalloc and check for u32 overflow */ if (htab->n_buckets == 0 || htab->n_buckets > U32_MAX / sizeof(struct bucket)) goto free_htab; - if ((u64) htab->n_buckets * sizeof(struct bucket) + - (u64) htab->elem_size * htab->map.max_entries >= - U32_MAX - PAGE_SIZE) + cost = (u64) htab->n_buckets * sizeof(struct bucket) + + (u64) htab->elem_size * htab->map.max_entries; + + if (percpu) + cost += (u64) round_up(htab->map.value_size, 8) * + num_possible_cpus() * htab->map.max_entries; + + if (cost >= U32_MAX - PAGE_SIZE) /* make sure page count doesn't overflow */ goto free_htab; - htab->map.pages = round_up(htab->n_buckets * sizeof(struct bucket) + - htab->elem_size * htab->map.max_entries, - PAGE_SIZE) >> PAGE_SHIFT; + htab->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT; err = -ENOMEM; htab->buckets = kmalloc_array(htab->n_buckets, sizeof(struct bucket), @@ -148,7 +164,7 @@ static struct htab_elem *lookup_elem_raw(struct hlist_head *head, u32 hash, } /* Called from syscall or from eBPF program */ -static void *htab_map_lookup_elem(struct bpf_map *map, void *key) +static void *__htab_map_lookup_elem(struct bpf_map *map, void *key) { struct bpf_htab *htab = container_of(map, struct bpf_htab, map); struct hlist_head *head; @@ -166,6 +182,13 @@ static void *htab_map_lookup_elem(struct bpf_map *map, void *key) l = lookup_elem_raw(head, hash, key, key_size); + return l; +} + +static void *htab_map_lookup_elem(struct bpf_map *map, void *key) +{ + struct htab_elem *l = __htab_map_lookup_elem(map, key); + if (l) return l->key + round_up(map->key_size, 8); @@ -230,65 +253,139 @@ static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key) return -ENOENT; } + +static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size, + void __percpu *pptr) +{ + *(void __percpu **)(l->key + key_size) = pptr; +} + +static inline void __percpu *htab_elem_get_ptr(struct htab_elem *l, u32 key_size) +{ + return *(void __percpu **)(l->key + key_size); +} + +static void htab_percpu_elem_free(struct htab_elem *l) +{ + free_percpu(htab_elem_get_ptr(l, l->key_size)); + kfree(l); +} + +static void htab_percpu_elem_free_rcu(struct rcu_head *head) +{ + struct htab_elem *l = container_of(head, struct htab_elem, rcu); + + htab_percpu_elem_free(l); +} + +static void free_htab_elem(struct htab_elem *l, bool percpu, u32 key_size) +{ + if (percpu) { + l->key_size = key_size; + call_rcu(&l->rcu, htab_percpu_elem_free_rcu); + } else { + kfree_rcu(l, rcu); + } +} + +static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key, + void *value, u32 key_size, u32 hash, + bool percpu) +{ + u32 size = htab->map.value_size; + struct htab_elem *l_new; + void __percpu *pptr; + + l_new = kmalloc(htab->elem_size, GFP_ATOMIC | __GFP_NOWARN); + if (!l_new) + return NULL; + + memcpy(l_new->key, key, key_size); + if (percpu) { + /* round up value_size to 8 bytes */ + size = round_up(size, 8); + + /* alloc_percpu zero-fills */ + pptr = __alloc_percpu_gfp(size, 8, GFP_ATOMIC | __GFP_NOWARN); + if (!pptr) { + kfree(l_new); + return NULL; + } + + /* copy true value_size bytes */ + memcpy(this_cpu_ptr(pptr), value, htab->map.value_size); + htab_elem_set_ptr(l_new, key_size, pptr); + } else { + memcpy(l_new->key + round_up(key_size, 8), value, size); + } + + l_new->hash = hash; + return l_new; +} + +static int check_flags(struct bpf_htab *htab, struct htab_elem *l_old, + u64 map_flags) +{ + if (!l_old && unlikely(atomic_read(&htab->count) >= htab->map.max_entries)) + /* if elem with this 'key' doesn't exist and we've reached + * max_entries limit, fail insertion of new elem + */ + return -E2BIG; + + if (l_old && map_flags == BPF_NOEXIST) + /* elem already exists */ + return -EEXIST; + + if (!l_old && map_flags == BPF_EXIST) + /* elem doesn't exist, cannot update it */ + return -ENOENT; + + return 0; +} + /* Called from syscall or from eBPF program */ static int htab_map_update_elem(struct bpf_map *map, void *key, void *value, u64 map_flags) { struct bpf_htab *htab = container_of(map, struct bpf_htab, map); - struct htab_elem *l_new, *l_old; + struct htab_elem *l_new = NULL, *l_old; struct hlist_head *head; - struct bucket *b; unsigned long flags; - u32 key_size; + struct bucket *b; + u32 key_size, hash; int ret; - if (map_flags > BPF_EXIST) + if (unlikely(map_flags > BPF_EXIST)) /* unknown flags */ return -EINVAL; WARN_ON_ONCE(!rcu_read_lock_held()); - /* allocate new element outside of lock */ - l_new = kmalloc(htab->elem_size, GFP_ATOMIC | __GFP_NOWARN); + key_size = map->key_size; + + hash = htab_map_hash(key, key_size); + + /* allocate new element outside of the lock, since + * we're most likley going to insert it + */ + l_new = alloc_htab_elem(htab, key, value, key_size, hash, false); if (!l_new) return -ENOMEM; - key_size = map->key_size; - - memcpy(l_new->key, key, key_size); - memcpy(l_new->key + round_up(key_size, 8), value, map->value_size); - - l_new->hash = htab_map_hash(l_new->key, key_size); - b = __select_bucket(htab, l_new->hash); + b = __select_bucket(htab, hash); head = &b->head; /* bpf_map_update_elem() can be called in_irq() */ raw_spin_lock_irqsave(&b->lock, flags); - l_old = lookup_elem_raw(head, l_new->hash, key, key_size); + l_old = lookup_elem_raw(head, hash, key, key_size); - if (!l_old && unlikely(atomic_read(&htab->count) >= map->max_entries)) { - /* if elem with this 'key' doesn't exist and we've reached - * max_entries limit, fail insertion of new elem - */ - ret = -E2BIG; + ret = check_flags(htab, l_old, map_flags); + if (ret) goto err; - } - if (l_old && map_flags == BPF_NOEXIST) { - /* elem already exists */ - ret = -EEXIST; - goto err; - } - - if (!l_old && map_flags == BPF_EXIST) { - /* elem doesn't exist, cannot update it */ - ret = -ENOENT; - goto err; - } - - /* add new element to the head of the list, so that concurrent - * search will find it before old elem + /* add new element to the head of the list, so that + * concurrent search will find it before old elem */ hlist_add_head_rcu(&l_new->hash_node, head); if (l_old) { @@ -298,7 +395,6 @@ static int htab_map_update_elem(struct bpf_map *map, void *key, void *value, atomic_inc(&htab->count); } raw_spin_unlock_irqrestore(&b->lock, flags); - return 0; err: raw_spin_unlock_irqrestore(&b->lock, flags); @@ -306,10 +402,64 @@ static int htab_map_update_elem(struct bpf_map *map, void *key, void *value, return ret; } +static int htab_percpu_map_update_elem(struct bpf_map *map, void *key, + void *value, u64 map_flags) +{ + struct bpf_htab *htab = container_of(map, struct bpf_htab, map); + struct htab_elem *l_new = NULL, *l_old; + struct hlist_head *head; + unsigned long flags; + struct bucket *b; + u32 key_size, hash; + int ret; + + if (unlikely(map_flags > BPF_EXIST)) + /* unknown flags */ + return -EINVAL; + + WARN_ON_ONCE(!rcu_read_lock_held()); + + key_size = map->key_size; + + hash = htab_map_hash(key, key_size); + + b = __select_bucket(htab, hash); + head = &b->head; + + /* bpf_map_update_elem() can be called in_irq() */ + raw_spin_lock_irqsave(&b->lock, flags); + + l_old = lookup_elem_raw(head, hash, key, key_size); + + ret = check_flags(htab, l_old, map_flags); + if (ret) + goto err; + + if (l_old) { + /* per-cpu hash map can update value in-place */ + memcpy(this_cpu_ptr(htab_elem_get_ptr(l_old, key_size)), + value, htab->map.value_size); + } else { + l_new = alloc_htab_elem(htab, key, value, key_size, + hash, true); + if (!l_new) { + ret = -ENOMEM; + goto err; + } + hlist_add_head_rcu(&l_new->hash_node, head); + atomic_inc(&htab->count); + } + ret = 0; +err: + raw_spin_unlock_irqrestore(&b->lock, flags); + return ret; +} + /* Called from syscall or from eBPF program */ static int htab_map_delete_elem(struct bpf_map *map, void *key) { struct bpf_htab *htab = container_of(map, struct bpf_htab, map); + bool percpu = map->map_type == BPF_MAP_TYPE_PERCPU_HASH; struct hlist_head *head; struct bucket *b; struct htab_elem *l; @@ -332,7 +482,7 @@ static int htab_map_delete_elem(struct bpf_map *map, void *key) if (l) { hlist_del_rcu(&l->hash_node); atomic_dec(&htab->count); - kfree_rcu(l, rcu); + free_htab_elem(l, percpu, key_size); ret = 0; } @@ -352,7 +502,12 @@ static void delete_all_elements(struct bpf_htab *htab) hlist_for_each_entry_safe(l, n, head, hash_node) { hlist_del_rcu(&l->hash_node); atomic_dec(&htab->count); - kfree(l); + if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH) { + l->key_size = htab->map.key_size; + htab_percpu_elem_free(l); + } else { + kfree(l); + } } } } @@ -391,9 +546,35 @@ static struct bpf_map_type_list htab_type __read_mostly = { .type = BPF_MAP_TYPE_HASH, }; +/* Called from eBPF program */ +static void *htab_percpu_map_lookup_elem(struct bpf_map *map, void *key) +{ + struct htab_elem *l = __htab_map_lookup_elem(map, key); + + if (l) + return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size)); + else + return NULL; +} + +static const struct bpf_map_ops htab_percpu_ops = { + .map_alloc = htab_map_alloc, + .map_free = htab_map_free, + .map_get_next_key = htab_map_get_next_key, + .map_lookup_elem = htab_percpu_map_lookup_elem, + .map_update_elem = htab_percpu_map_update_elem, + .map_delete_elem = htab_map_delete_elem, +}; + +static struct bpf_map_type_list htab_percpu_type __read_mostly = { + .ops = &htab_percpu_ops, + .type = BPF_MAP_TYPE_PERCPU_HASH, +}; + static int __init register_htab_map(void) { bpf_register_map_type(&htab_type); + bpf_register_map_type(&htab_percpu_type); return 0; } late_initcall(register_htab_map); From a10423b87a7eae75da79ce80a8d9475047a674ee Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 1 Feb 2016 22:39:54 -0800 Subject: [PATCH 2/6] bpf: introduce BPF_MAP_TYPE_PERCPU_ARRAY map Primary use case is a histogram array of latency where bpf program computes the latency of block requests or other events and stores histogram of latency into array of 64 elements. All cpus are constantly running, so normal increment is not accurate, bpf_xadd causes cache ping-pong and this per-cpu approach allows fastest collision-free counters. Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller --- include/linux/bpf.h | 1 + include/uapi/linux/bpf.h | 1 + kernel/bpf/arraymap.c | 102 ++++++++++++++++++++++++++++++++++----- 3 files changed, 93 insertions(+), 11 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 83d1926c61e4..141fb0d45731 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -151,6 +151,7 @@ struct bpf_array { union { char value[0] __aligned(8); void *ptrs[0] __aligned(8); + void __percpu *pptrs[0] __aligned(8); }; }; #define MAX_TAIL_CALL_CNT 32 diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 43ae40c8763e..2ee0fde1bf96 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -82,6 +82,7 @@ enum bpf_map_type { BPF_MAP_TYPE_PROG_ARRAY, BPF_MAP_TYPE_PERF_EVENT_ARRAY, BPF_MAP_TYPE_PERCPU_HASH, + BPF_MAP_TYPE_PERCPU_ARRAY, }; enum bpf_prog_type { diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 89ebbc4d1164..b9bf1d7949ca 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -17,11 +17,39 @@ #include #include +static void bpf_array_free_percpu(struct bpf_array *array) +{ + int i; + + for (i = 0; i < array->map.max_entries; i++) + free_percpu(array->pptrs[i]); +} + +static int bpf_array_alloc_percpu(struct bpf_array *array) +{ + void __percpu *ptr; + int i; + + for (i = 0; i < array->map.max_entries; i++) { + ptr = __alloc_percpu_gfp(array->elem_size, 8, + GFP_USER | __GFP_NOWARN); + if (!ptr) { + bpf_array_free_percpu(array); + return -ENOMEM; + } + array->pptrs[i] = ptr; + } + + return 0; +} + /* Called from syscall */ static struct bpf_map *array_map_alloc(union bpf_attr *attr) { + bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY; struct bpf_array *array; - u32 elem_size, array_size; + u64 array_size; + u32 elem_size; /* check sanity of attributes */ if (attr->max_entries == 0 || attr->key_size != 4 || @@ -36,12 +64,16 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr) elem_size = round_up(attr->value_size, 8); - /* check round_up into zero and u32 overflow */ - if (elem_size == 0 || - attr->max_entries > (U32_MAX - PAGE_SIZE - sizeof(*array)) / elem_size) + array_size = sizeof(*array); + if (percpu) + array_size += (u64) attr->max_entries * sizeof(void *); + else + array_size += (u64) attr->max_entries * elem_size; + + /* make sure there is no u32 overflow later in round_up() */ + if (array_size >= U32_MAX - PAGE_SIZE) return ERR_PTR(-ENOMEM); - array_size = sizeof(*array) + attr->max_entries * elem_size; /* allocate all map elements and zero-initialize them */ array = kzalloc(array_size, GFP_USER | __GFP_NOWARN); @@ -52,12 +84,25 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr) } /* copy mandatory map attributes */ + array->map.map_type = attr->map_type; array->map.key_size = attr->key_size; array->map.value_size = attr->value_size; array->map.max_entries = attr->max_entries; - array->map.pages = round_up(array_size, PAGE_SIZE) >> PAGE_SHIFT; array->elem_size = elem_size; + if (!percpu) + goto out; + + array_size += (u64) attr->max_entries * elem_size * num_possible_cpus(); + + if (array_size >= U32_MAX - PAGE_SIZE || + elem_size > PCPU_MIN_UNIT_SIZE || bpf_array_alloc_percpu(array)) { + kvfree(array); + return ERR_PTR(-ENOMEM); + } +out: + array->map.pages = round_up(array_size, PAGE_SIZE) >> PAGE_SHIFT; + return &array->map; } @@ -67,12 +112,24 @@ static void *array_map_lookup_elem(struct bpf_map *map, void *key) struct bpf_array *array = container_of(map, struct bpf_array, map); u32 index = *(u32 *)key; - if (index >= array->map.max_entries) + if (unlikely(index >= array->map.max_entries)) return NULL; return array->value + array->elem_size * index; } +/* Called from eBPF program */ +static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key) +{ + struct bpf_array *array = container_of(map, struct bpf_array, map); + u32 index = *(u32 *)key; + + if (unlikely(index >= array->map.max_entries)) + return NULL; + + return this_cpu_ptr(array->pptrs[index]); +} + /* Called from syscall */ static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key) { @@ -99,19 +156,24 @@ static int array_map_update_elem(struct bpf_map *map, void *key, void *value, struct bpf_array *array = container_of(map, struct bpf_array, map); u32 index = *(u32 *)key; - if (map_flags > BPF_EXIST) + if (unlikely(map_flags > BPF_EXIST)) /* unknown flags */ return -EINVAL; - if (index >= array->map.max_entries) + if (unlikely(index >= array->map.max_entries)) /* all elements were pre-allocated, cannot insert a new one */ return -E2BIG; - if (map_flags == BPF_NOEXIST) + if (unlikely(map_flags == BPF_NOEXIST)) /* all elements already exist */ return -EEXIST; - memcpy(array->value + array->elem_size * index, value, map->value_size); + if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY) + memcpy(this_cpu_ptr(array->pptrs[index]), + value, map->value_size); + else + memcpy(array->value + array->elem_size * index, + value, map->value_size); return 0; } @@ -133,6 +195,9 @@ static void array_map_free(struct bpf_map *map) */ synchronize_rcu(); + if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY) + bpf_array_free_percpu(array); + kvfree(array); } @@ -150,9 +215,24 @@ static struct bpf_map_type_list array_type __read_mostly = { .type = BPF_MAP_TYPE_ARRAY, }; +static const struct bpf_map_ops percpu_array_ops = { + .map_alloc = array_map_alloc, + .map_free = array_map_free, + .map_get_next_key = array_map_get_next_key, + .map_lookup_elem = percpu_array_map_lookup_elem, + .map_update_elem = array_map_update_elem, + .map_delete_elem = array_map_delete_elem, +}; + +static struct bpf_map_type_list percpu_array_type __read_mostly = { + .ops = &percpu_array_ops, + .type = BPF_MAP_TYPE_PERCPU_ARRAY, +}; + static int __init register_array_map(void) { bpf_register_map_type(&array_type); + bpf_register_map_type(&percpu_array_type); return 0; } late_initcall(register_array_map); From 15a07b33814d14ca817887dbea8530728dc0fbe4 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 1 Feb 2016 22:39:55 -0800 Subject: [PATCH 3/6] bpf: add lookup/update support for per-cpu hash and array maps The functions bpf_map_lookup_elem(map, key, value) and bpf_map_update_elem(map, key, value, flags) need to get/set values from all-cpus for per-cpu hash and array maps, so that user space can aggregate/update them as necessary. Example of single counter aggregation in user space: unsigned int nr_cpus = sysconf(_SC_NPROCESSORS_CONF); long values[nr_cpus]; long value = 0; bpf_lookup_elem(fd, key, values); for (i = 0; i < nr_cpus; i++) value += values[i]; The user space must provide round_up(value_size, 8) * nr_cpus array to get/set values, since kernel will use 'long' copy of per-cpu values to try to copy good counters atomically. It's a best-effort, since bpf programs and user space are racing to access the same memory. Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller --- include/linux/bpf.h | 23 ++++++++++++ kernel/bpf/arraymap.c | 64 +++++++++++++++++++++++++++++++++ kernel/bpf/hashtab.c | 83 ++++++++++++++++++++++++++++++++++++++----- kernel/bpf/syscall.c | 57 ++++++++++++++++++++--------- 4 files changed, 201 insertions(+), 26 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 141fb0d45731..90ee6ab24bc5 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -183,6 +183,29 @@ int bpf_prog_new_fd(struct bpf_prog *prog); int bpf_obj_pin_user(u32 ufd, const char __user *pathname); int bpf_obj_get_user(const char __user *pathname); +int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value); +int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value); +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); + +/* 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. + * Best-effort only. No barriers here, since it _will_ race with concurrent + * updates from BPF programs. Called from bpf syscall and mostly used with + * size 8 or 16 bytes, so ask compiler to inline it. + */ +static inline void bpf_long_memcpy(void *dst, const void *src, u32 size) +{ + const long *lsrc = src; + long *ldst = dst; + + size /= sizeof(long); + while (size--) + *ldst++ = *lsrc++; +} + /* verify correctness of eBPF program */ int bpf_check(struct bpf_prog **fp, union bpf_attr *attr); #else diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index b9bf1d7949ca..bd3bdf2486a7 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -130,6 +130,32 @@ static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key) return this_cpu_ptr(array->pptrs[index]); } +int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value) +{ + struct bpf_array *array = container_of(map, struct bpf_array, map); + u32 index = *(u32 *)key; + void __percpu *pptr; + int cpu, off = 0; + u32 size; + + if (unlikely(index >= array->map.max_entries)) + return -ENOENT; + + /* per_cpu areas are zero-filled and bpf programs can only + * access 'value_size' of them, so copying rounded areas + * will not leak any kernel data + */ + size = round_up(map->value_size, 8); + rcu_read_lock(); + pptr = array->pptrs[index]; + for_each_possible_cpu(cpu) { + bpf_long_memcpy(value + off, per_cpu_ptr(pptr, cpu), size); + off += size; + } + rcu_read_unlock(); + return 0; +} + /* Called from syscall */ static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key) { @@ -177,6 +203,44 @@ static int array_map_update_elem(struct bpf_map *map, void *key, void *value, return 0; } +int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value, + u64 map_flags) +{ + struct bpf_array *array = container_of(map, struct bpf_array, map); + u32 index = *(u32 *)key; + void __percpu *pptr; + int cpu, off = 0; + u32 size; + + if (unlikely(map_flags > BPF_EXIST)) + /* unknown flags */ + return -EINVAL; + + if (unlikely(index >= array->map.max_entries)) + /* all elements were pre-allocated, cannot insert a new one */ + return -E2BIG; + + if (unlikely(map_flags == BPF_NOEXIST)) + /* all elements already exist */ + return -EEXIST; + + /* the user space will provide round_up(value_size, 8) bytes that + * will be copied into per-cpu area. bpf programs can only access + * value_size of it. During lookup the same extra bytes will be + * returned or zeros which were zero-filled by percpu_alloc, + * so no kernel data leaks possible + */ + size = round_up(map->value_size, 8); + rcu_read_lock(); + pptr = array->pptrs[index]; + for_each_possible_cpu(cpu) { + bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value + off, size); + off += size; + } + rcu_read_unlock(); + return 0; +} + /* Called from syscall or from eBPF program */ static int array_map_delete_elem(struct bpf_map *map, void *key) { diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 2be5f6e8bb04..fd5db8fe9360 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -290,7 +290,7 @@ static void free_htab_elem(struct htab_elem *l, bool percpu, u32 key_size) static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key, void *value, u32 key_size, u32 hash, - bool percpu) + bool percpu, bool onallcpus) { u32 size = htab->map.value_size; struct htab_elem *l_new; @@ -312,8 +312,18 @@ static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key, return NULL; } - /* copy true value_size bytes */ - memcpy(this_cpu_ptr(pptr), value, htab->map.value_size); + if (!onallcpus) { + /* copy true value_size bytes */ + memcpy(this_cpu_ptr(pptr), value, htab->map.value_size); + } else { + int off = 0, cpu; + + for_each_possible_cpu(cpu) { + bpf_long_memcpy(per_cpu_ptr(pptr, cpu), + value + off, size); + off += size; + } + } htab_elem_set_ptr(l_new, key_size, pptr); } else { memcpy(l_new->key + round_up(key_size, 8), value, size); @@ -368,7 +378,7 @@ static int htab_map_update_elem(struct bpf_map *map, void *key, void *value, /* allocate new element outside of the lock, since * we're most likley going to insert it */ - l_new = alloc_htab_elem(htab, key, value, key_size, hash, false); + l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false); if (!l_new) return -ENOMEM; @@ -402,8 +412,9 @@ static int htab_map_update_elem(struct bpf_map *map, void *key, void *value, return ret; } -static int htab_percpu_map_update_elem(struct bpf_map *map, void *key, - void *value, u64 map_flags) +static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key, + void *value, u64 map_flags, + bool onallcpus) { struct bpf_htab *htab = container_of(map, struct bpf_htab, map); struct htab_elem *l_new = NULL, *l_old; @@ -436,12 +447,25 @@ static int htab_percpu_map_update_elem(struct bpf_map *map, void *key, goto err; if (l_old) { + void __percpu *pptr = htab_elem_get_ptr(l_old, key_size); + u32 size = htab->map.value_size; + /* per-cpu hash map can update value in-place */ - memcpy(this_cpu_ptr(htab_elem_get_ptr(l_old, key_size)), - value, htab->map.value_size); + if (!onallcpus) { + memcpy(this_cpu_ptr(pptr), value, size); + } else { + int off = 0, cpu; + + size = round_up(size, 8); + for_each_possible_cpu(cpu) { + bpf_long_memcpy(per_cpu_ptr(pptr, cpu), + value + off, size); + off += size; + } + } } else { l_new = alloc_htab_elem(htab, key, value, key_size, - hash, true); + hash, true, onallcpus); if (!l_new) { ret = -ENOMEM; goto err; @@ -455,6 +479,12 @@ static int htab_percpu_map_update_elem(struct bpf_map *map, void *key, return ret; } +static int htab_percpu_map_update_elem(struct bpf_map *map, void *key, + void *value, u64 map_flags) +{ + return __htab_percpu_map_update_elem(map, key, value, map_flags, false); +} + /* Called from syscall or from eBPF program */ static int htab_map_delete_elem(struct bpf_map *map, void *key) { @@ -557,6 +587,41 @@ static void *htab_percpu_map_lookup_elem(struct bpf_map *map, void *key) return NULL; } +int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value) +{ + struct htab_elem *l; + void __percpu *pptr; + int ret = -ENOENT; + int cpu, off = 0; + u32 size; + + /* per_cpu areas are zero-filled and bpf programs can only + * access 'value_size' of them, so copying rounded areas + * will not leak any kernel data + */ + size = round_up(map->value_size, 8); + rcu_read_lock(); + l = __htab_map_lookup_elem(map, key); + if (!l) + goto out; + pptr = htab_elem_get_ptr(l, map->key_size); + for_each_possible_cpu(cpu) { + bpf_long_memcpy(value + off, + per_cpu_ptr(pptr, cpu), size); + off += size; + } + ret = 0; +out: + rcu_read_unlock(); + return ret; +} + +int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value, + u64 map_flags) +{ + return __htab_percpu_map_update_elem(map, key, value, map_flags, true); +} + static const struct bpf_map_ops htab_percpu_ops = { .map_alloc = htab_map_alloc, .map_free = htab_map_free, diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 637397059f76..c95a753c2007 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -239,6 +239,7 @@ static int map_lookup_elem(union bpf_attr *attr) int ufd = attr->map_fd; struct bpf_map *map; void *key, *value, *ptr; + u32 value_size; struct fd f; int err; @@ -259,23 +260,35 @@ static int map_lookup_elem(union bpf_attr *attr) if (copy_from_user(key, ukey, map->key_size) != 0) goto free_key; + if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH || + map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY) + value_size = round_up(map->value_size, 8) * num_possible_cpus(); + else + value_size = map->value_size; + err = -ENOMEM; - value = kmalloc(map->value_size, GFP_USER | __GFP_NOWARN); + value = kmalloc(value_size, GFP_USER | __GFP_NOWARN); if (!value) goto free_key; - rcu_read_lock(); - ptr = map->ops->map_lookup_elem(map, key); - if (ptr) - memcpy(value, ptr, map->value_size); - rcu_read_unlock(); + if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH) { + 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 { + rcu_read_lock(); + ptr = map->ops->map_lookup_elem(map, key); + if (ptr) + memcpy(value, ptr, value_size); + rcu_read_unlock(); + err = ptr ? 0 : -ENOENT; + } - err = -ENOENT; - if (!ptr) + if (err) goto free_value; err = -EFAULT; - if (copy_to_user(uvalue, value, map->value_size) != 0) + if (copy_to_user(uvalue, value, value_size) != 0) goto free_value; err = 0; @@ -298,6 +311,7 @@ static int map_update_elem(union bpf_attr *attr) int ufd = attr->map_fd; struct bpf_map *map; void *key, *value; + u32 value_size; struct fd f; int err; @@ -318,21 +332,30 @@ static int map_update_elem(union bpf_attr *attr) if (copy_from_user(key, ukey, map->key_size) != 0) goto free_key; + if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH || + map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY) + value_size = round_up(map->value_size, 8) * num_possible_cpus(); + else + value_size = map->value_size; + err = -ENOMEM; - value = kmalloc(map->value_size, GFP_USER | __GFP_NOWARN); + value = kmalloc(value_size, GFP_USER | __GFP_NOWARN); if (!value) goto free_key; err = -EFAULT; - if (copy_from_user(value, uvalue, map->value_size) != 0) + if (copy_from_user(value, uvalue, value_size) != 0) goto free_value; - /* eBPF program that use maps are running under rcu_read_lock(), - * therefore all map accessors rely on this fact, so do the same here - */ - rcu_read_lock(); - err = map->ops->map_update_elem(map, key, value, attr->flags); - rcu_read_unlock(); + if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH) { + err = bpf_percpu_hash_update(map, key, value, attr->flags); + } else if (map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY) { + err = bpf_percpu_array_update(map, key, value, attr->flags); + } else { + rcu_read_lock(); + err = map->ops->map_update_elem(map, key, value, attr->flags); + rcu_read_unlock(); + } free_value: kfree(value); From e15596717948c95587a0b15363030283c126c23a Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Mon, 1 Feb 2016 22:39:56 -0800 Subject: [PATCH 4/6] samples/bpf: unit test for BPF_MAP_TYPE_PERCPU_HASH A sanity test for BPF_MAP_TYPE_PERCPU_HASH. Signed-off-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller --- samples/bpf/test_maps.c | 96 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 96 insertions(+) diff --git a/samples/bpf/test_maps.c b/samples/bpf/test_maps.c index 6299ee95cd11..5f5fe5332148 100644 --- a/samples/bpf/test_maps.c +++ b/samples/bpf/test_maps.c @@ -89,6 +89,100 @@ static void test_hashmap_sanity(int i, void *data) close(map_fd); } +/* sanity tests for percpu map API */ +static void test_percpu_hashmap_sanity(int task, void *data) +{ + long long key, next_key; + int expected_key_mask = 0; + unsigned int nr_cpus = sysconf(_SC_NPROCESSORS_CONF); + long long value[nr_cpus]; + int map_fd, i; + + map_fd = bpf_create_map(BPF_MAP_TYPE_PERCPU_HASH, sizeof(key), + sizeof(value[0]), 2); + if (map_fd < 0) { + printf("failed to create hashmap '%s'\n", strerror(errno)); + exit(1); + } + + for (i = 0; i < nr_cpus; i++) + value[i] = i + 100; + key = 1; + /* insert key=1 element */ + assert(!(expected_key_mask & key)); + assert(bpf_update_elem(map_fd, &key, value, BPF_ANY) == 0); + expected_key_mask |= key; + + /* BPF_NOEXIST means: add new element if it doesn't exist */ + assert(bpf_update_elem(map_fd, &key, value, BPF_NOEXIST) == -1 && + /* key=1 already exists */ + errno == EEXIST); + + /* -1 is an invalid flag */ + assert(bpf_update_elem(map_fd, &key, value, -1) == -1 && + errno == EINVAL); + + /* check that key=1 can be found. value could be 0 if the lookup + * was run from a different cpu. + */ + value[0] = 1; + assert(bpf_lookup_elem(map_fd, &key, value) == 0 && value[0] == 100); + + key = 2; + /* check that key=2 is not found */ + assert(bpf_lookup_elem(map_fd, &key, value) == -1 && errno == ENOENT); + + /* BPF_EXIST means: update existing element */ + assert(bpf_update_elem(map_fd, &key, value, BPF_EXIST) == -1 && + /* key=2 is not there */ + errno == ENOENT); + + /* insert key=2 element */ + assert(!(expected_key_mask & key)); + assert(bpf_update_elem(map_fd, &key, value, BPF_NOEXIST) == 0); + expected_key_mask |= key; + + /* key=1 and key=2 were inserted, check that key=0 cannot be inserted + * due to max_entries limit + */ + key = 0; + assert(bpf_update_elem(map_fd, &key, value, BPF_NOEXIST) == -1 && + errno == E2BIG); + + /* check that key = 0 doesn't exist */ + assert(bpf_delete_elem(map_fd, &key) == -1 && errno == ENOENT); + + /* iterate over two elements */ + while (!bpf_get_next_key(map_fd, &key, &next_key)) { + assert((expected_key_mask & next_key) == next_key); + expected_key_mask &= ~next_key; + + assert(bpf_lookup_elem(map_fd, &next_key, value) == 0); + for (i = 0; i < nr_cpus; i++) + assert(value[i] == i + 100); + + key = next_key; + } + assert(errno == ENOENT); + + /* Update with BPF_EXIST */ + key = 1; + assert(bpf_update_elem(map_fd, &key, value, BPF_EXIST) == 0); + + /* delete both elements */ + key = 1; + assert(bpf_delete_elem(map_fd, &key) == 0); + key = 2; + assert(bpf_delete_elem(map_fd, &key) == 0); + assert(bpf_delete_elem(map_fd, &key) == -1 && errno == ENOENT); + + key = 0; + /* check that map is empty */ + assert(bpf_get_next_key(map_fd, &key, &next_key) == -1 && + errno == ENOENT); + close(map_fd); +} + static void test_arraymap_sanity(int i, void *data) { int key, next_key, map_fd; @@ -209,6 +303,7 @@ static void run_parallel(int tasks, void (*fn)(int i, void *data), void *data) static void test_map_stress(void) { run_parallel(100, test_hashmap_sanity, NULL); + run_parallel(100, test_percpu_hashmap_sanity, NULL); run_parallel(100, test_arraymap_sanity, NULL); } @@ -282,6 +377,7 @@ static void test_map_parallel(void) int main(void) { test_hashmap_sanity(0, NULL); + test_percpu_hashmap_sanity(0, NULL); test_arraymap_sanity(0, NULL); test_map_large(); test_map_parallel(); From df570f577231407d929bdc6f59ae2f53e0028e8a Mon Sep 17 00:00:00 2001 From: "tom.leiming@gmail.com" Date: Mon, 1 Feb 2016 22:39:57 -0800 Subject: [PATCH 5/6] samples/bpf: unit test for BPF_MAP_TYPE_PERCPU_ARRAY A sanity test for BPF_MAP_TYPE_PERCPU_ARRAY Signed-off-by: Ming Lei Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller --- samples/bpf/test_maps.c | 92 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 92 insertions(+) diff --git a/samples/bpf/test_maps.c b/samples/bpf/test_maps.c index 5f5fe5332148..ad466ed33093 100644 --- a/samples/bpf/test_maps.c +++ b/samples/bpf/test_maps.c @@ -236,6 +236,94 @@ static void test_arraymap_sanity(int i, void *data) close(map_fd); } +static void test_percpu_arraymap_many_keys(void) +{ + unsigned nr_cpus = sysconf(_SC_NPROCESSORS_CONF); + unsigned nr_keys = 20000; + long values[nr_cpus]; + int key, map_fd, i; + + map_fd = bpf_create_map(BPF_MAP_TYPE_PERCPU_ARRAY, sizeof(key), + sizeof(values[0]), nr_keys); + if (map_fd < 0) { + printf("failed to create per-cpu arraymap '%s'\n", + strerror(errno)); + exit(1); + } + + for (i = 0; i < nr_cpus; i++) + values[i] = i + 10; + + for (key = 0; key < nr_keys; key++) + assert(bpf_update_elem(map_fd, &key, values, BPF_ANY) == 0); + + for (key = 0; key < nr_keys; key++) { + for (i = 0; i < nr_cpus; i++) + values[i] = 0; + assert(bpf_lookup_elem(map_fd, &key, values) == 0); + for (i = 0; i < nr_cpus; i++) + assert(values[i] == i + 10); + } + + close(map_fd); +} + +static void test_percpu_arraymap_sanity(int i, void *data) +{ + unsigned nr_cpus = sysconf(_SC_NPROCESSORS_CONF); + long values[nr_cpus]; + int key, next_key, map_fd; + + map_fd = bpf_create_map(BPF_MAP_TYPE_PERCPU_ARRAY, sizeof(key), + sizeof(values[0]), 2); + if (map_fd < 0) { + printf("failed to create arraymap '%s'\n", strerror(errno)); + exit(1); + } + + for (i = 0; i < nr_cpus; i++) + values[i] = i + 100; + + key = 1; + /* insert key=1 element */ + assert(bpf_update_elem(map_fd, &key, values, BPF_ANY) == 0); + + values[0] = 0; + assert(bpf_update_elem(map_fd, &key, values, BPF_NOEXIST) == -1 && + errno == EEXIST); + + /* check that key=1 can be found */ + assert(bpf_lookup_elem(map_fd, &key, values) == 0 && values[0] == 100); + + key = 0; + /* check that key=0 is also found and zero initialized */ + assert(bpf_lookup_elem(map_fd, &key, values) == 0 && + values[0] == 0 && values[nr_cpus - 1] == 0); + + + /* check that key=2 cannot be inserted due to max_entries limit */ + key = 2; + assert(bpf_update_elem(map_fd, &key, values, BPF_EXIST) == -1 && + errno == E2BIG); + + /* check that key = 2 doesn't exist */ + assert(bpf_lookup_elem(map_fd, &key, values) == -1 && errno == ENOENT); + + /* iterate over two elements */ + assert(bpf_get_next_key(map_fd, &key, &next_key) == 0 && + next_key == 0); + assert(bpf_get_next_key(map_fd, &next_key, &next_key) == 0 && + next_key == 1); + assert(bpf_get_next_key(map_fd, &next_key, &next_key) == -1 && + errno == ENOENT); + + /* delete shouldn't succeed */ + key = 1; + assert(bpf_delete_elem(map_fd, &key) == -1 && errno == EINVAL); + + close(map_fd); +} + #define MAP_SIZE (32 * 1024) static void test_map_large(void) { @@ -305,6 +393,7 @@ static void test_map_stress(void) run_parallel(100, test_hashmap_sanity, NULL); run_parallel(100, test_percpu_hashmap_sanity, NULL); run_parallel(100, test_arraymap_sanity, NULL); + run_parallel(100, test_percpu_arraymap_sanity, NULL); } #define TASKS 1024 @@ -379,6 +468,9 @@ int main(void) test_hashmap_sanity(0, NULL); test_percpu_hashmap_sanity(0, NULL); test_arraymap_sanity(0, NULL); + test_percpu_arraymap_sanity(0, NULL); + test_percpu_arraymap_many_keys(); + test_map_large(); test_map_parallel(); test_map_stress(); From 3059303f59cf90a84e7fdef154ff0b215bcfaa97 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 1 Feb 2016 22:39:58 -0800 Subject: [PATCH 6/6] samples/bpf: update tracex[23] examples to use per-cpu maps Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller --- samples/bpf/tracex2_kern.c | 2 +- samples/bpf/tracex2_user.c | 7 ++++++- samples/bpf/tracex3_kern.c | 8 ++++---- samples/bpf/tracex3_user.c | 21 ++++++++++++++------- 4 files changed, 25 insertions(+), 13 deletions(-) diff --git a/samples/bpf/tracex2_kern.c b/samples/bpf/tracex2_kern.c index b32367cfbff4..09c1adc27d42 100644 --- a/samples/bpf/tracex2_kern.c +++ b/samples/bpf/tracex2_kern.c @@ -70,7 +70,7 @@ struct hist_key { }; struct bpf_map_def SEC("maps") my_hist_map = { - .type = BPF_MAP_TYPE_HASH, + .type = BPF_MAP_TYPE_PERCPU_HASH, .key_size = sizeof(struct hist_key), .value_size = sizeof(long), .max_entries = 1024, diff --git a/samples/bpf/tracex2_user.c b/samples/bpf/tracex2_user.c index cd0241c1447a..ab5b19e68acf 100644 --- a/samples/bpf/tracex2_user.c +++ b/samples/bpf/tracex2_user.c @@ -37,6 +37,8 @@ struct hist_key { static void print_hist_for_pid(int fd, void *task) { struct hist_key key = {}, next_key; + unsigned int nr_cpus = sysconf(_SC_NPROCESSORS_CONF); + long values[nr_cpus]; char starstr[MAX_STARS]; long value; long data[MAX_INDEX] = {}; @@ -49,7 +51,10 @@ static void print_hist_for_pid(int fd, void *task) key = next_key; continue; } - bpf_lookup_elem(fd, &next_key, &value); + bpf_lookup_elem(fd, &next_key, values); + value = 0; + for (i = 0; i < nr_cpus; i++) + value += values[i]; ind = next_key.index; data[ind] = value; if (value && ind > max_ind) diff --git a/samples/bpf/tracex3_kern.c b/samples/bpf/tracex3_kern.c index bf337fbb0947..9974c3d7c18b 100644 --- a/samples/bpf/tracex3_kern.c +++ b/samples/bpf/tracex3_kern.c @@ -20,7 +20,7 @@ struct bpf_map_def SEC("maps") my_map = { /* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe * example will no longer be meaningful */ -SEC("kprobe/blk_mq_start_request") +SEC("kprobe/blk_start_request") int bpf_prog1(struct pt_regs *ctx) { long rq = PT_REGS_PARM1(ctx); @@ -42,13 +42,13 @@ static unsigned int log2l(unsigned long long n) #define SLOTS 100 struct bpf_map_def SEC("maps") lat_map = { - .type = BPF_MAP_TYPE_ARRAY, + .type = BPF_MAP_TYPE_PERCPU_ARRAY, .key_size = sizeof(u32), .value_size = sizeof(u64), .max_entries = SLOTS, }; -SEC("kprobe/blk_update_request") +SEC("kprobe/blk_account_io_completion") int bpf_prog2(struct pt_regs *ctx) { long rq = PT_REGS_PARM1(ctx); @@ -81,7 +81,7 @@ int bpf_prog2(struct pt_regs *ctx) value = bpf_map_lookup_elem(&lat_map, &index); if (value) - __sync_fetch_and_add((long *)value, 1); + *value += 1; return 0; } diff --git a/samples/bpf/tracex3_user.c b/samples/bpf/tracex3_user.c index 0aaa933ab938..48716f7f0d8b 100644 --- a/samples/bpf/tracex3_user.c +++ b/samples/bpf/tracex3_user.c @@ -20,11 +20,13 @@ static void clear_stats(int fd) { + unsigned int nr_cpus = sysconf(_SC_NPROCESSORS_CONF); + __u64 values[nr_cpus]; __u32 key; - __u64 value = 0; + memset(values, 0, sizeof(values)); for (key = 0; key < SLOTS; key++) - bpf_update_elem(fd, &key, &value, BPF_ANY); + bpf_update_elem(fd, &key, values, BPF_ANY); } const char *color[] = { @@ -75,15 +77,20 @@ static void print_banner(void) static void print_hist(int fd) { - __u32 key; - __u64 value; - __u64 cnt[SLOTS]; - __u64 max_cnt = 0; + unsigned int nr_cpus = sysconf(_SC_NPROCESSORS_CONF); __u64 total_events = 0; + long values[nr_cpus]; + __u64 max_cnt = 0; + __u64 cnt[SLOTS]; + __u64 value; + __u32 key; + int i; for (key = 0; key < SLOTS; key++) { + bpf_lookup_elem(fd, &key, values); value = 0; - bpf_lookup_elem(fd, &key, &value); + for (i = 0; i < nr_cpus; i++) + value += values[i]; cnt[key] = value; total_events += value; if (value > max_cnt)