Merge branch 'bpf-per-cpu-maps'

Alexei Starovoitov says:

====================
bpf: introduce per-cpu maps

We've started to use bpf to trace every packet and atomic add
instruction (event JITed) started to show up in perf profile.
The solution is to do per-cpu counters.
For PERCPU_(HASH|ARRAY) map the existing bpf_map_lookup() helper
returns per-cpu area which bpf programs can use to store and
increment the counters. The BPF_MAP_LOOKUP_ELEM syscall command
returns areas from all cpus and user process aggregates the counters.
The usage example is in patch 6. The api turned out to be very
easy to use from bpf program and from user space.
Long term we were discussing to add 'bounded loop' instruction,
so bpf programs can do aggregation within the program which may
help some use cases. Right now user space aggregation of
per-cpu counters fits the best.

This patch set is new approach for per-cpu hash and array maps.
I've reused the map tests written by Martin and Ming, but
implementation and api is new. Old discussion here:
http://thread.gmane.org/gmane.linux.kernel/2123800/focus=2126435
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 26 insertions, 0 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 83d1926c61e4..90ee6ab24bc5 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
@@ -182,6 +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/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index aa6f8571de13..2ee0fde1bf96 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -81,6 +81,8 @@ enum bpf_map_type {
 	BPF_MAP_TYPE_ARRAY,
 	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 {