[PATCH bpf-next v3 0/2] Introduce access remote cpu elem support in BPF percpu map

[PATCH bpf-next v3 0/2] Introduce access remote cpu elem support in BPF percpu map

[Feng zhou]

From: Feng Zhou <zhoufeng.zf@bytedance.com>

Trace some functions, such as enqueue_task_fair, need to access the
corresponding cpu, not the current cpu, and bpf_map_lookup_elem percpu map
cannot do it. So add bpf_map_lookup_percpu_elem to accomplish it for
percpu_array_map, percpu_hash_map, lru_percpu_hash_map.

Changelog:
----------
v2->v3: Addressed comments from Andrii Nakryiko.
- use /* */ instead of //
- use libbpf_num_possible_cpus() instead of sysconf(_SC_NPROCESSORS_ONLN)
- use 8 bytes for value size
- fix memory leak
- use ASSERT_EQ instead of ASSERT_OK
- add bpf_loop to fetch values on each possible CPU
some details in here:
https://lore.kernel.org/lkml/20220511093854.411-1-zhoufeng.zf@bytedance.com/T/

v1->v2: Addressed comments from Alexei Starovoitov.
- add a selftest for bpf_map_lookup_percpu_elem.

Feng Zhou (2):
  bpf: add bpf_map_lookup_percpu_elem for percpu map
  selftests/bpf: add test case for bpf_map_lookup_percpu_elem

 include/linux/bpf.h                           |  2 +
 include/uapi/linux/bpf.h                      |  9 +++
 kernel/bpf/arraymap.c                         | 15 ++++
 kernel/bpf/core.c                             |  1 +
 kernel/bpf/hashtab.c                          | 32 +++++++++
 kernel/bpf/helpers.c                          | 18 +++++
 kernel/bpf/verifier.c                         | 17 ++++-
 kernel/trace/bpf_trace.c                      |  2 +
 tools/include/uapi/linux/bpf.h                |  9 +++
 .../bpf/prog_tests/map_lookup_percpu_elem.c   | 59 +++++++++++++++
 .../bpf/progs/test_map_lookup_percpu_elem.c   | 71 +++++++++++++++++++
 11 files changed, 233 insertions(+), 2 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/map_lookup_percpu_elem.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_map_lookup_percpu_elem.c

-- 
2.20.1

[PATCH bpf-next v3 1/2] bpf: add bpf_map_lookup_percpu_elem for percpu map

[Feng zhou]

From: Feng Zhou <zhoufeng.zf@bytedance.com>

Add new ebpf helpers bpf_map_lookup_percpu_elem.

The implementation method is relatively simple, refer to the implementation
method of map_lookup_elem of percpu map, increase the parameters of cpu, and
obtain it according to the specified cpu.

Signed-off-by: Feng Zhou <zhoufeng.zf@bytedance.com>
---
 include/linux/bpf.h            |  2 ++
 include/uapi/linux/bpf.h       |  9 +++++++++
 kernel/bpf/arraymap.c          | 15 +++++++++++++++
 kernel/bpf/core.c              |  1 +
 kernel/bpf/hashtab.c           | 32 ++++++++++++++++++++++++++++++++
 kernel/bpf/helpers.c           | 18 ++++++++++++++++++
 kernel/bpf/verifier.c          | 17 +++++++++++++++--
 kernel/trace/bpf_trace.c       |  2 ++
 tools/include/uapi/linux/bpf.h |  9 +++++++++
 9 files changed, 103 insertions(+), 2 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 3ded8711457f..5061ccd8b2dc 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -89,6 +89,7 @@ struct bpf_map_ops {
 	int (*map_push_elem)(struct bpf_map *map, void *value, u64 flags);
 	int (*map_pop_elem)(struct bpf_map *map, void *value);
 	int (*map_peek_elem)(struct bpf_map *map, void *value);
+	void *(*map_lookup_percpu_elem)(struct bpf_map *map, void *key, u32 cpu);
 
 	/* funcs called by prog_array and perf_event_array map */
 	void *(*map_fd_get_ptr)(struct bpf_map *map, struct file *map_file,
@@ -2184,6 +2185,7 @@ extern const struct bpf_func_proto bpf_map_delete_elem_proto;
 extern const struct bpf_func_proto bpf_map_push_elem_proto;
 extern const struct bpf_func_proto bpf_map_pop_elem_proto;
 extern const struct bpf_func_proto bpf_map_peek_elem_proto;
+extern const struct bpf_func_proto bpf_map_lookup_percpu_elem_proto;
 
 extern const struct bpf_func_proto bpf_get_prandom_u32_proto;
 extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index bc7f89948f54..0210f85131b3 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5164,6 +5164,14 @@ union bpf_attr {
  *		if not NULL, is a reference which must be released using its
  *		corresponding release function, or moved into a BPF map before
  *		program exit.
+ *
+ * void *bpf_map_lookup_percpu_elem(struct bpf_map *map, const void *key, u32 cpu)
+ * 	Description
+ * 		Perform a lookup in *percpu map* for an entry associated to
+ * 		*key* on *cpu*.
+ * 	Return
+ * 		Map value associated to *key* on *cpu*, or **NULL** if no entry
+ * 		was found or *cpu* is invalid.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -5361,6 +5369,7 @@ union bpf_attr {
 	FN(skb_set_tstamp),		\
 	FN(ima_file_hash),		\
 	FN(kptr_xchg),			\
+	FN(map_lookup_percpu_elem),     \
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 724613da6576..fe40d3b9458f 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -243,6 +243,20 @@ static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key)
 	return this_cpu_ptr(array->pptrs[index & array->index_mask]);
 }
 
+static void *percpu_array_map_lookup_percpu_elem(struct bpf_map *map, void *key, u32 cpu)
+{
+	struct bpf_array *array = container_of(map, struct bpf_array, map);
+	u32 index = *(u32 *)key;
+
+	if (cpu >= nr_cpu_ids)
+		return NULL;
+
+	if (unlikely(index >= array->map.max_entries))
+		return NULL;
+
+	return per_cpu_ptr(array->pptrs[index & array->index_mask], cpu);
+}
+
 int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
 {
 	struct bpf_array *array = container_of(map, struct bpf_array, map);
@@ -725,6 +739,7 @@ const struct bpf_map_ops percpu_array_map_ops = {
 	.map_lookup_elem = percpu_array_map_lookup_elem,
 	.map_update_elem = array_map_update_elem,
 	.map_delete_elem = array_map_delete_elem,
+	.map_lookup_percpu_elem = percpu_array_map_lookup_percpu_elem,
 	.map_seq_show_elem = percpu_array_map_seq_show_elem,
 	.map_check_btf = array_map_check_btf,
 	.map_lookup_batch = generic_map_lookup_batch,
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 13e9dbeeedf3..76f68d0a7ae8 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2619,6 +2619,7 @@ const struct bpf_func_proto bpf_map_delete_elem_proto __weak;
 const struct bpf_func_proto bpf_map_push_elem_proto __weak;
 const struct bpf_func_proto bpf_map_pop_elem_proto __weak;
 const struct bpf_func_proto bpf_map_peek_elem_proto __weak;
+const struct bpf_func_proto bpf_map_lookup_percpu_elem_proto __weak;
 const struct bpf_func_proto bpf_spin_lock_proto __weak;
 const struct bpf_func_proto bpf_spin_unlock_proto __weak;
 const struct bpf_func_proto bpf_jiffies64_proto __weak;
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 705841279d16..17fb69c0e0dc 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -2199,6 +2199,20 @@ static void *htab_percpu_map_lookup_elem(struct bpf_map *map, void *key)
 		return NULL;
 }
 
+static void *htab_percpu_map_lookup_percpu_elem(struct bpf_map *map, void *key, u32 cpu)
+{
+	struct htab_elem *l;
+
+	if (cpu >= nr_cpu_ids)
+		return NULL;
+
+	l = __htab_map_lookup_elem(map, key);
+	if (l)
+		return per_cpu_ptr(htab_elem_get_ptr(l, map->key_size), cpu);
+	else
+		return NULL;
+}
+
 static void *htab_lru_percpu_map_lookup_elem(struct bpf_map *map, void *key)
 {
 	struct htab_elem *l = __htab_map_lookup_elem(map, key);
@@ -2211,6 +2225,22 @@ static void *htab_lru_percpu_map_lookup_elem(struct bpf_map *map, void *key)
 	return NULL;
 }
 
+static void *htab_lru_percpu_map_lookup_percpu_elem(struct bpf_map *map, void *key, u32 cpu)
+{
+	struct htab_elem *l;
+
+	if (cpu >= nr_cpu_ids)
+		return NULL;
+
+	l = __htab_map_lookup_elem(map, key);
+	if (l) {
+		bpf_lru_node_set_ref(&l->lru_node);
+		return per_cpu_ptr(htab_elem_get_ptr(l, map->key_size), cpu);
+	}
+
+	return NULL;
+}
+
 int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value)
 {
 	struct htab_elem *l;
@@ -2300,6 +2330,7 @@ const struct bpf_map_ops htab_percpu_map_ops = {
 	.map_lookup_and_delete_elem = htab_percpu_map_lookup_and_delete_elem,
 	.map_update_elem = htab_percpu_map_update_elem,
 	.map_delete_elem = htab_map_delete_elem,
+	.map_lookup_percpu_elem = htab_percpu_map_lookup_percpu_elem,
 	.map_seq_show_elem = htab_percpu_map_seq_show_elem,
 	.map_set_for_each_callback_args = map_set_for_each_callback_args,
 	.map_for_each_callback = bpf_for_each_hash_elem,
@@ -2318,6 +2349,7 @@ const struct bpf_map_ops htab_lru_percpu_map_ops = {
 	.map_lookup_and_delete_elem = htab_lru_percpu_map_lookup_and_delete_elem,
 	.map_update_elem = htab_lru_percpu_map_update_elem,
 	.map_delete_elem = htab_lru_map_delete_elem,
+	.map_lookup_percpu_elem = htab_lru_percpu_map_lookup_percpu_elem,
 	.map_seq_show_elem = htab_percpu_map_seq_show_elem,
 	.map_set_for_each_callback_args = map_set_for_each_callback_args,
 	.map_for_each_callback = bpf_for_each_hash_elem,
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 3e709fed5306..d5f104a39092 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -119,6 +119,22 @@ const struct bpf_func_proto bpf_map_peek_elem_proto = {
 	.arg2_type	= ARG_PTR_TO_UNINIT_MAP_VALUE,
 };
 
+BPF_CALL_3(bpf_map_lookup_percpu_elem, struct bpf_map *, map, void *, key, u32, cpu)
+{
+	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_bh_held());
+	return (unsigned long) map->ops->map_lookup_percpu_elem(map, key, cpu);
+}
+
+const struct bpf_func_proto bpf_map_lookup_percpu_elem_proto = {
+	.func		= bpf_map_lookup_percpu_elem,
+	.gpl_only	= false,
+	.pkt_access	= true,
+	.ret_type	= RET_PTR_TO_MAP_VALUE_OR_NULL,
+	.arg1_type	= ARG_CONST_MAP_PTR,
+	.arg2_type	= ARG_PTR_TO_MAP_KEY,
+	.arg3_type	= ARG_ANYTHING,
+};
+
 const struct bpf_func_proto bpf_get_prandom_u32_proto = {
 	.func		= bpf_user_rnd_u32,
 	.gpl_only	= false,
@@ -1420,6 +1436,8 @@ bpf_base_func_proto(enum bpf_func_id func_id)
 		return &bpf_map_pop_elem_proto;
 	case BPF_FUNC_map_peek_elem:
 		return &bpf_map_peek_elem_proto;
+	case BPF_FUNC_map_lookup_percpu_elem:
+		return &bpf_map_lookup_percpu_elem_proto;
 	case BPF_FUNC_get_prandom_u32:
 		return &bpf_get_prandom_u32_proto;
 	case BPF_FUNC_get_smp_processor_id:
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index c27fee73a2cb..05c1b6656824 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -6137,6 +6137,12 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
 		    map->map_type != BPF_MAP_TYPE_BLOOM_FILTER)
 			goto error;
 		break;
+	case BPF_FUNC_map_lookup_percpu_elem:
+		if (map->map_type != BPF_MAP_TYPE_PERCPU_ARRAY &&
+		    map->map_type != BPF_MAP_TYPE_PERCPU_HASH &&
+		    map->map_type != BPF_MAP_TYPE_LRU_PERCPU_HASH)
+			goto error;
+		break;
 	case BPF_FUNC_sk_storage_get:
 	case BPF_FUNC_sk_storage_delete:
 		if (map->map_type != BPF_MAP_TYPE_SK_STORAGE)
@@ -6750,7 +6756,8 @@ record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
 	    func_id != BPF_FUNC_map_pop_elem &&
 	    func_id != BPF_FUNC_map_peek_elem &&
 	    func_id != BPF_FUNC_for_each_map_elem &&
-	    func_id != BPF_FUNC_redirect_map)
+	    func_id != BPF_FUNC_redirect_map &&
+	    func_id != BPF_FUNC_map_lookup_percpu_elem)
 		return 0;
 
 	if (map == NULL) {
@@ -13810,7 +13817,8 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
 		     insn->imm == BPF_FUNC_map_pop_elem    ||
 		     insn->imm == BPF_FUNC_map_peek_elem   ||
 		     insn->imm == BPF_FUNC_redirect_map    ||
-		     insn->imm == BPF_FUNC_for_each_map_elem)) {
+		     insn->imm == BPF_FUNC_for_each_map_elem ||
+		     insn->imm == BPF_FUNC_map_lookup_percpu_elem)) {
 			aux = &env->insn_aux_data[i + delta];
 			if (bpf_map_ptr_poisoned(aux))
 				goto patch_call_imm;
@@ -13859,6 +13867,8 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
 					      bpf_callback_t callback_fn,
 					      void *callback_ctx,
 					      u64 flags))NULL));
+			BUILD_BUG_ON(!__same_type(ops->map_lookup_percpu_elem,
+				     (void *(*)(struct bpf_map *map, void *key, u32 cpu))NULL));
 
 patch_map_ops_generic:
 			switch (insn->imm) {
@@ -13886,6 +13896,9 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
 			case BPF_FUNC_for_each_map_elem:
 				insn->imm = BPF_CALL_IMM(ops->map_for_each_callback);
 				continue;
+			case BPF_FUNC_map_lookup_percpu_elem:
+				insn->imm = BPF_CALL_IMM(ops->map_lookup_percpu_elem);
+				continue;
 			}
 
 			goto patch_call_imm;
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 2eaac094caf8..7141ca8a1c2d 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1197,6 +1197,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 		return &bpf_map_pop_elem_proto;
 	case BPF_FUNC_map_peek_elem:
 		return &bpf_map_peek_elem_proto;
+	case BPF_FUNC_map_lookup_percpu_elem:
+		return &bpf_map_lookup_percpu_elem_proto;
 	case BPF_FUNC_ktime_get_ns:
 		return &bpf_ktime_get_ns_proto;
 	case BPF_FUNC_ktime_get_boot_ns:
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index bc7f89948f54..0210f85131b3 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5164,6 +5164,14 @@ union bpf_attr {
  *		if not NULL, is a reference which must be released using its
  *		corresponding release function, or moved into a BPF map before
  *		program exit.
+ *
+ * void *bpf_map_lookup_percpu_elem(struct bpf_map *map, const void *key, u32 cpu)
+ * 	Description
+ * 		Perform a lookup in *percpu map* for an entry associated to
+ * 		*key* on *cpu*.
+ * 	Return
+ * 		Map value associated to *key* on *cpu*, or **NULL** if no entry
+ * 		was found or *cpu* is invalid.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -5361,6 +5369,7 @@ union bpf_attr {
 	FN(skb_set_tstamp),		\
 	FN(ima_file_hash),		\
 	FN(kptr_xchg),			\
+	FN(map_lookup_percpu_elem),     \
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
-- 
2.20.1

[PATCH bpf-next v3 2/2] selftests/bpf: add test case for bpf_map_lookup_percpu_elem

[Feng zhou]

From: Feng Zhou <zhoufeng.zf@bytedance.com>

test_progs:
Tests new ebpf helpers bpf_map_lookup_percpu_elem.

Signed-off-by: Feng Zhou <zhoufeng.zf@bytedance.com>
---
 .../bpf/prog_tests/map_lookup_percpu_elem.c   | 59 +++++++++++++++
 .../bpf/progs/test_map_lookup_percpu_elem.c   | 71 +++++++++++++++++++
 2 files changed, 130 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/map_lookup_percpu_elem.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_map_lookup_percpu_elem.c

diff --git a/tools/testing/selftests/bpf/prog_tests/map_lookup_percpu_elem.c b/tools/testing/selftests/bpf/prog_tests/map_lookup_percpu_elem.c
new file mode 100644
index 000000000000..89ca170f1c25
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/map_lookup_percpu_elem.c
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2022 Bytedance */
+
+#include <test_progs.h>
+
+#include "test_map_lookup_percpu_elem.skel.h"
+
+void test_map_lookup_percpu_elem(void)
+{
+	struct test_map_lookup_percpu_elem *skel;
+	__u64 key = 0, sum;
+	int ret, i;
+	int nr_cpus = libbpf_num_possible_cpus();
+	__u64 *buf;
+
+	buf = (__u64 *)malloc(nr_cpus*sizeof(__u64));
+	if (!ASSERT_OK_PTR(buf, "malloc"))
+		return;
+
+	for (i=0; i<nr_cpus; i++)
+		buf[i] = i;
+	sum = (nr_cpus-1)*nr_cpus/2;
+
+	skel = test_map_lookup_percpu_elem__open();
+	if (!ASSERT_OK_PTR(skel, "test_map_lookup_percpu_elem__open"))
+		goto exit;
+
+	skel->rodata->nr_cpus = nr_cpus;
+
+	ret = test_map_lookup_percpu_elem__load(skel);
+	if (!ASSERT_OK(ret, "test_map_lookup_percpu_elem__load"))
+		goto cleanup;
+
+	ret = test_map_lookup_percpu_elem__attach(skel);
+	if (!ASSERT_OK(ret, "test_map_lookup_percpu_elem__attach"))
+		goto cleanup;
+
+	ret = bpf_map_update_elem(bpf_map__fd(skel->maps.percpu_array_map), &key, buf, 0);
+	ASSERT_OK(ret, "percpu_array_map update");
+
+	ret = bpf_map_update_elem(bpf_map__fd(skel->maps.percpu_hash_map), &key, buf, 0);
+	ASSERT_OK(ret, "percpu_hash_map update");
+
+	ret = bpf_map_update_elem(bpf_map__fd(skel->maps.percpu_lru_hash_map), &key, buf, 0);
+	ASSERT_OK(ret, "percpu_lru_hash_map update");
+
+	syscall(__NR_getuid);
+
+	test_map_lookup_percpu_elem__detach(skel);
+
+	ASSERT_EQ(skel->bss->percpu_array_elem_sum, sum, "percpu_array lookup percpu elem");
+	ASSERT_EQ(skel->bss->percpu_hash_elem_sum, sum, "percpu_hash lookup percpu elem");
+	ASSERT_EQ(skel->bss->percpu_lru_hash_elem_sum, sum, "percpu_lru_hash lookup percpu elem");
+
+cleanup:
+	test_map_lookup_percpu_elem__destroy(skel);
+exit:
+	free(buf);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_map_lookup_percpu_elem.c b/tools/testing/selftests/bpf/progs/test_map_lookup_percpu_elem.c
new file mode 100644
index 000000000000..75479180571f
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_map_lookup_percpu_elem.c
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2022 Bytedance */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+
+__u64 percpu_array_elem_sum = 0;
+__u64 percpu_hash_elem_sum = 0;
+__u64 percpu_lru_hash_elem_sum = 0;
+const volatile int nr_cpus;
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u64);
+} percpu_array_map SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_HASH);
+	__uint(max_entries, 1);
+	__type(key, __u64);
+	__type(value, __u64);
+} percpu_hash_map SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_LRU_PERCPU_HASH);
+	__uint(max_entries, 1);
+	__type(key, __u64);
+	__type(value, __u64);
+} percpu_lru_hash_map SEC(".maps");
+
+struct read_percpu_elem_ctx {
+	void *map;
+	__u64 sum;
+};
+
+static int read_percpu_elem_callback(__u32 index, struct read_percpu_elem_ctx *ctx)
+{
+	__u64 key = 0;
+	__u64 *value;
+	value = bpf_map_lookup_percpu_elem(ctx->map, &key, index);
+	if (value)
+		ctx->sum += *value;
+	return 0;
+}
+
+SEC("tp/syscalls/sys_enter_getuid")
+int sysenter_getuid(const void *ctx)
+{
+	struct read_percpu_elem_ctx map_ctx;
+
+	map_ctx.map = &percpu_array_map;
+	map_ctx.sum = 0;
+	bpf_loop(nr_cpus, read_percpu_elem_callback, &map_ctx, 0);
+	percpu_array_elem_sum = map_ctx.sum;
+
+	map_ctx.map = &percpu_hash_map;
+	map_ctx.sum = 0;
+	bpf_loop(nr_cpus, read_percpu_elem_callback, &map_ctx, 0);
+	percpu_hash_elem_sum = map_ctx.sum;
+
+	map_ctx.map = &percpu_lru_hash_map;
+	map_ctx.sum = 0;
+	bpf_loop(nr_cpus, read_percpu_elem_callback, &map_ctx, 0);
+	percpu_lru_hash_elem_sum = map_ctx.sum;
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.20.1

Re: [PATCH bpf-next v3 0/2] Introduce access remote cpu elem support in BPF percpu map

[Daniel Borkmann]

On 5/13/22 8:39 AM, Feng zhou wrote:
[...]
> Changelog:
> ----------
> v2->v3: Addressed comments from Andrii Nakryiko.
> - use /* */ instead of //
> - use libbpf_num_possible_cpus() instead of sysconf(_SC_NPROCESSORS_ONLN)
> - use 8 bytes for value size
> - fix memory leak
> - use ASSERT_EQ instead of ASSERT_OK
> - add bpf_loop to fetch values on each possible CPU
> some details in here:
> https://lore.kernel.org/lkml/20220511093854.411-1-zhoufeng.zf@bytedance.com/T/

The v2 of your series is already in bpf-next tree, please just send a relative diff for
the selftest patch.

https://lore.kernel.org/lkml/165231901346.29050.11394051230756915389.git-patchwork-notify@kernel.org/

Thanks,
Daniel

Re: [External] Re: [PATCH bpf-next v3 0/2] Introduce access remote cpu elem support in BPF percpu map

[Feng Zhou]

在 2022/5/13 下午11:01, Daniel Borkmann 写道:
> On 5/13/22 8:39 AM, Feng zhou wrote:
> [...]
>> Changelog:
>> ----------
>> v2->v3: Addressed comments from Andrii Nakryiko.
>> - use /* */ instead of //
>> - use libbpf_num_possible_cpus() instead of 
>> sysconf(_SC_NPROCESSORS_ONLN)
>> - use 8 bytes for value size
>> - fix memory leak
>> - use ASSERT_EQ instead of ASSERT_OK
>> - add bpf_loop to fetch values on each possible CPU
>> some details in here:
>> https://lore.kernel.org/lkml/20220511093854.411-1-zhoufeng.zf@bytedance.com/T/ 
>>
>
> The v2 of your series is already in bpf-next tree, please just send a 
> relative diff for
> the selftest patch.
>
> https://lore.kernel.org/lkml/165231901346.29050.11394051230756915389.git-patchwork-notify@kernel.org/ 
>
>
> Thanks,
> Daniel

Ok, will do. Thanks.