A bpf_map_sum_elem_count kfunc was added to simplify getting the sum of the map
per-cpu element counters. If a map doesn't implement the counter, then the
function will always return 0.
Signed-off-by: Anton Protopopov <aspsk@xxxxxxxxxxxxx>
---
kernel/bpf/map_iter.c | 39 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 38 insertions(+), 1 deletion(-)
diff --git a/kernel/bpf/map_iter.c b/kernel/bpf/map_iter.c
index b0fa190b0979..d06d3b7150e5 100644
--- a/kernel/bpf/map_iter.c
+++ b/kernel/bpf/map_iter.c
@@ -93,7 +93,7 @@ static struct bpf_iter_reg bpf_map_reg_info = {
.ctx_arg_info_size = 1,
.ctx_arg_info = {
{ offsetof(struct bpf_iter__bpf_map, map),
- PTR_TO_BTF_ID_OR_NULL },
+ PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED },
},
.seq_info = &bpf_map_seq_info,
};
@@ -193,3 +193,40 @@ static int __init bpf_map_iter_init(void)
}
late_initcall(bpf_map_iter_init);
+
+__diag_push();
+__diag_ignore_all("-Wmissing-prototypes",
+ "Global functions as their definitions will be in vmlinux BTF");
+
+__bpf_kfunc s64 bpf_map_sum_elem_count(struct bpf_map *map)
+{
+ s64 *pcount;
+ s64 ret = 0;
+ int cpu;
+
+ if (!map || !map->elem_count)
+ return 0;
+
+ for_each_possible_cpu(cpu) {
+ pcount = per_cpu_ptr(map->elem_count, cpu);
+ ret += READ_ONCE(*pcount);
+ }
+ return ret;
+}
+
+__diag_pop();
+
+BTF_SET8_START(bpf_map_iter_kfunc_ids)
+BTF_ID_FLAGS(func, bpf_map_sum_elem_count, KF_TRUSTED_ARGS)
+BTF_SET8_END(bpf_map_iter_kfunc_ids)
+
+static const struct btf_kfunc_id_set bpf_map_iter_kfunc_set = {
+ .owner = THIS_MODULE,
+ .set = &bpf_map_iter_kfunc_ids,
+};
+
+static int init_subsystem(void)
+{
+ return register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_map_iter_kfunc_set);
+}
+late_initcall(init_subsystem);
--
2.34.1
