From 803370d3d37579e080e8c59f2360a072d0e45aff Mon Sep 17 00:00:00 2001 From: Anton Protopopov Date: Thu, 6 Jul 2023 13:39:29 +0000 Subject: [PATCH] bpf: add a new kfunc to return current bpf_map elements count 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 Link: https://lore.kernel.org/r/20230706133932.45883-3-aspsk@isovalent.com Signed-off-by: Alexei Starovoitov --- 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);