1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright 2022 Google LLC.
  4 */
  5#include "vmlinux.h"
  6#include <bpf/bpf_helpers.h>
  7#include <bpf/bpf_tracing.h>
  8#include <bpf/bpf_core_read.h>
  9
 10char _license[] SEC("license") = "GPL";
 11
 12struct percpu_attach_counter {
 13	/* Previous percpu state, to figure out if we have new updates */
 14	__u64 prev;
 15	/* Current percpu state */
 16	__u64 state;
 17};
 18
 19struct attach_counter {
 20	/* State propagated through children, pending aggregation */
 21	__u64 pending;
 22	/* Total state, including all cpus and all children */
 23	__u64 state;
 24};
 25
 26struct {
 27	__uint(type, BPF_MAP_TYPE_PERCPU_HASH);
 28	__uint(max_entries, 1024);
 29	__type(key, __u64);
 30	__type(value, struct percpu_attach_counter);
 31} percpu_attach_counters SEC(".maps");
 32
 33struct {
 34	__uint(type, BPF_MAP_TYPE_HASH);
 35	__uint(max_entries, 1024);
 36	__type(key, __u64);
 37	__type(value, struct attach_counter);
 38} attach_counters SEC(".maps");
 39
 40extern void cgroup_rstat_updated(struct cgroup *cgrp, int cpu) __ksym;
 41extern void cgroup_rstat_flush(struct cgroup *cgrp) __ksym;
 42
 43static uint64_t cgroup_id(struct cgroup *cgrp)
 44{
 45	return cgrp->kn->id;
 46}
 47
 48static int create_percpu_attach_counter(__u64 cg_id, __u64 state)
 49{
 50	struct percpu_attach_counter pcpu_init = {.state = state, .prev = 0};
 51
 52	return bpf_map_update_elem(&percpu_attach_counters, &cg_id,
 53				   &pcpu_init, BPF_NOEXIST);
 54}
 55
 56static int create_attach_counter(__u64 cg_id, __u64 state, __u64 pending)
 57{
 58	struct attach_counter init = {.state = state, .pending = pending};
 59
 60	return bpf_map_update_elem(&attach_counters, &cg_id,
 61				   &init, BPF_NOEXIST);
 62}
 63
 64SEC("fentry/cgroup_attach_task")
 65int BPF_PROG(counter, struct cgroup *dst_cgrp, struct task_struct *leader,
 66	     bool threadgroup)
 67{
 68	__u64 cg_id = cgroup_id(dst_cgrp);
 69	struct percpu_attach_counter *pcpu_counter = bpf_map_lookup_elem(
 70			&percpu_attach_counters,
 71			&cg_id);
 72
 73	if (pcpu_counter)
 74		pcpu_counter->state += 1;
 75	else if (create_percpu_attach_counter(cg_id, 1))
 76		return 0;
 77
 78	cgroup_rstat_updated(dst_cgrp, bpf_get_smp_processor_id());
 79	return 0;
 80}
 81
 82SEC("fentry/bpf_rstat_flush")
 83int BPF_PROG(flusher, struct cgroup *cgrp, struct cgroup *parent, int cpu)
 84{
 85	struct percpu_attach_counter *pcpu_counter;
 86	struct attach_counter *total_counter, *parent_counter;
 87	__u64 cg_id = cgroup_id(cgrp);
 88	__u64 parent_cg_id = parent ? cgroup_id(parent) : 0;
 89	__u64 state;
 90	__u64 delta = 0;
 91
 92	/* Add CPU changes on this level since the last flush */
 93	pcpu_counter = bpf_map_lookup_percpu_elem(&percpu_attach_counters,
 94						  &cg_id, cpu);
 95	if (pcpu_counter) {
 96		state = pcpu_counter->state;
 97		delta += state - pcpu_counter->prev;
 98		pcpu_counter->prev = state;
 99	}
100
101	total_counter = bpf_map_lookup_elem(&attach_counters, &cg_id);
102	if (!total_counter) {
103		if (create_attach_counter(cg_id, delta, 0))
104			return 0;
105		goto update_parent;
106	}
107
108	/* Collect pending stats from subtree */
109	if (total_counter->pending) {
110		delta += total_counter->pending;
111		total_counter->pending = 0;
112	}
113
114	/* Propagate changes to this cgroup's total */
115	total_counter->state += delta;
116
117update_parent:
118	/* Skip if there are no changes to propagate, or no parent */
119	if (!delta || !parent_cg_id)
120		return 0;
121
122	/* Propagate changes to cgroup's parent */
123	parent_counter = bpf_map_lookup_elem(&attach_counters,
124					     &parent_cg_id);
125	if (parent_counter)
126		parent_counter->pending += delta;
127	else
128		create_attach_counter(parent_cg_id, 0, delta);
129	return 0;
130}
131
132SEC("iter.s/cgroup")
133int BPF_PROG(dumper, struct bpf_iter_meta *meta, struct cgroup *cgrp)
134{
135	struct seq_file *seq = meta->seq;
136	struct attach_counter *total_counter;
137	__u64 cg_id = cgrp ? cgroup_id(cgrp) : 0;
138
139	/* Do nothing for the terminal call */
140	if (!cg_id)
141		return 1;
142
143	/* Flush the stats to make sure we get the most updated numbers */
144	cgroup_rstat_flush(cgrp);
145
146	total_counter = bpf_map_lookup_elem(&attach_counters, &cg_id);
147	if (!total_counter) {
148		BPF_SEQ_PRINTF(seq, "cg_id: %llu, attach_counter: 0\n",
149			       cg_id);
150	} else {
151		BPF_SEQ_PRINTF(seq, "cg_id: %llu, attach_counter: %llu\n",
152			       cg_id, total_counter->state);
153	}
154	return 0;
155}