1/* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com
2 *
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of version 2 of the GNU General Public
5 * License as published by the Free Software Foundation.
6 */
7#include <linux/skbuff.h>
8#include <linux/netdevice.h>
9#include <linux/version.h>
10#include <uapi/linux/bpf.h>
11#include <bpf/bpf_helpers.h>
12#include <bpf/bpf_tracing.h>
13#include "trace_common.h"
14
15struct {
16	__uint(type, BPF_MAP_TYPE_HASH);
17	__type(key, long);
18	__type(value, long);
19	__uint(max_entries, 1024);
20} my_map SEC(".maps");
21
22/* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe
23 * example will no longer be meaningful
24 */
25SEC("kprobe/kfree_skb")
26int bpf_prog2(struct pt_regs *ctx)
27{
28	long loc = 0;
29	long init_val = 1;
30	long *value;
31
32	/* read ip of kfree_skb caller.
33	 * non-portable version of __builtin_return_address(0)
34	 */
35	BPF_KPROBE_READ_RET_IP(loc, ctx);
36
37	value = bpf_map_lookup_elem(&my_map, &loc);
38	if (value)
39		*value += 1;
40	else
41		bpf_map_update_elem(&my_map, &loc, &init_val, BPF_ANY);
42	return 0;
43}
44
45static unsigned int log2(unsigned int v)
46{
47	unsigned int r;
48	unsigned int shift;
49
50	r = (v > 0xFFFF) << 4; v >>= r;
51	shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
52	shift = (v > 0xF) << 2; v >>= shift; r |= shift;
53	shift = (v > 0x3) << 1; v >>= shift; r |= shift;
54	r |= (v >> 1);
55	return r;
56}
57
58static unsigned int log2l(unsigned long v)
59{
60	unsigned int hi = v >> 32;
61	if (hi)
62		return log2(hi) + 32;
63	else
64		return log2(v);
65}
66
67struct hist_key {
68	char comm[16];
69	u64 pid_tgid;
70	u64 uid_gid;
71	u64 index;
72};
73
74struct {
75	__uint(type, BPF_MAP_TYPE_PERCPU_HASH);
76	__uint(key_size, sizeof(struct hist_key));
77	__uint(value_size, sizeof(long));
78	__uint(max_entries, 1024);
79} my_hist_map SEC(".maps");
80
81SEC("kprobe/" SYSCALL(sys_write))
82int bpf_prog3(struct pt_regs *ctx)
83{
84	long write_size = PT_REGS_PARM3(ctx);
85	long init_val = 1;
86	long *value;
87	struct hist_key key;
88
89	key.index = log2l(write_size);
90	key.pid_tgid = bpf_get_current_pid_tgid();
91	key.uid_gid = bpf_get_current_uid_gid();
92	bpf_get_current_comm(&key.comm, sizeof(key.comm));
93
94	value = bpf_map_lookup_elem(&my_hist_map, &key);
95	if (value)
96		__sync_fetch_and_add(value, 1);
97	else
98		bpf_map_update_elem(&my_hist_map, &key, &init_val, BPF_ANY);
99	return 0;
100}
101char _license[] SEC("license") = "GPL";
102u32 _version SEC("version") = LINUX_VERSION_CODE;
103