LXR linux/samples/bpf/tracex2

   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_helpers.h"
  12
  13struct bpf_map_def SEC("maps") my_map = {
  14        .type = BPF_MAP_TYPE_HASH,
  15        .key_size = sizeof(long),
  16        .value_size = sizeof(long),
  17        .max_entries = 1024,
  18};
  19
  20/* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe
  21 * example will no longer be meaningful
  22 */
  23SEC("kprobe/kfree_skb")
  24int bpf_prog2(struct pt_regs *ctx)
  25{
  26        long loc = 0;
  27        long init_val = 1;
  28        long *value;
  29
  30        /* read ip of kfree_skb caller.
  31         * non-portable version of __builtin_return_address(0)
  32         */
  33        BPF_KPROBE_READ_RET_IP(loc, ctx);
  34
  35        value = bpf_map_lookup_elem(&my_map, &loc);
  36        if (value)
  37                *value += 1;
  38        else
  39                bpf_map_update_elem(&my_map, &loc, &init_val, BPF_ANY);
  40        return 0;
  41}
  42
  43static unsigned int log2(unsigned int v)
  44{
  45        unsigned int r;
  46        unsigned int shift;
  47
  48        r = (v > 0xFFFF) << 4; v >>= r;
  49        shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
  50        shift = (v > 0xF) << 2; v >>= shift; r |= shift;
  51        shift = (v > 0x3) << 1; v >>= shift; r |= shift;
  52        r |= (v >> 1);
  53        return r;
  54}
  55
  56static unsigned int log2l(unsigned long v)
  57{
  58        unsigned int hi = v >> 32;
  59        if (hi)
  60                return log2(hi) + 32;
  61        else
  62                return log2(v);
  63}
  64
  65struct hist_key {
  66        char comm[16];
  67        u64 pid_tgid;
  68        u64 uid_gid;
  69        u64 index;
  70};
  71
  72struct bpf_map_def SEC("maps") my_hist_map = {
  73        .type = BPF_MAP_TYPE_PERCPU_HASH,
  74        .key_size = sizeof(struct hist_key),
  75        .value_size = sizeof(long),
  76        .max_entries = 1024,
  77};
  78
  79SEC("kprobe/sys_write")
  80int bpf_prog3(struct pt_regs *ctx)
  81{
  82        long write_size = PT_REGS_PARM3(ctx);
  83        long init_val = 1;
  84        long *value;
  85        struct hist_key key;
  86
  87        key.index = log2l(write_size);
  88        key.pid_tgid = bpf_get_current_pid_tgid();
  89        key.uid_gid = bpf_get_current_uid_gid();
  90        bpf_get_current_comm(&key.comm, sizeof(key.comm));
  91
  92        value = bpf_map_lookup_elem(&my_hist_map, &key);
  93        if (value)
  94                __sync_fetch_and_add(value, 1);
  95        else
  96                bpf_map_update_elem(&my_hist_map, &key, &init_val, BPF_ANY);
  97        return 0;
  98}
  99char _license[] SEC("license") = "GPL";
 100u32 _version SEC("version") = LINUX_VERSION_CODE;
 101