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/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