linux-imx

/* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of version 2 of the GNU General Public

 * License as published by the Free Software Foundation.

 */

#include <linux/skbuff.h>

#include <linux/netdevice.h>

#include <linux/version.h>

#include <uapi/linux/bpf.h>

#include "bpf_helpers.h"

​

struct bpf_map_def SEC("maps") my_map = {

    .type = BPF_MAP_TYPE_HASH,

    .key_size = sizeof(long),

    .value_size = sizeof(u64),

    .max_entries = 4096,

};

​

/* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe

 * example will no longer be meaningful

 */

SEC("kprobe/blk_mq_start_request")

int bpf_prog1(struct pt_regs *ctx)

{

    long rq = PT_REGS_PARM1(ctx);

    u64 val = bpf_ktime_get_ns();

​

    bpf_map_update_elem(&my_map, &rq, &val, BPF_ANY);

    return 0;

}

​

static unsigned int log2l(unsigned long long n)

{

#define S(k) if (n >= (1ull << k)) { i += k; n >>= k; }

    int i = -(n == 0);

    S(32); S(16); S(8); S(4); S(2); S(1);

    return i;

#undef S

}

​

#define SLOTS 100

​

struct bpf_map_def SEC("maps") lat_map = {

    .type = BPF_MAP_TYPE_PERCPU_ARRAY,

    .key_size = sizeof(u32),

    .value_size = sizeof(u64),

    .max_entries = SLOTS,

};

​

SEC("kprobe/blk_account_io_completion")

int bpf_prog2(struct pt_regs *ctx)

{

    long rq = PT_REGS_PARM1(ctx);

    u64 *value, l, base;

    u32 index;

​

    value = bpf_map_lookup_elem(&my_map, &rq);

    if (!value)

        return 0;

​

    u64 cur_time = bpf_ktime_get_ns();

    u64 delta = cur_time - *value;