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/* 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(long),
.max_entries = 1024,
};
/* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe
* example will no longer be meaningful
*/
SEC("kprobe/kfree_skb")
int bpf_prog2(struct pt_regs *ctx)
{
long loc = 0;
long init_val = 1;
long *value;
/* x64 specific: read ip of kfree_skb caller.
* non-portable version of __builtin_return_address(0)
*/
bpf_probe_read(&loc, sizeof(loc), (void *)ctx->sp);
value = bpf_map_lookup_elem(&my_map, &loc);
if (value)
*value += 1;
else
bpf_map_update_elem(&my_map, &loc, &init_val, BPF_ANY);
return 0;
}
static unsigned int log2(unsigned int v)
{
unsigned int r;
unsigned int shift;
r = (v > 0xFFFF) << 4; v >>= r;
shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
shift = (v > 0xF) << 2; v >>= shift; r |= shift;
shift = (v > 0x3) << 1; v >>= shift; r |= shift;
r |= (v >> 1);
return r;
}
static unsigned int log2l(unsigned long v)
{
unsigned int hi = v >> 32;
if (hi)
return log2(hi) + 32;
else
return log2(v);
}
struct bpf_map_def SEC("maps") my_hist_map = {
.type = BPF_MAP_TYPE_ARRAY,
.key_size = sizeof(u32),
.value_size = sizeof(long),
.max_entries = 64,
};
SEC("kprobe/sys_write")
int bpf_prog3(struct pt_regs *ctx)
{
long write_size = ctx->dx; /* arg3 */
long init_val = 1;
long *value;
u32 index = log2l(write_size);
value = bpf_map_lookup_elem(&my_hist_map, &index);
if (value)
__sync_fetch_and_add(value, 1);
return 0;
}
char _license[] SEC("license") = "GPL";
u32 _version SEC("version") = LINUX_VERSION_CODE;
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