cregit-Linux how code gets into the kernel

Release 4.10 samples/bpf/tracex1_kern.c

Directory: samples/bpf
/* Copyright (c) 2013-2015 PLUMgrid,
 * 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 <uapi/linux/bpf.h>
#include <linux/version.h>
#include "bpf_helpers.h"

#define _(P) ({typeof(P) val = 0; bpf_probe_read(&val, sizeof(val), &P); val;})

/* kprobe is NOT a stable ABI
 * kernel functions can be removed, renamed or completely change semantics.
 * Number of arguments and their positions can change, etc.
 * In such case this bpf+kprobe example will no longer be meaningful

int bpf_prog1(struct pt_regs *ctx) { /* attaches to kprobe netif_receive_skb, * looks for packets on loobpack device and prints them */ char devname[IFNAMSIZ]; struct net_device *dev; struct sk_buff *skb; int len; /* non-portable! works for the given kernel only */ skb = (struct sk_buff *) PT_REGS_PARM1(ctx); dev = _(skb->dev); len = _(skb->len); bpf_probe_read(devname, sizeof(devname), dev->name); if (devname[0] == 'l' && devname[1] == 'o') { char fmt[] = "skb %p len %d\n"; /* using bpf_trace_printk() for DEBUG ONLY */ bpf_trace_printk(fmt, sizeof(fmt), skb, len); } return 0; }


alexei starovoitovalexei starovoitov11497.44%150.00%
michael holzheumichael holzheu32.56%150.00%

char _license[] SEC("license") = "GPL"; u32 _version SEC("version") = LINUX_VERSION_CODE;

Overall Contributors

alexei starovoitovalexei starovoitov16198.17%150.00%
michael holzheumichael holzheu31.83%150.00%
Directory: samples/bpf
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