1 /* Copyright (c) 2016 Facebook
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 "vmlinux.h"
8 #include <linux/version.h>
9 #include <bpf/bpf_helpers.h>
10 #include <bpf/bpf_tracing.h>
11 
12 #define _(P)                                                                   \
13 	({                                                                     \
14 		typeof(P) val = 0;                                             \
15 		bpf_probe_read_kernel(&val, sizeof(val), &(P));                \
16 		val;                                                           \
17 	})
18 
19 SEC("kprobe/__set_task_comm")
20 int prog(struct pt_regs *ctx)
21 {
22 	struct signal_struct *signal;
23 	struct task_struct *tsk;
24 	char oldcomm[TASK_COMM_LEN] = {};
25 	char newcomm[TASK_COMM_LEN] = {};
26 	u16 oom_score_adj;
27 	u32 pid;
28 
29 	tsk = (void *)PT_REGS_PARM1(ctx);
30 
31 	pid = _(tsk->pid);
32 	bpf_probe_read_kernel_str(oldcomm, sizeof(oldcomm), &tsk->comm);
33 	bpf_probe_read_kernel_str(newcomm, sizeof(newcomm),
34 				  (void *)PT_REGS_PARM2(ctx));
35 	signal = _(tsk->signal);
36 	oom_score_adj = _(signal->oom_score_adj);
37 	return 0;
38 }
39 
40 SEC("kprobe/fib_table_lookup")
41 int prog2(struct pt_regs *ctx)
42 {
43 	return 0;
44 }
45 
46 char _license[] SEC("license") = "GPL";
47 u32 _version SEC("version") = LINUX_VERSION_CODE;
48