samples/bpf/test_overhead_kprobe.bpf.c

   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;