LXR linux/tools/testing/selftests/bpf/progs/test_core_read

   1// SPDX-License-Identifier: GPL-2.0
   2// Copyright (c) 2020 Facebook
   3
   4#include "vmlinux.h"
   5#include <bpf/bpf_helpers.h>
   6#include <bpf/bpf_core_read.h>
   7
   8char _license[] SEC("license") = "GPL";
   9
  10/* shuffled layout for relocatable (CO-RE) reads */
  11struct callback_head___shuffled {
  12        void (*func)(struct callback_head___shuffled *head);
  13        struct callback_head___shuffled *next;
  14};
  15
  16struct callback_head k_probe_in = {};
  17struct callback_head___shuffled k_core_in = {};
  18
  19struct callback_head *u_probe_in = 0;
  20struct callback_head___shuffled *u_core_in = 0;
  21
  22long k_probe_out = 0;
  23long u_probe_out = 0;
  24
  25long k_core_out = 0;
  26long u_core_out = 0;
  27
  28int my_pid = 0;
  29
  30SEC("raw_tracepoint/sys_enter")
  31int handler(void *ctx)
  32{
  33        int pid = bpf_get_current_pid_tgid() >> 32;
  34
  35        if (my_pid != pid)
  36                return 0;
  37
  38        /* next pointers for kernel address space have to be initialized from
  39         * BPF side, user-space mmaped addresses are stil user-space addresses
  40         */
  41        k_probe_in.next = &k_probe_in;
  42        __builtin_preserve_access_index(({k_core_in.next = &k_core_in;}));
  43
  44        k_probe_out = (long)BPF_PROBE_READ(&k_probe_in, next, next, func);
  45        k_core_out = (long)BPF_CORE_READ(&k_core_in, next, next, func);
  46        u_probe_out = (long)BPF_PROBE_READ_USER(u_probe_in, next, next, func);
  47        u_core_out = (long)BPF_CORE_READ_USER(u_core_in, next, next, func);
  48
  49        return 0;
  50}
  51