root/tools/testing/selftests/bpf/progs/test_core_reloc_misc.c

DEFINITIONS

1. SEC

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (c) 2019 Facebook
   3 
   4 #include <linux/bpf.h>
   5 #include <stdint.h>
   6 #include "bpf_helpers.h"
   7 
   8 char _license[] SEC("license") = "GPL";
   9 
  10 static volatile struct data {
  11         char in[256];
  12         char out[256];
  13 } data;
  14 
  15 struct core_reloc_misc_output {
  16         int a, b, c;
  17 };
  18 
  19 struct core_reloc_misc___a {
  20         int a1;
  21         int a2;
  22 };
  23 
  24 struct core_reloc_misc___b {
  25         int b1;
  26         int b2;
  27 };
  28 
  29 /* fixed two first members, can be extended with new fields */
  30 struct core_reloc_misc_extensible {
  31         int a;
  32         int b;
  33 };
  34 
  35 SEC("raw_tracepoint/sys_enter")
  36 int test_core_misc(void *ctx)
  37 {
  38         struct core_reloc_misc___a *in_a = (void *)&data.in;
  39         struct core_reloc_misc___b *in_b = (void *)&data.in;
  40         struct core_reloc_misc_extensible *in_ext = (void *)&data.in;
  41         struct core_reloc_misc_output *out = (void *)&data.out;
  42 
  43         /* record two different relocations with the same accessor string */
  44         if (BPF_CORE_READ(&out->a, &in_a->a1) ||        /* accessor: 0:0 */
  45             BPF_CORE_READ(&out->b, &in_b->b1))          /* accessor: 0:0 */
  46                 return 1;
  47 
  48         /* Validate relocations capture array-only accesses for structs with
  49          * fixed header, but with potentially extendable tail. This will read
  50          * first 4 bytes of 2nd element of in_ext array of potentially
  51          * variably sized struct core_reloc_misc_extensible. */ 
  52         if (BPF_CORE_READ(&out->c, &in_ext[2]))         /* accessor: 2 */
  53                 return 1;
  54 
  55         return 0;
  56 }
  57