test_core_reloc_misc.c

 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/bpf_helpers.h>
 7#include <bpf/bpf_core_read.h>
 8
 9char _license[] SEC("license") = "GPL";
10
11struct {
12	char in[256];
13	char out[256];
14} data = {};
15
16struct core_reloc_misc_output {
17	int a, b, c;
18};
19
20struct core_reloc_misc___a {
21	int a1;
22	int a2;
23};
24
25struct core_reloc_misc___b {
26	int b1;
27	int b2;
28};
29
30/* fixed two first members, can be extended with new fields */
31struct core_reloc_misc_extensible {
32	int a;
33	int b;
34};
35
36#define CORE_READ(dst, src) bpf_core_read(dst, sizeof(*(dst)), src)
37
38SEC("raw_tracepoint/sys_enter")
39int test_core_misc(void *ctx)
40{
41	struct core_reloc_misc___a *in_a = (void *)&data.in;
42	struct core_reloc_misc___b *in_b = (void *)&data.in;
43	struct core_reloc_misc_extensible *in_ext = (void *)&data.in;
44	struct core_reloc_misc_output *out = (void *)&data.out;
45
46	/* record two different relocations with the same accessor string */
47	if (CORE_READ(&out->a, &in_a->a1) ||		/* accessor: 0:0 */
48	    CORE_READ(&out->b, &in_b->b1))		/* accessor: 0:0 */
49		return 1;
50
51	/* Validate relocations capture array-only accesses for structs with
52	 * fixed header, but with potentially extendable tail. This will read
53	 * first 4 bytes of 2nd element of in_ext array of potentially
54	 * variably sized struct core_reloc_misc_extensible. */ 
55	if (CORE_READ(&out->c, &in_ext[2]))		/* accessor: 2 */
56		return 1;
57
58	return 0;
59}
60