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selftests/bpf: Add a C test for btf_type_tag

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The following is the main btf_type_tag usage in the
C test:
  #define __tag1 __attribute__((btf_type_tag("tag1")))
  #define __tag2 __attribute__((btf_type_tag("tag2")))
  struct btf_type_tag_test {
       int __tag1 * __tag1 __tag2 *p;
  } g;

The bpftool raw dump with related types:
  [4] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED
  [11] STRUCT 'btf_type_tag_test' size=8 vlen=1
          'p' type_id=14 bits_offset=0
  [12] TYPE_TAG 'tag1' type_id=16
  [13] TYPE_TAG 'tag2' type_id=12
  [14] PTR '(anon)' type_id=13
  [15] TYPE_TAG 'tag1' type_id=4
  [16] PTR '(anon)' type_id=15
  [17] VAR 'g' type_id=11, linkage=global

With format C dump, we have
  struct btf_type_tag_test {
        int __attribute__((btf_type_tag("tag1"))) * __attribute__((btf_type_tag("tag1"))) __attribute__((btf_type_tag("tag2"))) *p;
  };
The result C code is identical to the original definition except macro's are gone.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211112012646.1508231-1-yhs@fb.com
This commit is contained in:
Yonghong Song 2021-11-11 17:26:46 -08:00 committed by Alexei Starovoitov
parent 26c79fcbfa
commit 5698a42a73
2 changed files with 49 additions and 0 deletions
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24
tools/testing/selftests/bpf/prog_tests/btf_tag.c
View File

@ -3,6 +3,12 @@
#include <test_progs.h>
#include "btf_decl_tag.skel.h"
/* struct btf_type_tag_test is referenced in btf_type_tag.skel.h */
struct btf_type_tag_test {
int **p;
};
#include "btf_type_tag.skel.h"
static void test_btf_decl_tag(void)
{
struct btf_decl_tag *skel;
@ -19,8 +25,26 @@ static void test_btf_decl_tag(void)
btf_decl_tag__destroy(skel);
}
static void test_btf_type_tag(void)
{
struct btf_type_tag *skel;
skel = btf_type_tag__open_and_load();
if (!ASSERT_OK_PTR(skel, "btf_type_tag"))
return;
if (skel->rodata->skip_tests) {
printf("%s:SKIP: btf_type_tag attribute not supported", __func__);
test__skip();
}
btf_type_tag__destroy(skel);
}
void test_btf_tag(void)
{
if (test__start_subtest("btf_decl_tag"))
test_btf_decl_tag();
if (test__start_subtest("btf_type_tag"))
test_btf_type_tag();
}

25
tools/testing/selftests/bpf/progs/btf_type_tag.c Normal file
View File

@ -0,0 +1,25 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2021 Facebook */
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#if __has_attribute(btf_type_tag)
#define __tag1 __attribute__((btf_type_tag("tag1")))
#define __tag2 __attribute__((btf_type_tag("tag2")))
volatile const bool skip_tests = false;
#else
#define __tag1
#define __tag2
volatile const bool skip_tests = true;
#endif
struct btf_type_tag_test {
int __tag1 * __tag1 __tag2 *p;
} g;
SEC("fentry/bpf_fentry_test1")
int BPF_PROG(sub, int x)
{
return 0;
}