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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2026, Oracle and/or its affiliates. */
#include <test_progs.h>
#include <bpf/btf.h>
#include <bpf/libbpf.h>
/* Verify kind encoding exists for each kind */
static void test_btf_kind_encoding(void)
{
LIBBPF_OPTS(btf_new_opts, opts);
const struct btf_header *hdr;
const void *raw_btf;
struct btf *btf;
__u32 raw_size;
opts.add_layout = true;
btf = btf__new_empty_opts(&opts);
if (!ASSERT_OK_PTR(btf, "btf_new"))
return;
raw_btf = btf__raw_data(btf, &raw_size);
if (!ASSERT_OK_PTR(raw_btf, "btf__raw_data"))
return;
hdr = raw_btf;
ASSERT_EQ(hdr->layout_off % 4, 0, "layout_aligned");
ASSERT_EQ(hdr->layout_len, sizeof(struct btf_layout) * NR_BTF_KINDS,
"layout_len");
ASSERT_EQ(hdr->str_off, hdr->layout_off + hdr->layout_len, "str_after_layout");
btf__free(btf);
opts.add_layout = false;
btf = btf__new_empty_opts(&opts);
if (!ASSERT_OK_PTR(btf, "btf_new"))
return;
raw_btf = btf__raw_data(btf, &raw_size);
if (!ASSERT_OK_PTR(raw_btf, "btf__raw_data"))
return;
hdr = raw_btf;
ASSERT_EQ(hdr->layout_off, 0, "no_layout_off");
ASSERT_EQ(hdr->layout_len, 0, "no_layout_len");
ASSERT_EQ(hdr->str_off, hdr->type_off + hdr->type_len, "strs_after_types");
btf__free(btf);
}
static int write_raw_btf(void *raw_btf, size_t raw_size, char *file)
{
int fd = mkstemp(file);
ssize_t n;
if (!ASSERT_OK_FD(fd, "open_raw_btf"))
return -1;
n = write(fd, raw_btf, raw_size);
close(fd);
if (!ASSERT_EQ(n, (ssize_t)raw_size, "write_raw_btf"))
return -1;
return 0;
}
/*
* Fabricate an unrecognized kind at BTF_KIND_MAX + 1, and after adding
* the appropriate struct/typedefs to the BTF such that it recognizes
* this kind, ensure that parsing of BTF containing the unrecognized kind
* can succeed.
*/
void test_btf_kind_decoding(void)
{
char btf_kind_file1[] = "/tmp/test_btf_kind.XXXXXX";
char btf_kind_file2[] = "/tmp/test_btf_kind.XXXXXX";
char btf_kind_file3[] = "/tmp/test_btf_kind.XXXXXX";
struct btf *btf = NULL, *new_btf = NULL;
__s32 int_id, unrec_id, id, id2;
LIBBPF_OPTS(btf_new_opts, opts);
struct btf_layout *l;
struct btf_header *hdr;
const void *raw_btf;
struct btf_type *t;
void *new_raw_btf;
void *str_data;
__u32 raw_size;
opts.add_layout = true;
btf = btf__new_empty_opts(&opts);
if (!ASSERT_OK_PTR(btf, "btf_new"))
return;
int_id = btf__add_int(btf, "test_char", 1, BTF_INT_CHAR);
if (!ASSERT_GT(int_id, 0, "add_int_id"))
return;
/*
* Create our type with unrecognized kind by adding a typedef kind
* we will overwrite it with our unrecognized kind value.
*/
unrec_id = btf__add_typedef(btf, "unrec_kind", int_id);
if (!ASSERT_GT(unrec_id, 0, "add_unrec_id"))
return;
/*
* Add an id after it that we will look up to verify we can parse
* beyond unrecognized kinds.
*/
id = btf__add_typedef(btf, "test_lookup", int_id);
if (!ASSERT_GT(id, 0, "add_test_lookup_id"))
return;
id2 = btf__add_typedef(btf, "test_lookup2", int_id);
if (!ASSERT_GT(id2, 0, "add_test_lookup_id2"))
return;
raw_btf = (void *)btf__raw_data(btf, &raw_size);
if (!ASSERT_OK_PTR(raw_btf, "btf__raw_data"))
return;
new_raw_btf = calloc(1, raw_size + sizeof(*l));
if (!ASSERT_OK_PTR(new_raw_btf, "calloc_raw_btf"))
return;
memcpy(new_raw_btf, raw_btf, raw_size);
hdr = new_raw_btf;
/* Move strings to make space for one new layout description */
raw_size += sizeof(*l);
str_data = new_raw_btf + hdr->hdr_len + hdr->str_off;
memmove(str_data + sizeof(*l), str_data, hdr->str_len);
hdr->str_off += sizeof(*l);
/* Add new layout description */
hdr->layout_len += sizeof(*l);
l = new_raw_btf + hdr->hdr_len + hdr->layout_off;
l[NR_BTF_KINDS].info_sz = 0;
l[NR_BTF_KINDS].elem_sz = 0;
l[NR_BTF_KINDS].flags = 0;
/* Now modify typedef added above to be an unrecognized kind. */
t = (void *)hdr + hdr->hdr_len + hdr->type_off + sizeof(struct btf_type) +
sizeof(__u32);
t->info = (NR_BTF_KINDS << 24);
/* Write BTF to a raw file, ready for parsing. */
if (write_raw_btf(new_raw_btf, raw_size, btf_kind_file1))
goto out;
/*
* Verify parsing succeeds, and that we can read type info past
* the unrecognized kind.
*/
new_btf = btf__parse_raw(btf_kind_file1);
if (ASSERT_OK_PTR(new_btf, "btf__parse_raw")) {
ASSERT_EQ(btf__find_by_name(new_btf, "unrec_kind"), unrec_id,
"unrec_kind_found");
ASSERT_EQ(btf__find_by_name_kind(new_btf, "test_lookup",
BTF_KIND_TYPEDEF), id,
"verify_id_lookup");
ASSERT_EQ(btf__find_by_name_kind(new_btf, "test_lookup2",
BTF_KIND_TYPEDEF), id2,
"verify_id2_lookup");
}
btf__free(new_btf);
new_btf = NULL;
/*
* Next, change info_sz to equal sizeof(struct btf_type); this means the
* "test_lookup" kind will be reinterpreted as a singular info element
* following the unrecognized kind.
*/
l[NR_BTF_KINDS].info_sz = sizeof(struct btf_type);
if (write_raw_btf(new_raw_btf, raw_size, btf_kind_file2))
goto out;
new_btf = btf__parse_raw(btf_kind_file2);
if (ASSERT_OK_PTR(new_btf, "btf__parse_raw")) {
ASSERT_EQ(btf__find_by_name_kind(new_btf, "test_lookup",
BTF_KIND_TYPEDEF), -ENOENT,
"verify_id_not_found");
/* id of "test_lookup2" will be id2 -1 as we have removed one type */
ASSERT_EQ(btf__find_by_name_kind(new_btf, "test_lookup2",
BTF_KIND_TYPEDEF), id2 - 1,
"verify_id_lookup2");
}
btf__free(new_btf);
new_btf = NULL;
/*
* Change elem_sz to equal sizeof(struct btf_type) and set vlen
* associated with unrecognized type to 1; this allows us to verify
* vlen-specified BTF can still be parsed.
*/
l[NR_BTF_KINDS].info_sz = 0;
l[NR_BTF_KINDS].elem_sz = sizeof(struct btf_type);
t->info |= 1;
if (write_raw_btf(new_raw_btf, raw_size, btf_kind_file3))
goto out;
new_btf = btf__parse_raw(btf_kind_file3);
if (ASSERT_OK_PTR(new_btf, "btf__parse_raw")) {
ASSERT_EQ(btf__find_by_name_kind(new_btf, "test_lookup",
BTF_KIND_TYPEDEF), -ENOENT,
"verify_id_not_found");
/* id of "test_lookup2" will be id2 -1 as we have removed one type */
ASSERT_EQ(btf__find_by_name_kind(new_btf, "test_lookup2",
BTF_KIND_TYPEDEF), id2 - 1,
"verify_id_lookup2");
}
out:
btf__free(new_btf);
free(new_raw_btf);
unlink(btf_kind_file1);
unlink(btf_kind_file2);
unlink(btf_kind_file3);
btf__free(btf);
}
void test_btf_kind(void)
{
if (test__start_subtest("btf_kind_encoding"))
test_btf_kind_encoding();
if (test__start_subtest("btf_kind_decoding"))
test_btf_kind_decoding();
}
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