On Mon, May 5, 2025 at 11:39 AM Lorenz Bauer lmb@isovalent.com wrote:
Add a basic test for the ability to mmap /sys/kernel/btf/vmlinux. Since libbpf doesn't have an API to parse BTF from memory we do some basic sanity checks ourselves.
Signed-off-by: Lorenz Bauer lmb@isovalent.com
tools/testing/selftests/bpf/prog_tests/btf_sysfs.c | 83 ++++++++++++++++++++++ 1 file changed, 83 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/btf_sysfs.c b/tools/testing/selftests/bpf/prog_tests/btf_sysfs.c new file mode 100644 index 0000000000000000000000000000000000000000..3319cf758897d46cefa8ca25e16acb162f4e9889 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/btf_sysfs.c @@ -0,0 +1,83 @@ +// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause +/* Copyright (c) 2025 Isovalent */
+#include <test_progs.h> +#include <bpf/btf.h> +#include <sys/stat.h> +#include <sys/mman.h> +#include <fcntl.h> +#include <unistd.h>
+static void test_btf_mmap_sysfs(const char *path, struct btf *base) +{
struct stat st;__u64 btf_size, end;void *raw_data = NULL;int fd = -1;long page_size;struct btf *btf = NULL;page_size = sysconf(_SC_PAGESIZE);if (!ASSERT_GE(page_size, 0, "get_page_size"))goto cleanup;if (!ASSERT_OK(stat(path, &st), "stat_btf"))goto cleanup;btf_size = st.st_size;end = (btf_size + page_size - 1) / page_size * page_size;fd = open(path, O_RDONLY);if (!ASSERT_GE(fd, 0, "open_btf"))goto cleanup;raw_data = mmap(NULL, btf_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);if (!ASSERT_EQ(raw_data, MAP_FAILED, "mmap_btf_writable"))goto cleanup;raw_data = mmap(NULL, btf_size, PROT_READ, MAP_SHARED, fd, 0);if (!ASSERT_EQ(raw_data, MAP_FAILED, "mmap_btf_shared"))goto cleanup;raw_data = mmap(NULL, end + 1, PROT_READ, MAP_PRIVATE, fd, 0);if (!ASSERT_EQ(raw_data, MAP_FAILED, "mmap_btf_invalid_size"))goto cleanup;raw_data = mmap(NULL, end, PROT_READ, MAP_PRIVATE, fd, 0);if (!ASSERT_NEQ(raw_data, MAP_FAILED, "mmap_btf"))
ASSERT_OK_PTR()?
goto cleanup;if (!ASSERT_EQ(mprotect(raw_data, btf_size, PROT_READ | PROT_WRITE), -1,"mprotect_writable"))goto cleanup;if (!ASSERT_EQ(mprotect(raw_data, btf_size, PROT_READ | PROT_EXEC), -1,"mprotect_executable"))goto cleanup;/* Check padding is zeroed */for (int i = btf_size; i < end; i++) {if (((__u8 *)raw_data)[i] != 0) {PRINT_FAIL("tail of BTF is not zero at page offset %d\n", i);goto cleanup;}}btf = btf__new_split(raw_data, btf_size, base);if (!ASSERT_NEQ(btf, NULL, "parse_btf"))
ASSERT_OK_PTR()
goto cleanup;+cleanup:
if (raw_data && raw_data != MAP_FAILED)munmap(raw_data, btf_size);if (btf)
no need to check this, all libbpf destructor APIs deal with NULL correctly (ignoring them)
btf__free(btf);if (fd >= 0)close(fd);+}
+void test_btf_sysfs(void) +{
if (test__start_subtest("vmlinux"))test_btf_mmap_sysfs("/sys/kernel/btf/vmlinux", NULL);
Do you intend to add more subtests? if not, why even using a subtest structure
+}
-- 2.49.0