Commit e5e4799e authored by Namhyung Kim's avatar Namhyung Kim Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add a test for open coded kmem_cache iter 



The new subtest runs with bpf_prog_test_run_opts() as a syscall prog.
It iterates the kmem_cache using bpf_for_each loop and count the number
of entries.  Finally it checks it with the number of entries from the
regular iterator.

  $ ./vmtest.sh -- ./test_progs -t kmem_cache_iter
  ...
  #130/1   kmem_cache_iter/check_task_struct:OK
  #130/2   kmem_cache_iter/check_slabinfo:OK
  #130/3   kmem_cache_iter/open_coded_iter:OK
  #130     kmem_cache_iter:OK
  Summary: 1/3 PASSED, 0 SKIPPED, 0 FAILED

Also simplify the code by using attach routine of the skeleton.

Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20241030222819.1800667-2-namhyung@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 2e9a5480

tools/testing/selftests/bpf/bpf_experimental.h

+6 −0
Original line number Diff line number Diff line
@@ -582,4 +582,10 @@ extern int bpf_wq_set_callback_impl(struct bpf_wq *wq, 
		unsigned int flags__k, void *aux__ign) __ksym;

#define bpf_wq_set_callback(timer, cb, flags) \

	bpf_wq_set_callback_impl(timer, cb, flags, NULL)



struct bpf_iter_kmem_cache;

extern int bpf_iter_kmem_cache_new(struct bpf_iter_kmem_cache *it) __weak __ksym;

extern struct kmem_cache *bpf_iter_kmem_cache_next(struct bpf_iter_kmem_cache *it) __weak __ksym;

extern void bpf_iter_kmem_cache_destroy(struct bpf_iter_kmem_cache *it) __weak __ksym;



#endif

tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c

+23 −12
Original line number Diff line number Diff line
@@ -68,12 +68,27 @@ static void subtest_kmem_cache_iter_check_slabinfo(struct kmem_cache_iter *skel) 
	fclose(fp);

}



static void subtest_kmem_cache_iter_open_coded(struct kmem_cache_iter *skel)

{

	LIBBPF_OPTS(bpf_test_run_opts, topts);

	int err, fd;



	/* No need to attach it, just run it directly */

	fd = bpf_program__fd(skel->progs.open_coded_iter);



	err = bpf_prog_test_run_opts(fd, &topts);

	if (!ASSERT_OK(err, "test_run_opts err"))

		return;

	if (!ASSERT_OK(topts.retval, "test_run_opts retval"))

		return;



	/* It should be same as we've seen from the explicit iterator */

	ASSERT_EQ(skel->bss->open_coded_seen, skel->bss->kmem_cache_seen, "open_code_seen_eq");

}



void test_kmem_cache_iter(void)

{

	DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts);

	struct kmem_cache_iter *skel = NULL;

	union bpf_iter_link_info linfo = {};

	struct bpf_link *link;

	char buf[256];

	int iter_fd;
@@ -81,16 +96,12 @@ void test_kmem_cache_iter(void) 
	if (!ASSERT_OK_PTR(skel, "kmem_cache_iter__open_and_load"))

		return;



	opts.link_info = &linfo;

	opts.link_info_len = sizeof(linfo);



	link = bpf_program__attach_iter(skel->progs.slab_info_collector, &opts);

	if (!ASSERT_OK_PTR(link, "attach_iter"))

	if (!ASSERT_OK(kmem_cache_iter__attach(skel), "skel_attach"))

		goto destroy;



	iter_fd = bpf_iter_create(bpf_link__fd(link));

	iter_fd = bpf_iter_create(bpf_link__fd(skel->links.slab_info_collector));

	if (!ASSERT_GE(iter_fd, 0, "iter_create"))

		goto free_link;

		goto destroy;



	memset(buf, 0, sizeof(buf));

	while (read(iter_fd, buf, sizeof(buf) > 0)) {
@@ -105,11 +116,11 @@ void test_kmem_cache_iter(void) 
		subtest_kmem_cache_iter_check_task_struct(skel);

	if (test__start_subtest("check_slabinfo"))

		subtest_kmem_cache_iter_check_slabinfo(skel);

	if (test__start_subtest("open_coded_iter"))

		subtest_kmem_cache_iter_open_coded(skel);



	close(iter_fd);



free_link:

	bpf_link__destroy(link);

destroy:

	kmem_cache_iter__destroy(skel);

}

tools/testing/selftests/bpf/progs/kmem_cache_iter.c

+22 −0
Original line number Diff line number Diff line
@@ -3,6 +3,7 @@ 
#include <vmlinux.h>

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>

#include "bpf_experimental.h"



char _license[] SEC("license") = "GPL";
@@ -32,6 +33,7 @@ extern struct kmem_cache *bpf_get_kmem_cache(u64 addr) __ksym; 
/* Result, will be checked by userspace */

int task_struct_found;

int kmem_cache_seen;

int open_coded_seen;



SEC("iter/kmem_cache")

int slab_info_collector(struct bpf_iter__kmem_cache *ctx)
@@ -84,3 +86,23 @@ int BPF_PROG(check_task_struct) 
		task_struct_found = -2;

	return 0;

}



SEC("syscall")

int open_coded_iter(const void *ctx)

{

	struct kmem_cache *s;



	bpf_for_each(kmem_cache, s) {

		struct kmem_cache_result *r;



		r = bpf_map_lookup_elem(&slab_result, &open_coded_seen);

		if (!r)

			break;



		if (r->obj_size != s->size)

			break;



		open_coded_seen++;

	}

	return 0;

}