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Message-ID: <20241024074815.1255066-2-namhyung@kernel.org>
Date: Thu, 24 Oct 2024 00:48:15 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>
Cc: Martin KaFai Lau <martin.lau@...ux.dev>,
Eduard Zingerman <eddyz87@...il.com>,
Song Liu <song@...nel.org>,
Yonghong Song <yonghong.song@...ux.dev>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...nel.org>,
Stanislav Fomichev <sdf@...ichev.me>,
Hao Luo <haoluo@...gle.com>,
Jiri Olsa <jolsa@...nel.org>,
LKML <linux-kernel@...r.kernel.org>,
bpf@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
Christoph Lameter <cl@...ux.com>,
Pekka Enberg <penberg@...nel.org>,
David Rientjes <rientjes@...gle.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Vlastimil Babka <vbabka@...e.cz>,
Roman Gushchin <roman.gushchin@...ux.dev>,
Hyeonggon Yoo <42.hyeyoo@...il.com>,
linux-mm@...ck.org,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Kees Cook <kees@...nel.org>
Subject: [PATCH v2 bpf-next 2/2] selftests/bpf: Add a test for open coded kmem_cache iter
The new subtest is attached to sleepable fentry of syncfs() syscall.
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: Namhyung Kim <namhyung@...nel.org>
---
v2)
* remove unnecessary detach (Martin)
* check pid in syncfs to prevent surprise (Martin)
* remove unnecessary local variable (Andrii)
.../testing/selftests/bpf/bpf_experimental.h | 6 ++++
.../bpf/prog_tests/kmem_cache_iter.c | 28 +++++++++++--------
.../selftests/bpf/progs/kmem_cache_iter.c | 28 +++++++++++++++++++
3 files changed, 50 insertions(+), 12 deletions(-)
diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
index b0668f29f7b394eb..cd8ecd39c3f3c68d 100644
--- a/tools/testing/selftests/bpf/bpf_experimental.h
+++ b/tools/testing/selftests/bpf/bpf_experimental.h
@@ -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
diff --git a/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c
index 848d8fc9171fae45..778b55bc1f912b98 100644
--- a/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c
+++ b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c
@@ -68,12 +68,20 @@ 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)
+{
+ skel->bss->tgid = getpid();
+
+ /* To trigger the open coded iterator attached to the syscall */
+ syncfs(0);
+
+ /* 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 +89,12 @@ 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 +109,11 @@ 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);
}
diff --git a/tools/testing/selftests/bpf/progs/kmem_cache_iter.c b/tools/testing/selftests/bpf/progs/kmem_cache_iter.c
index 72c9dafecd98406b..e62807caa7593604 100644
--- a/tools/testing/selftests/bpf/progs/kmem_cache_iter.c
+++ b/tools/testing/selftests/bpf/progs/kmem_cache_iter.c
@@ -2,6 +2,8 @@
/* Copyright (c) 2024 Google */
#include "bpf_iter.h"
+#include "bpf_experimental.h"
+#include "bpf_misc.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
@@ -30,9 +32,12 @@ struct {
extern struct kmem_cache *bpf_get_kmem_cache(u64 addr) __ksym;
+unsigned int tgid;
+
/* 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)
@@ -85,3 +90,26 @@ int BPF_PROG(check_task_struct)
task_struct_found = -2;
return 0;
}
+
+SEC("fentry.s/" SYS_PREFIX "sys_syncfs")
+int open_coded_iter(const void *ctx)
+{
+ struct kmem_cache *s;
+
+ if (tgid != bpf_get_current_pid_tgid() >> 32)
+ return 0;
+
+ bpf_for_each(kmem_cache, s) {
+ struct kmem_cache_result *r;
+
+ r = bpf_map_lookup_elem(&slab_result, &open_coded_seen);
+ if (!r)
+ break;
+
+ open_coded_seen++;
+
+ if (r->obj_size != s->size)
+ break;
+ }
+ return 0;
+}
--
2.47.0.105.g07ac214952-goog
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