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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727590421; bh=K1yicp/bGL8F91qvGqt+1UnHa6FWbR1s/iEvXrsN5Rw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=P5UUxHGtQUu638bUVVX5IG9DsMPkLZUmJZiPMaqKExcUqR5Fz4Y78JcuP18aepHLt 7LLcI8R/WB4W2YFQpBlTJzUNyrpPXsRkvobrNE3N58HlwdRe17mwuc64Kqx/z6AVcE LevWQHqsImQz4eBPle2PF4HIarw6LD8IcqARcMT7LiCNVlRAB603QlGTprA3fawx7E ab5ppjgaEz1tMahm4x/F3OcuWaLUrtQodj7qpzUSreLt2YZlbVFm2PtXDMT98EeKB0 Ta3XM3Hx1uQfv3PWmCH0HD5piAxRZpEaMWfCM1+upWppKW8qEqY6SXl2WKQTv6kf3+ ap0ylKZkjX4IA== Date: Sat, 28 Sep 2024 23:13:36 -0700 From: Namhyung Kim To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , LKML , bpf@vger.kernel.org, Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, Arnaldo Carvalho de Melo Subject: Re: [RFC/PATCH bpf-next 3/3] selftests/bpf: Add a test for kmem_cache_iter Message-ID: References: <20240927184133.968283-1-namhyung@kernel.org> <20240927184133.968283-4-namhyung@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240927184133.968283-4-namhyung@kernel.org> X-Rspamd-Queue-Id: B3B22A0004 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 1w73mgmmxwh1sbu17sm1qkc7g5hqd74b X-HE-Tag: 1727590422-355465 X-HE-Meta: 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 wM1PjHEI hmrVumJoGh/h1vn3GXTXGlAzVkfqaa6ED4Pfb5QssPGRBvBfQTzB1XJVx1M25h+K3pQa9QXeiyuYgD8ycXp1sqDKa8AHu8ByQsQEj7xUqmKRgpeLD0MPuLpfjPbUIXVFQ8dxbbeQdMSld/kEc67wbU8xW3diMTsDtQOwdSPKLJrXzh/Do3nzU/c28fZNEUd+bzNMCs+GfeHwUh2ZojUU5BVnyisWGISNRDoDCwdfLVGgN7hBdz7TtbQ1TXCpi7WXJvoGR6it995TYEV6dsj4luLbRu8wEPDTKmBVljZhG5lVAPyFSqlFkgCJ2o6xdwhNUp/wukd0X8BmPUAKmnbrPaJHPWQRQYlUiVl2GQn2qngXfkJbI6GG+726gz7Bu1PVeYcvPeNszxMg3grcG92hQzgXI2sOsm8NyHOEposs2ZzclOdA0ZVVNJIIEiA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Sep 27, 2024 at 11:41:33AM -0700, Namhyung Kim wrote: > The test traverses all slab caches using the kmem_cache_iter and check > if current task's pointer is from "task_struct" slab cache. > > Signed-off-by: Namhyung Kim > --- > .../bpf/prog_tests/kmem_cache_iter.c | 64 ++++++++++++++++++ > tools/testing/selftests/bpf/progs/bpf_iter.h | 7 ++ > .../selftests/bpf/progs/kmem_cache_iter.c | 66 +++++++++++++++++++ > 3 files changed, 137 insertions(+) > create mode 100644 tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c > create mode 100644 tools/testing/selftests/bpf/progs/kmem_cache_iter.c > > diff --git a/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c > new file mode 100644 > index 0000000000000000..814bcc453e9f3ccd > --- /dev/null > +++ b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c > @@ -0,0 +1,64 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2024 Google */ > + > +#include > +#include > +#include > +#include "kmem_cache_iter.skel.h" > + > +static void test_kmem_cache_iter_check_task(struct kmem_cache_iter *skel) > +{ > + LIBBPF_OPTS(bpf_test_run_opts, opts, > + .flags = BPF_F_TEST_RUN_ON_CPU, > + ); > + int prog_fd = bpf_program__fd(skel->progs.check_task_struct); > + > + /* get task_struct and check it if's from a slab cache */ > + bpf_prog_test_run_opts(prog_fd, &opts); > + > + /* the BPF program should set 'found' variable */ > + ASSERT_EQ(skel->bss->found, 1, "found task_struct"); Hmm.. I'm seeing a failure with found being -1, which means ... > +} > + > +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[1024]; > + int iter_fd; > + > + skel = kmem_cache_iter__open_and_load(); > + 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")) > + goto destroy; > + > + iter_fd = bpf_iter_create(bpf_link__fd(link)); > + if (!ASSERT_GE(iter_fd, 0, "iter_create")) > + goto free_link; > + > + memset(buf, 0, sizeof(buf)); > + while (read(iter_fd, buf, sizeof(buf) > 0)) { > + /* read out all contents */ > + printf("%s", buf); > + } > + > + /* next reads should return 0 */ > + ASSERT_EQ(read(iter_fd, buf, sizeof(buf)), 0, "read"); > + > + test_kmem_cache_iter_check_task(skel); > + > + close(iter_fd); > + > +free_link: > + bpf_link__destroy(link); > +destroy: > + kmem_cache_iter__destroy(skel); > +} > diff --git a/tools/testing/selftests/bpf/progs/bpf_iter.h b/tools/testing/selftests/bpf/progs/bpf_iter.h > index c41ee80533ca219a..3305dc3a74b32481 100644 > --- a/tools/testing/selftests/bpf/progs/bpf_iter.h > +++ b/tools/testing/selftests/bpf/progs/bpf_iter.h > @@ -24,6 +24,7 @@ > #define BTF_F_PTR_RAW BTF_F_PTR_RAW___not_used > #define BTF_F_ZERO BTF_F_ZERO___not_used > #define bpf_iter__ksym bpf_iter__ksym___not_used > +#define bpf_iter__kmem_cache bpf_iter__kmem_cache___not_used > #include "vmlinux.h" > #undef bpf_iter_meta > #undef bpf_iter__bpf_map > @@ -48,6 +49,7 @@ > #undef BTF_F_PTR_RAW > #undef BTF_F_ZERO > #undef bpf_iter__ksym > +#undef bpf_iter__kmem_cache > > struct bpf_iter_meta { > struct seq_file *seq; > @@ -165,3 +167,8 @@ struct bpf_iter__ksym { > struct bpf_iter_meta *meta; > struct kallsym_iter *ksym; > }; > + > +struct bpf_iter__kmem_cache { > + struct bpf_iter_meta *meta; > + struct kmem_cache *s; > +} __attribute__((preserve_access_index)); > diff --git a/tools/testing/selftests/bpf/progs/kmem_cache_iter.c b/tools/testing/selftests/bpf/progs/kmem_cache_iter.c > new file mode 100644 > index 0000000000000000..3f6ec15a1bf6344c > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/kmem_cache_iter.c > @@ -0,0 +1,66 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2024 Google */ > + > +#include "bpf_iter.h" > +#include > +#include > + > +char _license[] SEC("license") = "GPL"; > + > +#define SLAB_NAME_MAX 256 > + > +struct { > + __uint(type, BPF_MAP_TYPE_HASH); > + __uint(key_size, sizeof(void *)); > + __uint(value_size, SLAB_NAME_MAX); > + __uint(max_entries, 1024); > +} slab_hash SEC(".maps"); > + > +extern struct kmem_cache *bpf_get_kmem_cache(__u64 addr) __ksym; > + > +/* result, will be checked by userspace */ > +int found; > + > +SEC("iter/kmem_cache") > +int slab_info_collector(struct bpf_iter__kmem_cache *ctx) > +{ > + struct seq_file *seq = ctx->meta->seq; > + struct kmem_cache *s = ctx->s; > + > + if (s) { > + char name[SLAB_NAME_MAX]; > + > + /* > + * To make sure if the slab_iter implements the seq interface > + * properly and it's also useful for debugging. > + */ > + BPF_SEQ_PRINTF(seq, "%s: %u\n", s->name, s->object_size); > + > + bpf_probe_read_kernel_str(name, sizeof(name), s->name); > + bpf_map_update_elem(&slab_hash, &s, name, BPF_NOEXIST); > + } > + > + return 0; > +} > + > +SEC("raw_tp/bpf_test_finish") > +int BPF_PROG(check_task_struct) > +{ > + __u64 curr = bpf_get_current_task(); > + struct kmem_cache *s; > + char *name; > + > + s = bpf_get_kmem_cache(curr); > + if (s == NULL) { > + found = -1; > + return 0; ... it cannot find a kmem_cache for the current task. This program is run by bpf_prog_test_run_opts() with BPF_F_TEST_RUN_ON_CPU. So I think the curr should point a task_struct in a slab cache. Am I missing something? Thanks, Namhyung > + } > + > + name = bpf_map_lookup_elem(&slab_hash, &s); > + if (name && !bpf_strncmp(name, 11, "task_struct")) > + found = 1; > + else > + found = -2; > + > + return 0; > +} > -- > 2.46.1.824.gd892dcdcdd-goog >