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Tue, 07 Mar 2023 17:32:29 -0800 (PST) MIME-Version: 1.0 References: <20230228093206.821563-1-jolsa@kernel.org> <20230228093206.821563-10-jolsa@kernel.org> In-Reply-To: <20230228093206.821563-10-jolsa@kernel.org> From: Andrii Nakryiko Date: Tue, 7 Mar 2023 17:32:17 -0800 Message-ID: Subject: Re: [PATCH RFC v2 bpf-next 9/9] selftests/bpf: Add iter_task_vma_buildid test To: Jiri Olsa Cc: Alexei Starovoitov , Andrii Nakryiko , Hao Luo , Andrew Morton , Alexander Viro , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Matthew Wilcox , bpf@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-perf-users@vger.kernel.org, Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Daniel Borkmann , Namhyung Kim Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 3BE211A000B X-Stat-Signature: xd95xd6d7kut8gm7qa8rkzpmbz595t4q X-Rspam-User: X-HE-Tag: 1678239150-93416 X-HE-Meta: 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 jQTqPIU8 VN96KBeo1RAkdACLP+WvOcKzQjVtlQBLqSuK32h0qgB53R3eIXRdLsKnzxbGctN0FQSEPA2aHnbyB5l36le73fOkHVAilavP31lKj8Ri+FGURSfncKh/Io2rV3J7GYNamWFaX+fR7XPqigDNnoRQLNX7pJ16ipS3ZGyKM8iQNUdCutd8MW4sPjAo5J0ZVWXErhyUdL1xf2S/yuB2nuuE9aIbRbB+DboJoIJPw0K+7N4gG8hhZva4GpsghHiMRU3KL6Mk3DXmcKHTg39rf7baRpqdvlk3wPgLSkInyu1Gm3opGEfuB4ht6KJv4LeSsKPrklLZOX7RrJ4Mkg8M5I5JLL8F7QAHEWGHGKCnQM+jBaEDKXjTxrlJnr/cF7CQ18sYdwv8tLwesczFY0YLTRZuiFkajF9sRQhxuv89xqBva+mmK5xAFbKYNFHw6Gpu9v7gdG2RmGyoNJXqNzeCFAyIcUn0KD7Muocptgwn0WYY1RHcivvRWnLcfwALglKqopkiC/Aw6Hr9Jc6BUWubsvHCgPbEUkwa0ZYmsGUebK7RPg8roiGnPkJzHVDtze1TOJGfn+LRLvyw7VLWiQdA= 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: On Tue, Feb 28, 2023 at 1:34=E2=80=AFAM Jiri Olsa wrote: > > Testing iterator access to build id in vma->vm_file->f_inode > object by storing each binary with buildid into map and checking > it against buildid retrieved in user space. > > Signed-off-by: Jiri Olsa > --- > .../selftests/bpf/prog_tests/bpf_iter.c | 78 +++++++++++++++++++ > .../bpf/progs/bpf_iter_task_vma_buildid.c | 60 ++++++++++++++ > 2 files changed, 138 insertions(+) > create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_task_vma_b= uildid.c > > diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/te= sting/selftests/bpf/prog_tests/bpf_iter.c > index 1f02168103dd..c7dd89e7cad0 100644 > --- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c > +++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c > @@ -33,6 +33,7 @@ > #include "bpf_iter_bpf_link.skel.h" > #include "bpf_iter_ksym.skel.h" > #include "bpf_iter_sockmap.skel.h" > +#include "bpf_iter_task_vma_buildid.skel.h" > > static int duration; > > @@ -1536,6 +1537,81 @@ static void test_task_vma_dead_task(void) > bpf_iter_task_vma__destroy(skel); > } > > +#define D_PATH_BUF_SIZE 1024 > + > +struct build_id { > + u32 sz; > + char data[BPF_BUILD_ID_SIZE]; > +}; > + > +static void test_task_vma_buildid(void) > +{ > + int err, iter_fd =3D -1, proc_maps_fd =3D -1, sz; > + struct bpf_iter_task_vma_buildid *skel; > + char key[D_PATH_BUF_SIZE], *prev_key; > + char build_id[BPF_BUILD_ID_SIZE]; > + int len, files_fd, cnt =3D 0; > + struct build_id val; > + char c; > + > + skel =3D bpf_iter_task_vma_buildid__open_and_load(); > + if (!ASSERT_OK_PTR(skel, "bpf_iter_task_vma_buildid__open_and_loa= d")) > + return; > + > + skel->links.proc_maps =3D bpf_program__attach_iter( > + skel->progs.proc_maps, NULL); > + > + if (!ASSERT_OK_PTR(skel->links.proc_maps, "bpf_program__attach_it= er")) { > + skel->links.proc_maps =3D NULL; > + goto out; > + } > + > + iter_fd =3D bpf_iter_create(bpf_link__fd(skel->links.proc_maps)); > + if (!ASSERT_GE(iter_fd, 0, "create_iter")) > + goto out; > + > + /* trigger the iterator, there's no output, just map */ > + len =3D read(iter_fd, &c, 1); > + ASSERT_EQ(len, 0, "len_check"); > + > + files_fd =3D bpf_map__fd(skel->maps.files); > + > + prev_key =3D NULL; > + > + while (true) { > + err =3D bpf_map_get_next_key(files_fd, prev_key, &key); > + if (err) { > + if (errno =3D=3D ENOENT) > + err =3D 0; > + break; > + } > + if (bpf_map_lookup_elem(files_fd, key, &val)) > + break; > + if (!ASSERT_LE(val.sz, BPF_BUILD_ID_SIZE, "buildid_size")= ) > + break; > + > + sz =3D read_build_id(key, build_id); > + /* If there's an error, the build id is not present or ma= lformed, kernel > + * should see the same result and bpf program pushed zero= build id. > + */ > + if (sz < 0) { > + memset(build_id, 0x0, BPF_BUILD_ID_SIZE); > + sz =3D BPF_BUILD_ID_SIZE; > + } > + ASSERT_EQ(val.sz, sz, "build_id_size"); > + ASSERT_MEMEQ(val.data, build_id, sz, "build_id_data"); > + > + prev_key =3D key; > + cnt++; > + } > + > + printf("checked %d files\n", cnt); > +out: > + close(proc_maps_fd); > + close(iter_fd); > + bpf_iter_task_vma_buildid__destroy(skel); > +} > + > void test_bpf_sockmap_map_iter_fd(void) > { > struct bpf_iter_sockmap *skel; > @@ -1659,6 +1735,8 @@ void test_bpf_iter(void) > test_task_vma(); > if (test__start_subtest("task_vma_dead_task")) > test_task_vma_dead_task(); > + if (test__start_subtest("task_vma_buildid")) > + test_task_vma_buildid(); > if (test__start_subtest("task_btf")) > test_task_btf(); > if (test__start_subtest("tcp4")) > diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.= c b/tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.c > new file mode 100644 > index 000000000000..dc528a4783ec > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.c > @@ -0,0 +1,60 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +#include "bpf_iter.h" > +#include "err.h" > +#include > +#include > + > +char _license[] SEC("license") =3D "GPL"; > + > +#define VM_EXEC 0x00000004 > +#define D_PATH_BUF_SIZE 1024 > + > +struct { > + __uint(type, BPF_MAP_TYPE_HASH); > + __uint(max_entries, 10000); > + __type(key, char[D_PATH_BUF_SIZE]); > + __type(value, struct build_id); > +} files SEC(".maps"); > + > +static char path[D_PATH_BUF_SIZE]; > +static struct build_id build_id; > + > +SEC("iter/task_vma") > +int proc_maps(struct bpf_iter__task_vma *ctx) > +{ > + struct vm_area_struct *vma =3D ctx->vma; > + struct seq_file *seq =3D ctx->meta->seq; > + struct task_struct *task =3D ctx->task; > + unsigned long file_key; > + struct inode *inode; > + struct file *file; > + > + if (task =3D=3D (void *)0 || vma =3D=3D (void *)0) > + return 0; > + > + if (!(vma->vm_flags & VM_EXEC)) > + return 0; > + > + file =3D vma->vm_file; > + if (!file) > + return 0; > + > + __builtin_memset(path, 0x0, D_PATH_BUF_SIZE); > + bpf_d_path(&file->f_path, (char *) &path, D_PATH_BUF_SIZE); > + > + if (bpf_map_lookup_elem(&files, &path)) > + return 0; > + > + inode =3D file->f_inode; > + if (IS_ERR_OR_NULL(inode->i_build_id)) { > + /* On error return empty build id. */ > + __builtin_memset(&build_id.data, 0x0, sizeof(build_id.dat= a)); > + build_id.sz =3D 20; let's replace `#define BUILD_ID_SIZE_MAX 20` in include/linux/buildid.h with `enum { BUILD_ID_SIZE_MAX =3D 20 };`. This will "expose" this constant into BTF and thus vmlinux.h, so we won't have to hard-code anything. BPF users would be grateful as well. No downsides of doing this. > + } else { > + __builtin_memcpy(&build_id, inode->i_build_id, sizeof(*in= ode->i_build_id)); > + } > + > + bpf_map_update_elem(&files, &path, &build_id, 0); > + return 0; > +} > -- > 2.39.2 >