From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andriin@fb.com>,
Wenbo Zhang <ethercflow@gmail.com>,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
Martin KaFai Lau <kafai@fb.com>, David Miller <davem@redhat.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>,
Brendan Gregg <bgregg@netflix.com>,
Florent Revest <revest@chromium.org>,
Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH v9 bpf-next 13/14] selftests/bpf: Add test for d_path helper
Date: Tue, 4 Aug 2020 23:40:05 -0700 [thread overview]
Message-ID: <CAEf4BzYq5jhTPZRiRzDmi_92qg+0vwobmkyLEqB50mrG_39BeQ@mail.gmail.com> (raw)
In-Reply-To: <20200801170322.75218-14-jolsa@kernel.org>
On Sat, Aug 1, 2020 at 10:05 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> Adding test for d_path helper which is pretty much
> copied from Wenbo Zhang's test for bpf_get_fd_path,
> which never made it in.
>
> The test is doing fstat/close on several fd types,
> and verifies we got the d_path helper working on
> kernel probes for vfs_getattr/filp_close functions.
>
> Original-patch-by: Wenbo Zhang <ethercflow@gmail.com>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
Nothing wrong with this BPF implementation, but seem one suggestion below.
Acked-by: Andrii Nakryiko <andriin@fb.com>
> .../testing/selftests/bpf/prog_tests/d_path.c | 147 ++++++++++++++++++
> .../testing/selftests/bpf/progs/test_d_path.c | 64 ++++++++
> 2 files changed, 211 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/prog_tests/d_path.c
> create mode 100644 tools/testing/selftests/bpf/progs/test_d_path.c
>
[...]
> diff --git a/tools/testing/selftests/bpf/progs/test_d_path.c b/tools/testing/selftests/bpf/progs/test_d_path.c
> new file mode 100644
> index 000000000000..9d342d7a1de6
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_d_path.c
> @@ -0,0 +1,64 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include "vmlinux.h"
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +
> +#define MAX_PATH_LEN 128
> +#define MAX_FILES 7
> +
> +pid_t my_pid = 0;
> +__u32 cnt_stat = 0;
> +__u32 cnt_close = 0;
> +char paths_stat[MAX_FILES][MAX_PATH_LEN] = {};
> +char paths_close[MAX_FILES][MAX_PATH_LEN] = {};
> +int rets_stat[MAX_FILES] = {};
> +int rets_close[MAX_FILES] = {};
> +
> +SEC("fentry/vfs_getattr")
> +int BPF_PROG(prog_stat, struct path *path, struct kstat *stat,
> + __u32 request_mask, unsigned int query_flags)
> +{
> + pid_t pid = bpf_get_current_pid_tgid() >> 32;
> + int ret;
> +
> + if (pid != my_pid)
> + return 0;
> +
> + if (cnt_stat >= MAX_FILES)
> + return 0;
> + ret = bpf_d_path(path, paths_stat[cnt_stat], MAX_PATH_LEN);
> +
> + /* We need to recheck cnt_stat for verifier. */
> + if (cnt_stat >= MAX_FILES)
> + return 0;
> + rets_stat[cnt_stat] = ret;
> +
> + cnt_stat++;
> + return 0;
> +}
> +
> +SEC("fentry/filp_close")
> +int BPF_PROG(prog_close, struct file *file, void *id)
> +{
> + pid_t pid = bpf_get_current_pid_tgid() >> 32;
> + int ret;
> +
> + if (pid != my_pid)
> + return 0;
> +
> + if (cnt_close >= MAX_FILES)
> + return 0;
> + ret = bpf_d_path(&file->f_path,
> + paths_close[cnt_close], MAX_PATH_LEN);
> +
> + /* We need to recheck cnt_stat for verifier. */
you need to do it because you are re-reading a global variable; if you
stored cnt_close in a local variable, then did >= MAX_FILES check
once, you probably could have avoided this duplication. Same for
another instance above.
> + if (cnt_close >= MAX_FILES)
> + return 0;
> + rets_close[cnt_close] = ret;
> +
> + cnt_close++;
> + return 0;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> --
> 2.25.4
>
next prev parent reply other threads:[~2020-08-05 6:40 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-01 17:03 [PATCH v9 bpf-next 00/14] bpf: Add d_path helper Jiri Olsa
2020-08-01 17:03 ` [PATCH v9 bpf-next 01/14] tools resolve_btfids: Add size check to get_id function Jiri Olsa
2020-08-05 6:00 ` Andrii Nakryiko
2020-08-01 17:03 ` [PATCH v9 bpf-next 02/14] tools resolve_btfids: Add support for set symbols Jiri Olsa
2020-08-05 6:04 ` Andrii Nakryiko
2020-08-01 17:03 ` [PATCH v9 bpf-next 03/14] bpf: Move btf_resolve_size into __btf_resolve_size Jiri Olsa
2020-08-01 17:03 ` [PATCH v9 bpf-next 04/14] bpf: Add elem_id pointer as argument to __btf_resolve_size Jiri Olsa
2020-08-01 17:03 ` [PATCH v9 bpf-next 05/14] bpf: Add type_id " Jiri Olsa
2020-08-05 6:05 ` Andrii Nakryiko
2020-08-01 17:03 ` [PATCH v9 bpf-next 06/14] bpf: Remove recursion call in btf_struct_access Jiri Olsa
2020-08-05 6:12 ` Andrii Nakryiko
2020-08-05 17:36 ` Jiri Olsa
2020-08-01 17:03 ` [PATCH v9 bpf-next 07/14] bpf: Factor btf_struct_access function Jiri Olsa
2020-08-05 6:18 ` Andrii Nakryiko
2020-08-01 17:03 ` [PATCH v9 bpf-next 08/14] bpf: Add btf_struct_ids_match function Jiri Olsa
2020-08-05 6:27 ` Andrii Nakryiko
2020-08-05 17:56 ` Jiri Olsa
2020-08-05 21:31 ` Jiri Olsa
2020-08-05 21:57 ` Andrii Nakryiko
2020-08-01 17:03 ` [PATCH v9 bpf-next 09/14] bpf: Add BTF_SET_START/END macros Jiri Olsa
2020-08-05 6:29 ` Andrii Nakryiko
2020-08-01 17:03 ` [PATCH v9 bpf-next 10/14] bpf: Add d_path helper Jiri Olsa
2020-08-02 3:13 ` Alexei Starovoitov
2020-08-02 18:26 ` Jiri Olsa
2020-08-05 6:35 ` Andrii Nakryiko
2020-08-05 17:58 ` Jiri Olsa
2020-08-05 21:01 ` Jiri Olsa
2020-08-05 21:09 ` Andrii Nakryiko
2020-08-07 0:31 ` KP Singh
2020-08-07 8:35 ` Jiri Olsa
2020-08-07 9:42 ` KP Singh
2020-08-01 17:03 ` [PATCH v9 bpf-next 11/14] bpf: Update .BTF_ids section in btf.rst with sets info Jiri Olsa
2020-08-01 17:03 ` [PATCH v9 bpf-next 12/14] selftests/bpf: Add verifier test for d_path helper Jiri Olsa
2020-08-01 17:03 ` [PATCH v9 bpf-next 13/14] selftests/bpf: Add " Jiri Olsa
2020-08-05 6:40 ` Andrii Nakryiko [this message]
2020-08-05 18:00 ` Jiri Olsa
2020-08-01 17:03 ` [PATCH v9 bpf-next 14/14] selftests/bpf: Add set test to resolve_btfids Jiri Olsa
2020-08-05 6:41 ` Andrii Nakryiko
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