From: Jiri Olsa <jolsa@redhat.com>
To: KP Singh <kpsingh@chromium.org>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>,
Jiri Olsa <jolsa@kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
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>,
Wenbo Zhang <ethercflow@gmail.com>,
Andrii Nakryiko <andriin@fb.com>,
Brendan Gregg <bgregg@netflix.com>,
Florent Revest <revest@chromium.org>,
Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH v4 bpf-next 10/14] bpf: Add d_path helper
Date: Fri, 17 Jul 2020 10:28:35 +0200 [thread overview]
Message-ID: <20200717082835.GB522549@krava> (raw)
In-Reply-To: <6f3fd6b0-cc3d-57e7-0444-dcaf399e6abd@chromium.org>
On Fri, Jul 17, 2020 at 01:13:23AM +0200, KP Singh wrote:
>
>
> On 6/28/20 9:42 PM, Jiri Olsa wrote:
> > On Fri, Jun 26, 2020 at 01:38:27PM -0700, Andrii Nakryiko wrote:
> >> On Thu, Jun 25, 2020 at 4:49 PM Jiri Olsa <jolsa@kernel.org> wrote:
> >>>
> >>> Adding d_path helper function that returns full path
> >>> for give 'struct path' object, which needs to be the
> >>> kernel BTF 'path' object.
> >>>
> >>> The helper calls directly d_path function.
> >>>
> >>> Updating also bpf.h tools uapi header and adding
> >>> 'path' to bpf_helpers_doc.py script.
> >>>
> >>> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> >>> ---
> >>> include/uapi/linux/bpf.h | 14 +++++++++-
> >>> kernel/trace/bpf_trace.c | 47 ++++++++++++++++++++++++++++++++++
> >>> scripts/bpf_helpers_doc.py | 2 ++
> >>> tools/include/uapi/linux/bpf.h | 14 +++++++++-
> >>> 4 files changed, 75 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> >>> index 0cb8ec948816..23274c81f244 100644
> >>> --- a/include/uapi/linux/bpf.h
> >>> +++ b/include/uapi/linux/bpf.h
> >>> @@ -3285,6 +3285,17 @@ union bpf_attr {
> >>> * Dynamically cast a *sk* pointer to a *udp6_sock* pointer.
> >>> * Return
> >>> * *sk* if casting is valid, or NULL otherwise.
> >>> + *
> >>> + * int bpf_d_path(struct path *path, char *buf, u32 sz)
> >>> + * Description
> >>> + * Return full path for given 'struct path' object, which
> >>> + * needs to be the kernel BTF 'path' object. The path is
> >>> + * returned in buffer provided 'buf' of size 'sz'.
> >>> + *
> >>> + * Return
> >>> + * length of returned string on success, or a negative
> >>> + * error in case of failure
> >>
> >> It's important to note whether string is always zero-terminated (I'm
> >> guessing it is, right?).
> >
> > right, will add
>
> Also note that bpf_probe_read_{kernel, user}_str return the length including
> the NUL byte:
>
> * Return
> * On success, the strictly positive length of the string,
> * including the trailing NUL character. On error, a negative
> * value.
>
> It would be good to keep this uniform. So you will need a len += 1 here as well.
good point, will keep it that way
thanks,
jirka
next prev parent reply other threads:[~2020-07-17 8:28 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-25 22:12 [PATCH v4 bpf-next 00/14] bpf: Add d_path helper Jiri Olsa
2020-06-25 22:12 ` [PATCH v4 bpf-next 01/14] bpf: Add resolve_btfids tool to resolve BTF IDs in ELF object Jiri Olsa
2020-06-26 20:53 ` Andrii Nakryiko
2020-06-26 21:09 ` Yonghong Song
2020-06-28 19:09 ` Alexei Starovoitov
2020-06-28 19:35 ` Jiri Olsa
2020-06-28 20:53 ` Yonghong Song
2020-06-25 22:12 ` [PATCH v4 bpf-next 02/14] bpf: Compile resolve_btfids tool at kernel compilation start Jiri Olsa
2020-06-26 21:28 ` Andrii Nakryiko
2020-06-28 19:48 ` Jiri Olsa
2020-06-25 22:12 ` [PATCH v4 bpf-next 03/14] bpf: Add BTF_ID_LIST/BTF_ID macros Jiri Olsa
2020-06-26 21:32 ` Andrii Nakryiko
2020-06-28 19:50 ` Jiri Olsa
2020-06-25 22:12 ` [PATCH v4 bpf-next 04/14] bpf: Resolve BTF IDs in vmlinux image Jiri Olsa
2020-06-26 21:34 ` Andrii Nakryiko
2020-06-25 22:12 ` [PATCH v4 bpf-next 05/14] bpf: Remove btf_id helpers resolving Jiri Olsa
2020-06-26 21:36 ` Yonghong Song
2020-06-26 21:40 ` Andrii Nakryiko
2020-06-26 23:29 ` Yonghong Song
2020-06-28 18:50 ` Alexei Starovoitov
2020-06-28 20:00 ` Andrii Nakryiko
2020-06-28 20:16 ` Jiri Olsa
2020-06-28 20:59 ` Yonghong Song
2020-06-28 21:20 ` Jiri Olsa
2020-06-25 22:12 ` [PATCH v4 bpf-next 06/14] bpf: Use BTF_ID to resolve bpf_ctx_convert struct Jiri Olsa
2020-06-26 21:44 ` Andrii Nakryiko
2020-06-26 21:44 ` Yonghong Song
2020-06-28 19:52 ` Jiri Olsa
2020-06-25 22:12 ` [PATCH v4 bpf-next 07/14] bpf: Allow nested BTF object to be refferenced by BTF object + offset Jiri Olsa
2020-06-30 1:52 ` Andrii Nakryiko
2020-06-30 13:54 ` Jiri Olsa
2020-06-30 20:05 ` Andrii Nakryiko
2020-06-30 20:07 ` Andrii Nakryiko
2020-07-02 10:08 ` Jiri Olsa
2020-07-06 23:15 ` Andrii Nakryiko
2020-06-25 22:12 ` [PATCH v4 bpf-next 08/14] bpf: Add BTF_SET_START/END macros Jiri Olsa
2020-06-26 21:49 ` Andrii Nakryiko
2020-06-25 22:12 ` [PATCH v4 bpf-next 09/14] bpf: Add info about .BTF.ids section to btf.rst Jiri Olsa
2020-06-25 22:13 ` [PATCH v4 bpf-next 10/14] bpf: Add d_path helper Jiri Olsa
2020-06-26 20:38 ` Andrii Nakryiko
2020-06-28 19:42 ` Jiri Olsa
2020-07-16 23:13 ` KP Singh
2020-07-17 8:28 ` Jiri Olsa [this message]
2020-06-25 22:13 ` [PATCH v4 bpf-next 11/14] tools headers: Adopt verbatim copy of btf_ids.h from kernel sources Jiri Olsa
2020-06-26 21:51 ` Andrii Nakryiko
2020-06-25 22:13 ` [PATCH v4 bpf-next 12/14] selftests/bpf: Add verifier test for d_path helper Jiri Olsa
2020-06-30 1:30 ` Andrii Nakryiko
2020-06-25 22:13 ` [PATCH v4 bpf-next 13/14] selftests/bpf: Add " Jiri Olsa
2020-06-26 21:55 ` Andrii Nakryiko
2020-06-28 19:55 ` Jiri Olsa
2020-06-25 22:13 ` [PATCH v4 bpf-next 14/14] selftests/bpf: Add test for resolve_btfids Jiri Olsa
2020-06-30 1:43 ` Andrii Nakryiko
2020-06-30 14:27 ` Jiri Olsa
2020-06-30 18:13 ` Andrii Nakryiko
2020-06-30 1:54 ` [PATCH v4 bpf-next 00/14] bpf: Add d_path helper Andrii Nakryiko
2020-06-30 13:55 ` Jiri Olsa
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