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>,
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>,
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 10/14] bpf: Add d_path helper
Date: Tue, 4 Aug 2020 23:35:53 -0700 [thread overview]
Message-ID: <CAEf4BzY5b8GhoovkKZgT4YSUUW=GPZBU0Qjg4eqeHNjoPHCMTw@mail.gmail.com> (raw)
In-Reply-To: <20200801170322.75218-11-jolsa@kernel.org>
On Sat, Aug 1, 2020 at 10:04 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> Adding d_path helper function that returns 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' and is zero terminated.
>
> bpf_d_path(&file->f_path, buf, size);
>
> The helper calls directly d_path function, so there's only
> limited set of function it can be called from. Adding just
> very modest set for the start.
>
> 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 | 13 +++++++++
> kernel/trace/bpf_trace.c | 48 ++++++++++++++++++++++++++++++++++
> scripts/bpf_helpers_doc.py | 2 ++
> tools/include/uapi/linux/bpf.h | 13 +++++++++
> 4 files changed, 76 insertions(+)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index eb5e0c38eb2c..a356ea1357bf 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -3389,6 +3389,18 @@ union bpf_attr {
> * A non-negative value equal to or less than *size* on success,
> * or a negative error in case of failure.
> *
> + * int bpf_d_path(struct path *path, char *buf, u32 sz)
nit: probably would be good to do `const struct path *` here, even if
we don't do const-ification properly in all helpers.
> + * 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' and
typo: in the provided buffer 'buf' of size ... ?
> + * is zero terminated.
> + *
> + * Return
> + * On success, the strictly positive length of the string,
> + * including the trailing NUL character. On error, a negative
> + * value.
> + *
> */
> #define __BPF_FUNC_MAPPER(FN) \
> FN(unspec), \
> @@ -3533,6 +3545,7 @@ union bpf_attr {
> FN(skc_to_tcp_request_sock), \
> FN(skc_to_udp6_sock), \
> FN(get_task_stack), \
> + FN(d_path), \
> /* */
>
> /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index cb91ef902cc4..02a76e246545 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -1098,6 +1098,52 @@ static const struct bpf_func_proto bpf_send_signal_thread_proto = {
> .arg1_type = ARG_ANYTHING,
> };
>
> +BPF_CALL_3(bpf_d_path, struct path *, path, char *, buf, u32, sz)
> +{
> + int len;
> + char *p;
> +
> + if (!sz)
> + return -ENAMETOOLONG;
if we are modeling this after bpf_probe_read_str(), sz == 0 returns
success and just does nothing. I don't think anyone will ever handle
or expect this error. I'd just return 0.
> +
> + p = d_path(path, buf, sz);
> + if (IS_ERR(p)) {
> + len = PTR_ERR(p);
> + } else {
> + len = buf + sz - p;
> + memmove(buf, p, len);
> + }
> +
> + return len;
> +}
> +
[...]
next prev parent reply other threads:[~2020-08-05 6:36 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 [this message]
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
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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