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From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH v2 bpf-next 10/16] bpf: Add bpf_btf_find_by_name_kind() helper.
Date: Mon, 26 Apr 2021 15:46:29 -0700	[thread overview]
Message-ID: <CAEf4BzYkzzN=ZD2X1bOg8U39Whbe6oTPuUEMOpACw6NPEW69NA@mail.gmail.com> (raw)
In-Reply-To: <20210423002646.35043-11-alexei.starovoitov@gmail.com>

On Thu, Apr 22, 2021 at 5:27 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> From: Alexei Starovoitov <ast@kernel.org>
>
> Add new helper:
>
> long bpf_btf_find_by_name_kind(u32 btf_fd, char *name, u32 kind, int flags)
>         Description
>                 Find given name with given type in BTF pointed to by btf_fd.
>                 If btf_fd is zero look for the name in vmlinux BTF and in module's BTFs.
>         Return
>                 Returns btf_id and btf_obj_fd in lower and upper 32 bits.
>
> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
> ---
>  include/linux/bpf.h            |  1 +
>  include/uapi/linux/bpf.h       |  8 ++++
>  kernel/bpf/btf.c               | 68 ++++++++++++++++++++++++++++++++++
>  kernel/bpf/syscall.c           |  2 +
>  tools/include/uapi/linux/bpf.h |  8 ++++
>  5 files changed, 87 insertions(+)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 0f841bd0cb85..4cf361eb6a80 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -1972,6 +1972,7 @@ extern const struct bpf_func_proto bpf_get_socket_ptr_cookie_proto;
>  extern const struct bpf_func_proto bpf_task_storage_get_proto;
>  extern const struct bpf_func_proto bpf_task_storage_delete_proto;
>  extern const struct bpf_func_proto bpf_for_each_map_elem_proto;
> +extern const struct bpf_func_proto bpf_btf_find_by_name_kind_proto;
>
>  const struct bpf_func_proto *bpf_tracing_func_proto(
>         enum bpf_func_id func_id, const struct bpf_prog *prog);
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index de58a714ed36..253f5f031f08 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -4748,6 +4748,13 @@ union bpf_attr {
>   *             Execute bpf syscall with given arguments.
>   *     Return
>   *             A syscall result.
> + *
> + * long bpf_btf_find_by_name_kind(u32 btf_fd, char *name, u32 kind, int flags)
> + *     Description
> + *             Find given name with given type in BTF pointed to by btf_fd.

"Find BTF type with given name"? Should the limits on name length be
specified? KSYM_NAME_LEN is a pretty arbitrary restriction. Also,
would it still work fine if the caller provides a pointer to a much
shorter piece of memory?

Why not add name_sz right after name, as we do with a lot of other
arguments like this?

> + *             If btf_fd is zero look for the name in vmlinux BTF and in module's BTFs.
> + *     Return
> + *             Returns btf_id and btf_obj_fd in lower and upper 32 bits.

Mention that for vmlinux BTF btf_obj_fd will be zero? Also who "owns"
the FD? If the BPF program doesn't close it, when are they going to be
cleaned up?

>   */
>  #define __BPF_FUNC_MAPPER(FN)          \
>         FN(unspec),                     \
> @@ -4917,6 +4924,7 @@ union bpf_attr {
>         FN(for_each_map_elem),          \
>         FN(snprintf),                   \
>         FN(sys_bpf),                    \
> +       FN(btf_find_by_name_kind),      \
>         /* */
>

[...]

  reply	other threads:[~2021-04-26 22:46 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-23  0:26 [PATCH v2 bpf-next 00/16] bpf: syscall program, FD array, loader program, light skeleton Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 01/16] bpf: Introduce bpf_sys_bpf() helper and program type Alexei Starovoitov
2021-04-23 18:15   ` Yonghong Song
2021-04-23 18:28     ` Alexei Starovoitov
2021-04-23 19:32       ` Yonghong Song
2021-04-26 16:51   ` Andrii Nakryiko
2021-04-27 18:45   ` John Fastabend
2021-04-23  0:26 ` [PATCH v2 bpf-next 02/16] bpf: Introduce bpfptr_t user/kernel pointer Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 03/16] bpf: Prepare bpf syscall to be used from kernel and user space Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 04/16] libbpf: Support for syscall program type Alexei Starovoitov
2021-04-26 22:24   ` Andrii Nakryiko
2021-04-23  0:26 ` [PATCH v2 bpf-next 05/16] selftests/bpf: Test " Alexei Starovoitov
2021-04-26 17:02   ` Andrii Nakryiko
2021-04-27  2:43     ` Alexei Starovoitov
2021-04-27 16:28       ` Andrii Nakryiko
2021-04-23  0:26 ` [PATCH v2 bpf-next 06/16] bpf: Make btf_load command to be bpfptr_t compatible Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 07/16] selftests/bpf: Test for btf_load command Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 08/16] bpf: Introduce fd_idx Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 09/16] libbpf: Support for fd_idx Alexei Starovoitov
2021-04-26 17:14   ` Andrii Nakryiko
2021-04-27  2:53     ` Alexei Starovoitov
2021-04-27 16:36       ` Andrii Nakryiko
2021-04-28  1:32         ` Alexei Starovoitov
2021-04-28 18:40           ` Andrii Nakryiko
2021-04-23  0:26 ` [PATCH v2 bpf-next 10/16] bpf: Add bpf_btf_find_by_name_kind() helper Alexei Starovoitov
2021-04-26 22:46   ` Andrii Nakryiko [this message]
2021-04-27  3:37     ` Alexei Starovoitov
2021-04-27 17:45       ` Andrii Nakryiko
2021-04-28  1:55         ` Alexei Starovoitov
2021-04-28 18:44           ` Andrii Nakryiko
2021-04-27 21:00   ` John Fastabend
2021-04-27 21:05     ` John Fastabend
2021-04-28  2:10     ` Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 11/16] bpf: Add bpf_sys_close() helper Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 12/16] libbpf: Change the order of data and text relocations Alexei Starovoitov
2021-04-26 17:29   ` Andrii Nakryiko
2021-04-27  3:00     ` Alexei Starovoitov
2021-04-27 16:47       ` Andrii Nakryiko
2021-04-23  0:26 ` [PATCH v2 bpf-next 13/16] libbpf: Add bpf_object pointer to kernel_supports() Alexei Starovoitov
2021-04-26 17:30   ` Andrii Nakryiko
2021-04-23  0:26 ` [PATCH v2 bpf-next 14/16] libbpf: Generate loader program out of BPF ELF file Alexei Starovoitov
2021-04-26 22:22   ` Andrii Nakryiko
2021-04-27  3:25     ` Alexei Starovoitov
2021-04-27 17:34       ` Andrii Nakryiko
2021-04-28  1:42         ` Alexei Starovoitov
2021-04-23  0:26 ` [PATCH v2 bpf-next 15/16] bpftool: Use syscall/loader program in "prog load" and "gen skeleton" command Alexei Starovoitov
2021-04-26 22:35   ` Andrii Nakryiko
2021-04-27  3:28     ` Alexei Starovoitov
2021-04-27 17:38       ` Andrii Nakryiko
2021-04-23  0:26 ` [PATCH v2 bpf-next 16/16] selftests/bpf: Convert few tests to light skeleton Alexei Starovoitov
2021-04-23 21:36 ` [PATCH v2 bpf-next 00/16] bpf: syscall program, FD array, loader program, " Yonghong Song
2021-04-23 23:16   ` Alexei Starovoitov

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