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From: Martin Lau <kafai@fb.com>
To: Andrii Nakryiko <andriin@fb.com>
Cc: "bpf@vger.kernel.org" <bpf@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Alexei Starovoitov <ast@fb.com>,
	"daniel@iogearbox.net" <daniel@iogearbox.net>,
	"andrii.nakryiko@gmail.com" <andrii.nakryiko@gmail.com>,
	Kernel Team <Kernel-team@fb.com>
Subject: Re: [PATCH bpf-next 00/15] Add code-generated BPF object skeleton support
Date: Wed, 11 Dec 2019 22:55:25 +0000	[thread overview]
Message-ID: <20191211225506.w3cv6sur3we6qiu3@kafai-mbp> (raw)
In-Reply-To: <20191210011438.4182911-1-andriin@fb.com>

On Mon, Dec 09, 2019 at 05:14:23PM -0800, Andrii Nakryiko wrote:
> This patch set introduces an alternative and complimentary to existing libbpf
> API interface for working with BPF objects, maps, programs, and global data
> from userspace side. This approach is relying on code generation. bpftool
> produces a struct (a.k.a. skeleton) tailored and specific to provided BPF
> object file. It includes hard-coded fields and data structures for every map,
> program, link, and global data present.
> 
> Altogether this approach significantly reduces amount of userspace boilerplate
> code required to open, load, attach, and work with BPF objects. It improves
> attach/detach story, by providing pre-allocated space for bpf_links, and
> ensuring they are properly detached on shutdown. It allows to do away with by
> name/title lookups of maps and programs, because libbpf's skeleton API, in
> conjunction with generated code from bpftool, is filling in hard-coded fields
> with actual pointers to corresponding struct bpf_map/bpf_program/bpf_link.
> 
> Also, thanks to BPF array mmap() support, working with global data (variables)
> from userspace is now as natural as it is from BPF side: each variable is just
> a struct field inside skeleton struct. Furthermore, this allows to have
> a natural way for userspace to pre-initialize global data (including
> previously impossible to initialize .rodata) by just assigning values to the
> same per-variable fields. Libbpf will carefully take into account this
> initialization image, will use it to pre-populate BPF maps at creation time,
> and will re-mmap() BPF map's contents at exactly the same userspace memory
> address such that it can continue working with all the same pointers without
> any interruptions. If kernel doesn't support mmap(), global data will still be
> successfully initialized, but after map creation global data structures inside
> skeleton will be NULL-ed out. This allows userspace application to gracefully
> handle lack of mmap() support, if necessary.
> 
> A bunch of selftests are also converted to using skeletons, demonstrating
> significant simplification of userspace part of test and reduction in amount
> of code necessary.
Changes look good to me.

Acked-by: Martin KaFai Lau <kafai@fb.com>

which should not stop the on-going discussion.

      parent reply	other threads:[~2019-12-11 22:55 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-10  1:14 [PATCH bpf-next 00/15] Add code-generated BPF object skeleton support Andrii Nakryiko
2019-12-10  1:14 ` [PATCH bpf-next 01/15] libbpf: don't require root for bpf_object__open() Andrii Nakryiko
2019-12-10  1:14 ` [PATCH bpf-next 02/15] libbpf: add generic bpf_program__attach() Andrii Nakryiko
2019-12-10  1:14 ` [PATCH bpf-next 03/15] libbpf: move non-public APIs from libbpf.h to libbpf_internal.h Andrii Nakryiko
2019-12-10  1:33   ` Jakub Kicinski
2019-12-10 17:04     ` Andrii Nakryiko
2019-12-10 18:17       ` Jakub Kicinski
2019-12-10 18:47         ` Andrii Nakryiko
2019-12-10  1:14 ` [PATCH bpf-next 04/15] libbpf: add BPF_EMBED_OBJ macro for embedding BPF .o files Andrii Nakryiko
2019-12-10  1:14 ` [PATCH bpf-next 05/15] libbpf: expose field/var declaration emitting API internally Andrii Nakryiko
2019-12-10  1:14 ` [PATCH bpf-next 06/15] libbpf: expose BPF program's function name Andrii Nakryiko
2019-12-11 19:38   ` [Potential Spoof] " Martin Lau
2019-12-11 19:54     ` Andrii Nakryiko
2019-12-10  1:14 ` [PATCH bpf-next 07/15] libbpf: refactor global data map initialization Andrii Nakryiko
2019-12-10  1:14 ` [PATCH bpf-next 08/15] libbpf: postpone BTF ID finding for TRACING programs to load phase Andrii Nakryiko
2019-12-10  1:14 ` [PATCH bpf-next 09/15] libbpf: reduce log level of supported section names dump Andrii Nakryiko
2019-12-10  1:14 ` [PATCH bpf-next 10/15] libbpf: add experimental BPF object skeleton support Andrii Nakryiko
2019-12-10  1:14 ` [PATCH bpf-next 11/15] bpftool: add skeleton codegen command Andrii Nakryiko
2019-12-10  1:57   ` Jakub Kicinski
2019-12-10 17:11     ` Andrii Nakryiko
2019-12-10 18:05       ` Jakub Kicinski
2019-12-10 18:56         ` Andrii Nakryiko
2019-12-10 21:44         ` Stanislav Fomichev
2019-12-10 22:33           ` Andrii Nakryiko
2019-12-10 22:59             ` Stanislav Fomichev
2019-12-11  7:07               ` Andrii Nakryiko
2019-12-11 17:24                 ` Stanislav Fomichev
2019-12-11 18:26                   ` Andrii Nakryiko
2019-12-11 19:15                     ` Stanislav Fomichev
2019-12-11 19:41                       ` Andrii Nakryiko
2019-12-11 20:09                         ` Stanislav Fomichev
2019-12-12  0:50                           ` Andrii Nakryiko
2019-12-12  2:57                             ` Stanislav Fomichev
2019-12-12  7:27                               ` Andrii Nakryiko
2019-12-12 16:29                                 ` Stanislav Fomichev
2019-12-12 16:53                                   ` Andrii Nakryiko
2019-12-12 18:43                                     ` Jakub Kicinski
2019-12-12 18:58                                       ` Stanislav Fomichev
2019-12-12 19:23                                         ` Jakub Kicinski
2019-12-12 19:54                                       ` Alexei Starovoitov
2019-12-12 20:21                                         ` Jakub Kicinski
2019-12-12 21:28                                           ` Alexei Starovoitov
2019-12-12 21:59                                             ` Jakub Kicinski
2019-12-13  6:48                                           ` Andrii Nakryiko
2019-12-13 17:47                                             ` Jakub Kicinski
2019-12-12 21:45                                         ` Stanislav Fomichev
2019-12-13  6:23                                           ` Andrii Nakryiko
2019-12-11 22:50   ` [Potential Spoof] " Martin Lau
2019-12-16 14:16   ` Daniel Borkmann
2019-12-16 18:53     ` Andrii Nakryiko
2019-12-17 13:59       ` Daniel Borkmann
2019-12-17 15:45         ` Alexei Starovoitov
2019-12-10  1:14 ` [PATCH bpf-next 12/15] selftests/bpf: add BPF skeletons selftests and convert attach_probe.c Andrii Nakryiko
2019-12-10  1:14 ` [PATCH bpf-next 13/15] selftests/bpf: convert few more selftest to skeletons Andrii Nakryiko
2019-12-10  1:14 ` [PATCH bpf-next 14/15] selftests/bpf: add test validating data section to struct convertion layout Andrii Nakryiko
2019-12-10  1:14 ` [PATCH bpf-next 15/15] bpftool: add `gen skeleton` BASH completions Andrii Nakryiko
2019-12-11 22:55 ` Martin Lau [this message]

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