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From: Yonghong Song <yhs@fb.com>
To: Andrii Nakryiko <andrii@kernel.org>, <bpf@vger.kernel.org>,
	<ast@kernel.org>, <daniel@iogearbox.net>
Cc: <kernel-team@fb.com>, Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v3 bpf-next 05/14] bpf: allow to specify user-provided bpf_cookie for BPF perf links
Date: Fri, 30 Jul 2021 15:02:32 -0700	[thread overview]
Message-ID: <2cedfed1-2db8-31f5-b214-619701873dc0@fb.com> (raw)
In-Reply-To: <20210730053413.1090371-6-andrii@kernel.org>



On 7/29/21 10:34 PM, Andrii Nakryiko wrote:
> Add ability for users to specify custom u64 value (bpf_cookie) when creating
> BPF link for perf_event-backed BPF programs (kprobe/uprobe, perf_event,
> tracepoints).
> 
> This is useful for cases when the same BPF program is used for attaching and
> processing invocation of different tracepoints/kprobes/uprobes in a generic
> fashion, but such that each invocation is distinguished from each other (e.g.,
> BPF program can look up additional information associated with a specific
> kernel function without having to rely on function IP lookups). This enables
> new use cases to be implemented simply and efficiently that previously were
> possible only through code generation (and thus multiple instances of almost
> identical BPF program) or compilation at runtime (BCC-style) on target hosts
> (even more expensive resource-wise). For uprobes it is not even possible in
> some cases to know function IP before hand (e.g., when attaching to shared
> library without PID filtering, in which case base load address is not known
> for a library).
> 
> This is done by storing u64 bpf_cookie in struct bpf_prog_array_item,
> corresponding to each attached and run BPF program. Given cgroup BPF programs
> already use two 8-byte pointers for their needs and cgroup BPF programs don't
> have (yet?) support for bpf_cookie, reuse that space through union of
> cgroup_storage and new bpf_cookie field.
> 
> Make it available to kprobe/tracepoint BPF programs through bpf_trace_run_ctx.
> This is set by BPF_PROG_RUN_ARRAY, used by kprobe/uprobe/tracepoint BPF
> program execution code, which luckily is now also split from
> BPF_PROG_RUN_ARRAY_CG. This run context will be utilized by a new BPF helper
> giving access to this user-provided cookie value from inside a BPF program.
> Generic perf_event BPF programs will access this value from perf_event itself
> through passed in BPF program context.
> 
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

Acked-by: Yonghong Song <yhs@fb.com>

  reply	other threads:[~2021-07-30 22:02 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-30  5:33 [PATCH v3 bpf-next 00/14] BPF perf link and user-provided bpf_cookie Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 01/14] bpf: refactor BPF_PROG_RUN into a function Andrii Nakryiko
2021-07-30 17:19   ` Yonghong Song
2021-08-09 22:43   ` Daniel Borkmann
2021-08-10  0:28     ` Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 02/14] bpf: refactor BPF_PROG_RUN_ARRAY family of macros into functions Andrii Nakryiko
2021-08-09 23:00   ` Daniel Borkmann
2021-08-10  0:36     ` Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 03/14] bpf: refactor perf_event_set_bpf_prog() to use struct bpf_prog input Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 04/14] bpf: implement minimal BPF perf link Andrii Nakryiko
2021-07-30 17:24   ` Yonghong Song
2021-07-30  5:34 ` [PATCH v3 bpf-next 05/14] bpf: allow to specify user-provided bpf_cookie for BPF perf links Andrii Nakryiko
2021-07-30 22:02   ` Yonghong Song [this message]
2021-08-09 23:30   ` Daniel Borkmann
2021-08-10  0:52     ` Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 06/14] bpf: add bpf_get_attach_cookie() BPF helper to access bpf_cookie value Andrii Nakryiko
2021-07-30 22:13   ` Yonghong Song
2021-07-30  5:34 ` [PATCH v3 bpf-next 07/14] libbpf: re-build libbpf.so when libbpf.map changes Andrii Nakryiko
2021-07-30 22:31   ` Yonghong Song
2021-07-30  5:34 ` [PATCH v3 bpf-next 08/14] libbpf: remove unused bpf_link's destroy operation, but add dealloc Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 09/14] libbpf: use BPF perf link when supported by kernel Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 10/14] libbpf: add bpf_cookie support to bpf_link_create() API Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 11/14] libbpf: add bpf_cookie to perf_event, kprobe, uprobe, and tp attach APIs Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 12/14] selftests/bpf: test low-level perf BPF link API Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 13/14] selftests/bpf: extract uprobe-related helpers into trace_helpers.{c,h} Andrii Nakryiko
2021-07-30  5:34 ` [PATCH v3 bpf-next 14/14] selftests/bpf: add bpf_cookie selftests for high-level APIs Andrii Nakryiko
2021-08-01  5:11 ` [PATCH bpf-next v4] libbpf: introduce legacy kprobe events support Rafael David Tinoco
2021-08-06 22:29   ` Andrii Nakryiko
2021-09-12  6:48     ` [PATCH bpf-next v5] " Rafael David Tinoco
2021-09-12  6:52       ` Rafael David Tinoco
2021-09-14  4:44       ` Andrii Nakryiko
2021-09-14  5:02         ` Rafael David Tinoco
2021-09-14  5:21           ` Andrii Nakryiko
2021-09-14 14:27             ` sunyucong
2021-09-14 15:42               ` Rafael David Tinoco
2021-09-14 20:34                 ` [PATCH bpf-next] libbpf: fix build error introduced by legacy kprobe feature Rafael David Tinoco
2021-09-14 21:04                   ` Alexei Starovoitov
2021-09-14 21:35                 ` [PATCH bpf-next v2] " Rafael David Tinoco
2021-09-14 21:39                   ` Rafael David Tinoco
2021-09-14 21:48                     ` Andrii Nakryiko

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