linux-kernel - Re: [PATCH bpf-next v1 01/13] bpf: Refactor BPF

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Message-ID: <CAEf4BzZJf_GBCXYYmE0Hk7O2GdeOr-3VCxdAaxCUk-MHRar3Og@mail.gmail.com>
Date:   Fri, 20 Dec 2019 12:10:32 -0800
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     KP Singh <kpsingh@...omium.org>
Cc:     open list <linux-kernel@...r.kernel.org>,
        bpf <bpf@...r.kernel.org>, linux-security-module@...r.kernel.org,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        James Morris <jmorris@...ei.org>,
        Kees Cook <keescook@...omium.org>,
        Thomas Garnier <thgarnie@...omium.org>,
        Michael Halcrow <mhalcrow@...gle.com>,
        Paul Turner <pjt@...gle.com>,
        Brendan Gregg <brendan.d.gregg@...il.com>,
        Jann Horn <jannh@...gle.com>,
        Matthew Garrett <mjg59@...gle.com>,
        Christian Brauner <christian@...uner.io>,
        Mickaël Salaün <mic@...ikod.net>,
        Florent Revest <revest@...omium.org>,
        Brendan Jackman <jackmanb@...omium.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Stanislav Fomichev <sdf@...gle.com>,
        Quentin Monnet <quentin.monnet@...ronome.com>,
        Andrey Ignatov <rdna@...com>, Joe Stringer <joe@...d.net.nz>
Subject: Re: [PATCH bpf-next v1 01/13] bpf: Refactor BPF_EVENT context macros
 to its own header.

On Fri, Dec 20, 2019 at 7:43 AM KP Singh <kpsingh@...omium.org> wrote:
>
> From: KP Singh <kpsingh@...gle.com>
>
> These macros are useful for other program types than tracing.
> i.e. KRSI (an upccoming BPF based LSM) which does not use
> BPF_PROG_TYPE_TRACE but uses verifiable BTF accesses similar
> to raw tracepoints.
>
> Signed-off-by: KP Singh <kpsingh@...gle.com>
> ---
>  include/linux/bpf_event.h | 78 +++++++++++++++++++++++++++++++++++++++
>  include/trace/bpf_probe.h | 30 +--------------
>  kernel/trace/bpf_trace.c  | 24 +-----------
>  3 files changed, 81 insertions(+), 51 deletions(-)
>  create mode 100644 include/linux/bpf_event.h
>
> diff --git a/include/linux/bpf_event.h b/include/linux/bpf_event.h
> new file mode 100644
> index 000000000000..353eb1f5a3d0
> --- /dev/null
> +++ b/include/linux/bpf_event.h
> @@ -0,0 +1,78 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +
> +/*
> + * Copyright (c) 2018 Facebook
> + * Copyright 2019 Google LLC.
> + */
> +
> +#ifndef _LINUX_BPF_EVENT_H
> +#define _LINUX_BPF_EVENT_H
> +
> +#ifdef CONFIG_BPF_EVENTS
> +
> +/* cast any integer, pointer, or small struct to u64 */
> +#define UINTTYPE(size) \
> +       __typeof__(__builtin_choose_expr(size == 1,  (u8)1, \
> +                  __builtin_choose_expr(size == 2, (u16)2, \
> +                  __builtin_choose_expr(size == 4, (u32)3, \
> +                  __builtin_choose_expr(size == 8, (u64)4, \
> +                                        (void)5)))))
> +#define __CAST_TO_U64(x) ({ \
> +       typeof(x) __src = (x); \
> +       UINTTYPE(sizeof(x)) __dst; \
> +       memcpy(&__dst, &__src, sizeof(__dst)); \
> +       (u64)__dst; })
> +
> +#define __CAST0(...) 0
> +#define __CAST1(a, ...) __CAST_TO_U64(a)
> +#define __CAST2(a, ...) __CAST_TO_U64(a), __CAST1(__VA_ARGS__)
> +#define __CAST3(a, ...) __CAST_TO_U64(a), __CAST2(__VA_ARGS__)
> +#define __CAST4(a, ...) __CAST_TO_U64(a), __CAST3(__VA_ARGS__)
> +#define __CAST5(a, ...) __CAST_TO_U64(a), __CAST4(__VA_ARGS__)
> +#define __CAST6(a, ...) __CAST_TO_U64(a), __CAST5(__VA_ARGS__)
> +#define __CAST7(a, ...) __CAST_TO_U64(a), __CAST6(__VA_ARGS__)
> +#define __CAST8(a, ...) __CAST_TO_U64(a), __CAST7(__VA_ARGS__)
> +#define __CAST9(a, ...) __CAST_TO_U64(a), __CAST8(__VA_ARGS__)
> +#define __CAST10(a ,...) __CAST_TO_U64(a), __CAST9(__VA_ARGS__)
> +#define __CAST11(a, ...) __CAST_TO_U64(a), __CAST10(__VA_ARGS__)
> +#define __CAST12(a, ...) __CAST_TO_U64(a), __CAST11(__VA_ARGS__)
> +/* tracepoints with more than 12 arguments will hit build error */
> +#define CAST_TO_U64(...) CONCATENATE(__CAST, COUNT_ARGS(__VA_ARGS__))(__VA_ARGS__)
> +
> +#define UINTTYPE(size) \
> +       __typeof__(__builtin_choose_expr(size == 1,  (u8)1, \
> +                  __builtin_choose_expr(size == 2, (u16)2, \
> +                  __builtin_choose_expr(size == 4, (u32)3, \
> +                  __builtin_choose_expr(size == 8, (u64)4, \
> +                                        (void)5)))))

Is it the same macro as above?

> +

[...]