Re: [PATCH bpf-next v1 01/13] bpf: Refactor BPF_EVENT context macros to its own header.

[KP Singh]

On 20-Dez 12:10, Andrii Nakryiko wrote:
> On Fri, Dec 20, 2019 at 7:43 AM KP Singh <kpsingh@xxxxxxxxxxxx> wrote:
> >
> > From: KP Singh <kpsingh@xxxxxxxxxx>
> >
> > 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@xxxxxxxxxx>
> > ---
> >  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?

Yes, sorry did not notice this. Will fix it in the next revision.

- KP

> 
> > +
> 
> [...]