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From: Jiri Olsa <jolsa@redhat.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>, Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andriin@fb.com>,
	Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
	Martin KaFai Lau <kafai@fb.com>, David Miller <davem@redhat.com>,
	John Fastabend <john.fastabend@gmail.com>,
	Wenbo Zhang <ethercflow@gmail.com>,
	KP Singh <kpsingh@chromium.org>,
	Brendan Gregg <bgregg@netflix.com>,
	Florent Revest <revest@chromium.org>,
	Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH v8 bpf-next 08/13] bpf: Add BTF_SET_START/END macros
Date: Wed, 29 Jul 2020 13:54:29 +0200
Message-ID: <20200729115429.GI1319041@krava> (raw)
In-Reply-To: <CAEf4BzbwJ+FXYWOK2k6UZ8X1f-2XQP1rRLFAFO6_OyK2iKv8Eg@mail.gmail.com>

On Tue, Jul 28, 2020 at 12:39:06PM -0700, Andrii Nakryiko wrote:

SNIP

> 
> [...]
> 
> > +#define BTF_SET_START(name)                            \
> > +__BTF_ID_LIST(name, local)                             \
> > +asm(                                                   \
> > +".pushsection " BTF_IDS_SECTION ",\"a\";       \n"     \
> > +".local __BTF_ID__set__" #name ";              \n"     \
> > +"__BTF_ID__set__" #name ":;                    \n"     \
> > +".zero 4                                       \n"     \
> > +".popsection;                                  \n");
> > +
> > +#define BTF_SET_END(name)                              \
> > +asm(                                                   \
> > +".pushsection " BTF_IDS_SECTION ",\"a\";      \n"      \
> > +".size __BTF_ID__set__" #name ", .-" #name "  \n"      \
> > +".popsection;                                 \n");    \
> > +extern struct btf_id_set name;
> > +
> >  #else
> 
> This local symbol assumption will probably at some point bite us.
> Yonghong already did global vs static variants for BTF ID list, we'll
> end up doing something like that for sets of BTF IDs as well. Let's do
> this similarly from the get go.

sure, will add that

> 
> >
> >  #define BTF_ID_LIST(name) static u32 name[5];
> >  #define BTF_ID(prefix, name)
> >  #define BTF_ID_UNUSED
> >  #define BTF_ID_LIST_GLOBAL(name) u32 name[1];
> > +#define BTF_SET_START(name) static struct btf_id_set name = { 0 };
> 
> nit: this zero is unnecessary and misleading (it's initialized for
> only the first member of a struct). Just {} is enough.

ok

> 
> > +#define BTF_SET_END(name)
> >
> >  #endif /* CONFIG_DEBUG_INFO_BTF */
> >
> > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> > index 562d4453fad3..06714cdda0a9 100644
> > --- a/kernel/bpf/btf.c
> > +++ b/kernel/bpf/btf.c
> > @@ -21,6 +21,8 @@
> >  #include <linux/btf_ids.h>
> >  #include <linux/skmsg.h>
> >  #include <linux/perf_event.h>
> > +#include <linux/bsearch.h>
> > +#include <linux/btf_ids.h>
> >  #include <net/sock.h>
> >
> >  /* BTF (BPF Type Format) is the meta data format which describes
> > @@ -4740,3 +4742,15 @@ u32 btf_id(const struct btf *btf)
> >  {
> >         return btf->id;
> >  }
> > +
> > +static int btf_id_cmp_func(const void *a, const void *b)
> > +{
> > +       const int *pa = a, *pb = b;
> > +
> > +       return *pa - *pb;
> > +}
> > +
> > +bool btf_id_set_contains(struct btf_id_set *set, u32 id)
> > +{
> > +       return bsearch(&id, set->ids, set->cnt, sizeof(int), btf_id_cmp_func) != NULL;
> 
> very nit ;) sizeof(__u32)

sure ;-)

thanks,
jirka


  reply index

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-22 21:12 [PATCH v8 bpf-next 00/13] bpf: Add d_path helper Jiri Olsa
2020-07-22 21:12 ` [PATCH v8 bpf-next 01/13] selftests/bpf: Fix resolve_btfids test Jiri Olsa
2020-07-28 20:27   ` Andrii Nakryiko
2020-07-29 20:06     ` Jiri Olsa
2020-07-29 21:38       ` Andrii Nakryiko
2020-07-22 21:12 ` [PATCH v8 bpf-next 02/13] tools resolve_btfids: Add support for set symbols Jiri Olsa
2020-07-28  0:53   ` Andrii Nakryiko
2020-07-28  9:35     ` Jiri Olsa
2020-07-22 21:12 ` [PATCH v8 bpf-next 03/13] bpf: Move btf_resolve_size into __btf_resolve_size Jiri Olsa
2020-07-28 20:29   ` Andrii Nakryiko
2020-07-22 21:12 ` [PATCH v8 bpf-next 04/13] bpf: Add elem_id pointer as argument to __btf_resolve_size Jiri Olsa
2020-07-28 20:30   ` Andrii Nakryiko
2020-07-22 21:12 ` [PATCH v8 bpf-next 05/13] bpf: Add type_id " Jiri Olsa
2020-07-22 21:12 ` [PATCH v8 bpf-next 06/13] bpf: Factor btf_struct_access function Jiri Olsa
2020-07-28 23:27   ` Andrii Nakryiko
2020-07-29 15:59     ` Jiri Olsa
2020-07-22 21:12 ` [PATCH v8 bpf-next 07/13] bpf: Add btf_struct_ids_match function Jiri Olsa
2020-07-28 23:35   ` Andrii Nakryiko
2020-07-29 16:04     ` Jiri Olsa
2020-07-29 17:51       ` Andrii Nakryiko
2020-07-29 18:55         ` Jiri Olsa
2020-07-22 21:12 ` [PATCH v8 bpf-next 08/13] bpf: Add BTF_SET_START/END macros Jiri Olsa
2020-07-28 19:39   ` Andrii Nakryiko
2020-07-29 11:54     ` Jiri Olsa [this message]
2020-07-22 21:12 ` [PATCH v8 bpf-next 09/13] bpf: Add d_path helper Jiri Olsa
2020-07-28 19:47   ` Andrii Nakryiko
2020-07-29 15:54     ` Jiri Olsa
2020-07-29 20:11   ` Al Viro
2020-07-30 10:22     ` Jiri Olsa
2020-07-29 20:17   ` Al Viro
2020-07-30 10:09     ` Jiri Olsa
2020-07-22 21:12 ` [PATCH v8 bpf-next 10/13] bpf: Update .BTF_ids section in btf.rst with sets info Jiri Olsa
2020-07-22 21:12 ` [PATCH v8 bpf-next 11/13] selftests/bpf: Add verifier test for d_path helper Jiri Olsa
2020-07-28 19:49   ` Andrii Nakryiko
2020-07-22 21:12 ` [PATCH v8 bpf-next 12/13] selftests/bpf: Add " Jiri Olsa
2020-07-28 19:53   ` Andrii Nakryiko
2020-07-29 11:25     ` Jiri Olsa
2020-07-22 21:12 ` [PATCH v8 bpf-next 13/13] selftests/bpf: Add set test to resolve_btfids Jiri Olsa
2020-07-28 19:56   ` Andrii Nakryiko
2020-07-29 15:34     ` Jiri Olsa

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