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From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: bpf@vger.kernel.org, Dave Marchevsky <davemarchevsky@fb.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Dave Marchevsky <davemarchevsky@meta.com>,
	Delyan Kratunov <delyank@meta.com>
Subject: Re: [PATCH bpf-next v2 23/25] libbpf: Add support for private BSS map section
Date: Mon, 17 Oct 2022 21:03:46 -0700	[thread overview]
Message-ID: <CAEf4BzaLvTTnUtAmfZiLSJ6q+sMEhk97vns58_c_mTaA2JtDBw@mail.gmail.com> (raw)
In-Reply-To: <20221013062303.896469-24-memxor@gmail.com>

On Wed, Oct 12, 2022 at 11:24 PM Kumar Kartikeya Dwivedi
<memxor@gmail.com> wrote:
>
> From: Dave Marchevsky <davemarchevsky@fb.com>
>
> Currently libbpf does not allow declaration of a struct bpf_spin_lock in
> global scope. Attempting to do so results in "failed to re-mmap" error,
> as .bss arraymap containing spinlock is not allowed to be mmap'd.
>
> This patch adds support for a .bss.private section. The maps contained
> in this section will not be mmaped into userspace by libbpf, nor will
> they be exposed via bpftool-generated skeleton.
>
> Intent here is to allow more natural programming pattern for
> global-scope spinlocks which will be used by rbtree locking mechanism in
> further patches in this series.
>
> Notes:
>
>   * Initially I called the section .bss.no_mmap, but the broader
>     'private' term better indicates that skeleton shouldn't expose these
>     maps at all, IMO.
>
>   * bpftool/gen.c's is_internal_mmapable_map function checks whether the
>     map flags have BPF_F_MMAPABLE, so no bpftool changes were necessary
>     to remove .bss.private maps from skeleton
>
> Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
> ---

Please see [0] for what I think is a better way forward specifically
for the libbpf-side part.

  [0] https://patchwork.kernel.org/project/netdevbpf/list/?series=686066&state=*

>  tools/lib/bpf/libbpf.c | 65 ++++++++++++++++++++++++++++--------------
>  1 file changed, 44 insertions(+), 21 deletions(-)
>

[...]

  reply	other threads:[~2022-10-18  4:04 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-13  6:22 [PATCH bpf-next v2 00/25] Local kptrs, BPF linked lists Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 01/25] bpf: Document UAPI details for special BPF types Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 02/25] bpf: Allow specifying volatile type modifier for kptrs Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 03/25] bpf: Clobber stack slot when writing over spilled PTR_TO_BTF_ID Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 04/25] bpf: Fix slot type check in check_stack_write_var_off Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 05/25] bpf: Drop reg_type_may_be_refcounted_or_null Kumar Kartikeya Dwivedi
2022-10-19 16:04   ` Dave Marchevsky
2022-10-13  6:22 ` [PATCH bpf-next v2 06/25] bpf: Refactor kptr_off_tab into fields_tab Kumar Kartikeya Dwivedi
2022-10-19  1:35   ` Alexei Starovoitov
2022-10-19  5:42     ` Kumar Kartikeya Dwivedi
2022-10-19 15:54       ` Alexei Starovoitov
2022-10-19 23:57         ` Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 07/25] bpf: Consolidate spin_lock, timer management " Kumar Kartikeya Dwivedi
2022-10-19  1:40   ` Alexei Starovoitov
2022-10-19  5:43     ` Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 08/25] bpf: Refactor map->off_arr handling Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 09/25] bpf: Support bpf_list_head in map values Kumar Kartikeya Dwivedi
2022-10-19  1:59   ` Alexei Starovoitov
2022-10-19  5:48     ` Kumar Kartikeya Dwivedi
2022-10-19 15:57       ` Alexei Starovoitov
2022-10-19 23:59         ` Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 10/25] bpf: Introduce local kptrs Kumar Kartikeya Dwivedi
2022-10-13 13:48   ` kernel test robot
2022-10-19 17:15   ` Dave Marchevsky
2022-10-20  0:48     ` Kumar Kartikeya Dwivedi
2022-10-25 16:27       ` Dave Marchevsky
2022-10-25 18:11         ` Kumar Kartikeya Dwivedi
2022-10-25 16:32   ` Dave Marchevsky
2022-10-25 18:11     ` Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 11/25] bpf: Recognize bpf_{spin_lock,list_head,list_node} in " Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 12/25] bpf: Verify ownership relationships for owning types Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 13/25] bpf: Support locking bpf_spin_lock in local kptr Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 14/25] bpf: Allow locking bpf_spin_lock global variables Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 15/25] bpf: Rewrite kfunc argument handling Kumar Kartikeya Dwivedi
2022-10-13 13:48   ` kernel test robot
2022-10-13  6:22 ` [PATCH bpf-next v2 16/25] bpf: Drop kfunc bits from btf_check_func_arg_match Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 17/25] bpf: Support constant scalar arguments for kfuncs Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 18/25] bpf: Teach verifier about non-size constant arguments Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 19/25] bpf: Introduce bpf_kptr_new Kumar Kartikeya Dwivedi
2022-10-19  2:31   ` Alexei Starovoitov
2022-10-19  5:58     ` Kumar Kartikeya Dwivedi
2022-10-19 16:31       ` Alexei Starovoitov
2022-10-20  0:44         ` Kumar Kartikeya Dwivedi
2022-10-20  1:11           ` Alexei Starovoitov
2022-10-13  6:22 ` [PATCH bpf-next v2 20/25] bpf: Introduce bpf_kptr_drop Kumar Kartikeya Dwivedi
2022-10-13  6:22 ` [PATCH bpf-next v2 21/25] bpf: Permit NULL checking pointer with non-zero fixed offset Kumar Kartikeya Dwivedi
2022-10-13  6:23 ` [PATCH bpf-next v2 22/25] bpf: Introduce single ownership BPF linked list API Kumar Kartikeya Dwivedi
2022-10-25 17:45   ` Dave Marchevsky
2022-10-25 19:00     ` Kumar Kartikeya Dwivedi
2022-10-13  6:23 ` [PATCH bpf-next v2 23/25] libbpf: Add support for private BSS map section Kumar Kartikeya Dwivedi
2022-10-18  4:03   ` Andrii Nakryiko [this message]
2022-10-13  6:23 ` [PATCH bpf-next v2 24/25] selftests/bpf: Add __contains macro to bpf_experimental.h Kumar Kartikeya Dwivedi
2022-10-13  6:23 ` [PATCH bpf-next v2 25/25] selftests/bpf: Add BPF linked list API tests Kumar Kartikeya Dwivedi

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