netdev - [PATCH bpf-next v2 0/2] load-acquire/store-release barriers for AF

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210305094113.413544-1-bjorn.topel@gmail.com>
Date:   Fri,  5 Mar 2021 10:41:11 +0100
From:   Björn Töpel <bjorn.topel@...il.com>
To:     ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Cc:     Björn Töpel <bjorn.topel@...il.com>,
        bjorn.topel@...el.com, magnus.karlsson@...el.com,
        jonathan.lemon@...il.com, maximmi@...dia.com, andrii@...nel.org,
        toke@...hat.com, will@...nel.org, paulmck@...nel.org,
        stern@...land.harvard.edu
Subject: [PATCH bpf-next v2 0/2] load-acquire/store-release barriers for AF_XDP rings

This two-patch series introduces load-acquire/store-release barriers
for the AF_XDP rings.

For most contemporary architectures, this is more effective than a
SPSC ring based on smp_{r,w,}mb() barriers. More importantly,
load-acquire/store-release semantics make the ring code easier to
follow.

This is effectively the change done in commit 6c43c091bdc5
("documentation: Update circular buffer for
load-acquire/store-release"), but for the AF_XDP rings.

Both libbpf and the kernel-side are updated.

Full details are outlined in the commits!

Thanks to the LKMM-folks (Paul/Alan/Will) for helping me out in this
complicated matter!

@Andrii I kept the barriers in libbpf_util.h to separate userfacing
        APIs (xsk.h) from internals.

@Toke I kept "barriers" but reworded. Acquire/release are also
      barriers.

@Will I'd really appreciate if you could take a look this change.

Changelog

v1[1]->v2: 
* Expanded the commit message for patch 1, and included the LKMM
  litmus tests. Hopefully this clear things up. (Daniel)

* Clarified why the smp_mb()/smp_load_acquire() is not needed in (A);
  control dependency with load to store. (Toke)

[1] https://lore.kernel.org/bpf/20210301104318.263262-1-bjorn.topel@gmail.com/

Thanks,
Björn

Björn Töpel (2):
  xsk: update rings for load-acquire/store-release barriers
  libbpf, xsk: add libbpf_smp_store_release libbpf_smp_load_acquire

 net/xdp/xsk_queue.h         | 30 +++++++---------
 tools/lib/bpf/libbpf_util.h | 72 +++++++++++++++++++++++++------------
 tools/lib/bpf/xsk.h         | 17 +++------
 3 files changed, 68 insertions(+), 51 deletions(-)

base-commit: bce8623135fbe54bd86797df72cb85bfe4118b6e
-- 
2.27.0