1. 27 Apr, 2018 36 commits
  2. 26 Apr, 2018 4 commits
    • Wang Sheng-Hui's avatar
      samples, bpf: remove redundant ret assignment in bpf_load_program() · c0885f61
      Wang Sheng-Hui authored
      
      
      2 redundant ret assignments removed:
      
      * 'ret = 1' before the logic 'if (data_maps)', and if any errors jump to
        label 'done'. No 'ret = 1' needed before the error jump.
      
      * After the '/* load programs */' part, if everything goes well, then
        the BPF code will be loaded and 'ret' set to 0 by load_and_attach().
        If something goes wrong, 'ret' set to none-O, the redundant 'ret = 0'
        after the for clause will make the error skipped.
      
        For example, if some BPF code cannot provide supported program types
        in ELF SEC("unknown"), the for clause will not call load_and_attach()
        to load the BPF code. 1 should be returned to callees instead of 0.
      
      Signed-off-by: default avatarWang Sheng-Hui <shhuiw@foxmail.com>
      Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      c0885f61
    • Daniel Borkmann's avatar
      Merge branch 'bpf-uapi-helper-doc' · a6712d45
      Daniel Borkmann authored
      
      
      Quentin Monnet says:
      
      ====================
      eBPF helper functions can be called from within eBPF programs to perform
      a variety of tasks that would be otherwise hard or impossible to do with
      eBPF itself. There is a growing number of such helper functions in the
      kernel, but documentation is scarce. The main user space header file
      does contain a short commented description of most helpers, but it is
      somewhat outdated and not complete. It is more a "cheat sheet" than a
      real documentation accessible to new eBPF developers.
      
      This commit attempts to improve the situation by replacing the existing
      overview for the helpers with a more developed description. Furthermore,
      a Python script is added to generate a manual page for eBPF helpers. The
      workflow is the following, and requires the rst2man utility:
      
          $ ./scripts/bpf_helpers_doc.py \
                  --filename include/uapi/linux/bpf.h > /tmp/bpf-helpers.rst
          $ rst2man /tmp/bpf-helpers.rst > /tmp/bpf-helpers.7
          $ man /tmp/bpf-helpers.7
      
      The objective is to keep all documentation related to the helpers in a
      single place, and to be able to generate from here a manual page that
      could be packaged in the man-pages repository and shipped with most
      distributions.
      
      Additionally, parsing the prototypes of the helper functions could
      hopefully be reused, with a different Printer object, to generate
      header files needed in some eBPF-related projects.
      
      Regarding the description of each helper, it comprises several items:
      
      - The function prototype.
      - A description of the function and of its arguments (except for a
        couple of cases, when there are no arguments and the return value
        makes the function usage really obvious).
      - A description of return values (if not void).
      
      Additional items such as the list of compatible eBPF program and map
      types for each helper, Linux kernel version that introduced the helper,
      GPL-only restriction, and commit hash could be added in the future, but
      it was decided on the mailing list to leave them aside for now.
      
      For several helpers, descriptions are inspired (at times, nearly copied)
      from the commit logs introducing them in the kernel--Many thanks to
      their respective authors! Some sentences were also adapted from comments
      from the reviews, thanks to the reviewers as well. Descriptions were
      completed as much as possible, the objective being to have something easily
      accessible even for people just starting with eBPF. There is probably a bit
      more work to do in this direction for some helpers.
      
      Some RST formatting is used in the descriptions (not in function
      prototypes, to keep them readable, but the Python script provided in
      order to generate the RST for the manual page does add formatting to
      prototypes, to produce something pretty) to get "bold" and "italics" in
      manual pages. Hopefully, the descriptions in bpf.h file remains
      perfectly readable. Note that the few trailing white spaces are
      intentional, removing them would break paragraphs for rst2man.
      
      The descriptions should ideally be updated each time someone adds a new
      helper, or updates the behaviour (new socket option supported, ...) or
      the interface (new flags available, ...) of existing ones.
      
      To ease the review process, the documentation has been split into several
      patches.
      
      v3 -> v4:
      - Add a patch (#9) for newly added BPF helpers.
      - Add a patch (#10) to update UAPI bpf.h version under tools/.
      - Use SPDX tag in Python script.
      - Several fixes on man page header and footer, and helpers documentation.
        Please refer to individual patches for details.
      
      RFC v2 -> PATCH v3:
      Several fixes on man page header and footer, and helpers documentation.
      Please refer to individual patches for details.
      
      RFC v1 -> RFC v2:
      - Remove "For" (compatible program and map types), "Since" (minimal
        Linux kernel version required), "GPL only" sections and commit hashes
        for the helpers.
      - Add comment on top of the description list to explain how this
        documentation is supposed to be processed.
      - Update Python script accordingly (remove the same sections, and remove
        paragraphs on program types and GPL restrictions from man page
        header).
      - Split series into several patches.
      ====================
      
      Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      Cc: linux-doc@vger.kernel.org
      Cc: linux-man@vger.kernel.org
      a6712d45
    • Quentin Monnet's avatar
      bpf: update bpf.h uapi header for tools · 9cde0c88
      Quentin Monnet authored
      
      
      Update tools/include/uapi/linux/bpf.h file in order to reflect the
      changes for BPF helper functions documentation introduced in previous
      commits.
      
      Signed-off-by: default avatarQuentin Monnet <quentin.monnet@netronome.com>
      Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      9cde0c88
    • Quentin Monnet's avatar
      bpf: add documentation for eBPF helpers (65-66) · 2d020dd7
      Quentin Monnet authored
      
      
      Add documentation for eBPF helper functions to bpf.h user header file.
      This documentation can be parsed with the Python script provided in
      another commit of the patch series, in order to provide a RST document
      that can later be converted into a man page.
      
      The objective is to make the documentation easily understandable and
      accessible to all eBPF developers, including beginners.
      
      This patch contains descriptions for the following helper functions:
      
      Helper from Nikita:
      - bpf_xdp_adjust_tail()
      
      Helper from Eyal:
      - bpf_skb_get_xfrm_state()
      
      v4:
      - New patch (helpers did not exist yet for previous versions).
      
      Cc: Nikita V. Shirokov <tehnerd@tehnerd.com>
      Cc: Eyal Birger <eyal.birger@gmail.com>
      Signed-off-by: default avatarQuentin Monnet <quentin.monnet@netronome.com>
      Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      2d020dd7