Commit d2afa89f authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 

Alexei Starovoitov says:

====================
pull-request: bpf-next 2023-07-13

We've added 67 non-merge commits during the last 15 day(s) which contain
a total of 106 files changed, 4444 insertions(+), 619 deletions(-).

The main changes are:

1) Fix bpftool build in presence of stale vmlinux.h,
   from Alexander Lobakin.

2) Introduce bpf_me_mcache_free_rcu() and fix OOM under stress,
   from Alexei Starovoitov.

3) Teach verifier actual bounds of bpf_get_smp_processor_id()
   and fix perf+libbpf issue related to custom section handling,
   from Andrii Nakryiko.

4) Introduce bpf map element count, from Anton Protopopov.

5) Check skb ownership against full socket, from Kui-Feng Lee.

6) Support for up to 12 arguments in BPF trampoline, from Menglong Dong.

7) Export rcu_request_urgent_qs_task, from Paul E. McKenney.

8) Fix BTF walking of unions, from Yafang Shao.

9) Extend link_info for kprobe_multi and perf_event links,
   from Yafang Shao.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (67 commits)
  selftests/bpf: Add selftest for PTR_UNTRUSTED
  bpf: Fix an error in verifying a field in a union
  selftests/bpf: Add selftests for nested_trust
  bpf: Fix an error around PTR_UNTRUSTED
  selftests/bpf: add testcase for TRACING with 6+ arguments
  bpf, x86: allow function arguments up to 12 for TRACING
  bpf, x86: save/restore regs with BPF_DW size
  bpftool: Use "fallthrough;" keyword instead of comments
  bpf: Add object leak check.
  bpf: Convert bpf_cpumask to bpf_mem_cache_free_rcu.
  bpf: Introduce bpf_mem_free_rcu() similar to kfree_rcu().
  selftests/bpf: Improve test coverage of bpf_mem_alloc.
  rcu: Export rcu_request_urgent_qs_task()
  bpf: Allow reuse from waiting_for_gp_ttrace list.
  bpf: Add a hint to allocated objects.
  bpf: Change bpf_mem_cache draining process.
  bpf: Further refactor alloc_bulk().
  bpf: Factor out inc/dec of active flag into helpers.
  bpf: Refactor alloc_bulk().
  bpf: Let free_all() return the number of freed elements.
  ...
====================

Link: https://lore.kernel.org/r/20230714020910.80794-1-alexei.starovoitov@gmail.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents eb1b24a9 1cd0e771

Documentation/bpf/bpf_devel_QA.rst

+5 −5
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@@ -635,12 +635,12 @@ test coverage. 


Q: clang flag for target bpf?

-----------------------------

Q: In some cases clang flag ``-target bpf`` is used but in other cases the

Q: In some cases clang flag ``--target=bpf`` is used but in other cases the

default clang target, which matches the underlying architecture, is used.

What is the difference and when I should use which?



A: Although LLVM IR generation and optimization try to stay architecture

independent, ``-target <arch>`` still has some impact on generated code:

independent, ``--target=<arch>`` still has some impact on generated code:



- BPF program may recursively include header file(s) with file scope

  inline assembly codes. The default target can handle this well,
@@ -658,7 +658,7 @@ independent, ``-target <arch>`` still has some impact on generated code: 
  The clang option ``-fno-jump-tables`` can be used to disable

  switch table generation.



- For clang ``-target bpf``, it is guaranteed that pointer or long /

- For clang ``--target=bpf``, it is guaranteed that pointer or long /

  unsigned long types will always have a width of 64 bit, no matter

  whether underlying clang binary or default target (or kernel) is

  32 bit. However, when native clang target is used, then it will
@@ -668,7 +668,7 @@ independent, ``-target <arch>`` still has some impact on generated code: 
  while the BPF LLVM back end still operates in 64 bit. The native

  target is mostly needed in tracing for the case of walking ``pt_regs``

  or other kernel structures where CPU's register width matters.

  Otherwise, ``clang -target bpf`` is generally recommended.

  Otherwise, ``clang --target=bpf`` is generally recommended.



You should use default target when:
@@ -685,7 +685,7 @@ when: 
  into these structures is verified by the BPF verifier and may result

  in verification failures if the native architecture is not aligned with

  the BPF architecture, e.g. 64-bit. An example of this is

  BPF_PROG_TYPE_SK_MSG require ``-target bpf``

  BPF_PROG_TYPE_SK_MSG require ``--target=bpf``





.. Links

Documentation/bpf/btf.rst

+2 −2
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@@ -990,7 +990,7 @@ format.:: 
    } g2;

    int main() { return 0; }

    int test() { return 0; }

    -bash-4.4$ clang -c -g -O2 -target bpf t2.c

    -bash-4.4$ clang -c -g -O2 --target=bpf t2.c

    -bash-4.4$ readelf -S t2.o

      ......

      [ 8] .BTF              PROGBITS         0000000000000000  00000247
@@ -1000,7 +1000,7 @@ format.:: 
      [10] .rel.BTF.ext      REL              0000000000000000  000007e0

           0000000000000040  0000000000000010          16     9     8

      ......

    -bash-4.4$ clang -S -g -O2 -target bpf t2.c

    -bash-4.4$ clang -S -g -O2 --target=bpf t2.c

    -bash-4.4$ cat t2.s

      ......

            .section        .BTF,"",@progbits

Documentation/bpf/index.rst

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@@ -12,9 +12,9 @@ that goes into great technical depth about the BPF Architecture. 
.. toctree::

   :maxdepth: 1



   instruction-set

   verifier

   libbpf/index

   standardization/index

   btf

   faq

   syscall_api
@@ -29,7 +29,6 @@ that goes into great technical depth about the BPF Architecture. 
   bpf_licensing

   test_debug

   clang-notes

   linux-notes

   other

   redirect

Documentation/bpf/llvm_reloc.rst

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@@ -28,7 +28,7 @@ For example, for the following code:: 
    return g1 + g2 + l1 + l2;

  }



Compiled with ``clang -target bpf -O2 -c test.c``, the following is

Compiled with ``clang --target=bpf -O2 -c test.c``, the following is

the code with ``llvm-objdump -dr test.o``::



       0:       18 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 r1 = 0 ll
@@ -157,7 +157,7 @@ and ``call`` instructions. For example:: 
    return gfunc(a, b) +  lfunc(a, b) + global;

  }



Compiled with ``clang -target bpf -O2 -c test.c``, we will have

Compiled with ``clang --target=bpf -O2 -c test.c``, we will have

following code with `llvm-objdump -dr test.o``::



  Disassembly of section .text:
@@ -203,7 +203,7 @@ The following is an example to show how R_BPF_64_ABS64 could be generated:: 
  int global() { return 0; }

  struct t { void *g; } gbl = { global };



Compiled with ``clang -target bpf -O2 -g -c test.c``, we will see a

Compiled with ``clang --target=bpf -O2 -g -c test.c``, we will see a

relocation below in ``.data`` section with command

``llvm-readelf -r test.o``::

Documentation/bpf/standardization/index.rst

0 → 100644
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.. SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)



===================

BPF Standardization

===================



This directory contains documents that are being iterated on as part of the BPF

standardization effort with the IETF. See the `IETF BPF Working Group`_ page

for the working group charter, documents, and more.



.. toctree::

   :maxdepth: 1



   instruction-set

   linux-notes



.. Links:

.. _IETF BPF Working Group: https://datatracker.ietf.org/wg/bpf/about/