linux-stable/tools/testing/selftests/bpf
Hou Tao fa7f17d066 bpf/selftests: Add test for writable bare tracepoint
Add a writable bare tracepoint in bpf_testmod module, and
trigger its calling when reading /sys/kernel/bpf_testmod
with a specific buffer length. The reading will return
the value in writable context if the early return flag
is enabled in writable context.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211004094857.30868-4-hotforest@gmail.com
2021-10-08 13:22:57 -07:00
..
benchs selftests/bpf: Turn on libbpf 1.0 mode and fix all IS_ERR checks 2021-05-25 17:32:35 -07:00
bpf_testmod bpf/selftests: Add test for writable bare tracepoint 2021-10-08 13:22:57 -07:00
gnu
map_tests bpf, selftests: Update array map tests for per-cpu batched ops 2021-04-28 01:18:12 +02:00
prog_tests bpf/selftests: Add test for writable bare tracepoint 2021-10-08 13:22:57 -07:00
progs bpf/selftests: Add test for writable bare tracepoint 2021-10-08 13:22:57 -07:00
verifier bpf, x64: Save bytes for DIV by reducing reg copies 2021-10-06 15:24:36 +02:00
.gitignore selftests/bpf: Fix .gitignore to not ignore test_progs.c 2021-09-14 18:41:14 -07:00
bench.c selftests/bpf: Turn on libbpf 1.0 mode and fix all IS_ERR checks 2021-05-25 17:32:35 -07:00
bench.h
bpf_legacy.h
bpf_rand.h
bpf_rlimit.h
bpf_sockopt_helpers.h
bpf_tcp_helpers.h bpf: selftests: Add sk_state to bpf_tcp_helpers.h 2021-08-25 17:40:35 -07:00
bpf_util.h
btf_helpers.c selftests/bpf: Test libbpf API function btf__add_tag() 2021-09-14 18:45:52 -07:00
btf_helpers.h
cgroup_helpers.c bpf, selftests: Add cgroup v1 net_cls classid helpers 2021-09-13 16:35:58 -07:00
cgroup_helpers.h bpf, selftests: Add cgroup v1 net_cls classid helpers 2021-09-13 16:35:58 -07:00
config bpf: selftests: Specify CONFIG_DYNAMIC_FTRACE in the testing config 2021-04-03 09:09:50 -07:00
flow_dissector_load.c
flow_dissector_load.h
get_cgroup_id_user.c selftests/bpf: Use nanosleep() syscall instead of sleep() in get_cgroup_id 2021-03-17 00:16:59 +01:00
ima_setup.sh
Makefile bpftool: Add install-bin target to install binary only 2021-10-08 12:02:40 -07:00
Makefile.docs selftests, bpf: Make docs tests fail more reliably 2021-06-08 22:04:35 +02:00
netcnt_common.h bpf: Increase supported cgroup storage value size 2021-07-27 15:59:29 -07:00
network_helpers.c bpf, selftests: Add test case for mixed cgroup v1/v2 2021-09-13 16:35:58 -07:00
network_helpers.h bpf, selftests: Add test case for mixed cgroup v1/v2 2021-09-13 16:35:58 -07:00
README.rst bpf: selftest: A bpf prog that has a 32bit scalar spill 2021-09-26 13:07:28 -07:00
settings
test_bpftool.py bpftool: Only probe trace_vprintk feature in 'full' mode 2021-09-17 14:02:05 -07:00
test_bpftool.sh selftests/bpf: Add missing files required by test_bpftool.sh for installing 2021-08-24 14:01:10 -07:00
test_bpftool_build.sh selftests/bpf: Better clean up for runqslower in test_bpftool_build.sh 2021-10-08 12:02:38 -07:00
test_bpftool_metadata.sh
test_bpftool_synctypes.py selftests/bpf: Update bpftool's consistency script for checking options 2021-07-30 15:40:27 -07:00
test_btf.h selftests/bpf: Add BTF_KIND_TAG unit tests 2021-09-14 18:45:52 -07:00
test_cgroup_storage.c
test_cpp.cpp
test_dev_cgroup.c
test_doc_build.sh selftests/bpf: Exit with KSFT_SKIP if no Makefile found 2021-08-24 14:01:10 -07:00
test_flow_dissector.c
test_flow_dissector.sh
test_ftrace.sh
test_iptunnel_common.h
test_kmod.sh
test_lirc_mode2.sh
test_lirc_mode2_user.c
test_lpm_map.c
test_lru_map.c selftests/bpf: Add bpf_lookup_and_delete_elem tests 2021-05-24 13:30:52 -07:00
test_lwt_ip_encap.sh selftests, bpf: test_lwt_ip_encap: Really disable rp_filter 2021-09-28 09:30:38 +02:00
test_lwt_seg6local.sh
test_maps.c selftests/bpf: Enlarge select() timeout for test_maps 2021-08-24 14:01:10 -07:00
test_maps.h
test_offload.py
test_progs.c bpf/selftests: Add test for writable bare tracepoint 2021-10-08 13:22:57 -07:00
test_progs.h bpf/selftests: Add test for writable bare tracepoint 2021-10-08 13:22:57 -07:00
test_select_reuseport_common.h
test_skb_cgroup_id.sh
test_skb_cgroup_id_user.c
test_sock.c
test_sock_addr.c
test_sock_addr.sh
test_sockmap.c selftests/bpf: Simplify the calculation of variables 2021-03-04 19:25:31 -08:00
test_stub.c
test_sysctl.c
test_tag.c
test_tc_edt.sh
test_tc_tunnel.sh selftests, bpf: test_tc_tunnel.sh nc: Cannot use -p and -l 2021-07-20 13:43:00 -07:00
test_tcp_check_syncookie.sh selftests/bpf: Switch SEC("classifier*") usage to a strict SEC("tc") 2021-09-28 13:51:19 -07:00
test_tcp_check_syncookie_user.c
test_tcp_hdr_options.h
test_tcpbpf.h
test_tcpnotify.h
test_tcpnotify_user.c selftests/bpf: Turn on libbpf 1.0 mode and fix all IS_ERR checks 2021-05-25 17:32:35 -07:00
test_tunnel.sh seltests: bpf: test_tunnel: Use ip neigh 2021-09-21 20:40:16 -07:00
test_verifier.c bpf, selftests: Adjust few selftest outcomes wrt unreachable code 2021-06-14 23:06:38 +02:00
test_verifier_log.c
test_xdp_meta.sh selftests/bpf: Use kselftest skip code for skipped tests 2021-09-30 23:09:17 +02:00
test_xdp_redirect.sh selftests/bpf: Normalize XDP section names in selftests 2021-09-28 13:51:19 -07:00
test_xdp_redirect_multi.sh selftests/bpf: Normalize XDP section names in selftests 2021-09-28 13:51:19 -07:00
test_xdp_veth.sh selftests/bpf: Normalize XDP section names in selftests 2021-09-28 13:51:19 -07:00
test_xdp_vlan.sh selftests/bpf: Use kselftest skip code for skipped tests 2021-09-30 23:09:17 +02:00
test_xdp_vlan_mode_generic.sh
test_xdp_vlan_mode_native.sh
test_xdping.sh
test_xsk.sh selftests: xsk: Remove color mode 2021-08-25 12:21:59 -07:00
testing_helpers.c
testing_helpers.h
trace_helpers.c selftests/bpf: Add test for bpf_get_branch_snapshot 2021-09-13 10:53:50 -07:00
trace_helpers.h selftests/bpf: Add test for bpf_get_branch_snapshot 2021-09-13 10:53:50 -07:00
urandom_read.c
vmtest.sh selftests/bpf: Add an option for a debug shell in vmtest.sh 2021-03-30 22:05:23 -07:00
with_addr.sh
with_tunnels.sh
xdp_redirect_multi.c selftests/bpf: Add xdp_redirect_multi test 2021-05-26 09:46:16 +02:00
xdping.c selftests/bpf: Switch to new bpf_object__next_{map,program} APIs 2021-10-06 12:34:02 -07:00
xdping.h
xdpxceiver.c selftests: xsk: Add frame_headroom test 2021-09-28 00:18:35 +02:00
xdpxceiver.h selftests: xsk: Add frame_headroom test 2021-09-28 00:18:35 +02:00
xsk_prereqs.sh selftests: xsk: Remove the num_tx_packets option 2021-08-25 12:22:00 -07:00

==================
BPF Selftest Notes
==================
General instructions on running selftests can be found in
`Documentation/bpf/bpf_devel_QA.rst`__.

__ /Documentation/bpf/bpf_devel_QA.rst#q-how-to-run-bpf-selftests

=========================
Running Selftests in a VM
=========================

It's now possible to run the selftests using ``tools/testing/selftests/bpf/vmtest.sh``.
The script tries to ensure that the tests are run with the same environment as they
would be run post-submit in the CI used by the Maintainers.

This script downloads a suitable Kconfig and VM userspace image from the system used by
the CI. It builds the kernel (without overwriting your existing Kconfig), recompiles the
bpf selftests, runs them (by default ``tools/testing/selftests/bpf/test_progs``) and
saves the resulting output (by default in ``~/.bpf_selftests``).

Script dependencies:
- clang (preferably built from sources, https://github.com/llvm/llvm-project);
- pahole (preferably built from sources, https://git.kernel.org/pub/scm/devel/pahole/pahole.git/);
- qemu;
- docutils (for ``rst2man``);
- libcap-devel.

For more information on about using the script, run:

.. code-block:: console

  $ tools/testing/selftests/bpf/vmtest.sh -h

.. note:: The script uses pahole and clang based on host environment setting.
          If you want to change pahole and llvm, you can change `PATH` environment
          variable in the beginning of script.

.. note:: The script currently only supports x86_64.

Additional information about selftest failures are
documented here.

profiler[23] test failures with clang/llvm <12.0.0
==================================================

With clang/llvm <12.0.0, the profiler[23] test may fail.
The symptom looks like

.. code-block:: c

  // r9 is a pointer to map_value
  // r7 is a scalar
  17:       bf 96 00 00 00 00 00 00 r6 = r9
  18:       0f 76 00 00 00 00 00 00 r6 += r7
  math between map_value pointer and register with unbounded min value is not allowed

  // the instructions below will not be seen in the verifier log
  19:       a5 07 01 00 01 01 00 00 if r7 < 257 goto +1
  20:       bf 96 00 00 00 00 00 00 r6 = r9
  // r6 is used here

The verifier will reject such code with above error.
At insn 18 the r7 is indeed unbounded. The later insn 19 checks the bounds and
the insn 20 undoes map_value addition. It is currently impossible for the
verifier to understand such speculative pointer arithmetic.
Hence `this patch`__ addresses it on the compiler side. It was committed on llvm 12.

__ https://reviews.llvm.org/D85570

The corresponding C code

.. code-block:: c

  for (int i = 0; i < MAX_CGROUPS_PATH_DEPTH; i++) {
          filepart_length = bpf_probe_read_str(payload, ...);
          if (filepart_length <= MAX_PATH) {
                  barrier_var(filepart_length); // workaround
                  payload += filepart_length;
          }
  }

bpf_iter test failures with clang/llvm 10.0.0
=============================================

With clang/llvm 10.0.0, the following two bpf_iter tests failed:
  * ``bpf_iter/ipv6_route``
  * ``bpf_iter/netlink``

The symptom for ``bpf_iter/ipv6_route`` looks like

.. code-block:: c

  2: (79) r8 = *(u64 *)(r1 +8)
  ...
  14: (bf) r2 = r8
  15: (0f) r2 += r1
  ; BPF_SEQ_PRINTF(seq, "%pi6 %02x ", &rt->fib6_dst.addr, rt->fib6_dst.plen);
  16: (7b) *(u64 *)(r8 +64) = r2
  only read is supported

The symptom for ``bpf_iter/netlink`` looks like

.. code-block:: c

  ; struct netlink_sock *nlk = ctx->sk;
  2: (79) r7 = *(u64 *)(r1 +8)
  ...
  15: (bf) r2 = r7
  16: (0f) r2 += r1
  ; BPF_SEQ_PRINTF(seq, "%pK %-3d ", s, s->sk_protocol);
  17: (7b) *(u64 *)(r7 +0) = r2
  only read is supported

This is due to a llvm BPF backend bug. `The fix`__
has been pushed to llvm 10.x release branch and will be
available in 10.0.1. The patch is available in llvm 11.0.0 trunk.

__  https://reviews.llvm.org/D78466

bpf_verif_scale/loop6.o test failure with Clang 12
==================================================

With Clang 12, the following bpf_verif_scale test failed:
  * ``bpf_verif_scale/loop6.o``

The verifier output looks like

.. code-block:: c

  R1 type=ctx expected=fp
  The sequence of 8193 jumps is too complex.

The reason is compiler generating the following code

.. code-block:: c

  ;       for (i = 0; (i < VIRTIO_MAX_SGS) && (i < num); i++) {
      14:       16 05 40 00 00 00 00 00 if w5 == 0 goto +64 <LBB0_6>
      15:       bc 51 00 00 00 00 00 00 w1 = w5
      16:       04 01 00 00 ff ff ff ff w1 += -1
      17:       67 05 00 00 20 00 00 00 r5 <<= 32
      18:       77 05 00 00 20 00 00 00 r5 >>= 32
      19:       a6 01 01 00 05 00 00 00 if w1 < 5 goto +1 <LBB0_4>
      20:       b7 05 00 00 06 00 00 00 r5 = 6
  00000000000000a8 <LBB0_4>:
      21:       b7 02 00 00 00 00 00 00 r2 = 0
      22:       b7 01 00 00 00 00 00 00 r1 = 0
  ;       for (i = 0; (i < VIRTIO_MAX_SGS) && (i < num); i++) {
      23:       7b 1a e0 ff 00 00 00 00 *(u64 *)(r10 - 32) = r1
      24:       7b 5a c0 ff 00 00 00 00 *(u64 *)(r10 - 64) = r5

Note that insn #15 has w1 = w5 and w1 is refined later but
r5(w5) is eventually saved on stack at insn #24 for later use.
This cause later verifier failure. The bug has been `fixed`__ in
Clang 13.

__  https://reviews.llvm.org/D97479

BPF CO-RE-based tests and Clang version
=======================================

A set of selftests use BPF target-specific built-ins, which might require
bleeding-edge Clang versions (Clang 12 nightly at this time).

Few sub-tests of core_reloc test suit (part of test_progs test runner) require
the following built-ins, listed with corresponding Clang diffs introducing
them to Clang/LLVM. These sub-tests are going to be skipped if Clang is too
old to support them, they shouldn't cause build failures or runtime test
failures:

- __builtin_btf_type_id() [0_, 1_, 2_];
- __builtin_preserve_type_info(), __builtin_preserve_enum_value() [3_, 4_].

.. _0: https://reviews.llvm.org/D74572
.. _1: https://reviews.llvm.org/D74668
.. _2: https://reviews.llvm.org/D85174
.. _3: https://reviews.llvm.org/D83878
.. _4: https://reviews.llvm.org/D83242

Floating-point tests and Clang version
======================================

Certain selftests, e.g. core_reloc, require support for the floating-point
types, which was introduced in `Clang 13`__. The older Clang versions will
either crash when compiling these tests, or generate an incorrect BTF.

__  https://reviews.llvm.org/D83289

Kernel function call test and Clang version
===========================================

Some selftests (e.g. kfunc_call and bpf_tcp_ca) require a LLVM support
to generate extern function in BTF.  It was introduced in `Clang 13`__.

Without it, the error from compiling bpf selftests looks like:

.. code-block:: console

  libbpf: failed to find BTF for extern 'tcp_slow_start' [25] section: -2

__ https://reviews.llvm.org/D93563

btf_tag test and Clang version
==============================

The btf_tag selftest require LLVM support to recognize the btf_tag attribute.
It was introduced in `Clang 14`__.

Without it, the btf_tag selftest will be skipped and you will observe:

.. code-block:: console

  #<test_num> btf_tag:SKIP

__ https://reviews.llvm.org/D106614

Clang dependencies for static linking tests
===========================================

linked_vars, linked_maps, and linked_funcs tests depend on `Clang fix`__ to
generate valid BTF information for weak variables. Please make sure you use
Clang that contains the fix.

__ https://reviews.llvm.org/D100362

Clang relocation changes
========================

Clang 13 patch `clang reloc patch`_  made some changes on relocations such
that existing relocation types are broken into more types and
each new type corresponds to only one way to resolve relocation.
See `kernel llvm reloc`_ for more explanation and some examples.
Using clang 13 to compile old libbpf which has static linker support,
there will be a compilation failure::

  libbpf: ELF relo #0 in section #6 has unexpected type 2 in .../bpf_tcp_nogpl.o

Here, ``type 2`` refers to new relocation type ``R_BPF_64_ABS64``.
To fix this issue, user newer libbpf.

.. Links
.. _clang reloc patch: https://reviews.llvm.org/D102712
.. _kernel llvm reloc: /Documentation/bpf/llvm_reloc.rst

Clang dependencies for the u32 spill test (xdpwall)
===================================================
The xdpwall selftest requires a change in `Clang 14`__.

Without it, the xdpwall selftest will fail and the error message
from running test_progs will look like:

.. code-block:: console

  test_xdpwall:FAIL:Does LLVM have https://reviews.llvm.org/D109073? unexpected error: -4007

__ https://reviews.llvm.org/D109073