linux-stable/tools/testing/selftests/bpf
Felix Maurer 61d06f01f9 selftests: bpf: Check bpf_msg_push_data return value
bpf_msg_push_data may return a non-zero value to indicate an error. The
return value should be checked to prevent undetected errors.

To indicate an error, the BPF programs now perform a different action
than their intended one to make the userspace test program notice the
error, i.e., the programs supposed to pass/redirect drop, the program
supposed to drop passes.

Fixes: 84fbfe026a ("bpf: test_sockmap add options to use msg_push_data")
Signed-off-by: Felix Maurer <fmaurer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/89f767bb44005d6b4dd1f42038c438f76b3ebfad.1644601294.git.fmaurer@redhat.com
2022-02-15 10:10:31 -08:00
..
benchs selftests/bpf: Add benchmark for bpf_strncmp() helper 2021-12-11 17:40:23 -08:00
bpf_testmod selftest/bpf: Add a test that reads various addresses. 2021-12-16 21:41:13 +01:00
gnu
map_tests selftests/bpf: Replace all uses of bpf_load_btf() with bpf_btf_load() 2021-12-10 15:29:18 -08:00
prog_tests selftests/bpf: Add test for bpf_timer overwriting crash 2022-02-11 13:13:04 -08:00
progs selftests: bpf: Check bpf_msg_push_data return value 2022-02-15 10:10:31 -08:00
verifier bpf, selftests: Add ringbuf memory type confusion test 2022-01-19 01:27:03 +01:00
.gitignore selftests/bpf: Fix .gitignore to not ignore test_progs.c 2021-09-14 18:41:14 -07:00
bench.c selftests/bpf: Remove explicit setrlimit(RLIMIT_MEMLOCK) in main selftests 2021-12-14 22:16:54 +01:00
bench.h selftests/bpf: Fix checkpatch error on empty function parameter 2021-12-11 17:40:23 -08:00
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_type_tag() 2021-11-11 17:41:11 -08:00
btf_helpers.h
cgroup_helpers.c selftests/bpf: Remove duplicated include in cgroup_helpers 2021-10-20 10:45:09 -07:00
cgroup_helpers.h selftests/bpf: Add per worker cgroup suffix 2021-10-08 14:45:18 -07:00
config selftests/bpf: Add libbpf feature-probing API selftests 2021-12-17 23:11:13 +01:00
flow_dissector_load.c selftests/bpf: Fix flow dissector tests 2021-10-22 16:53:38 -07:00
flow_dissector_load.h selftests/bpf: Use explicit bpf_prog_test_load() calls everywhere 2021-11-07 08:34:23 -08:00
get_cgroup_id_user.c selftests/bpf: Use explicit bpf_prog_test_load() calls everywhere 2021-11-07 08:34:23 -08:00
ima_setup.sh
Makefile selftests/bpf: Enable cross-building with clang 2021-12-16 12:15:05 -08:00
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 selftests/bpf: Clarify llvm dependency with btf_tag selftest 2021-11-11 17:41:11 -08:00
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: Configure dir paths via env in test_bpftool_synctypes.py 2021-11-16 13:56:22 +01:00
test_btf.h selftests/bpf: Add BTF_KIND_TYPE_TAG unit tests 2021-11-11 17:41:11 -08:00
test_cgroup_storage.c selftests/bpf: Migrate selftests to bpf_map_create() 2021-11-25 23:37:38 +01:00
test_cpp.cpp selftests/bpf: Add btf_dump__new to test_cpp 2021-12-23 10:23:51 -08:00
test_dev_cgroup.c selftests/bpf: Use explicit bpf_prog_test_load() calls everywhere 2021-11-07 08:34:23 -08:00
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 selftests/bpf: Fix flow dissector tests 2021-10-22 16:53:38 -07:00
test_ftrace.sh
test_iptunnel_common.h
test_kmod.sh
test_lirc_mode2.sh
test_lirc_mode2_user.c tools headers UAPI: remove stale lirc.h 2022-01-25 17:56:24 -08:00
test_lpm_map.c selftests/bpf: Migrate selftests to bpf_map_create() 2021-11-25 23:37:38 +01:00
test_lru_map.c selftests/bpf: Migrate selftests to bpf_map_create() 2021-11-25 23:37:38 +01:00
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: Remove explicit setrlimit(RLIMIT_MEMLOCK) in main selftests 2021-12-14 22:16:54 +01:00
test_maps.h
test_offload.py
test_progs.c selftests/bpf: Remove explicit setrlimit(RLIMIT_MEMLOCK) in main selftests 2021-12-14 22:16:54 +01:00
test_progs.h selftests/bpf: Add parallelism to test_progs 2021-10-08 14:37:56 -07:00
test_select_reuseport_common.h
test_skb_cgroup_id.sh
test_skb_cgroup_id_user.c
test_sock.c bpf: selftests: Add bind retry for post_bind{4, 6} 2022-01-06 17:08:35 -08:00
test_sock_addr.c selftests/bpf: Remove all the uses of deprecated bpf_prog_load_xattr() 2021-12-02 15:23:40 -08:00
test_sock_addr.sh
test_sockmap.c selftests, bpf: Add one test for sockmap with strparser 2021-11-01 17:08:21 +01:00
test_sysctl.c selftests/bpf: Use explicit bpf_prog_test_load() calls everywhere 2021-11-07 08:34:23 -08:00
test_tag.c selftests/bpf: Migrate selftests to bpf_map_create() 2021-11-25 23:37:38 +01:00
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: Migrate all deprecated perf_buffer uses 2021-11-11 16:54:05 -08:00
test_tunnel.sh seltests: bpf: test_tunnel: Use ip neigh 2021-09-21 20:40:16 -07:00
test_verifier.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-12-31 14:35:40 +00:00
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/xdp_redirect_multi: Limit the tests in netns 2021-11-05 16:42:56 +01:00
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 selftests/bpf: Remove the only use of deprecated bpf_object__load_xattr() 2021-12-10 15:29:18 -08:00
testing_helpers.h selftests/bpf: Merge test_stub.c into testing_helpers.c 2021-11-07 08:34:23 -08:00
trace_helpers.c selftests/bpf: Guess function end for test_get_branch_snapshot 2021-10-25 21:43:05 -07:00
trace_helpers.h selftests/bpf: Guess function end for test_get_branch_snapshot 2021-10-25 21:43:05 -07:00
urandom_read.c
vmtest.sh selftests/bpf: Correct the INDEX address in vmtest.sh 2021-12-20 11:01:31 -08:00
with_addr.sh
with_tunnels.sh
xdp_redirect_multi.c selftests/bpf: Remove all the uses of deprecated bpf_prog_load_xattr() 2021-12-02 15:23:40 -08:00
xdping.c selftests/bpf: Use explicit bpf_prog_test_load() calls everywhere 2021-11-07 08:34:23 -08:00
xdping.h
xdpxceiver.c selftests/bpf: Mute xdpxceiver.c's deprecation warnings 2021-12-02 15:23:40 -08:00
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 requires LLVM support to recognize the btf_decl_tag and
btf_type_tag attributes. They are introduced in `Clang 14` [0_, 1_].

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

.. code-block:: console

  #<test_num> btf_tag:SKIP

.. _0: https://reviews.llvm.org/D111588
.. _1: https://reviews.llvm.org/D111199

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