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linux/tools/testing/selftests/bpf
Daniel Borkmann 973377ffe8 bpf, selftests: Adjust few selftest outcomes wrt unreachable code
In almost all cases from test_verifier that have been changed in here, we've
had an unreachable path with a load from a register which has an invalid
address on purpose. This was basically to make sure that we never walk this
path and to have the verifier complain if it would otherwise. Change it to
match on the right error for unprivileged given we now test these paths
under speculative execution.

There's one case where we match on exact # of insns_processed. Due to the
extra path, this will of course mismatch on unprivileged. Thus, restrict the
test->insn_processed check to privileged-only.

In one other case, we result in a 'pointer comparison prohibited' error. This
is similarly due to verifying an 'invalid' branch where we end up with a value
pointer on one side of the comparison.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
2021-06-14 23:06:38 +02:00
..
benchs bpf/benchs/bench_ringbufs: Remove unneeded semicolon 2021-02-08 13:41:24 -08:00
bpf_testmod selftests: bpf: Add a new test for bare tracepoints 2021-01-20 14:14:05 -08:00
gnu selftests/bpf: get rid of -D__x86_64__ 2017-05-03 09:51:25 -04:00
map_tests bpf, selftests: Update array map tests for per-cpu batched ops 2021-04-28 01:18:12 +02:00
prog_tests selftests/bpf: Add test for l3 use of bpf_redirect_peer 2021-05-25 18:00:28 +02:00
progs selftests/bpf: Add test for l3 use of bpf_redirect_peer 2021-05-25 18:00:28 +02:00
verifier bpf, selftests: Adjust few selftest outcomes wrt unreachable code 2021-06-14 23:06:38 +02:00
.gitignore selftests/bpf: Test syscall command parsing 2021-03-04 18:39:45 -08:00
bench.c selftests: Remove fmod_ret from test_overhead 2020-09-28 17:20:28 -07:00
bench.h selftests/bpf: Add benchmark runner infrastructure 2020-05-13 12:19:38 -07:00
bpf_legacy.h selftests: bpf: Remove unused bpf_map_def_legacy struct 2020-07-08 01:33:14 +02:00
bpf_rand.h bpf: add ld64 imm test cases 2018-05-14 19:11:45 -07:00
bpf_rlimit.h bpf: unify rlimit handling in selftests 2018-02-26 20:11:23 -08:00
bpf_sockopt_helpers.h bpf: Enable bpf_{g,s}etsockopt in BPF_CGROUP_UDP{4,6}_SENDMSG 2021-01-29 02:09:05 +01:00
bpf_tcp_helpers.h bpf: selftests: Bpf_cubic and bpf_dctcp calling kernel functions 2021-03-26 20:41:52 -07:00
bpf_util.h selftests: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
btf_helpers.c selftest/bpf: Add BTF_KIND_FLOAT tests 2021-03-04 17:58:16 -08:00
btf_helpers.h selftests/bpf: Add split BTF dedup selftests 2020-11-05 18:37:31 -08:00
cgroup_helpers.c bpf, selftests: Use single cgroup helpers for both test_sockmap/progs 2020-08-01 20:20:59 -07:00
cgroup_helpers.h bpf, selftests: Use single cgroup helpers for both test_sockmap/progs 2020-08-01 20:20:59 -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 selftests/bpf: run flow dissector tests in skb-less mode 2019-04-23 18:36:34 +02:00
flow_dissector_load.h selftests/bpf: Don't use deprecated libbpf APIs 2020-09-03 17:14:40 -07:00
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 selftests/bpf: Silence ima_setup.sh when not running in verbose mode. 2020-12-10 22:14:32 -08:00
Makefile Kbuild updates for v5.13 2021-04-29 14:24:39 -07:00
Makefile.docs selftests/bpf: Test syscall command parsing 2021-03-04 18:39:45 -08:00
netcnt_common.h selftests/bpf: cgroup local storage-based network counters 2018-10-01 16:18:33 +02:00
network_helpers.c selftests/bpf: Rewrite test_tc_redirect.sh as prog_tests/tc_redirect.c 2021-05-11 23:15:43 +02:00
network_helpers.h selftests/bpf: Rewrite test_tc_redirect.sh as prog_tests/tc_redirect.c 2021-05-11 23:15:43 +02:00
README.rst selftests/bpf: Document latest Clang fix expectations for linking tests 2021-04-23 14:05:28 -07:00
settings selftests: bpf: Switch off timeout 2020-08-06 16:57:05 -07:00
test_bpftool.py selftests/bpf: Add test for "bpftool feature" command 2020-02-26 18:34:34 +01:00
test_bpftool.sh selftests/bpf: Add test for "bpftool feature" command 2020-02-26 18:34:34 +01:00
test_bpftool_build.sh tools/bpf: Remove bpf-helpers from bpftool docs 2021-03-04 18:39:45 -08:00
test_bpftool_metadata.sh selftests/bpf: Test load and dump metadata with btftool and skel 2020-09-15 18:28:27 -07:00
test_btf.h selftest/bpf: Add BTF_KIND_FLOAT tests 2021-03-04 17:58:16 -08:00
test_cgroup_storage.c bpf: Rename BPF_XADD and prepare to encode other atomics in .imm 2021-01-14 18:34:29 -08:00
test_cpp.cpp selftests: Use consistent include paths for libbpf 2020-01-20 16:37:45 -08:00
test_dev_cgroup.c bpf, selftests: Use single cgroup helpers for both test_sockmap/progs 2020-08-01 20:20:59 -07:00
test_doc_build.sh tools/bpf: Remove bpf-helpers from bpftool docs 2021-03-04 18:39:45 -08:00
test_flow_dissector.c selftests/bpf: Remove unneeded semicolon 2021-02-08 17:54:24 -08:00
test_flow_dissector.sh selftests/bpf: Add test based on port range for BPF flow dissector 2020-01-27 11:25:07 +01:00
test_ftrace.sh selftests/bpf: Test function_graph tracer and bpf trampoline together 2019-12-11 15:19:29 -08:00
test_iptunnel_common.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 206 2019-05-30 11:29:53 -07:00
test_kmod.sh selftests: bpf: test_kmod.sh: Fix running out of srctree 2020-07-21 13:26:24 -07:00
test_lirc_mode2.sh media: bpf: add bpf function to report mouse movement 2018-12-09 14:37:18 -08:00
test_lirc_mode2_user.c media: bpf: add bpf function to report mouse movement 2018-12-09 14:37:18 -08:00
test_lpm_map.c bpf: lpm_trie: check left child of last leftmost node for NULL 2019-06-11 13:52:37 +02:00
test_lru_map.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 206 2019-05-30 11:29:53 -07:00
test_lwt_ip_encap.sh selftests/bpf: More compatible nc options in test_lwt_ip_encap 2019-10-08 23:59:22 +02:00
test_lwt_seg6local.sh selftests/bpf: Fix test_lwt_seg6local.sh hangs 2020-07-21 13:26:26 -07:00
test_maps.c selftests/bpf: Work-around EBUSY errors from hashmap update/delete 2020-12-24 01:35:46 +01:00
test_maps.h bpf: Add BPF_MAP_TYPE_SK_STORAGE test to test_maps 2019-04-27 09:07:05 -07:00
test_netcnt.c bpf, selftests: Use single cgroup helpers for both test_sockmap/progs 2020-08-01 20:20:59 -07:00
test_offload.py Kbuild updates for v5.11 2020-12-22 14:02:39 -08:00
test_progs.c selftests/bpf: Don't exit on failed bpf_testmod unload 2021-01-26 17:02:00 +01:00
test_progs.h selftests/bpf: Add remaining ASSERT_xxx() variants 2021-04-26 18:37:13 -07:00
test_select_reuseport_common.h bpf: Test BPF_PROG_TYPE_SK_REUSEPORT 2018-08-11 01:58:46 +02:00
test_skb_cgroup_id.sh kselftests/bpf: use ping6 as the default ipv6 ping binary if it exists 2018-10-31 23:05:30 +01:00
test_skb_cgroup_id_user.c bpf, selftests: Use single cgroup helpers for both test_sockmap/progs 2020-08-01 20:20:59 -07:00
test_sock.c bpf, selftests: Use single cgroup helpers for both test_sockmap/progs 2020-08-01 20:20:59 -07:00
test_sock_addr.c selftests/bpf: Rewrite recvmsg{4,6} asm progs to c in test_sock_addr 2021-01-29 02:09:05 +01:00
test_sock_addr.sh kselftests/bpf: use ping6 as the default ipv6 ping binary if it exists 2018-10-31 23:05:30 +01:00
test_sockmap.c selftests/bpf: Simplify the calculation of variables 2021-03-04 19:25:31 -08:00
test_stub.c selftests/bpf: Integrate verbose verifier log into test_progs 2019-11-24 16:58:45 -08:00
test_sysctl.c bpf, selftests: Use single cgroup helpers for both test_sockmap/progs 2020-08-01 20:20:59 -07:00
test_tag.c bpf: unify rlimit handling in selftests 2018-02-26 20:11:23 -08:00
test_tc_edt.sh selftests/bpf: More compatible nc options in test_tc_edt 2019-10-18 22:33:57 +02:00
test_tc_tunnel.sh selftests, bpf: Extend test_tc_tunnel test with vxlan 2021-03-05 23:58:59 +01:00
test_tcp_check_syncookie.sh selftests/bpf: add test for bpf_tcp_gen_syncookie 2019-07-30 21:03:05 -07:00
test_tcp_check_syncookie_user.c selftests/bpf: add test for bpf_tcp_gen_syncookie 2019-07-30 21:03:05 -07:00
test_tcp_hdr_options.h bpf: selftest: Ensure the child sk inherited all bpf_sock_ops_cb_flags 2020-10-02 11:34:48 -07:00
test_tcpbpf.h selftests/bpf: Add Userspace tests for TCP_WINDOW_CLAMP 2020-12-03 17:23:24 -08:00
test_tcpnotify.h selftests/bpf: add a test case for sock_ops perf-event notification 2018-11-09 09:40:17 +01:00
test_tcpnotify_user.c bpf: Fix compilation warning of selftests 2020-08-06 16:58:42 -07:00
test_tunnel.sh selftest/bpf: Add missed ip6ip6 test back 2020-11-10 15:37:45 -08:00
test_verifier.c bpf, selftests: Adjust few selftest outcomes wrt unreachable code 2021-06-14 23:06:38 +02:00
test_verifier_log.c bpf: unify rlimit handling in selftests 2018-02-26 20:11:23 -08:00
test_xdp_meta.sh tools/bpf: fix batch-mode test failure of test_xdp_redirect.sh 2018-02-06 11:34:42 +01:00
test_xdp_redirect.sh selftests/bpf: Convert test_xdp_redirect.sh to bash 2021-02-11 16:28:02 +01:00
test_xdp_veth.sh selftests, bpf: Add test for veth native XDP 2019-06-24 18:18:30 -07:00
test_xdp_vlan.sh selftests/bpf: reduce time to execute test_xdp_vlan.sh 2019-08-05 11:17:40 -07:00
test_xdp_vlan_mode_generic.sh selftests/bpf: add wrapper scripts for test_xdp_vlan.sh 2019-08-05 11:17:40 -07:00
test_xdp_vlan_mode_native.sh selftests/bpf: add wrapper scripts for test_xdp_vlan.sh 2019-08-05 11:17:40 -07:00
test_xdping.sh selftests/bpf: measure RTT from xdp using xdping 2019-05-31 19:53:45 -07:00
test_xsk.sh selftests: xsk: Implement bpf_link test 2021-03-30 09:24:39 -07:00
testing_helpers.c selftests/bpf: Add link detach tests for cgroup, netns, and xdp bpf_links 2020-08-01 20:38:28 -07:00
testing_helpers.h selftests/bpf: Add link detach tests for cgroup, netns, and xdp bpf_links 2020-08-01 20:38:28 -07:00
trace_helpers.c selftests/bpf: Ksyms_btf to test typed ksyms 2020-10-02 14:59:25 -07:00
trace_helpers.h selftests/bpf: Ksyms_btf to test typed ksyms 2020-10-02 14:59:25 -07:00
urandom_read.c selftests: bpf: modify urandom_read and link it non-statically 2019-03-21 19:37:30 -07:00
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 selftests/bpf: test bpf flow dissection 2018-09-14 12:04:33 -07:00
with_tunnels.sh selftests/bpf: test bpf flow dissection 2018-09-14 12:04:33 -07:00
xdping.c selftests: bpf: correct perror strings 2019-11-28 22:40:30 -08:00
xdping.h selftests/bpf: measure RTT from xdp using xdping 2019-05-31 19:53:45 -07:00
xdpxceiver.c selftests: xsk: Remove unused defines 2021-03-30 09:24:40 -07:00
xdpxceiver.h selftests: xsk: Remove unused defines 2021-03-30 09:24:40 -07:00
xsk_prereqs.sh selftests/bpf: Restructure xsk selftests 2021-02-26 12:08:48 -08:00

==================
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``).

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

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