Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 268 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/README.rst b/tools/testing/selftests/bpf/README.rst
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+==================
+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
+
+In case of linker errors when running selftests, try using static linking:
+
+.. code-block:: console
+
+  $ LDLIBS=-static vmtest.sh
+
+.. note:: Some distros may not support static linking.
+
+.. 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 and s390x architectures.
+
+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.bpf.o test failure with Clang 12
+======================================================
+
+With Clang 12, the following bpf_verif_scale test failed:
+  * ``bpf_verif_scale/loop6.bpf.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_].
+The subtests ``btf_type_tag_user_{mod1, mod2, vmlinux}`` also requires
+pahole version ``1.23``.
+
+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.bpf.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