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This change adds a brief summary of the BPF continuous integration (CI)
to the BPF selftest documentation. The summary focuses not so much on
actual workings of the CI, as it is maintained outside of the
repository, but aims to document the few bits of it that are sourced
from this repository and that developers may want to adjust as part of
patch submissions: the BPF kernel configuration and the deny list
file(s).
Changelog:
- v1->v2:
- use s390x instead of s390 for consistency
Signed-off-by: Daniel Müller <deso@posteo.net>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20221018164015.1970862-1-deso@posteo.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Since commit 40b09653b197 ("selftests/bpf: Adjust vmtest.sh to use local
kernel configuration") the vmtest.sh script no longer downloads a kernel
configuration but uses the local, in-repository one.
This change updates the README, which still mentions the old behavior.
Signed-off-by: Daniel Müller <deso@posteo.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221017232458.1272762-1-deso@posteo.net
BPF object files are, in a way, the final artifact produced as part of
the ahead-of-time compilation process. That makes them somewhat special
compared to "regular" object files, which are a intermediate build
artifacts that can typically be removed safely. As such, it can make
sense to name them differently to make it easier to spot this difference
at a glance.
Among others, libbpf-bootstrap [0] has established the extension .bpf.o
for BPF object files. It seems reasonable to follow this example and
establish the same denomination for selftest build artifacts. To that
end, this change adjusts the corresponding part of the build system and
the test programs loading BPF object files to work with .bpf.o files.
[0] https://github.com/libbpf/libbpf-bootstrap
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Müller <deso@posteo.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220901222253.1199242-1-deso@posteo.net
Dynamic linking when compiling on the host can cause issues when the
libc version does not match the one in the VM image. Update the
docs to explain how to do this.
Before:
./vmtest.sh -- ./test_progs -t test_ima
./test_progs: /usr/lib/libc.so.6: version `GLIBC_2.33' not found (required by ./test_progs)
After:
LDLIBS=-static ./vmtest.sh -- ./test_progs -t test_ima
test_ima:OK
Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED
Reported-by: "Geyslan G. Bem" <geyslan@gmail.com>
Signed-off-by: KP Singh <kpsingh@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220307133048.1287644-1-kpsingh@kernel.org
btf_tag selftest needs certain llvm versions (>= llvm14).
Make it clear in the selftests README.rst file.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211112012651.1508549-1-yhs@fb.com
Patch set [1] introduced BTF_KIND_TAG to allow tagging
declarations for struct/union, struct/union field, var, func
and func arguments and these tags will be encoded into
dwarf. They are also encoded to btf by llvm for the bpf target.
After BTF_KIND_TAG is introduced, we intended to use it
for kernel __user attributes. But kernel __user is actually
a type attribute. Upstream and internal discussion showed
it is not a good idea to mix declaration attribute and
type attribute. So we proposed to introduce btf_type_tag
as a type attribute and existing btf_tag renamed to
btf_decl_tag ([2]).
This patch renamed BTF_KIND_TAG to BTF_KIND_DECL_TAG and some
other declarations with *_tag to *_decl_tag to make it clear
the tag is for declaration. In the future, BTF_KIND_TYPE_TAG
might be introduced per [3].
[1] https://lore.kernel.org/bpf/20210914223004.244411-1-yhs@fb.com/
[2] https://reviews.llvm.org/D111588
[3] https://reviews.llvm.org/D111199
Fixes: b5ea834dde6b ("bpf: Support for new btf kind BTF_KIND_TAG")
Fixes: 5b84bd10363e ("libbpf: Add support for BTF_KIND_TAG")
Fixes: 5c07f2fec003 ("bpftool: Add support for BTF_KIND_TAG")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211012164838.3345699-1-yhs@fb.com
Commit c240ba287890 ("selftests/bpf: Add a test with a bpf
program with btf_tag attributes") added btf_tag selftest
to test BTF_KIND_TAG generation from C source code, and to
test kernel validation of generated BTF types.
But if an old clang (clang 13 or earlier) is used, the
following compiler warning may be seen:
progs/tag.c:23:20: warning: unknown attribute 'btf_tag' ignored
and the test itself is marked OK. The compiler warning is bad
and the test itself shouldn't be marked OK.
This patch added the check for btf_tag attribute support.
If btf_tag is not supported by the clang, the attribute will
not be used in the code and the test will be marked as skipped.
For example, with clang 13:
./test_progs -t btf_tag
#21 btf_tag:SKIP
Summary: 1/0 PASSED, 1 SKIPPED, 0 FAILED
The selftests/README.rst is updated to clarify when the btf_tag
test may be skipped.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210915061036.2577971-1-yhs@fb.com
Add a list of vmtest script dependencies to make it easier for new
contributors to get going.
Signed-off-by: Evgeniy Litvinenko <evgeniyl@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210723223645.907802-1-evgeniyl@fb.com
LLVM upstream commit https://reviews.llvm.org/D102712 made some changes
to bpf relocations to make them llvm linker lld friendly. The scope of
existing relocations R_BPF_64_{64,32} is narrowed and new relocations
R_BPF_64_{ABS32,ABS64,NODYLD32} are introduced.
Let us add some documentation about llvm bpf relocations so people can
understand how to resolve them properly in their respective tools.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210526152457.335210-1-yhs@fb.com
This patch updates the README.rst to specify the clang requirement
to compile the bpf selftests that call kernel function.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210330054156.2933804-1-kafai@fb.com
Verify that bpf_core_field_size() is working correctly with floats.
Also document the required clang version.
Suggested-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210309005649.162480-2-iii@linux.ibm.com
The original bcc pull request https://github.com/iovisor/bcc/pull/3270 exposed
a verifier failure with Clang 12/13 while Clang 4 works fine.
Further investigation exposed two issues:
Issue 1: LLVM may generate code which uses less refined value. The issue is
fixed in LLVM patch: https://reviews.llvm.org/D97479
Issue 2: Spills with initial value 0 are marked as precise which makes later
state pruning less effective. This is my rough initial analysis and
further investigation is needed to find how to improve verifier
pruning in such cases.
With the above LLVM patch, for the new loop6.c test, which has smaller loop
bound compared to original test, I got:
$ test_progs -s -n 10/16
...
stack depth 64
processed 390735 insns (limit 1000000) max_states_per_insn 87
total_states 8658 peak_states 964 mark_read 6
#10/16 loop6.o:OK
Use the original loop bound, i.e., commenting out "#define WORKAROUND", I got:
$ test_progs -s -n 10/16
...
BPF program is too large. Processed 1000001 insn
stack depth 64
processed 1000001 insns (limit 1000000) max_states_per_insn 91
total_states 23176 peak_states 5069 mark_read 6
...
#10/16 loop6.o:FAIL
The purpose of this patch is to provide a regression test for the above LLVM fix
and also provide a test case for further analyzing the verifier pruning issue.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Zhenwei Pi <pizhenwei@bytedance.com>
Link: https://lore.kernel.org/bpf/20210226223810.236472-1-yhs@fb.com
Add a short note to make contributors aware of the existence of the
script. The documentation does not intentionally document all the
options of the script to avoid mentioning it in two places (it's
available in the usage / help message of the script).
Signed-off-by: KP Singh <kpsingh@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210204194544.3383814-3-kpsingh@kernel.org
A couple of places in the readme had invalid rst formatting causing the
rendering to be off. This patch fixes them with minimal edits.
Signed-off-by: Andrei Matei <andreimatei1@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20201122022205.57229-2-andreimatei1@gmail.com
The link was bad because of invalid rst; it was pointing to itself and
was rendering badly.
Signed-off-by: Andrei Matei <andreimatei1@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20201122022205.57229-1-andreimatei1@gmail.com
The main purpose of the profiler test to check different llvm generation
patterns to make sure the verifier can load these large programs.
Note that profiler.inc.h test doesn't follow strict kernel coding style.
The code was formatted in the kernel style, but variable declarations are
kept as-is to preserve original llvm IR pattern.
profiler1.c should pass with older and newer llvm
profiler[23].c may fail on older llvm that don't have:
https://reviews.llvm.org/D85570
because llvm may do speculative code motion optimization that
will generate code like this:
// 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
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 the error:
"math between map_value pointer and register with unbounded min value is not allowed"
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 llvm D85570
addresses it on the compiler side.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20201009011240.48506-4-alexei.starovoitov@gmail.com
Record which built-ins are optional and needed for some of recent BPF CO-RE
subtests. Document Clang diff that fixed corner-case issue with
__builtin_btf_type_id().
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200820061411.1755905-4-andriin@fb.com
Getting a clean BPF selftests run involves ensuring latest trunk LLVM/clang
are used, pahole is recent (>=1.16) and config matches the specified
config file as closely as possible. Add to bpf_devel_QA.rst and point
tools/testing/selftests/bpf/README.rst to it.
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/1590146674-25485-1-git-send-email-alan.maguire@oracle.com
Commit 6879c042e105 ("tools/bpf: selftests: Add bpf_iter selftests")
added self tests for bpf_iter feature. But two subtests
ipv6_route and netlink needs llvm latest 10.x release branch
or trunk due to a bug in llvm BPF backend. This patch added
the file README.rst to document these two failures
so people using llvm 10.0.0 can be aware of them.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200513180215.2949237-1-yhs@fb.com
