Revision tags: v6.6.25, v6.6.24, v6.6.23, v6.6.16, v6.6.15, v6.6.14, v6.6.13, v6.6.12, v6.6.11, v6.6.10, v6.6.9, v6.6.8, v6.6.7, v6.6.6, v6.6.5, v6.6.4, v6.6.3, v6.6.2, v6.5.11, v6.6.1, v6.5.10, v6.6, v6.5.9, v6.5.8, v6.5.7, v6.5.6, v6.5.5, v6.5.4, v6.5.3, v6.5.2, v6.1.51, v6.5.1, v6.1.50, v6.5, v6.1.49, v6.1.48, v6.1.46, v6.1.45, v6.1.44 |
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898f55f5 |
| 08-Aug-2023 |
Eduard Zingerman <eddyz87@gmail.com> |
selftests/bpf: relax expected log messages to allow emitting BPF_ST
Update [1] to LLVM BPF backend seeks to enable generation of BPF_ST instruction when CPUv4 is selected. This affects expected log
selftests/bpf: relax expected log messages to allow emitting BPF_ST
Update [1] to LLVM BPF backend seeks to enable generation of BPF_ST instruction when CPUv4 is selected. This affects expected log messages for the following selftests: - log_fixup/missing_map - spin_lock/lock_id_mapval_preserve - spin_lock/lock_id_innermapval_preserve
Expected messages in these tests hard-code instruction numbers for BPF programs compiled from C. These instruction numbers change when BPF_ST is allowed because single BPF_ST instruction replaces a pair of BPF_MOV/BPF_STX instructions, e.g.:
r1 = 42; *(u32 *)(r10 - 8) = r1; ---> *(u32 *)(r10 - 8) = 42;
This commit updates expected log messages to avoid matching specific instruction numbers (program position still could be uniquely identified).
[1] https://reviews.llvm.org/D140804 "[BPF] support for BPF_ST instruction in codegen"
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20230808162755.392606-1-eddyz87@gmail.com Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
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Revision tags: v6.1.43, v6.1.42, v6.1.41, v6.1.40, v6.1.39, v6.1.38, v6.1.37, v6.1.36, v6.4, v6.1.35, v6.1.34, v6.1.33, v6.1.32, v6.1.31, v6.1.30, v6.1.29, v6.1.28, v6.1.27, v6.1.26, v6.3, v6.1.25 |
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30bbfe32 |
| 17-Apr-2023 |
Andrii Nakryiko <andrii@kernel.org> |
selftests/bpf: add missing __weak kfunc log fixup test
Add test validating that libbpf correctly poisons and reports __weak unresolved kfuncs in post-processed verifier log.
Signed-off-by: Andrii N
selftests/bpf: add missing __weak kfunc log fixup test
Add test validating that libbpf correctly poisons and reports __weak unresolved kfuncs in post-processed verifier log.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20230418002148.3255690-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Revision tags: v6.1.24 |
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12166409 |
| 06-Apr-2023 |
Andrii Nakryiko <andrii@kernel.org> |
bpf: Switch BPF verifier log to be a rotating log by default
Currently, if user-supplied log buffer to collect BPF verifier log turns out to be too small to contain full log, bpf() syscall returns -
bpf: Switch BPF verifier log to be a rotating log by default
Currently, if user-supplied log buffer to collect BPF verifier log turns out to be too small to contain full log, bpf() syscall returns -ENOSPC, fails BPF program verification/load, and preserves first N-1 bytes of the verifier log (where N is the size of user-supplied buffer).
This is problematic in a bunch of common scenarios, especially when working with real-world BPF programs that tend to be pretty complex as far as verification goes and require big log buffers. Typically, it's when debugging tricky cases at log level 2 (verbose). Also, when BPF program is successfully validated, log level 2 is the only way to actually see verifier state progression and all the important details.
Even with log level 1, it's possible to get -ENOSPC even if the final verifier log fits in log buffer, if there is a code path that's deep enough to fill up entire log, even if normally it would be reset later on (there is a logic to chop off successfully validated portions of BPF verifier log).
In short, it's not always possible to pre-size log buffer. Also, what's worse, in practice, the end of the log most often is way more important than the beginning, but verifier stops emitting log as soon as initial log buffer is filled up.
This patch switches BPF verifier log behavior to effectively behave as rotating log. That is, if user-supplied log buffer turns out to be too short, verifier will keep overwriting previously written log, effectively treating user's log buffer as a ring buffer. -ENOSPC is still going to be returned at the end, to notify user that log contents was truncated, but the important last N bytes of the log would be returned, which might be all that user really needs. This consistent -ENOSPC behavior, regardless of rotating or fixed log behavior, allows to prevent backwards compatibility breakage. The only user-visible change is which portion of verifier log user ends up seeing *if buffer is too small*. Given contents of verifier log itself is not an ABI, there is no breakage due to this behavior change. Specialized tools that rely on specific contents of verifier log in -ENOSPC scenario are expected to be easily adapted to accommodate old and new behaviors.
Importantly, though, to preserve good user experience and not require every user-space application to adopt to this new behavior, before exiting to user-space verifier will rotate log (in place) to make it start at the very beginning of user buffer as a continuous zero-terminated string. The contents will be a chopped off N-1 last bytes of full verifier log, of course.
Given beginning of log is sometimes important as well, we add BPF_LOG_FIXED (which equals 8) flag to force old behavior, which allows tools like veristat to request first part of verifier log, if necessary. BPF_LOG_FIXED flag is also a simple and straightforward way to check if BPF verifier supports rotating behavior.
On the implementation side, conceptually, it's all simple. We maintain 64-bit logical start and end positions. If we need to truncate the log, start position will be adjusted accordingly to lag end position by N bytes. We then use those logical positions to calculate their matching actual positions in user buffer and handle wrap around the end of the buffer properly. Finally, right before returning from bpf_check(), we rotate user log buffer contents in-place as necessary, to make log contents contiguous. See comments in relevant functions for details.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Lorenz Bauer <lmb@isovalent.com> Link: https://lore.kernel.org/bpf/20230406234205.323208-4-andrii@kernel.org
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Revision tags: v6.1.23, v6.1.22, v6.1.21, v6.1.20, v6.1.19, v6.1.18, v6.1.17, v6.1.16, v6.1.15 |
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fffc893b |
| 02-Mar-2023 |
Andrii Nakryiko <andrii@kernel.org> |
selftests/bpf: adjust log_fixup's buffer size for proper truncation
Adjust log_fixup's expected buffer length to fix the test. It's pretty finicky in its length expectation, but it doesn't break oft
selftests/bpf: adjust log_fixup's buffer size for proper truncation
Adjust log_fixup's expected buffer length to fix the test. It's pretty finicky in its length expectation, but it doesn't break often. So just adjust the length to work on current kernel and with follow up iterator changes as well.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20230302235015.2044271-6-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Revision tags: v6.1.14, v6.1.13, v6.2, v6.1.12, v6.1.11, v6.1.10, v6.1.9, v6.1.8, v6.1.7, v6.1.6, v6.1.5, v6.0.19, v6.0.18, v6.1.4, v6.1.3, v6.0.17, v6.1.2, v6.0.16, v6.1.1, v6.0.15, v6.0.14, v6.0.13, v6.1, v6.0.12, v6.0.11, v6.0.10, v5.15.80, v6.0.9, v5.15.79, v6.0.8, v5.15.78, v6.0.7, v5.15.77, v5.15.76, v6.0.6, v6.0.5, v5.15.75, v6.0.4, v6.0.3, v6.0.2, v5.15.74, v5.15.73, v6.0.1, v5.15.72, v6.0, v5.15.71, v5.15.70, v5.15.69, v5.15.68, v5.15.67, v5.15.66, v5.15.65, v5.15.64, v5.15.63, v5.15.62, v5.15.61, v5.15.60, v5.15.59, v5.19, v5.15.58, v5.15.57, v5.15.56, v5.15.55, v5.15.54, v5.15.53, v5.15.52, v5.15.51, v5.15.50, v5.15.49, v5.15.48, v5.15.47, v5.15.46, v5.15.45, v5.15.44, v5.15.43, v5.15.42, v5.18, v5.15.41, v5.15.40, v5.15.39, v5.15.38, v5.15.37 |
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68964e15 |
| 27-Apr-2022 |
Andrii Nakryiko <andrii@kernel.org> |
selftests/bpf: Test bpf_map__set_autocreate() and related log fixup logic
Add a subtest that excercises bpf_map__set_autocreate() API and validates that libbpf properly fixes up BPF verifier log wit
selftests/bpf: Test bpf_map__set_autocreate() and related log fixup logic
Add a subtest that excercises bpf_map__set_autocreate() API and validates that libbpf properly fixes up BPF verifier log with correct map information.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220428041523.4089853-5-andrii@kernel.org
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Revision tags: v5.15.36 |
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ea4128eb |
| 25-Apr-2022 |
Andrii Nakryiko <andrii@kernel.org> |
selftests/bpf: Add libbpf's log fixup logic selftests
Add tests validating that libbpf is indeed patching up BPF verifier log with CO-RE relocation details. Also test partial and full truncation sce
selftests/bpf: Add libbpf's log fixup logic selftests
Add tests validating that libbpf is indeed patching up BPF verifier log with CO-RE relocation details. Also test partial and full truncation scenarios.
This test might be a bit fragile due to changing BPF verifier log format. If that proves to be frequently breaking, we can simplify tests or remove the truncation subtests. But for now it seems useful to test it in those conditions that are otherwise rarely occuring in practice.
Also test CO-RE relo failure in a subprog as that excercises subprogram CO-RE relocation mapping logic which doesn't work out of the box without extra relo storage previously done only for gen_loader case.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220426004511.2691730-11-andrii@kernel.org
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