Merge branch 'bpf-fix-a-couple-of-test-failures-with-lto-kernel'

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Yonghong Song says:

====================
bpf: Fix a couple of test failures with LTO kernel

With a LTO kernel built with clang, with one of earlier version of kernel,
I encountered two test failures, ksyms and kprobe_multi_bench_attach/kernel.
Now with latest bpf-next, only kprobe_multi_bench_attach/kernel failed.
But it is possible in the future ksyms selftest may fail again.

Both test failures are due to static variable/function renaming
due to cross-file inlining. For Ksyms failure, the solution is
to strip .llvm.<hash> suffixes for symbols in /proc/kallsyms before
comparing against the ksym in bpf program.
For kprobe_multi_bench_attach/kernel failure, the solution is
to either provide names in /proc/kallsyms to the kernel or
ignore those names who have .llvm.<hash> suffix since the kernel
sym name comparison is against /proc/kallsyms.

Please see each individual patches for details.

Changelogs:
  v2 -> v3:
    - no need to check config file, directly so strstr with '.llvm.'.
    - for kprobe_multi_bench with syms, instead of skipping the syms,
      consult /proc/kallyms to find corresponding names.
    - add a test with populating addrs to the kernel for kprobe
      multi attach.
  v1 -> v2:
    - Let libbpf handle .llvm.<hash suffixes since it may impact
      bpf program ksym.
====================

Link: https://lore.kernel.org/r/20240326041443.1197498-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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This commit is contained in:

Alexei Starovoitov 2024-03-27 18:53:49 -07:00

parent 5da7fb0490 6302bdeb91

commit e478cf26c5

6 changed files with 281 additions and 81 deletions

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26

tools/lib/bpf/libbpf.c

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5

tools/lib/bpf/libbpf_internal.h

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260

tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c

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30

tools/testing/selftests/bpf/prog_tests/ksyms.c

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tools/testing/selftests/bpf/trace_helpers.c

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7

tools/testing/selftests/bpf/trace_helpers.h

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