selftests/bpf: validate eliminated global subprog is not freplaceable

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Add selftest that establishes dead code-eliminated valid global subprog
(global_dead) and makes sure that it's not possible to freplace it, as
it's effectively not there. This test will fail with unexpected success
before 2afae08c9d ("bpf: Validate global subprogs lazily").

v2->v3:
  - add missing err assignment (Alan);
  - undo unnecessary signature changes in verifier_global_subprogs.c (Eduard);
v1->v2:
  - don't rely on assembly output in verifier log, which changes between
    compiler versions (CI).

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20231211174131.2324306-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

...

This commit is contained in:

Andrii Nakryiko 2023-12-11 09:41:31 -08:00 • committed by Alexei Starovoitov

parent 2ebe81c814

commit e72c1ccfd4

3 changed files with 83 additions and 3 deletions

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60

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

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11

tools/testing/selftests/bpf/progs/freplace_dead_global_func.c

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15

tools/testing/selftests/bpf/progs/verifier_global_subprogs.c

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