selftests/bpf: Fix trace_virtqueue_add_sgs test issue with LLVM 17.

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LLVM commit https://reviews.llvm.org/D143726 introduced hoistMinMax optimization
that transformed
  (i < VIRTIO_MAX_SGS) && (i < out_sgs)
into
  i < MIN(VIRTIO_MAX_SGS, out_sgs)

and caused the verifier to stop recognizing such loop as bounded.

Which resulted in the following test failure:

libbpf: prog 'trace_virtqueue_add_sgs': BPF program load failed: Bad address
libbpf: prog 'trace_virtqueue_add_sgs': -- BEGIN PROG LOAD LOG --
The sequence of 8193 jumps is too complex.
verification time 789206 usec
stack depth 56
processed 156446 insns (limit 1000000) max_states_per_insn 7 total_states 1746 peak_states 1701 mark_read 12
-- END PROG LOAD LOG --
libbpf: prog 'trace_virtqueue_add_sgs': failed to load: -14
libbpf: failed to load object 'loop6.bpf.o'

Workaround the verifier limitation for now with inline asm that
prevents this particular optimization.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

...

This commit is contained in:

Alexei Starovoitov 2023-03-14 15:28:11 -07:00

parent 5584d9e63e

commit 3c2611bac0

1 changed files with 3 additions and 0 deletions

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tools/testing/selftests/bpf/progs/loop6.c

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