selftests/bpf: Test 32-bit scalar spill pruning in stacksafe()

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Add a test verifying that stacksafe() correctly handles 32-bit scalar
spills when comparing stack states for equivalence during state pruning.

A 32-bit scalar spill creates slot[0-3] = STACK_INVALID and
slot[4-7] = STACK_SPILL. Without the im=4 check in stacksafe(), the
STACK_SPILL vs STACK_MISC mismatch at byte 4 causes pruning to fail,
forcing the verifier to re-explore a path that is provably safe.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260323022410.75444-2-alexei.starovoitov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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Alexei Starovoitov 2026-03-22 19:24:10 -07:00

parent 596bef1d71

commit 7b4f1a29c7

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

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