selftests/bpf: Check per-CPU address resolution per register

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An ld_imm64 of a per-CPU map value is followed by a mov_percpu_addr that
reuses the same register, so which register the address lands in decides
how the JIT encodes the add. Getting the REX prefix wrong there is
invisible to a functional test unless the address happens to land in an
extended register, which is why this went unnoticed.

Load a .percpu variable into every register in one program and match the
JITed add against the register each one must resolve into.

Signed-off-by: Vineet Gupta <vineet.gupta@linux.dev>
Link: https://patch.msgid.link/20260814220254.3797467-3-vineet.gupta@linux.dev
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>

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Vineet Gupta 2026-08-14 15:02:54 -07:00 • committed by Eduard Zingerman

parent 5bbbce02e5

commit f61306e8c9

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

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72

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

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