bpf: Fix arg_track_join log to use sa prefix for stack arg slots

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arg_track_join() logs state transitions at CFG merge points. For
stack arg slots (r >= MAX_BPF_REG), it printed "r11:", "r12:", etc.,
which is misleading since r11 is a special register (BPF_REG_PARAMS)
not meaningful to the user.

Fix it to print "sa0:", "sa1:", etc., matching the per-instruction
transition log in arg_track_log() which already uses the "sa" prefix.

Update the existing stack_arg_pruning_type_mismatch selftest to expect
the corrected format.

Fixes: 2af4e79277 ("bpf: Extend liveness analysis to track stack argument slots")
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260515225056.823086-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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Yonghong Song 2026-05-15 15:50:56 -07:00 • committed by Alexei Starovoitov

parent 0e2647792f

commit d1dbe443a0

2 changed files with 4 additions and 2 deletions

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4

kernel/bpf/liveness.c

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2

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

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