selftests/bpf: Log arg_track_join for stack arg slots in liveness analysis

Commit 2af4e792773f ("bpf: Extend liveness analysis to track stack argument slots")
added stack arg supports. For selftest
  verifier_stack_arg/stack_arg: pruning with different stack arg types
the following are two arg JOIN messages:
  arg JOIN insn 9 -> 10 r1: fp0-8 + _ => fp0-8|fp0+0
  arg JOIN insn 9 -> 10 r11: fp0-8 + _ => fp0-8|fp0+0

Here the "r11:" label for stack arg slot 0 is misleading since r11
is a special register (BPF_REG_PARAMS). The next patch corrects
this to "sa0:", properly representing the 'stack arg slot 0'.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260515225051.822739-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/progs/verifier_stack_arg.c b/tools/testing/selftests/bpf/progs/verifier_stack_arg.c
index d45339b837959a03fb6d920696d211a5929d8c99..df0c3438529e808d2248a8cc751a8ff5189d9026 100644 (file)
--- a/tools/testing/selftests/bpf/progs/verifier_stack_arg.c
+++ b/tools/testing/selftests/bpf/progs/verifier_stack_arg.c
@@ -114,8 +114,10 @@ __naked void stack_arg_gap_at_minus8(void)
 
 SEC("tc")
 __description("stack_arg: pruning with different stack arg types")
-__failure
+__failure __log_level(2)
 __flag(BPF_F_TEST_STATE_FREQ)
+__msg("arg JOIN insn 9 -> 10 r1: fp0-8 + _ => fp0-8|fp0+0")
+__msg("arg JOIN insn 9 -> 10 r11: fp0-8 + _ => fp0-8|fp0+0")
 __msg("R{{[0-9]}} invalid mem access 'scalar'")
 __naked void stack_arg_pruning_type_mismatch(void)
 {