From: Yonghong Song Date: Fri, 15 May 2026 22:50:56 +0000 (-0700) Subject: bpf: Fix arg_track_join log to use sa prefix for stack arg slots X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d1dbe443a0abb4ea3ec35a16e36efe6d3bbf72f6;p=thirdparty%2Flinux.git bpf: Fix arg_track_join log to use sa prefix for stack arg slots 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: 2af4e792773f ("bpf: Extend liveness analysis to track stack argument slots") Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20260515225056.823086-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov --- diff --git a/kernel/bpf/liveness.c b/kernel/bpf/liveness.c index 7f4a0e4c2c49d..0aadfbae0acc5 100644 --- a/kernel/bpf/liveness.c +++ b/kernel/bpf/liveness.c @@ -806,7 +806,9 @@ static bool arg_track_join(struct bpf_verifier_env *env, int idx, int target, in return true; verbose(env, "arg JOIN insn %d -> %d ", idx, target); - if (r >= 0) + if (r >= MAX_BPF_REG) + verbose(env, "sa%d: ", r - MAX_BPF_REG); + else if (r >= 0) verbose(env, "r%d: ", r); else verbose(env, "fp%+d: ", r * 8); diff --git a/tools/testing/selftests/bpf/progs/verifier_stack_arg.c b/tools/testing/selftests/bpf/progs/verifier_stack_arg.c index df0c3438529e8..7e0ce5db28a0d 100644 --- a/tools/testing/selftests/bpf/progs/verifier_stack_arg.c +++ b/tools/testing/selftests/bpf/progs/verifier_stack_arg.c @@ -117,7 +117,7 @@ __description("stack_arg: pruning with different stack arg types") __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("arg JOIN insn 9 -> 10 sa0: fp0-8 + _ => fp0-8|fp0+0") __msg("R{{[0-9]}} invalid mem access 'scalar'") __naked void stack_arg_pruning_type_mismatch(void) {