[bpf-next PATCH 2/4] bpf: selftests, verifier case for non null pointer check branch taken

[John Fastabend]

When we have pointer type that is known to be non-null we only follow
the non-null branch. This adds tests to cover this case for reference
tracking.

Signed-off-by: John Fastabend <john.fastab...@gmail.com>
---
 .../testing/selftests/bpf/verifier/ref_tracking.c  |   16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/tools/testing/selftests/bpf/verifier/ref_tracking.c 
b/tools/testing/selftests/bpf/verifier/ref_tracking.c
index 604b461..d8f7c04 100644
--- a/tools/testing/selftests/bpf/verifier/ref_tracking.c
+++ b/tools/testing/selftests/bpf/verifier/ref_tracking.c
@@ -821,3 +821,19 @@
        .result = REJECT,
        .errstr = "invalid mem access",
 },
+{
+       "reference tracking: branch tracking valid pointer null comparison",
+       .insns = {
+       BPF_SK_LOOKUP(sk_lookup_tcp),
+       BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+       BPF_MOV64_IMM(BPF_REG_3, 1),
+       BPF_JMP_IMM(BPF_JNE, BPF_REG_6, 0, 1),
+       BPF_MOV64_IMM(BPF_REG_3, 0),
+       BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 2),
+       BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+       BPF_EMIT_CALL(BPF_FUNC_sk_release),
+       BPF_EXIT_INSN(),
+       },
+       .prog_type = BPF_PROG_TYPE_SCHED_CLS,
+       .result = ACCEPT,
+},