[PATCH bpf-next 1/8] bpf/verifier: Handle BPF_LOAD_ACQ instructions in insn_def_regno()

[Peilin Ye]

In preparation for supporting BPF load-acquire and store-release
instructions for architectures where bpf_jit_needs_zext() returns true
(e.g. riscv64), make insn_def_regno() handle load-acquires properly.

Signed-off-by: Peilin Ye <yepeilin at google.com>
---
 kernel/bpf/verifier.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 54c6953a8b84..6435ea23fee4 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3649,13 +3649,16 @@ static int insn_def_regno(const struct bpf_insn *insn)
 	case BPF_ST:
 		return -1;
 	case BPF_STX:
-		if ((BPF_MODE(insn->code) == BPF_ATOMIC ||
-		     BPF_MODE(insn->code) == BPF_PROBE_ATOMIC) &&
-		    (insn->imm & BPF_FETCH)) {
+		if (BPF_MODE(insn->code) == BPF_ATOMIC ||
+		    BPF_MODE(insn->code) == BPF_PROBE_ATOMIC) {
 			if (insn->imm == BPF_CMPXCHG)
 				return BPF_REG_0;
-			else
+			else if (insn->imm == BPF_LOAD_ACQ)
+				return insn->dst_reg;
+			else if (insn->imm & BPF_FETCH)
 				return insn->src_reg;
+			else
+				return -1;
 		} else {
 			return -1;
 		}
-- 
2.49.0.901.g37484f566f-goog