Commit fce7bd8e authored May 07, 2025 by Peilin Ye Committed by Alexei Starovoitov May 09, 2025

bpf/verifier: Handle BPF_LOAD_ACQ instructions in insn_def_regno()



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.

Acked-by: Björn Töpel <bjorn@kernel.org>
Tested-by: Björn Töpel <bjorn@rivosinc.com> # QEMU/RVA23
Signed-off-by: Peilin Ye <yepeilin@google.com>
Reviewed-by: Pu Lehui <pulehui@huawei.com>
Link: https://lore.kernel.org/r/09cb2aec979aaed9d16db41f0f5b364de39377c0.1746588351.git.yepeilin@google.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>

parent b69d4413

kernel/bpf/verifier.c

+6 −6

Original line number	Diff line number	Diff line
		@@ -3649,16 +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;
		}
		return -1;
		default:
		return insn->dst_reg;
		}