ARM_R1
[BPF_REG_0] = {ARM_R1, ARM_R0},
const int exclude_mask = BIT(ARM_R0) | BIT(ARM_R1);
if (rn != ARM_R1) {
emit(ARM_MOV_R(tmp[0], ARM_R1), ctx);
emit(ARM_MOV_R(ARM_R1, rn), ctx);
if (rn != ARM_R1)
emit(ARM_MOV_R(ARM_R1, tmp[0]), ctx);
emit(ARM_PUSH(BIT(ARM_R0) | BIT(ARM_R1)), ctx);
emit(ARM_MOV_R(ARM_R1, rm[0]), ctx);
emit(ARM_MOV_R(rd[0], ARM_R1), ctx);
emit(ARM_POP(BIT(ARM_R0) | BIT(ARM_R1)), ctx);
#define CALLER_MASK (1 << ARM_R0 | 1 << ARM_R1 | 1 << ARM_R2 | 1 << ARM_R3)