How can we manipulate the 32 bits high order and 32 bits low order of u64 type in Linux kernel. I tried this one, but the compiler reported a lot of warnings.

```
#define HI_BYTES(_a) (_a & 0xffffffff00000000)
#define LO_BYTES(_a) (_a & 0x00000000ffffffff)
/* _v is 32 bit value */
#define HI_BYTES_SET(_a, _v) do {_a = (_a & 0x00000000ffffffff) | (_v << 32)} while (0)
#define LO_BYTES_SET(_a, _v) do {_a = (_a & 0xffffffff00000000) | (_v)} while (0)

```

Any suggestions are appreciated. Thank a lot!