On Mon, Dec 4, 2023 at 1:12 AM Hou Tao <houtao@xxxxxxxxxxxxxxx> wrote: > > Hi, > > On 12/4/2023 3:04 AM, Alexei Starovoitov wrote: > > On Thu, Nov 30, 2023 at 10:01:20PM +0800, Hou Tao wrote: > >> > >> - prog_load_attr.license = (long) license; > >> - prog_load_attr.insns = (long) insns; > >> + prog_load_attr.license = (unsigned long)license; > >> + prog_load_attr.insns = (unsigned long)insns; > > Maybes keep it as (long) ? > > There are plenty of case where we cast a pointer to (long) because > > it's less verbose. Signedness shouldn't really matter. > > It matters for 32-bits host. Because insns and license are the pointers > in kernel space, so the MSB of these pointer must be 1 under 32-bits > host. Assuming the value of license is 0xc000-0000, if using (u64)(long) > to cast the value of license, the final value will be > 0xffff-ffff-c000-0000, instead of 0x0000-0000-c000-0000. but on 32-bit host upper bits will be ignored anyway. The kernel will cast aligned_u64 to (void*) first.
