On Fri, Jul 22, 2016 at 11:18 AM, Dave Hansen <[email protected]> wrote: > On 07/22/2016 11:10 AM, Andy Lutomirski wrote: >> On Jul 22, 2016 11:03 AM, "Dave Hansen" <[email protected]> wrote: >>> From: Dave Hansen <[email protected]> >>> >>> probe_kernel_address() has an unfortunate name since it is used >>> to probe kernel *and* userspace addresses. Add a comment >>> explaining some of the situation to help the next developer who >>> might make the silly assumption that it is for probing kernel >>> addresses. >> >> This can't work on architectures like s390 that have separate, >> overlapping user and kernel address spaces. Maybe we should fix x86 >> to stop abusing it and use get_user instead. (In which case, your new >> function should be called get_user_insn_byte or similar.) > > Urg. > > But can't the x86 use in no_context() be called from a kernel-initiated > fault? Like a prefetch instruction to a vmalloc() page that we needed > to do a vmalloc fault for? > > In either case, it would be awfully nice to have the clarity about > exactly what is being probed. The other 2 calls to is_prefetch() do > appear to be userspace-only.
Indeed. Perhaps we should pass a bool is_kernel into is_prefetch(). --Andy -- Andy Lutomirski AMA Capital Management, LLC
