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.
