On Wed, Jan 17, 2018 at 11:54:12AM -0800, Dan Williams wrote: > On Wed, Jan 17, 2018 at 10:52 AM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > > On Wed, Jan 17, 2018 at 02:17:26PM +0000, Alan Cox wrote: > [..] > > Incidentally, what about copy_to_iter() and friends? They > > check iov_iter flavour and go either into the "copy to kernel buffer" > > or "copy to userland" paths. Do we need to deal with mispredictions > > there? We are calling a bunch of those on read()... > > > > Those should be protected by the conversion of __uaccess_begin to > __uaccess_begin_nospec that includes the lfence. Huh? What the hell does it do to speculative execution of "memcpy those suckers" branch?
