On Fri, May 31, 2019 at 06:24:06PM +0200, Andrey Konovalov wrote: > On Fri, May 31, 2019 at 6:20 PM Catalin Marinas <catalin.marinas@xxxxxxx> wrote: > > On Fri, May 31, 2019 at 04:29:10PM +0200, Andrey Konovalov wrote: > > > On Thu, May 30, 2019 at 7:15 PM Catalin Marinas <catalin.marinas@xxxxxxx> wrote: > > > > On Tue, May 28, 2019 at 04:14:45PM +0200, Andrey Konovalov wrote: > > > > > Thanks for a lot of valuable input! I've read through all the replies > > > > > and got somewhat lost. What are the changes I need to do to this > > > > > series? > > > > > > > > > > 1. Should I move untagging for memory syscalls back to the generic > > > > > code so other arches would make use of it as well, or should I keep > > > > > the arm64 specific memory syscalls wrappers and address the comments > > > > > on that patch? > > > > > > > > Keep them generic again but make sure we get agreement with Khalid on > > > > the actual ABI implications for sparc. > > > > > > OK, will do. I find it hard to understand what the ABI implications > > > are. I'll post the next version without untagging in brk, mmap, > > > munmap, mremap (for new_address), mmap_pgoff, remap_file_pages, shmat > > > and shmdt. > > > > It's more about not relaxing the ABI to accept non-zero top-byte unless > > we have a use-case for it. For mmap() etc., I don't think that's needed > > but if you think otherwise, please raise it. > > > > > > > 2. Should I make untagging opt-in and controlled by a command line argument? > > > > > > > > Opt-in, yes, but per task rather than kernel command line option. > > > > prctl() is a possibility of opting in. > > > > > > OK. Should I store a flag somewhere in task_struct? Should it be > > > inheritable on clone? > > > > A TIF flag would do but I'd say leave it out for now (default opted in) > > until we figure out the best way to do this (can be a patch on top of > > this series). > > You mean leave the whole opt-in/prctl part out? So the only change > would be to move untagging for memory syscalls into generic code? Yes (or just wait until next week to see if the discussion settles down). -- Catalin
