On Thu, May 30, 2019 at 7:15 PM Catalin Marinas catalin.marinas@arm.com 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?
- 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.
- 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?
- Should I "add Documentation/core-api/user-addresses.rst to describe
proper care and handling of user space pointers with untagged_addr(), with examples based on all the cases seen so far in this series"? Which examples specifically should it cover?
I think we can leave 3 for now as not too urgent. What I'd like is for Vincenzo's TBI user ABI document to go into a more common place since we can expand it to cover both sparc and arm64. We'd need an arm64-specific doc as well for things like prctl() and later MTE that sparc may support differently.
OK.
-- Catalin