Re: [PATCH v8 0/8] arm64: untag user pointers passed to the kernel

On Thu, Nov 8, 2018 at 3:36 PM, Andrey Konovalov andreyknvl@google.com wrote:

[...]

Changes in v8:

• Rebased onto 65102238 (4.20-rc1).
• Added a note to the cover letter on why syscall wrappers/shims that untag user pointers won't work.
• Added a note to the cover letter that this patchset has been merged into the Pixel 2 kernel tree.
• Documentation fixes, in particular added a list of syscalls that don't support tagged user pointers.

Hi Catalin,

I've changed the documentation to be more specific, please take a look.

I haven't done anything about adding a way for the user to find out that the kernel supports this ABI extension. I don't know what would the the preferred way to do this, and we haven't received any comments on that from anybody else. Probing "on some innocuous syscall currently returning -EFAULT on tagged pointer arguments" works though, as you mentioned.

As mentioned in the cover letter, this patchset has been merged into the Pixel 2 kernel tree.

Thanks!