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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@xxxxxxxxxx> 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!