Re: [PATCH v16 05/16] arm64: untag user pointers passed to memory syscalls

Andrey Konovalov
2019-06-11T15:35:47Z

On Mon, Jun 10, 2019 at 4:28 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
>
> On Mon, Jun 03, 2019 at 06:55:07PM +0200, Andrey Konovalov wrote:
> > This patch is a part of a series that extends arm64 kernel ABI to allow to
> > pass tagged user pointers (with the top byte set to something else other
> > than 0x00) as syscall arguments.
> >
> > This patch allows tagged pointers to be passed to the following memory
> > syscalls: get_mempolicy, madvise, mbind, mincore, mlock, mlock2, mprotect,
> > mremap, msync, munlock.
> >
> > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
>
> I would add in the commit log (and possibly in the code with a comment)
> that mremap() and mmap() do not currently accept tagged hint addresses.
> Architectures may interpret the hint tag as a background colour for the
> corresponding vma. With this:

I'll change the commit log. Where do you you think I should put this
comment? Before mmap and mremap definitions in mm/?

Thanks!

>
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
>
> --
> Catalin