[PATCH v19 00/15] arm64: untag user pointers passed to the kernel

[Dave Hansen]

On 8/1/19 5:48 AM, Andrey Konovalov wrote:
> On Thu, Aug 1, 2019 at 2:11 PM Kevin Brodsky <kevin.brodsky at arm.com> wrote:
>> On 31/07/2019 17:50, Dave Hansen wrote:
>>> On 7/23/19 10:58 AM, Andrey Konovalov wrote:
>>>> The mmap and mremap (only new_addr) syscalls do not currently accept
>>>> tagged addresses. Architectures may interpret the tag as a background
>>>> colour for the corresponding vma.
>>> What the heck is a "background colour"? :)
>> Good point, this is some jargon that we started using for MTE, the idea being that
>> the kernel could set a tag value (specified during mmap()) as "background colour" for
>> anonymous pages allocated in that range.
>>
>> Anyway, this patch series is not about MTE. Andrey, for v20 (if any), I think it's
>> best to drop this last sentence to avoid any confusion.
> Sure, thanks!

OK, but what does that mean for tagged addresses getting passed to
mmap/mremap?  That sentence read to me like "architectures might allow
tags for ...something...".  So do we accept tagged addresses into those
syscalls?