Re: [musl] [PATCH] mallocng: Add MTE support for Aarch64

[Rich Felker <dalias@libc.org>]

On Mon, Jun 10, 2024 at 03:36:25PM +0300, Stefan Jumarea wrote:
> Add support for Memory Tagging Extension.
> 
> All the memory tagging code is placed within compiler guards, and is
> enabled by using the `--enable-mte` configure option.
> The option can only be used if compiling for Aarch64.
> 
> All the primitives for generating, storing and loading the memory tags
> are placed in a new header under `arch/aarch64/`.
> 
> For now, only the actual user data is tagged. All metadata is untagged.

It's exciting to see a (presumably working) implementation of this --
mallocng was designed with the intent to support things like MTE. I
haven't read it in detail but I think to be acceptable upstream it
will need some adjustments. One very minor thing is that all the
uint64_t should be uintptr_t. But it looks like there's a lot of
repetitition of the pattern of getting the untagged pointer, where in
many cases, it could be done in the function the pointer is passed to
(things like get_meta).

I'll follow up with more detailed review later.

Rich