Re: [PATCH] linux-user/aarch64: Do not clear PROT_MTE on mprotect

[Peter Maydell]

On Mon, 11 Jul 2022 at 04:14, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> The documentation for PROT_MTE says that it cannot be cleared
> by mprotect.  Further, the implementation of the VM_ARCH_CLEAR bit,
> contains PROT_BTI confiming that bit should be cleared.
>
> Introduce PAGE_TARGET_STICKY to allow target/arch/cpu.h to control
> which bits may be reset during page_set_flags.  This is sort of the
> opposite of VM_ARCH_CLEAR, but works better with qemu's PAGE_* bits
> that are separate from PROT_* bits.
>
> Reported-by: Vitaly Buka <vitalybuka@google.com>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>
> My initial reaction to the bug report was that we weren't treating
> the other PAGE_* bits properly during the update.  But auditing the
> code more thoroughly shows we are -- it's just PROT_MTE that's not
> up to scratch.


Applied to target-arm.next, thanks.

-- PMM