Re: [PATCH v2 4/4] x86/vmalloc: Add TLB efficient x86 arch_vunmap

[Nadav Amit]

> On Dec 11, 2018, at 4:03 PM, Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx> wrote:
> 
> This adds a more efficient x86 architecture specific implementation of
> arch_vunmap, that can free any type of special permission memory with only 1 TLB
> flush.
> 
> In order to enable this, _set_pages_p and _set_pages_np are made non-static and
> renamed set_pages_p_noflush and set_pages_np_noflush to better communicate
> their different (non-flushing) behavior from the rest of the set_pages_*
> functions.
> 
> The method for doing this with only 1 TLB flush was suggested by Andy
> Lutomirski.
> 

[snip]

> +	/*
> +	 * If the vm being freed has security sensitive capabilities such as
> +	 * executable we need to make sure there is no W window on the directmap
> +	 * before removing the X in the TLB. So we set not present first so we
> +	 * can flush without any other CPU picking up the mapping. Then we reset
> +	 * RW+P without a flush, since NP prevented it from being cached by
> +	 * other cpus.
> +	 */
> +	set_area_direct_np(area);
> +	vm_unmap_aliases();

Does vm_unmap_aliases() flush in the TLB the direct mapping range as well? I
can only find the flush of the vmalloc range.