Re: [PATCH 2/3] x86/mm/pti: Don't clear permissions in pti_clone_pmd()

[Dave Hansen]

On 08/07/2018 03:24 AM, Joerg Roedel wrote:
> The function sets the global-bit on cloned PMD entries,
> which only makes sense when the permissions are identical
> between the user and the kernel page-table.
> 
> Further, only write-permissions are cleared for entry-text
> and kernel-text sections, which are not writeable anyway.

I think this patch is correct, but I'd be curious if Andy remembers why
we chose to clear _PAGE_RW on these things.  It might have been that we
were trying to say that the *entry* code shouldn't write to this stuff,
regardless of whether the normal kernel can.

But, either way, I agree with the logic here that Global pages must
share permissions between both mappings, so feel free to add my Ack.  I
just want to make sure Andy doesn't remember some detail I'm forgetting.