Re: [RFC PATCH v2 16/19] x86/mm: Protect page tables with PKS

[Mike Rapoport]

On Mon, Aug 30, 2021 at 04:59:24PM -0700, Rick Edgecombe wrote:
> Write protect page tables with PKS. Toggle writeability inside the
> pgtable.h defined page table modifiction functions.
> 
> Do not protect the direct map page tables as it is more complicated and
> will come in a later patch.
> 
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
> ---
>  arch/x86/boot/compressed/ident_map_64.c |  5 ++
>  arch/x86/include/asm/pgtable.h          | 18 ++++++-
>  arch/x86/include/asm/pgtable_64.h       | 33 ++++++++++--
>  arch/x86/include/asm/pkeys_common.h     |  1 -
>  arch/x86/mm/pgtable.c                   | 71 ++++++++++++++++++++++---
>  arch/x86/mm/pkeys.c                     |  1 +
>  include/linux/pkeys.h                   |  1 +
>  mm/Kconfig                              |  6 +++
>  8 files changed, 123 insertions(+), 13 deletions(-)
 
...

> diff --git a/mm/Kconfig b/mm/Kconfig
> index 4184d0a7531d..0f8e8595a396 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -845,6 +845,12 @@ config ARCH_ENABLE_SUPERVISOR_PKEYS
>  	def_bool y
>  	depends on PKS_TEST || GENERAL_PKS_USER
>  
> +config PKS_PG_TABLES
> +	bool "PKS write protected page tables"
> +	select GENERAL_PKS_USER
> +	depends on !HIGHMEM && !X86_PAE && SPARSEMEM_VMEMMAP

Hmm, why is this x86-only feature is in mm/Kconfig?

> +	depends on ARCH_HAS_SUPERVISOR_PKEYS
> +
>  config PERCPU_STATS
>  	bool "Collect percpu memory statistics"
>  	help
> -- 
> 2.17.1
> 

-- 
Sincerely yours,
Mike.