[PATCH v2 2/2] powerpc/mm: Warn if W+X pages found on boot

[Michael Ellerman]

Russell Currey <ruscur at russell.cc> writes:

> Implement code to walk all pages and warn if any are found to be both
> writable and executable.  Depends on STRICT_KERNEL_RWX enabled, and is
> behind the DEBUG_WX config option.
>
> This only runs on boot and has no runtime performance implications.
>
> Very heavily influenced (and in some cases copied verbatim) from the
> ARM64 code written by Laura Abbott (thanks!), since our ptdump
> infrastructure is similar.
>
> Signed-off-by: Russell Currey <ruscur at russell.cc>
> ---
> v2: A myriad of fixes and cleanups thanks to Christophe Leroy
>
>  arch/powerpc/Kconfig.debug         | 19 ++++++++++++++
>  arch/powerpc/include/asm/pgtable.h |  6 +++++
>  arch/powerpc/mm/pgtable_32.c       |  3 +++
>  arch/powerpc/mm/pgtable_64.c       |  3 +++
>  arch/powerpc/mm/ptdump/ptdump.c    | 41 +++++++++++++++++++++++++++++-
>  5 files changed, 71 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
> index 4e00cb0a5464..9e8bcddd8b8f 100644
> --- a/arch/powerpc/Kconfig.debug
> +++ b/arch/powerpc/Kconfig.debug
> @@ -361,6 +361,25 @@ config PPC_PTDUMP
>  
>  	  If you are unsure, say N.
>  
> +config PPC_DEBUG_WX
> +	bool "Warn on W+X mappings at boot"
> +	select PPC_PTDUMP

That should be depends not select, I'll fix it up.

cheers