linux-kernel - Re: [RFC v6 19/62] powerpc: ability to create execute-disabled pkeys

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Message-Id: <87a83p51we.fsf@linux.vnet.ibm.com>
Date:   Thu, 27 Jul 2017 12:34:57 -0300
From:   Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>
To:     Ram Pai <linuxram@...ibm.com>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
        linux-doc@...r.kernel.org, linux-kselftest@...r.kernel.org,
        arnd@...db.de, corbet@....net, mhocko@...nel.org,
        dave.hansen@...el.com, mingo@...hat.com, paulus@...ba.org,
        aneesh.kumar@...ux.vnet.ibm.com, akpm@...ux-foundation.org,
        khandual@...ux.vnet.ibm.com
Subject: Re: [RFC v6 19/62] powerpc: ability to create execute-disabled pkeys


Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com> writes:
> diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
> index e31f5ee8e81f..67e6a3a343ae 100644
> --- a/arch/powerpc/include/asm/pkeys.h
> +++ b/arch/powerpc/include/asm/pkeys.h
> @@ -4,17 +4,6 @@
>  #include <asm/firmware.h>
>  
>  extern bool pkey_inited;
> -/* override any generic PKEY Permission defines */
> -#undef  PKEY_DISABLE_ACCESS
> -#define PKEY_DISABLE_ACCESS    0x1
> -#undef  PKEY_DISABLE_WRITE
> -#define PKEY_DISABLE_WRITE     0x2
> -#undef  PKEY_DISABLE_EXECUTE
> -#define PKEY_DISABLE_EXECUTE   0x4
> -#undef  PKEY_ACCESS_MASK
> -#define PKEY_ACCESS_MASK       (PKEY_DISABLE_ACCESS |\
> -				PKEY_DISABLE_WRITE  |\
> -				PKEY_DISABLE_EXECUTE)
>  
>  #define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | \
>  				VM_PKEY_BIT3 | VM_PKEY_BIT4)
> diff --git a/arch/powerpc/include/uapi/asm/mman.h b/arch/powerpc/include/uapi/asm/mman.h
> index ab45cc2f3101..dee43feb7c53 100644
> --- a/arch/powerpc/include/uapi/asm/mman.h
> +++ b/arch/powerpc/include/uapi/asm/mman.h
> @@ -45,4 +45,6 @@
>  #define MAP_HUGE_1GB	(30 << MAP_HUGE_SHIFT)	/* 1GB   HugeTLB Page */
>  #define MAP_HUGE_16GB	(34 << MAP_HUGE_SHIFT)	/* 16GB  HugeTLB Page */
>  
> +#define PKEY_DISABLE_EXECUTE   0x4
> +
>  #endif /* _UAPI_ASM_POWERPC_MMAN_H */
> diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
> index 72eb9a1bde79..777f8f8dff47 100644
> --- a/arch/powerpc/mm/pkeys.c
> +++ b/arch/powerpc/mm/pkeys.c
> @@ -12,7 +12,7 @@
>   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
>   * more details.
>   */
> -#include <uapi/asm-generic/mman-common.h>
> +#include <asm/mman.h>
>  #include <linux/pkeys.h>                /* PKEY_*                       */
>  
>  bool pkey_inited;
> diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h
> index 8c27db0c5c08..93e3841d9ada 100644
> --- a/include/uapi/asm-generic/mman-common.h
> +++ b/include/uapi/asm-generic/mman-common.h
> @@ -74,7 +74,15 @@
>  
>  #define PKEY_DISABLE_ACCESS	0x1
>  #define PKEY_DISABLE_WRITE	0x2
> +
> +/* The arch-specific code may define PKEY_DISABLE_EXECUTE */
> +#ifdef PKEY_DISABLE_EXECUTE
> +#define PKEY_ACCESS_MASK       (PKEY_DISABLE_ACCESS |	\
> +				PKEY_DISABLE_WRITE  |	\
> +				PKEY_DISABLE_EXECUTE)
> +#else
>  #define PKEY_ACCESS_MASK	(PKEY_DISABLE_ACCESS |\
>  				 PKEY_DISABLE_WRITE)
> +#endif
>  
>  #endif /* __ASM_GENERIC_MMAN_COMMON_H */

Actually, I just noticed that arch/powerpc/include/uapi/asm/mman.h
includes <asm-generic/mman-common.h>, so for the #ifdef above to work
the former has to #define PKEY_DISABLE_EXECUTE before including the
latter.

-- 
Thiago Jung Bauermann
IBM Linux Technology Center