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From: Florian Weimer <fweimer@redhat.com>
To: Ram Pai <linuxram@us.ibm.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
	linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org,
	linux-api@vger.kernel.org
Subject: Re: pkeys: Reserve PKEY_DISABLE_READ
Date: Tue, 27 Nov 2018 12:57:15 +0100	[thread overview]
Message-ID: <87zhtuhgx0.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <20181127102350.GA5795@ram.oc3035372033.ibm.com> (Ram Pai's message of "Tue, 27 Nov 2018 02:23:50 -0800")

* Ram Pai:

> diff --git a/arch/x86/include/uapi/asm/mman.h b/arch/x86/include/uapi/asm/mman.h
> index d4a8d04..e9b121b 100644
> --- a/arch/x86/include/uapi/asm/mman.h
> +++ b/arch/x86/include/uapi/asm/mman.h
> @@ -24,6 +24,11 @@
>  		((key) & 0x2 ? VM_PKEY_BIT1 : 0) |      \
>  		((key) & 0x4 ? VM_PKEY_BIT2 : 0) |      \
>  		((key) & 0x8 ? VM_PKEY_BIT3 : 0))
> +
> +/* Override any generic PKEY permission defines */
> +#undef PKEY_ACCESS_MASK
> +#define PKEY_ACCESS_MASK       (PKEY_DISABLE_ACCESS |\
> +				PKEY_DISABLE_WRITE)
>  #endif

I would have expected something that translates PKEY_DISABLE_WRITE |
PKEY_DISABLE_READ into PKEY_DISABLE_ACCESS, and also accepts
PKEY_DISABLE_ACCESS | PKEY_DISABLE_READ, for consistency with POWER.

(My understanding is that PKEY_DISABLE_ACCESS does not disable all
access, but produces execute-only memory.)

> diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h
> index e7ee328..61168e4 100644
> --- a/include/uapi/asm-generic/mman-common.h
> +++ b/include/uapi/asm-generic/mman-common.h
> @@ -71,7 +71,8 @@
>  
>  #define PKEY_DISABLE_ACCESS	0x1
>  #define PKEY_DISABLE_WRITE	0x2
> -#define PKEY_ACCESS_MASK	(PKEY_DISABLE_ACCESS |\
> -				 PKEY_DISABLE_WRITE)
> -
> +#define PKEY_DISABLE_EXECUTE	0x4
> +#define PKEY_DISABLE_READ	0x8
> +#define PKEY_ACCESS_MASK	0x0	/* arch can override and define its own
> +					   mask bits */
>  #endif /* __ASM_GENERIC_MMAN_COMMON_H */

I think Dave requested a value for PKEY_DISABLE_READ which is further
away from the existing bits.

Thanks,
Florian

WARNING: multiple messages have this Message-ID (diff)
From: Florian Weimer <fweimer@redhat.com>
To: Ram Pai <linuxram@us.ibm.com>
Cc: linux-mm@kvack.org, linux-api@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org,
	Dave Hansen <dave.hansen@intel.com>
Subject: Re: pkeys: Reserve PKEY_DISABLE_READ
Date: Tue, 27 Nov 2018 12:57:15 +0100	[thread overview]
Message-ID: <87zhtuhgx0.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <20181127102350.GA5795@ram.oc3035372033.ibm.com> (Ram Pai's message of "Tue, 27 Nov 2018 02:23:50 -0800")

* Ram Pai:

> diff --git a/arch/x86/include/uapi/asm/mman.h b/arch/x86/include/uapi/asm/mman.h
> index d4a8d04..e9b121b 100644
> --- a/arch/x86/include/uapi/asm/mman.h
> +++ b/arch/x86/include/uapi/asm/mman.h
> @@ -24,6 +24,11 @@
>  		((key) & 0x2 ? VM_PKEY_BIT1 : 0) |      \
>  		((key) & 0x4 ? VM_PKEY_BIT2 : 0) |      \
>  		((key) & 0x8 ? VM_PKEY_BIT3 : 0))
> +
> +/* Override any generic PKEY permission defines */
> +#undef PKEY_ACCESS_MASK
> +#define PKEY_ACCESS_MASK       (PKEY_DISABLE_ACCESS |\
> +				PKEY_DISABLE_WRITE)
>  #endif

I would have expected something that translates PKEY_DISABLE_WRITE |
PKEY_DISABLE_READ into PKEY_DISABLE_ACCESS, and also accepts
PKEY_DISABLE_ACCESS | PKEY_DISABLE_READ, for consistency with POWER.

(My understanding is that PKEY_DISABLE_ACCESS does not disable all
access, but produces execute-only memory.)

> diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h
> index e7ee328..61168e4 100644
> --- a/include/uapi/asm-generic/mman-common.h
> +++ b/include/uapi/asm-generic/mman-common.h
> @@ -71,7 +71,8 @@
>  
>  #define PKEY_DISABLE_ACCESS	0x1
>  #define PKEY_DISABLE_WRITE	0x2
> -#define PKEY_ACCESS_MASK	(PKEY_DISABLE_ACCESS |\
> -				 PKEY_DISABLE_WRITE)
> -
> +#define PKEY_DISABLE_EXECUTE	0x4
> +#define PKEY_DISABLE_READ	0x8
> +#define PKEY_ACCESS_MASK	0x0	/* arch can override and define its own
> +					   mask bits */
>  #endif /* __ASM_GENERIC_MMAN_COMMON_H */

I think Dave requested a value for PKEY_DISABLE_READ which is further
away from the existing bits.

Thanks,
Florian

  reply	other threads:[~2018-11-27 11:57 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-08 12:05 pkeys: Reserve PKEY_DISABLE_READ Florian Weimer
2018-11-08 14:57 ` Dave Hansen
2018-11-08 15:01   ` Florian Weimer
2018-11-08 17:14     ` Dave Hansen
2018-11-08 17:37       ` Florian Weimer
2018-11-08 20:12         ` Ram Pai
2018-11-08 20:12           ` Ram Pai
2018-11-08 20:23           ` Florian Weimer
2018-11-08 20:23             ` Florian Weimer
2018-11-09 18:09             ` Ram Pai
2018-11-09 18:09               ` Ram Pai
2018-11-12 12:00               ` Florian Weimer
2018-11-12 12:00                 ` Florian Weimer
2018-11-27 10:23                 ` Ram Pai
2018-11-27 10:23                   ` Ram Pai
2018-11-27 11:57                   ` Florian Weimer [this message]
2018-11-27 11:57                     ` Florian Weimer
2018-11-27 15:31                     ` Dave Hansen
2018-11-27 15:31                       ` Dave Hansen
2018-11-29 11:37                       ` Florian Weimer
2018-11-29 11:37                         ` Florian Weimer
2018-12-03  4:02                         ` Ram Pai
2018-12-03  4:02                           ` Ram Pai
2018-12-03 15:52                           ` Florian Weimer
2018-12-03 15:52                             ` Florian Weimer
2018-12-04  6:23                             ` Ram Pai
2018-12-04  6:23                               ` Ram Pai
2018-12-05 13:00                               ` Florian Weimer
2018-12-05 13:00                                 ` Florian Weimer
2018-12-05 20:23                                 ` Ram Pai
2018-12-05 20:23                                   ` Ram Pai
2018-12-05 16:21                           ` Andy Lutomirski
2018-12-05 16:21                             ` Andy Lutomirski
2018-12-05 20:36                             ` Ram Pai
2018-12-05 20:36                               ` Ram Pai
2018-11-08 20:08       ` Ram Pai
2018-11-08 20:11         ` Dave Hansen
2018-11-08 20:14         ` Florian Weimer
2018-11-08 19:22 ` Ram Pai
2018-11-08 19:22   ` Ram Pai
2018-11-12 10:29   ` Florian Weimer
2018-11-12 10:29     ` Florian Weimer

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