Subject: Re: [RFC v5 13/38] x86: disallow pkey creation with
 PKEY_DISABLE_EXECUTE
To: Ram Pai <linuxram@us.ibm.com>, linuxppc-dev@lists.ozlabs.org,
        linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-mm@kvack.org, x86@kernel.org, linux-doc@vger.kernel.org,
        linux-kselftest@vger.kernel.org
References: <1499289735-14220-1-git-send-email-linuxram@us.ibm.com>
 <1499289735-14220-14-git-send-email-linuxram@us.ibm.com>
Cc: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au,
        khandual@linux.vnet.ibm.com, aneesh.kumar@linux.vnet.ibm.com,
        bsingharora@gmail.com, hbabu@us.ibm.com, arnd@arndb.de,
        akpm@linux-foundation.org, corbet@lwn.net, mingo@redhat.com
From: Dave Hansen <dave.hansen@intel.com>
Message-ID: <1692f8f5-456c-dc4a-4502-a2ea63ede094@intel.com>
Date: Tue, 11 Jul 2017 11:12:37 -0700
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On 07/05/2017 02:21 PM, Ram Pai wrote:
> x86 does not support disabling execute permissions on a pkey.
> 
> Signed-off-by: Ram Pai <linuxram@us.ibm.com>
> ---
>  arch/x86/kernel/fpu/xstate.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
> index c24ac1e..d582631 100644
> --- a/arch/x86/kernel/fpu/xstate.c
> +++ b/arch/x86/kernel/fpu/xstate.c
> @@ -900,6 +900,9 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
>  	if (!boot_cpu_has(X86_FEATURE_OSPKE))
>  		return -EINVAL;
>  
> +	if (init_val & PKEY_DISABLE_EXECUTE)
> +		return -EINVAL;

I'd really rather that we define a supported mask instead of having each
architecture go through and list which ones it supports.