From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ram Pai Subject: [PATCH 1/1 v2] x86: pkey-mprotect must allow pkey-0 Date: Wed, 14 Mar 2018 00:46:14 -0700 Message-ID: <1521013574-27041-1-git-send-email-linuxram@us.ibm.com> Return-path: Sender: linux-kernel-owner@vger.kernel.org To: mingo@redhat.com Cc: mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, dave.hansen@intel.com, benh@kernel.crashing.org, paulus@samba.org, khandual@linux.vnet.ibm.com, aneesh.kumar@linux.vnet.ibm.com, bsingharora@gmail.com, hbabu@us.ibm.com, mhocko@kernel.org, bauerman@linux.vnet.ibm.com, ebiederm@xmission.com, linuxram@us.ibm.com, corbet@lwn.net, arnd@arndb.de, fweimer@redhat.com, msuchanek@suse.com List-Id: linux-arch.vger.kernel.org Once an address range is associated with an allocated pkey, it cannot be reverted back to key-0. There is no valid reason for the above behavior. On the contrary applications need the ability to do so. The patch relaxes the restriction. Tested on x86_64. cc: Dave Hansen cc: Michael Ellermen cc: Ingo Molnar Signed-off-by: Ram Pai --- arch/x86/include/asm/pkeys.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/pkeys.h b/arch/x86/include/asm/pkeys.h index a0ba1ff..6ea7486 100644 --- a/arch/x86/include/asm/pkeys.h +++ b/arch/x86/include/asm/pkeys.h @@ -52,7 +52,7 @@ bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey) * from pkey_alloc(). pkey 0 is special, and never * returned from pkey_alloc(). */ - if (pkey <= 0) + if (pkey < 0) return false; if (pkey >= arch_max_pkey()) return false; @@ -92,7 +92,8 @@ int mm_pkey_alloc(struct mm_struct *mm) static inline int mm_pkey_free(struct mm_struct *mm, int pkey) { - if (!mm_pkey_is_allocated(mm, pkey)) + /* pkey 0 is special and can never be freed */ + if (!pkey || !mm_pkey_is_allocated(mm, pkey)) return -EINVAL; mm_set_pkey_free(mm, pkey); -- 1.8.3.1 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f194.google.com ([209.85.216.194]:40342 "EHLO mail-qt0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753219AbeCNHrT (ORCPT ); Wed, 14 Mar 2018 03:47:19 -0400 From: Ram Pai Subject: [PATCH 1/1 v2] x86: pkey-mprotect must allow pkey-0 Date: Wed, 14 Mar 2018 00:46:14 -0700 Message-ID: <1521013574-27041-1-git-send-email-linuxram@us.ibm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: mingo@redhat.com Cc: mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, dave.hansen@intel.com, benh@kernel.crashing.org, paulus@samba.org, khandual@linux.vnet.ibm.com, aneesh.kumar@linux.vnet.ibm.com, bsingharora@gmail.com, hbabu@us.ibm.com, mhocko@kernel.org, bauerman@linux.vnet.ibm.com, ebiederm@xmission.com, linuxram@us.ibm.com, corbet@lwn.net, arnd@arndb.de, fweimer@redhat.com, msuchanek@suse.com Message-ID: <20180314074614.ZULdQlQXebvfrR1phZw_iF2Ia2KWiaOgYFbXO4hnHrM@z> Once an address range is associated with an allocated pkey, it cannot be reverted back to key-0. There is no valid reason for the above behavior. On the contrary applications need the ability to do so. The patch relaxes the restriction. Tested on x86_64. cc: Dave Hansen cc: Michael Ellermen cc: Ingo Molnar Signed-off-by: Ram Pai --- arch/x86/include/asm/pkeys.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/pkeys.h b/arch/x86/include/asm/pkeys.h index a0ba1ff..6ea7486 100644 --- a/arch/x86/include/asm/pkeys.h +++ b/arch/x86/include/asm/pkeys.h @@ -52,7 +52,7 @@ bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey) * from pkey_alloc(). pkey 0 is special, and never * returned from pkey_alloc(). */ - if (pkey <= 0) + if (pkey < 0) return false; if (pkey >= arch_max_pkey()) return false; @@ -92,7 +92,8 @@ int mm_pkey_alloc(struct mm_struct *mm) static inline int mm_pkey_free(struct mm_struct *mm, int pkey) { - if (!mm_pkey_is_allocated(mm, pkey)) + /* pkey 0 is special and can never be freed */ + if (!pkey || !mm_pkey_is_allocated(mm, pkey)) return -EINVAL; mm_set_pkey_free(mm, pkey); -- 1.8.3.1