From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f198.google.com (mail-qt0-f198.google.com [209.85.216.198]) by kanga.kvack.org (Postfix) with ESMTP id 207C86B0005 for ; Wed, 14 Mar 2018 03:45:14 -0400 (EDT) Received: by mail-qt0-f198.google.com with SMTP id n51so1580581qta.9 for ; Wed, 14 Mar 2018 00:45:14 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id m93sor1571635qte.88.2018.03.14.00.45.13 for (Google Transport Security); Wed, 14 Mar 2018 00:45:13 -0700 (PDT) From: Ram Pai Subject: [PATCH 1/1 v2] powerpc: pkey-mprotect must allow pkey-0 Date: Wed, 14 Mar 2018 00:45:00 -0700 Message-Id: <1521013500-26740-1-git-send-email-linuxram@us.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: mpe@ellerman.id.au Cc: linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, 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 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 powerpc. cc: Dave Hansen cc: Michael Ellermen cc: Ingo Molnar Signed-off-by: Ram Pai --- arch/powerpc/include/asm/pkeys.h | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h index 0409c80..3c1deec 100644 --- a/arch/powerpc/include/asm/pkeys.h +++ b/arch/powerpc/include/asm/pkeys.h @@ -101,10 +101,18 @@ static inline u16 pte_to_pkey_bits(u64 pteflags) static inline bool mm_pkey_is_allocated(struct mm_struct *mm, int pkey) { - /* A reserved key is never considered as 'explicitly allocated' */ - return ((pkey < arch_max_pkey()) && - !__mm_pkey_is_reserved(pkey) && - __mm_pkey_is_allocated(mm, pkey)); + /* pkey 0 is allocated by default. */ + if (!pkey) + return true; + + if (pkey < 0 || pkey >= arch_max_pkey()) + return false; + + /* Reserved keys are never allocated. */ + if (__mm_pkey_is_reserved(pkey)) + return false; + + return __mm_pkey_is_allocated(mm, pkey); } extern void __arch_activate_pkey(int pkey); @@ -150,7 +158,8 @@ static inline int mm_pkey_free(struct mm_struct *mm, int pkey) if (static_branch_likely(&pkey_disabled)) return -1; - if (!mm_pkey_is_allocated(mm, pkey)) + /* pkey 0 cannot be freed */ + if (!pkey || !mm_pkey_is_allocated(mm, pkey)) return -EINVAL; /* -- 1.8.3.1