From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-x244.google.com (mail-qt0-x244.google.com [IPv6:2607:f8b0:400d:c0d::244]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 401P2K1W74zF0p6 for ; Wed, 14 Mar 2018 18:47:20 +1100 (AEDT) Received: by mail-qt0-x244.google.com with SMTP id v90so2428549qte.12 for ; Wed, 14 Mar 2018 00:47:20 -0700 (PDT) Sender: Ram Pai From: Ram Pai 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 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> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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