From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id A43CB6B0005 for ; Fri, 9 Mar 2018 03:43:37 -0500 (EST) Received: by mail-wm0-f72.google.com with SMTP id u83so721669wmb.3 for ; Fri, 09 Mar 2018 00:43:37 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id p19sor249279wrb.42.2018.03.09.00.43.36 for (Google Transport Security); Fri, 09 Mar 2018 00:43:36 -0800 (PST) Date: Fri, 9 Mar 2018 09:43:32 +0100 From: Ingo Molnar Subject: Re: [PATCH] x86, powerpc : pkey-mprotect must allow pkey-0 Message-ID: <20180309084332.hk6xt6obghoqokbc@gmail.com> References: <1520583161-11741-1-git-send-email-linuxram@us.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1520583161-11741-1-git-send-email-linuxram@us.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Ram Pai Cc: mpe@ellerman.id.au, mingo@redhat.com, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.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, corbet@lwn.net, arnd@arndb.de, fweimer@redhat.com, msuchanek@suse.com, Ulrich.Weigand@de.ibm.com * Ram Pai wrote: > 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 and x86_64. > > cc: Dave Hansen > cc: Michael Ellermen > cc: Ingo Molnar > Signed-off-by: Ram Pai > --- > arch/powerpc/include/asm/pkeys.h | 19 ++++++++++++++----- > arch/x86/include/asm/pkeys.h | 5 +++-- > 2 files changed, 17 insertions(+), 7 deletions(-) > > diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h > index 0409c80..3e8abe4 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; Please capitalize in comments consistently, i.e.: /* Reserved keys are never allocated: */ > + > + return(__mm_pkey_is_allocated(mm, pkey)); 'return' is not a function. Thanks, Ingo