From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-x242.google.com (mail-pg0-x242.google.com [IPv6:2607:f8b0:400e:c05::242]) (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 3yHSJ05yZczDqFv for ; Thu, 19 Oct 2017 10:02:24 +1100 (AEDT) Received: by mail-pg0-x242.google.com with SMTP id g6so5486704pgn.6 for ; Wed, 18 Oct 2017 16:02:24 -0700 (PDT) Date: Thu, 19 Oct 2017 10:02:13 +1100 From: Balbir Singh To: Ram Pai Cc: mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, benh@kernel.crashing.org, paulus@samba.org, khandual@linux.vnet.ibm.com, aneesh.kumar@linux.vnet.ibm.com, hbabu@us.ibm.com, mhocko@kernel.org, bauerman@linux.vnet.ibm.com, ebiederm@xmission.com Subject: Re: [PATCH 11/25] powerpc: introduce execute-only pkey Message-ID: <20171019100213.421a76fe@MiWiFi-R3-srv> In-Reply-To: <20171018205739.GG5617@ram.oc3035372033.ibm.com> References: <1504910713-7094-1-git-send-email-linuxram@us.ibm.com> <1504910713-7094-20-git-send-email-linuxram@us.ibm.com> <20171018151522.4123fe34@firefly.ozlabs.ibm.com> <20171018205739.GG5617@ram.oc3035372033.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 18 Oct 2017 13:57:39 -0700 Ram Pai wrote: > On Wed, Oct 18, 2017 at 03:15:22PM +1100, Balbir Singh wrote: > > On Fri, 8 Sep 2017 15:44:59 -0700 > > Ram Pai wrote: > > > > > This patch provides the implementation of execute-only pkey. > > > The architecture-independent layer expects the arch-dependent > > > layer, to support the ability to create and enable a special > > > key which has execute-only permission. > > > > > > Signed-off-by: Ram Pai > > > --- > > > arch/powerpc/include/asm/book3s/64/mmu.h | 1 + > > > arch/powerpc/include/asm/pkeys.h | 9 ++++- > > > arch/powerpc/mm/pkeys.c | 57 ++++++++++++++++++++++++++++++ > > > 3 files changed, 66 insertions(+), 1 deletions(-) > > > > > > diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h b/arch/powerpc/include/asm/book3s/64/mmu.h > > > index 55950f4..ee18ba0 100644 > > > --- a/arch/powerpc/include/asm/book3s/64/mmu.h > > > +++ b/arch/powerpc/include/asm/book3s/64/mmu.h > > > @@ -115,6 +115,7 @@ struct patb_entry { > > > * bit unset -> key available for allocation > > > */ > > > u32 pkey_allocation_map; > > > + s16 execute_only_pkey; /* key holding execute-only protection */ > > > #endif > > > } mm_context_t; > > > > > > diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h > > > index 78c5362..0cf115f 100644 > > > --- a/arch/powerpc/include/asm/pkeys.h > > > +++ b/arch/powerpc/include/asm/pkeys.h > > > @@ -115,11 +115,16 @@ static inline int mm_pkey_free(struct mm_struct *mm, int pkey) > > > * Try to dedicate one of the protection keys to be used as an > > > * execute-only protection key. > > > */ > > > +extern int __execute_only_pkey(struct mm_struct *mm); > > > static inline int execute_only_pkey(struct mm_struct *mm) > > > { > > > - return 0; > > > + if (!pkey_inited || !pkey_execute_disable_support) > > > + return -1; > > > + > > > + return __execute_only_pkey(mm); > > > } > > > > > > + > > > static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma, > > > int prot, int pkey) > > > { > > > @@ -141,6 +146,8 @@ static inline void pkey_mm_init(struct mm_struct *mm) > > > if (!pkey_inited) > > > return; > > > mm_pkey_allocation_map(mm) = initial_allocation_mask; > > > + /* -1 means unallocated or invalid */ > > > + mm->context.execute_only_pkey = -1; > > > } > > > > > > extern void thread_pkey_regs_save(struct thread_struct *thread); > > > diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c > > > index 7cd1be4..8a24983 100644 > > > --- a/arch/powerpc/mm/pkeys.c > > > +++ b/arch/powerpc/mm/pkeys.c > > > @@ -188,3 +188,60 @@ void thread_pkey_regs_init(struct thread_struct *thread) > > > write_iamr(0x0ul); > > > write_uamor(0x0ul); > > > } > > > + > > > +static inline bool pkey_allows_readwrite(int pkey) > > > +{ > > > + int pkey_shift = pkeyshift(pkey); > > > + > > > + if (!(read_uamor() & (0x3UL << pkey_shift))) > > > + return true; > > > > If uamor for key 0 is 0x10 for example or 0x01 it's a bug. > > The above check might miss it. > > > The specs says both the bits corresponding to a key are set or > reset, cannot be anything else. > I agree, thats why I said it's a bug if the values are such. Do we care to validate that both bits are the same? Balbir Singh.