From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-x244.google.com (mail-pf0-x244.google.com [IPv6:2607:f8b0:400e:c00::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 3yH0243LXVzDrD6 for ; Wed, 18 Oct 2017 15:48:43 +1100 (AEDT) Received: by mail-pf0-x244.google.com with SMTP id b85so3020942pfj.13 for ; Tue, 17 Oct 2017 21:48:43 -0700 (PDT) Date: Wed, 18 Oct 2017 15:48:31 +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 17/25] powerpc: helper to validate key-access permissions of a pte Message-ID: <20171018154831.50b2abcb@firefly.ozlabs.ibm.com> In-Reply-To: <1504910713-7094-26-git-send-email-linuxram@us.ibm.com> References: <1504910713-7094-1-git-send-email-linuxram@us.ibm.com> <1504910713-7094-26-git-send-email-linuxram@us.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 Fri, 8 Sep 2017 15:45:05 -0700 Ram Pai wrote: > helper function that checks if the read/write/execute is allowed > on the pte. > > Signed-off-by: Ram Pai > --- > arch/powerpc/include/asm/book3s/64/pgtable.h | 4 +++ > arch/powerpc/include/asm/pkeys.h | 12 +++++++++++ > arch/powerpc/mm/pkeys.c | 28 ++++++++++++++++++++++++++ > 3 files changed, 44 insertions(+), 0 deletions(-) > > diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h > index 5935d4e..bd244b3 100644 > --- a/arch/powerpc/include/asm/book3s/64/pgtable.h > +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h > @@ -492,6 +492,10 @@ static inline void write_uamor(u64 value) > mtspr(SPRN_UAMOR, value); > } > > +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS > +extern bool arch_pte_access_permitted(u64 pte, bool write, bool execute); > +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */ > + > #define __HAVE_ARCH_PTEP_GET_AND_CLEAR > static inline pte_t ptep_get_and_clear(struct mm_struct *mm, > unsigned long addr, pte_t *ptep) > diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h > index cd3924c..50522a0 100644 > --- a/arch/powerpc/include/asm/pkeys.h > +++ b/arch/powerpc/include/asm/pkeys.h > @@ -80,6 +80,18 @@ static inline u64 pte_to_hpte_pkey_bits(u64 pteflags) > ((pteflags & H_PAGE_PKEY_BIT4) ? HPTE_R_KEY_BIT4 : 0x0UL)); > } > > +static inline u16 pte_to_pkey_bits(u64 pteflags) > +{ > + if (!pkey_inited) > + return 0x0UL; > + > + return (((pteflags & H_PAGE_PKEY_BIT0) ? 0x10 : 0x0UL) | > + ((pteflags & H_PAGE_PKEY_BIT1) ? 0x8 : 0x0UL) | > + ((pteflags & H_PAGE_PKEY_BIT2) ? 0x4 : 0x0UL) | > + ((pteflags & H_PAGE_PKEY_BIT3) ? 0x2 : 0x0UL) | > + ((pteflags & H_PAGE_PKEY_BIT4) ? 0x1 : 0x0UL)); > +} > + > #define ARCH_VM_PKEY_FLAGS (VM_PKEY_BIT0 | VM_PKEY_BIT1 | VM_PKEY_BIT2 | \ > VM_PKEY_BIT3 | VM_PKEY_BIT4) > #define AMR_BITS_PER_PKEY 2 > diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c > index fb1a76a..24589d9 100644 > --- a/arch/powerpc/mm/pkeys.c > +++ b/arch/powerpc/mm/pkeys.c > @@ -292,3 +292,31 @@ int __arch_override_mprotect_pkey(struct vm_area_struct *vma, int prot, > */ > return vma_pkey(vma); > } > + > +static bool pkey_access_permitted(int pkey, bool write, bool execute) > +{ > + int pkey_shift; > + u64 amr; > + > + if (!pkey) > + return true; Why would we have pkey set to 0, it's reserved. Why do we return true? > + > + pkey_shift = pkeyshift(pkey); > + if (!(read_uamor() & (0x3UL << pkey_shift))) > + return true; > + > + if (execute && !(read_iamr() & (IAMR_EX_BIT << pkey_shift))) > + return true; > + > + amr = read_amr(); /* delay reading amr uptil absolutely needed*/ > + return ((!write && !(amr & (AMR_RD_BIT << pkey_shift))) || > + (write && !(amr & (AMR_WR_BIT << pkey_shift)))); > +} > + > +bool arch_pte_access_permitted(u64 pte, bool write, bool execute) > +{ > + if (!pkey_inited) > + return true; Again, don't like the pkey_inited bits :) > + return pkey_access_permitted(pte_to_pkey_bits(pte), > + write, execute); > +} Balbir Singh