Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752976AbdGEVXY (ORCPT ); Wed, 5 Jul 2017 17:23:24 -0400 Received: from mail-qt0-f195.google.com ([209.85.216.195]:35340 "EHLO mail-qt0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752926AbdGEVXV (ORCPT ); Wed, 5 Jul 2017 17:23:21 -0400 From: Ram Pai To: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, khandual@linux.vnet.ibm.com, aneesh.kumar@linux.vnet.ibm.com, bsingharora@gmail.com, dave.hansen@intel.com, hbabu@us.ibm.com, linuxram@us.ibm.com, arnd@arndb.de, akpm@linux-foundation.org, corbet@lwn.net, mingo@redhat.com Subject: [RFC v5 21/38] powerpc: implementation for arch_override_mprotect_pkey() Date: Wed, 5 Jul 2017 14:21:58 -0700 Message-Id: <1499289735-14220-22-git-send-email-linuxram@us.ibm.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1499289735-14220-1-git-send-email-linuxram@us.ibm.com> References: <1499289735-14220-1-git-send-email-linuxram@us.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2810 Lines: 99 arch independent code calls arch_override_mprotect_pkey() to return a pkey that best matches the requested protection. This patch provides the implementation. Signed-off-by: Ram Pai --- arch/powerpc/include/asm/pkeys.h | 10 ++++++- arch/powerpc/mm/pkeys.c | 47 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 55 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h index f148e84..20846c2 100644 --- a/arch/powerpc/include/asm/pkeys.h +++ b/arch/powerpc/include/asm/pkeys.h @@ -13,6 +13,11 @@ static inline u64 pkey_to_vmflag_bits(u16 pkey) ((pkey & 0x10UL) ? VM_PKEY_BIT4 : 0x0UL)); } +static inline int vma_pkey(struct vm_area_struct *vma) +{ + return (vma->vm_flags & ARCH_VM_PKEY_FLAGS) >> VM_PKEY_SHIFT; +} + #define arch_max_pkey() 32 #define AMR_AD_BIT 0x1UL #define AMR_WD_BIT 0x2UL @@ -102,11 +107,12 @@ static inline int execute_only_pkey(struct mm_struct *mm) return __execute_only_pkey(mm); } - +extern int __arch_override_mprotect_pkey(struct vm_area_struct *vma, + int prot, int pkey); static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma, int prot, int pkey) { - return 0; + return __arch_override_mprotect_pkey(vma, prot, pkey); } extern int __arch_set_user_pkey_access(struct task_struct *tsk, int pkey, diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c index 6c90317..c60a045 100644 --- a/arch/powerpc/mm/pkeys.c +++ b/arch/powerpc/mm/pkeys.c @@ -123,3 +123,50 @@ int __execute_only_pkey(struct mm_struct *mm) mm->context.execute_only_pkey = execute_only_pkey; return execute_only_pkey; } + +static inline bool vma_is_pkey_exec_only(struct vm_area_struct *vma) +{ + /* Do this check first since the vm_flags should be hot */ + if ((vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)) != VM_EXEC) + return false; + + return (vma_pkey(vma) == vma->vm_mm->context.execute_only_pkey); +} + +/* + * This should only be called for *plain* mprotect calls. + */ +int __arch_override_mprotect_pkey(struct vm_area_struct *vma, int prot, + int pkey) +{ + /* + * Is this an mprotect_pkey() call? If so, never + * override the value that came from the user. + */ + if (pkey != -1) + return pkey; + + /* + * If the currently associated pkey is execute-only, + * but the requested protection requires read or write, + * move it back to the default pkey. + */ + if (vma_is_pkey_exec_only(vma) && + (prot & (PROT_READ|PROT_WRITE))) + return 0; + + /* + * the requested protection is execute-only. Hence + * lets use a execute-only pkey. + */ + if (prot == PROT_EXEC) { + pkey = execute_only_pkey(vma->vm_mm); + if (pkey > 0) + return pkey; + } + + /* + * nothing to override. + */ + return vma_pkey(vma); +} -- 1.7.1