From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3zxF732n1PzF1Zj for ; Thu, 8 Mar 2018 00:37:03 +1100 (AEDT) Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w27DZgxR128549 for ; Wed, 7 Mar 2018 08:37:00 -0500 Received: from e18.ny.us.ibm.com (e18.ny.us.ibm.com [129.33.205.208]) by mx0b-001b2d01.pphosted.com with ESMTP id 2gjdpq8v7u-1 (version=TLSv1.2 cipher=AES256-SHA256 bits=256 verify=NOT) for ; Wed, 07 Mar 2018 08:37:00 -0500 Received: from localhost by e18.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 7 Mar 2018 08:36:59 -0500 From: "Aneesh Kumar K.V" To: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, linuxram@us.ibm.com Cc: linuxppc-dev@lists.ozlabs.org, "Aneesh Kumar K.V" Subject: [PATCH 2/2] powerpc/mm/keys: Update documentation in key fault handling Date: Wed, 7 Mar 2018 19:06:45 +0530 In-Reply-To: <20180307133645.29290-1-aneesh.kumar@linux.vnet.ibm.com> References: <20180307133645.29290-1-aneesh.kumar@linux.vnet.ibm.com> Message-Id: <20180307133645.29290-2-aneesh.kumar@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , No functionality change in this patch. Adds more code comments. We also remove an unnecessary pkey check after we check for pkey error in this patch. Signed-off-by: Aneesh Kumar K.V --- arch/powerpc/mm/fault.c | 28 ++++++++++++---------------- arch/powerpc/mm/pkeys.c | 11 ++++------- 2 files changed, 16 insertions(+), 23 deletions(-) diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 866446cf2d9a..c01d627e687a 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -297,7 +297,12 @@ static bool access_error(bool is_write, bool is_exec, if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))) return true; - + /* + * We should ideally do the vma pkey access check here. But in the + * fault path, handle_mm_fault() also does the same check. To avoid + * these multiple checks, we skip it here and handle access error due + * to pkeys later. + */ return false; } @@ -518,25 +523,16 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, #ifdef CONFIG_PPC_MEM_KEYS /* - * if the HPTE is not hashed, hardware will not detect - * a key fault. Lets check if we failed because of a - * software detected key fault. + * we skipped checking for access error due to key earlier. + * Check that using handle_mm_fault error return. */ if (unlikely(fault & VM_FAULT_SIGSEGV) && - !arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE, - is_exec, 0)) { - /* - * The PGD-PDT...PMD-PTE tree may not have been fully setup. - * Hence we cannot walk the tree to locate the PTE, to locate - * the key. Hence let's use vma_pkey() to get the key; instead - * of get_mm_addr_key(). - */ + !arch_vma_access_permitted(vma, is_write, is_exec, 0)) { + int pkey = vma_pkey(vma); - if (likely(pkey)) { - up_read(&mm->mmap_sem); - return bad_key_fault_exception(regs, address, pkey); - } + up_read(&mm->mmap_sem); + return bad_key_fault_exception(regs, address, pkey); } #endif /* CONFIG_PPC_MEM_KEYS */ diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c index ba71c5481f42..56d33056a559 100644 --- a/arch/powerpc/mm/pkeys.c +++ b/arch/powerpc/mm/pkeys.c @@ -119,18 +119,15 @@ int pkey_initialize(void) #else os_reserved = 0; #endif + initial_allocation_mask = ~0x0; + pkey_amr_uamor_mask = ~0x0ul; + pkey_iamr_mask = ~0x0ul; /* - * Bits are in LE format. NOTE: 1, 0 are reserved. + * key 0, 1 are reserved. * key 0 is the default key, which allows read/write/execute. * key 1 is recommended not to be used. PowerISA(3.0) page 1015, * programming note. */ - initial_allocation_mask = ~0x0; - - /* register mask is in BE format */ - pkey_amr_uamor_mask = ~0x0ul; - pkey_iamr_mask = ~0x0ul; - for (i = 2; i < (pkeys_total - os_reserved); i++) { initial_allocation_mask &= ~(0x1 << i); pkey_amr_uamor_mask &= ~(0x3ul << pkeyshift(i)); -- 2.14.3