From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (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 41wfPL2jFfzF2Q2 for ; Thu, 23 Aug 2018 06:32:54 +1000 (AEST) Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w7MHDtBX027559 for ; Wed, 22 Aug 2018 13:16:16 -0400 Received: from e31.co.us.ibm.com (e31.co.us.ibm.com [32.97.110.149]) by mx0a-001b2d01.pphosted.com with ESMTP id 2m19wce289-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 22 Aug 2018 13:16:16 -0400 Received: from localhost by e31.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 22 Aug 2018 11:16:15 -0600 From: "Aneesh Kumar K.V" To: npiggin@gmail.com, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au Cc: linuxppc-dev@lists.ozlabs.org, "Aneesh Kumar K.V" Subject: [PATCH 1/2] powerpc/mm/books3s: Add new pte bit to mark pte temporarily invalid. Date: Wed, 22 Aug 2018 22:46:04 +0530 Message-Id: <20180822171605.15054-1-aneesh.kumar@linux.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , When splitting a huge pmd pte, we need to mark the pmd entry invalid. We can do that by clearing _PAGE_PRESENT bit. But then that will be taken as a swap pte. In order to differentiate between the two use a software pte bit when invalidating. For regular pte, due to bd5050e38aec ("powerpc/mm/radix: Change pte relax sequence to handle nest MMU hang") we need to mark the pte entry invalid when relaxing access permission. Instead of marking pte_none which can result in different page table walk routines possibly skipping this pte entry, invalidate it but still keep it marked present. Signed-off-by: Aneesh Kumar K.V --- arch/powerpc/include/asm/book3s/64/pgtable.h | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h index 676118743a06..13a688fc8cd0 100644 --- a/arch/powerpc/include/asm/book3s/64/pgtable.h +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h @@ -44,6 +44,16 @@ #define _PAGE_PTE 0x4000000000000000UL /* distinguishes PTEs from pointers */ #define _PAGE_PRESENT 0x8000000000000000UL /* pte contains a translation */ +/* + * We need to mark a pmd pte invalid while splitting. We can do that by clearing + * the _PAGE_PRESENT bit. But then that will be taken as a swap pte. In order to + * differentiate between two use a SW field when invalidating. + * + * We do that temporary invalidate for regular pte entry in ptep_set_access_flags + * + * This is used only when _PAGE_PRESENT is cleared. + */ +#define _PAGE_INVALID _RPAGE_SW0 /* * Top and bottom bits of RPN which can be used by hash @@ -568,7 +578,13 @@ static inline pte_t pte_clear_savedwrite(pte_t pte) static inline int pte_present(pte_t pte) { - return !!(pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT)); + /* + * A pte is considerent present if _PAGE_PRESENT is set. + * We also need to consider the pte present which is marked + * invalid during ptep_set_access_flags. Hence we look for _PAGE_INVALID + * if we find _PAGE_PRESENT cleared. + */ + return !!(pte_raw(pte) & cpu_to_be64(_PAGE_PRESENT | _PAGE_INVALID)); } #ifdef CONFIG_PPC_MEM_KEYS -- 2.17.1