From patchwork Wed Sep 16 19:03:06 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeremy Linton X-Patchwork-Id: 7198671 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id A0BAB9F336 for ; Wed, 16 Sep 2015 19:06:13 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id A154C2063C for ; Wed, 16 Sep 2015 19:06:12 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AA44120639 for ; Wed, 16 Sep 2015 19:06:11 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZcI0Q-0005Vu-Ub; Wed, 16 Sep 2015 19:04:34 +0000 Received: from eu-smtp-delivery-143.mimecast.com ([146.101.78.143]) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZcHzz-0005Id-JE for linux-arm-kernel@lists.infradead.org; Wed, 16 Sep 2015 19:04:08 +0000 Received: from cam-owa1.Emea.Arm.com (fw-tnat.cambridge.arm.com [217.140.96.140]) by eu-smtp-1.mimecast.com with ESMTP id uk-mta-5-6bdPlWWRT0aMmRW2vgUHjQ-1; Wed, 16 Sep 2015 20:03:48 +0100 Received: from mammon-v1.localdomain.com ([10.1.2.79]) by cam-owa1.Emea.Arm.com with Microsoft SMTPSVC(6.0.3790.3959); Wed, 16 Sep 2015 20:03:47 +0100 From: Jeremy Linton To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 7/7] arm64: Mark kernel page ranges contiguous Date: Wed, 16 Sep 2015 14:03:06 -0500 Message-Id: <1442430186-9083-8-git-send-email-jeremy.linton@arm.com> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1442430186-9083-1-git-send-email-jeremy.linton@arm.com> References: <1442430186-9083-1-git-send-email-jeremy.linton@arm.com> X-OriginalArrivalTime: 16 Sep 2015 19:03:48.0072 (UTC) FILETIME=[6AD1BE80:01D0F0B2] X-MC-Unique: 6bdPlWWRT0aMmRW2vgUHjQ-1 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20150916_120407_952018_8DBB3449 X-CRM114-Status: GOOD ( 12.81 ) X-Spam-Score: -5.2 (-----) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: steve.capper@arm.com, catalin.marinas@arm.com, dwoods@ezcip.com, linux-kernel@vger.kernel.org, will.deacon@arm.com, Jeremy Linton , shijie.huang@arm.com MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP With 64k pages, the next larger segment size is 512M. The linux kernel also uses different protection flags to cover its code and data. Because of this requirement, the vast majority of the kernel code and data structures end up being mapped with 64k pages instead of the larger pages common with a 4k page kernel. Recent ARM processors support a contiguous bit in the page tables which allows the a TLB to cover a range larger than a single PTE if that range is mapped into physically contiguous ram. So, for the kernel its a good idea to set this flag. Some basic micro benchmarks show it can significantly reduce the number of L1 dTLB refills. Signed-off-by: Jeremy Linton --- arch/arm64/mm/mmu.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 62 insertions(+), 8 deletions(-) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 9211b85..c7abbcc 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -80,19 +80,55 @@ static void split_pmd(pmd_t *pmd, pte_t *pte) do { /* * Need to have the least restrictive permissions available - * permissions will be fixed up later + * permissions will be fixed up later. Default the new page + * range as contiguous ptes. */ - set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC)); + set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC_CONT)); pfn++; } while (pte++, i++, i < PTRS_PER_PTE); } +/* + * Given a PTE with the CONT bit set, determine where the CONT range + * starts, and clear the entire range of PTE CONT bits. + */ +static void clear_cont_pte_range(pte_t *pte, unsigned long addr) +{ + int i; + + pte -= CONT_RANGE_OFFSET(addr); + for (i = 0; i < CONT_RANGE; i++) { + set_pte(pte, pte_mknoncont(*pte)); + pte++; + } + flush_tlb_all(); +} + +/* + * Given a range of PTEs set the pfn and provided page protection flags + */ +static void __populate_init_pte(pte_t *pte, unsigned long addr, + unsigned long end, phys_addr_t phys, + pgprot_t prot) +{ + unsigned long pfn = __phys_to_pfn(phys); + + do { + /* clear all the bits except the pfn, then apply the prot */ + set_pte(pte, pfn_pte(pfn, prot)); + pte++; + pfn++; + addr += PAGE_SIZE; + } while (addr != end); +} + static void alloc_init_pte(pmd_t *pmd, unsigned long addr, - unsigned long end, unsigned long pfn, + unsigned long end, phys_addr_t phys, pgprot_t prot, void *(*alloc)(unsigned long size)) { pte_t *pte; + unsigned long next; if (pmd_none(*pmd) || pmd_sect(*pmd)) { pte = alloc(PTRS_PER_PTE * sizeof(pte_t)); @@ -105,9 +141,28 @@ static void alloc_init_pte(pmd_t *pmd, unsigned long addr, pte = pte_offset_kernel(pmd, addr); do { - set_pte(pte, pfn_pte(pfn, prot)); - pfn++; - } while (pte++, addr += PAGE_SIZE, addr != end); + next = min(end, (addr + CONT_SIZE) & CONT_MASK); + if (((addr | next | phys) & CONT_RANGE_MASK) == 0) { + /* a block of CONT_RANGE_SIZE PTEs */ + __populate_init_pte(pte, addr, next, phys, + prot | __pgprot(PTE_CONT)); + pte += CONT_RANGE; + } else { + /* + * If the range being split is already inside of a + * contiguous range but this PTE isn't going to be + * contiguous, then we want to unmark the adjacent + * ranges, then update the portion of the range we + * are interrested in. + */ + clear_cont_pte_range(pte, addr); + __populate_init_pte(pte, addr, next, phys, prot); + pte += CONT_RANGE_OFFSET(next - addr); + } + + phys += next - addr; + addr = next; + } while (addr != end); } void split_pud(pud_t *old_pud, pmd_t *pmd) @@ -168,8 +223,7 @@ static void alloc_init_pmd(struct mm_struct *mm, pud_t *pud, } } } else { - alloc_init_pte(pmd, addr, next, __phys_to_pfn(phys), - prot, alloc); + alloc_init_pte(pmd, addr, next, phys, prot, alloc); } phys += next - addr; } while (pmd++, addr = next, addr != end);