From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=3.0 tests=DKIM_SIGNED, MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9FAD9C43334 for ; Thu, 6 Sep 2018 10:22:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 48D472075B for ; Thu, 6 Sep 2018 10:22:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="TOIsaVYJ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 48D472075B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728721AbeIFO52 (ORCPT ); Thu, 6 Sep 2018 10:57:28 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:44995 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726444AbeIFO51 (ORCPT ); Thu, 6 Sep 2018 10:57:27 -0400 Received: by mail-pl1-f195.google.com with SMTP id ba4-v6so4762594plb.11 for ; Thu, 06 Sep 2018 03:22:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=sCOjJCIPjuifYDa+05zHL+WPmPDOj/NAolPV8GEjiP4=; b=TOIsaVYJTHzrvs7ufNK+zs1lnHPddRhNS9vMssgDAOZvHX9Qht4OlYinQLaohyH6RD mU56zOj/ZYEC1IQIpnrH99T4gFbXZapBet5DD5vY3ZB/YlL1bxwJgJntD6xrBZKp/mdU H41EoRJPm1NL3yzWkuyRVW+HXGwVAcOt5eR1/Q6h7uZpmeLQOKl7Nr/JoWQIq8KNZsh8 b8cCqOLDwPUGep4h2RXQyIfN2DkCIS9TCkT5d2Ok6WRLN6i7kbWqP5LGOaOXw4/Akt59 Ih6dfjq+OB0kqAWyn8O8InWGb2EkdiWfIJTsea5hyzH10O2AYQYRC155TtRMj4SlLvNp RLRw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-transfer-encoding; bh=sCOjJCIPjuifYDa+05zHL+WPmPDOj/NAolPV8GEjiP4=; b=YpIdW4MpvcrJrEC1zwtbo89d8YrNn6EE55IqQYEaXTb6bfofp+OiPviCQ8TiRPOOSv pds35F30vb7QrbzO1/KFwSqWh8YCTDhUts8QPW3oeUR0fDK01QRIkJ0GppCZiWxM7cCi cJbmw22N4B3rAPLNnzP6A7scGEtvBx/WUKzgO+n2TJBGVZ+sElO9TETqefF9kmWvOgzg UdJFKhLYXxmOMY8uWpcTUKXm7iOZ5fk52ApPUMXCRbFqric9oXpDCnq5WaACqrqhBwET vECsgSgZXsMpxwZD2WDj1Wy9dTlj6qjKZ882xLq11C+M0gcmSDANYmD5SmYT/GcfbPiy q6ag== X-Gm-Message-State: APzg51CMMY7Xc+y+vKtZBr3yQeh35TZZuwN5anhnZI03JwLBej+qEfX2 6NJUc1ouGaTasRhZZvjRIkY= X-Google-Smtp-Source: ANB0Vdac3TqOVzfOTkd+mkLosV6H0nHL5sc7hGEcZLAJ54ZFX4GvaOM8fol92aWpVHkgP9/KImB+fQ== X-Received: by 2002:a17:902:46a4:: with SMTP id p33-v6mr1947964pld.205.1536229360600; Thu, 06 Sep 2018 03:22:40 -0700 (PDT) Received: from bbox-2.seo.corp.google.com ([2401:fa00:d:10:affa:813f:5380:6613]) by smtp.gmail.com with ESMTPSA id h82-v6sm7909555pfa.173.2018.09.06.03.22.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 06 Sep 2018 03:22:39 -0700 (PDT) From: Minchan Kim To: Andrew Morton , linux@armlinux.org.uk Cc: steve.capper@linaro.org, will.deacon@arm.com, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kernel-team@android.com, android-treble-mediatek-ext@partner.android.com, Minchan Kim Subject: [RFC 3/3] arm: mm: support get_user_pages_fast Date: Thu, 6 Sep 2018 19:22:12 +0900 Message-Id: <20180906102212.218294-4-minchan@kernel.org> X-Mailer: git-send-email 2.19.0.rc1.350.ge57e33dbd1-goog In-Reply-To: <20180906102212.218294-1-minchan@kernel.org> References: <20180906102212.218294-1-minchan@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Recently, there was a report get_user_pages_fast helps app launching speed due to reducing uninterruptible sleep time because we don't need to contend for mmap_sem, I believe. With get_user_pages_fast, that uniterruptible sleep time is reduced about 5~10% by testing. Cc: Russell King Cc: Catalin Marinas Cc: Will Deacon Cc: Steve Capper Signed-off-by: Minchan Kim --- arch/arm/mm/Makefile | 6 ++ arch/arm/mm/gup.c | 221 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 227 insertions(+) create mode 100644 arch/arm/mm/gup.c diff --git a/arch/arm/mm/Makefile b/arch/arm/mm/Makefile index 7cb1699fbfc4..f55f96d56843 100644 --- a/arch/arm/mm/Makefile +++ b/arch/arm/mm/Makefile @@ -13,6 +13,12 @@ obj-y += nommu.o obj-$(CONFIG_ARM_MPU) += pmsa-v7.o pmsa-v8.o endif +ifneq ($(CONFIG_ARM_LPAE),y) +ifeq ($(CONFIG_ARCH_HAS_PTE_SPECIAL),y) +obj-$(CONFIG_MMU) += gup.o +endif +endif + obj-$(CONFIG_ARM_PTDUMP_CORE) += dump.o obj-$(CONFIG_ARM_PTDUMP_DEBUGFS) += ptdump_debugfs.o obj-$(CONFIG_MODULES) += proc-syms.o diff --git a/arch/arm/mm/gup.c b/arch/arm/mm/gup.c new file mode 100644 index 000000000000..44e12fb7430e --- /dev/null +++ b/arch/arm/mm/gup.c @@ -0,0 +1,221 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include + +static inline pte_t gup_get_pte(pte_t *ptep) +{ + return READ_ONCE(*ptep); +} + +static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, + int write, struct page **pages, int *nr) +{ + int ret = 0; + pte_t *ptep, *ptem; + + ptem = ptep = pte_offset_map(&pmd, addr); + do { + pte_t pte = gup_get_pte(ptep); + struct page *page; + + if (!pte_access_permitted(pte, write)) + goto pte_unmap; + + if (pte_special(pte)) + goto pte_unmap; + + VM_BUG_ON(!pfn_valid(pte_pfn(pte))); + page = pte_page(pte); + + if (!page_cache_get_speculative(page)) + goto pte_unmap; + + if (unlikely(pte_val(pte) != pte_val(*ptep))) { + put_page(page); + goto pte_unmap; + } + + SetPageReferenced(page); + pages[*nr] = page; + (*nr)++; + + } while (ptep++, addr += PAGE_SIZE, addr != end); + + ret = 1; + +pte_unmap: + pte_unmap(ptem); + return ret; +} + +static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end, + int write, struct page **pages, int *nr) +{ + unsigned long next; + pmd_t *pmdp; + + pmdp = pmd_offset(&pud, addr); + do { + pmd_t pmd = READ_ONCE(*pmdp); + + next = pmd_addr_end(addr, end); + if (!pmd_present(pmd)) + return 0; + else if (!gup_pte_range(pmd, addr, next, write, pages, nr)) + return 0; + } while (pmdp++, addr = next, addr != end); + + return 1; +} + +static int gup_pud_range(p4d_t *p4dp, unsigned long addr, unsigned long end, + int write, struct page **pages, int *nr) +{ + unsigned long next; + pud_t *pudp; + + pudp = pud_offset(p4dp, addr); + do { + pud_t pud = READ_ONCE(*pudp); + + next = pud_addr_end(addr, end); + if (pud_none(pud)) + return 0; + else if (!gup_pmd_range(pud, addr, next, write, pages, nr)) + return 0; + } while (pudp++, addr = next, addr != end); + + return 1; +} + +static int gup_p4d_range(pgd_t *pgdp, unsigned long addr, unsigned long end, + int write, struct page **pages, int *nr) +{ + unsigned long next; + p4d_t *p4dp; + + p4dp = p4d_offset(pgdp, addr); + do { + next = p4d_addr_end(addr, end); + if (p4d_none(*p4dp)) { + return 0; + } else if (!gup_pud_range(p4dp, addr, next, write, pages, nr)) + return 0; + } while (p4dp++, addr = next, addr != end); + + return 1; +} + + +static void gup_pgd_range(unsigned long addr, unsigned long end, + int write, struct page **pages, int *nr) +{ + unsigned long next; + pgd_t *pgdp; + + pgdp = pgd_offset(current->mm, addr); + do { + next = pgd_addr_end(addr, end); + if (pgd_none(*pgdp)) + return; + else if (!gup_p4d_range(pgdp, addr, next, write, pages, nr)) + break; + } while (pgdp++, addr = next, addr != end); +} + +bool gup_fast_permitted(unsigned long start, int nr_pages, int write) +{ + unsigned long len, end; + + len = (unsigned long) nr_pages << PAGE_SHIFT; + end = start + len; + return end >= start; +} + +/* + * Like get_user_pages_fast() except its IRQ-safe in that it won't fall + * back to the regular GUP. + */ +int __get_user_pages_fast(unsigned long start, int nr_pages, int write, + struct page **pages) +{ + unsigned long addr, len, end; + unsigned long flags; + int nr = 0; + + start &= PAGE_MASK; + addr = start; + len = (unsigned long) nr_pages << PAGE_SHIFT; + end = start + len; + + if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ, + (void __user *)start, len))) + return 0; + + /* + * Disable interrupts. We use the nested form as we can already have + * interrupts disabled by get_futex_key. + * + * With interrupts disabled, we block page table pages from being + * freed from under us. See mmu_gather_tlb in asm-generic/tlb.h + * for more details. + * + * We do not adopt an rcu_read_lock(.) here as we also want to + * block IPIs that come from THPs splitting. + */ + + if (gup_fast_permitted(start, nr_pages, write)) { + local_irq_save(flags); + gup_pgd_range(addr, end, write, pages, &nr); + local_irq_restore(flags); + } + + return nr; +} + +int get_user_pages_fast(unsigned long start, int nr_pages, int write, + struct page **pages) +{ + unsigned long addr, len, end; + int nr = 0, ret = 0; + + start &= PAGE_MASK; + addr = start; + len = (unsigned long) nr_pages << PAGE_SHIFT; + end = start + len; + + if (nr_pages <= 0) + return 0; + + if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ, + (void __user *)start, len))) + return -EFAULT; + + if (gup_fast_permitted(start, nr_pages, write)) { + local_irq_disable(); + gup_pgd_range(addr, end, write, pages, &nr); + local_irq_enable(); + ret = nr; + } + + if (nr < nr_pages) { + /* Try to get the remaining pages with get_user_pages */ + start += nr << PAGE_SHIFT; + pages += nr; + + ret = get_user_pages_unlocked(start, nr_pages - nr, pages, + write ? FOLL_WRITE : 0); + + /* Have to be a bit careful with return values */ + if (nr > 0) { + if (ret < 0) + ret = nr; + else + ret += nr; + } + } + + return ret; +} -- 2.19.0.rc1.350.ge57e33dbd1-goog