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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 C4FA8C433DF for ; Fri, 15 May 2020 17:16:42 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7B85E206C0 for ; Fri, 15 May 2020 17:16:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7B85E206C0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 6B20A8E000C; Fri, 15 May 2020 13:16:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 577028E0001; Fri, 15 May 2020 13:16:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 351D38E000C; Fri, 15 May 2020 13:16:38 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0087.hostedemail.com [216.40.44.87]) by kanga.kvack.org (Postfix) with ESMTP id 1DC868E0001 for ; Fri, 15 May 2020 13:16:38 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id C3AAC1807C6C3 for ; Fri, 15 May 2020 17:16:37 +0000 (UTC) X-FDA: 76819607634.25.print51_9120822d1b70d X-HE-Tag: print51_9120822d1b70d X-Filterd-Recvd-Size: 7224 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf09.hostedemail.com (Postfix) with ESMTP for ; Fri, 15 May 2020 17:16:37 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9C7991042; Fri, 15 May 2020 10:16:36 -0700 (PDT) Received: from localhost.localdomain (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id CE8733F305; Fri, 15 May 2020 10:16:34 -0700 (PDT) From: Catalin Marinas To: linux-arm-kernel@lists.infradead.org Cc: linux-mm@kvack.org, linux-arch@vger.kernel.org, Will Deacon , Dave P Martin , Vincenzo Frascino , Szabolcs Nagy , Kevin Brodsky , Andrey Konovalov , Peter Collingbourne , Steven Price Subject: [PATCH v4 07/26] arm64: mte: Clear the tags when a page is mapped in user-space with PROT_MTE Date: Fri, 15 May 2020 18:15:53 +0100 Message-Id: <20200515171612.1020-8-catalin.marinas@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200515171612.1020-1-catalin.marinas@arm.com> References: <20200515171612.1020-1-catalin.marinas@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Pages allocated by the kernel are not guaranteed to have the tags zeroed, especially as the kernel does not yet use MTE itself. To ensure the user can still access such pages when mapped into its address space, clear the tags via set_pte_at(). A new page flag - PG_mte_tagged (PG_arch_2) - is used to track pages with valid allocation tags. Co-developed-by: Steven Price Signed-off-by: Steven Price Signed-off-by: Catalin Marinas Cc: Will Deacon --- Notes: New in v4. Replacing a previous page zeroing the tags in clear_page()= . arch/arm64/include/asm/assembler.h | 12 ++++++++++++ arch/arm64/include/asm/mte.h | 16 ++++++++++++++++ arch/arm64/include/asm/pgtable.h | 6 ++++++ arch/arm64/kernel/mte.c | 14 ++++++++++++++ arch/arm64/lib/Makefile | 2 ++ arch/arm64/lib/mte.S | 23 +++++++++++++++++++++++ 6 files changed, 73 insertions(+) create mode 100644 arch/arm64/lib/mte.S diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/= assembler.h index 0bff325117b4..dacd66df6c05 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -21,6 +21,7 @@ #include #include #include +#include #include =20 .macro save_and_disable_daif, flags @@ -736,4 +737,15 @@ USER(\label, ic ivau, \tmp2) // invalidate I line = PoU .Lyield_out_\@ : .endm =20 +/* + * multitag_transfer_size - set \reg to the block size that is accessed = by the + * LDGM/STGM instructions. + */ + .macro multitag_transfer_size, reg, tmp + mrs_s \reg, SYS_GMID_EL1 + ubfx \reg, \reg, #SYS_GMID_EL1_BS_SHIFT, #SYS_GMID_EL1_BS_SIZE + mov \tmp, #4 + lsl \reg, \tmp, \reg + .endm + #endif /* __ASM_ASSEMBLER_H */ diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h index a0bf310da74b..4310a7ff10c0 100644 --- a/arch/arm64/include/asm/mte.h +++ b/arch/arm64/include/asm/mte.h @@ -7,12 +7,28 @@ =20 #ifndef __ASSEMBLY__ =20 +#include + +#include + +void mte_clear_page_tags(void *addr, size_t size); + #ifdef CONFIG_ARM64_MTE =20 +/* track which pages have valid allocation tags */ +#define PG_mte_tagged PG_arch_2 + +void mte_sync_tags(pte_t *ptep, pte_t pte); void flush_mte_state(void); =20 #else =20 +/* unused if !CONFIG_ARM64_MTE, silence the compiler */ +#define PG_mte_tagged 0 + +static inline void mte_sync_tags(pte_t *ptep, pte_t pte) +{ +} static inline void flush_mte_state(void) { } diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pg= table.h index 538c85e62f86..647a3f0c7874 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -9,6 +9,7 @@ #include =20 #include +#include #include #include #include @@ -80,6 +81,8 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof= (unsigned long)]; #define pte_user_exec(pte) (!(pte_val(pte) & PTE_UXN)) #define pte_cont(pte) (!!(pte_val(pte) & PTE_CONT)) #define pte_devmap(pte) (!!(pte_val(pte) & PTE_DEVMAP)) +#define pte_tagged(pte) ((pte_val(pte) & PTE_ATTRINDX_MASK) =3D=3D \ + PTE_ATTRINDX(MT_NORMAL_TAGGED)) =20 #define pte_cont_addr_end(addr, end) \ ({ unsigned long __boundary =3D ((addr) + CONT_PTE_SIZE) & CONT_PTE_MASK= ; \ @@ -274,6 +277,9 @@ static inline void set_pte_at(struct mm_struct *mm, u= nsigned long addr, if (pte_present(pte) && pte_user_exec(pte) && !pte_special(pte)) __sync_icache_dcache(pte); =20 + if (system_supports_mte() && pte_present(pte) && pte_tagged(pte)) + mte_sync_tags(ptep, pte); + __check_racy_pte_update(mm, ptep, pte); =20 set_pte(ptep, pte); diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c index 032016823957..65a2f8490d18 100644 --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -3,12 +3,26 @@ * Copyright (C) 2020 ARM Ltd. */ =20 +#include +#include #include =20 #include #include #include =20 +void mte_sync_tags(pte_t *ptep, pte_t pte) +{ + struct page *page =3D pte_page(pte); + + /* if PG_mte_tagged is set, tags have already been initialised */ + if (test_and_set_bit(PG_mte_tagged, &page->flags)) + return; + + /* tags of the zero page will be cleared on first mapping */ + mte_clear_page_tags(page_address(page), page_size(page)); +} + void flush_mte_state(void) { if (!system_supports_mte()) diff --git a/arch/arm64/lib/Makefile b/arch/arm64/lib/Makefile index 2fc253466dbf..d31e1169d9b8 100644 --- a/arch/arm64/lib/Makefile +++ b/arch/arm64/lib/Makefile @@ -16,3 +16,5 @@ lib-$(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) +=3D uaccess_= flushcache.o obj-$(CONFIG_CRC32) +=3D crc32.o =20 obj-$(CONFIG_FUNCTION_ERROR_INJECTION) +=3D error-inject.o + +obj-$(CONFIG_ARM64_MTE) +=3D mte.o diff --git a/arch/arm64/lib/mte.S b/arch/arm64/lib/mte.S new file mode 100644 index 000000000000..130fb7047e17 --- /dev/null +++ b/arch/arm64/lib/mte.S @@ -0,0 +1,23 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2020 ARM Ltd. + */ +#include + +#include + + .arch armv8.5-a+memtag + +/* + * Clear the tags in a (potentially huge) page + * x0 - page address + * x1 - page size + */ +SYM_FUNC_START(mte_clear_page_tags) + multitag_transfer_size x2, x3 +1: stgm xzr, [x0] + add x0, x0, x2 + sub x1, x1, x2 + cbnz x1, 1b + ret +SYM_FUNC_END(mte_clear_page_tags)