From patchwork Mon Jan 18 18:30:32 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vincenzo Frascino X-Patchwork-Id: 12028003 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=-16.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 9972AC433E9 for ; Mon, 18 Jan 2021 18:32:40 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5D50A22CA1 for ; Mon, 18 Jan 2021 18:32:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5D50A22CA1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=+cvmDSBpzEsnuJu2ge1igOeEBIMryeCNL2FBV2KfF4w=; b=AHSEHqX58KbxoUroFlrtWHovh dApeXFkqcEmtjZ+3Tk0Vp1E3bWHCjhrNfZ6e1CdNdicOn6yRq1A5qxKWI86coa832WPAVPcNqpcYf w03IIYlvRZgKRgB25stGmT6Y08YE0Q/c77P7K4iA22sXlKMMa5g3Hr+NJ0KM4YjoBh3jBlwnLUddx dXp9MNjGpSJvO9N+H/QCSm6H/0ZrNuDYw0cX3+uCyRwRhUAfZFtf2VTillh9nsvDDdy5vDkxSYMES DHhi3/h60xskSIlkPz4a6KxySKsLvYFAJxOgKUaxN5gjCTmCT0HlR8DYcXfO9YAnXzXWt/epqpn5e 4ZN6vpSwA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l1ZJ7-00016G-Cx; Mon, 18 Jan 2021 18:31:18 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l1ZIm-00010N-OI for linux-arm-kernel@lists.infradead.org; Mon, 18 Jan 2021 18:30:59 +0000 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 979111063; Mon, 18 Jan 2021 10:30:55 -0800 (PST) Received: from e119884-lin.cambridge.arm.com (e119884-lin.cambridge.arm.com [10.1.196.72]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E93AA3F719; Mon, 18 Jan 2021 10:30:53 -0800 (PST) From: Vincenzo Frascino To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com Subject: [PATCH v4 4/5] arm64: mte: Enable async tag check fault Date: Mon, 18 Jan 2021 18:30:32 +0000 Message-Id: <20210118183033.41764-5-vincenzo.frascino@arm.com> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210118183033.41764-1-vincenzo.frascino@arm.com> References: <20210118183033.41764-1-vincenzo.frascino@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210118_133056_944821_52A7F7D6 X-CRM114-Status: GOOD ( 21.21 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Marco Elver , Catalin Marinas , Branislav Rankov , Alexander Potapenko , Evgenii Stepanov , Andrey Konovalov , Andrey Ryabinin , Vincenzo Frascino , Will Deacon , Dmitry Vyukov Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org MTE provides a mode that asynchronously updates the TFSR_EL1 register when a tag check exception is detected. To take advantage of this mode the kernel has to verify the status of the register at: 1. Context switching 2. Return to user/EL0 (Not required in entry from EL0 since the kernel did not run) 3. Kernel entry from EL1 4. Kernel exit to EL1 If the register is non-zero a trace is reported. Add the required features for EL1 detection and reporting. Note: ITFSB bit is set in the SCTLR_EL1 register hence it guaranties that the indirect writes to TFSR_EL1 are synchronized at exception entry to EL1. On the context switch path the synchronization is guarantied by the dsb() in __switch_to(). The dsb(nsh) in mte_check_tfsr_exit() is provisional pending confirmation by the architects. Cc: Catalin Marinas Cc: Will Deacon Signed-off-by: Vincenzo Frascino --- arch/arm64/include/asm/mte.h | 32 ++++++++++++++++++++++ arch/arm64/kernel/entry-common.c | 6 ++++ arch/arm64/kernel/mte.c | 47 ++++++++++++++++++++++++++++++++ 3 files changed, 85 insertions(+) diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h index d02aff9f493d..237bb2f7309d 100644 --- a/arch/arm64/include/asm/mte.h +++ b/arch/arm64/include/asm/mte.h @@ -92,5 +92,37 @@ static inline void mte_assign_mem_tag_range(void *addr, size_t size) #endif /* CONFIG_ARM64_MTE */ +#ifdef CONFIG_KASAN_HW_TAGS +void mte_check_tfsr_el1(void); + +static inline void mte_check_tfsr_entry(void) +{ + mte_check_tfsr_el1(); +} + +static inline void mte_check_tfsr_exit(void) +{ + /* + * The asynchronous faults are sync'ed automatically with + * TFSR_EL1 on kernel entry but for exit an explicit dsb() + * is required. + */ + dsb(nsh); + isb(); + + mte_check_tfsr_el1(); +} +#else +static inline void mte_check_tfsr_el1(void) +{ +} +static inline void mte_check_tfsr_entry(void) +{ +} +static inline void mte_check_tfsr_exit(void) +{ +} +#endif /* CONFIG_KASAN_HW_TAGS */ + #endif /* __ASSEMBLY__ */ #endif /* __ASM_MTE_H */ diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c index 5346953e4382..31666511ba67 100644 --- a/arch/arm64/kernel/entry-common.c +++ b/arch/arm64/kernel/entry-common.c @@ -37,6 +37,8 @@ static void noinstr enter_from_kernel_mode(struct pt_regs *regs) lockdep_hardirqs_off(CALLER_ADDR0); rcu_irq_enter_check_tick(); trace_hardirqs_off_finish(); + + mte_check_tfsr_entry(); } /* @@ -47,6 +49,8 @@ static void noinstr exit_to_kernel_mode(struct pt_regs *regs) { lockdep_assert_irqs_disabled(); + mte_check_tfsr_exit(); + if (interrupts_enabled(regs)) { if (regs->exit_rcu) { trace_hardirqs_on_prepare(); @@ -243,6 +247,8 @@ asmlinkage void noinstr enter_from_user_mode(void) asmlinkage void noinstr exit_to_user_mode(void) { + mte_check_tfsr_exit(); + trace_hardirqs_on_prepare(); lockdep_hardirqs_on_prepare(CALLER_ADDR0); user_enter_irqoff(); diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c index 78fc079a3b1e..0a9cc82a5301 100644 --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -170,6 +170,44 @@ void mte_enable_kernel_async(void) __mte_enable_kernel("asynchronous", SCTLR_ELx_TCF_ASYNC); } +#ifdef CONFIG_KASAN_HW_TAGS +static inline void mte_report_async(void) +{ + u64 pc = (u64)__builtin_return_address(0); + + kasan_report_async(0, 0, false, pc); +} + +void mte_check_tfsr_el1(void) +{ + u64 tfsr_el1; + + if (!system_supports_mte()) + return; + + tfsr_el1 = read_sysreg_s(SYS_TFSR_EL1); + + /* + * The kernel should never trigger an asynchronous fault on a + * TTBR0 address, so we should never see TF0 set. + * For futexes we disable checks via PSTATE.TCO. + */ + WARN_ONCE(tfsr_el1 & SYS_TFSR_EL1_TF0, + "Kernel async tag fault on TTBR0 address"); + + if (unlikely(tfsr_el1 & SYS_TFSR_EL1_TF1)) { + /* + * Note: isb() is not required after this direct write + * because there is no indirect read subsequent to it + * (per ARM DDI 0487F.c table D13-1). + */ + write_sysreg_s(0, SYS_TFSR_EL1); + + mte_report_async(); + } +} +#endif + static void update_sctlr_el1_tcf0(u64 tcf0) { /* ISB required for the kernel uaccess routines */ @@ -235,6 +273,15 @@ void mte_thread_switch(struct task_struct *next) /* avoid expensive SCTLR_EL1 accesses if no change */ if (current->thread.sctlr_tcf0 != next->thread.sctlr_tcf0) update_sctlr_el1_tcf0(next->thread.sctlr_tcf0); + + /* + * Check if an async tag exception occurred at EL1. + * + * Note: On the context switch path we rely on the dsb() present + * in __switch_to() to guarantee that the indirect writes to TFSR_EL1 + * are synchronized before this point. + */ + mte_check_tfsr_el1(); } void mte_suspend_exit(void)