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=-18.2 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 8E338C64E7B for ; Mon, 30 Nov 2020 12:03:58 +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 17E4D206D8 for ; Mon, 30 Nov 2020 12:03:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="vv1bh3bb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 17E4D206D8 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:MIME-Version:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id: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=+DFr75APuAeZ56fLHIY0mf1ifAEZuwi+T9z1s8Uto+8=; b=vv1bh3bbDktanprkql+srV/BZE eiS+sbz3JQZYlwRJhzZHwVHFlqm//saRTi2VkmldCxk5KA02HnHwwRPemeJmL51bzJDCEa8bEzQWx lIfPjlY+mdPEIpYkiqhaYf1dLwtO/ivD6FL+c8bm0CwqLaBaPmyTEqoiTd0hBHk9mX7gOCMUVW4Xk s+f/RF2cWcGd3tQu4JyU+l0bITQyQDs8pKuCV8ZP+IvqKQOeWEJtHPX6Lt1YyskY4mzm0syytVTik xquWxGAD1Ye7MDD7xFb/AymgyU9WFIPdzme4pJEnci3HYbyKGpt6XViFD8+8NBZMY911fuqGioBlA qtMn8PAQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kjhsj-0000sp-Q5; Mon, 30 Nov 2020 12:02:14 +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 1kjhqo-00007b-A8 for linux-arm-kernel@lists.infradead.org; Mon, 30 Nov 2020 12:00:22 +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 2A09813A1; Mon, 30 Nov 2020 04:00:14 -0800 (PST) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id E79093F66B; Mon, 30 Nov 2020 04:00:12 -0800 (PST) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org, will@kernel.org Subject: [PATCHv2 09/11] arm64: entry: fix non-NMI kernel<->kernel transitions Date: Mon, 30 Nov 2020 11:59:48 +0000 Message-Id: <20201130115950.22492-10-mark.rutland@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20201130115950.22492-1-mark.rutland@arm.com> References: <20201130115950.22492-1-mark.rutland@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201130_070014_559250_6A536F8C X-CRM114-Status: GOOD ( 20.05 ) 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: mark.rutland@arm.com, elver@google.com, paulmck@kernel.org, peterz@infradead.org, catalin.marinas@arm.com, james.morse@arm.com, dvyukov@google.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org There are periods in kernel mode when RCU is not watching and/or the scheduler tick is disabled, but we can still take exceptions such as interrupts. The arm64 exception handlers do not account for this, and it's possible that RCU is not watching while an exception handler runs. The x86/generic entry code handles this by ensuring that all (non-NMI) kernel exception handlers call irqentry_enter() and irqentry_exit(), which handle RCU, lockdep, and IRQ flag tracing. We can't yet move to the generic entry code, and already hadnle the user<->kernel transitions elsewhere, so we add new kernel<->kernel transition helpers alog the lines of the generic entry code. Since we now track interrupts becoming masked when an exception is taken, local_daif_inherit() is modified to track interrupts becoming re-enabled when the original context is inherited. To balance the entry/exit paths, each handler masks all DAIF exceptions before exit_to_kernel_mode(). Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: James Morse Cc: Will Deacon --- arch/arm64/include/asm/daifflags.h | 3 ++ arch/arm64/kernel/entry-common.c | 67 ++++++++++++++++++++++++++++++++++++-- 2 files changed, 67 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/daifflags.h b/arch/arm64/include/asm/daifflags.h index ec213b4a1650..1c26d7baa67f 100644 --- a/arch/arm64/include/asm/daifflags.h +++ b/arch/arm64/include/asm/daifflags.h @@ -128,6 +128,9 @@ static inline void local_daif_inherit(struct pt_regs *regs) { unsigned long flags = regs->pstate & DAIF_MASK; + if (interrupts_enabled(regs)) + trace_hardirqs_on(); + /* * We can't use local_daif_restore(regs->pstate) here as * system_has_prio_mask_debugging() won't restore the I bit if it can diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c index 49d1c1dd9baf..86622d8dd0d8 100644 --- a/arch/arm64/kernel/entry-common.c +++ b/arch/arm64/kernel/entry-common.c @@ -17,12 +17,58 @@ #include #include +/* + * This is intended to match the logic in irqentry_enter(), handling the kernel + * mode transitions only. + */ +static void noinstr enter_from_kernel_mode(struct pt_regs *regs) +{ + regs->exit_rcu = false; + + if (!IS_ENABLED(CONFIG_TINY_RCU) && is_idle_task(current)) { + lockdep_hardirqs_off(CALLER_ADDR0); + rcu_irq_enter(); + trace_hardirqs_off_finish(); + + regs->exit_rcu = true; + return; + } + + lockdep_hardirqs_off(CALLER_ADDR0); + rcu_irq_enter_check_tick(); + trace_hardirqs_off_finish(); +} + +/* + * This is intended to match the logic in irqentry_exit(), handling the kernel + * mode transitions only, and with preemption handled elsewhere. + */ +static void noinstr exit_to_kernel_mode(struct pt_regs *regs) +{ + lockdep_assert_irqs_disabled(); + + if (interrupts_enabled(regs)) { + if (regs->exit_rcu) { + trace_hardirqs_on_prepare(); + lockdep_hardirqs_on_prepare(CALLER_ADDR0); + rcu_irq_exit(); + lockdep_hardirqs_on(CALLER_ADDR0); + return; + } + + trace_hardirqs_on(); + } else { + if (regs->exit_rcu) + rcu_irq_exit(); + } +} + asmlinkage void noinstr enter_el1_irq_or_nmi(struct pt_regs *regs) { if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs)) nmi_enter(); - - trace_hardirqs_off(); + else + enter_from_kernel_mode(regs); } asmlinkage void noinstr exit_el1_irq_or_nmi(struct pt_regs *regs) @@ -30,36 +76,48 @@ asmlinkage void noinstr exit_el1_irq_or_nmi(struct pt_regs *regs) if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs)) nmi_exit(); else - trace_hardirqs_on(); + exit_to_kernel_mode(regs); } static void noinstr el1_abort(struct pt_regs *regs, unsigned long esr) { unsigned long far = read_sysreg(far_el1); + enter_from_kernel_mode(regs); local_daif_inherit(regs); far = untagged_addr(far); do_mem_abort(far, esr, regs); + local_daif_mask(); + exit_to_kernel_mode(regs); } static void noinstr el1_pc(struct pt_regs *regs, unsigned long esr) { unsigned long far = read_sysreg(far_el1); + enter_from_kernel_mode(regs); local_daif_inherit(regs); do_sp_pc_abort(far, esr, regs); + local_daif_mask(); + exit_to_kernel_mode(regs); } static void noinstr el1_undef(struct pt_regs *regs) { + enter_from_kernel_mode(regs); local_daif_inherit(regs); do_undefinstr(regs); + local_daif_mask(); + exit_to_kernel_mode(regs); } static void noinstr el1_inv(struct pt_regs *regs, unsigned long esr) { + enter_from_kernel_mode(regs); local_daif_inherit(regs); bad_mode(regs, 0, esr); + local_daif_mask(); + exit_to_kernel_mode(regs); } static void noinstr el1_dbg(struct pt_regs *regs, unsigned long esr) @@ -79,8 +137,11 @@ static void noinstr el1_dbg(struct pt_regs *regs, unsigned long esr) static void noinstr el1_fpac(struct pt_regs *regs, unsigned long esr) { + enter_from_kernel_mode(regs); local_daif_inherit(regs); do_ptrauth_fault(regs, esr); + local_daif_mask(); + exit_to_kernel_mode(regs); } asmlinkage void noinstr el1_sync_handler(struct pt_regs *regs) -- 2.11.0 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel