From patchwork Tue Nov 24 15:50:29 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 11929275 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=-17.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 13BD2C63777 for ; Tue, 24 Nov 2020 15:53:03 +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 7B226206F7 for ; Tue, 24 Nov 2020 15:53:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="a/x4vy2w"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="JKyTFfU9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7B226206F7 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-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=v2UsdRrB46KBuCIfogj+pU8V3Nms1NNqNGthesCj3gM=; b=a/x4vy2wKEqL/Y4oWEnQFs7JG 4a2OIZMVtvRVHhJDlcHu0hgicfS9kM79oP4zX9hsDeBjl07/kaUEccHnMiDAsGMYzaqH4L2AI9ez3 jvBM3gf4EF3JkH+/qrDp/6u3kMHd3Jky9CnRKuRzUoIVa3nCvg/JtTrkCmj/1iT0IkCjn3xGyYZFd So0TVPnJdwj2dOgHDs5xNhv+VhGLExu0JFqwbnHUdoBOd4JQFx4CvR1m+GKTkSdD0KW9pCOJ+/OEh nJFN7qzp66RwpSTSkiABxBiFUb1O1znQDwvrjP5zczY9J45ZRu8Vyxu0nCi9O3ssrCjMEa4Taqc7I HJdrTVyOQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1khabB-0004zq-WB; Tue, 24 Nov 2020 15:51:22 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1khaav-0004vF-Im for linux-arm-kernel@lists.infradead.org; Tue, 24 Nov 2020 15:51:08 +0000 Received: from localhost.localdomain (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 71B6320897; Tue, 24 Nov 2020 15:51:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1606233064; bh=VDmPonYWM7q0L5nJbpmReeXO+3GyBjiAqiksufL5TKI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JKyTFfU9pVsfAmFD+1KVDzwlro8uB6AJeadUC5h/sNvwM2aFYAtz2XO3kqlG8vpfj il5GXvXSyAtRC5+3WnkILbnBk5Cv6xpkFaAfDQ/u5ezWrDovSFuKZFYK3Py4gqSHME q9FX2uCjEdmtxr7Yhhg9aPK4xGfJ/5z9P0cxsSJw= From: Will Deacon To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v4 04/14] arm64: Kill 32-bit applications scheduled on 64-bit-only CPUs Date: Tue, 24 Nov 2020 15:50:29 +0000 Message-Id: <20201124155039.13804-5-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20201124155039.13804-1-will@kernel.org> References: <20201124155039.13804-1-will@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201124_105105_832595_9CE1D7D7 X-CRM114-Status: GOOD ( 20.30 ) 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: linux-arch@vger.kernel.org, Marc Zyngier , kernel-team@android.com, Vincent Guittot , Juri Lelli , Quentin Perret , Peter Zijlstra , Catalin Marinas , Johannes Weiner , linux-kernel@vger.kernel.org, Qais Yousef , Suren Baghdasaryan , Ingo Molnar , Li Zefan , Greg Kroah-Hartman , Tejun Heo , Will Deacon , Morten Rasmussen Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Scheduling a 32-bit application on a 64-bit-only CPU is a bad idea. Ensure that 32-bit applications always take the slow-path when returning to userspace on a system with mismatched support at EL0, so that we can avoid trying to run on a 64-bit-only CPU and force a SIGKILL instead. Signed-off-by: Will Deacon --- arch/arm64/kernel/process.c | 19 ++++++++++++++++++- arch/arm64/kernel/signal.c | 26 ++++++++++++++++++++++++++ 2 files changed, 44 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 4784011cecac..1540ab0fbf23 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -542,6 +542,15 @@ static void erratum_1418040_thread_switch(struct task_struct *prev, write_sysreg(val, cntkctl_el1); } +static void compat_thread_switch(struct task_struct *next) +{ + if (!is_compat_thread(task_thread_info(next))) + return; + + if (static_branch_unlikely(&arm64_mismatched_32bit_el0)) + set_tsk_thread_flag(next, TIF_NOTIFY_RESUME); +} + /* * Thread switching. */ @@ -558,6 +567,7 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev, uao_thread_switch(next); ssbs_thread_switch(next); erratum_1418040_thread_switch(prev, next); + compat_thread_switch(next); /* * Complete any pending TLB or cache maintenance on this CPU in case @@ -620,8 +630,15 @@ unsigned long arch_align_stack(unsigned long sp) */ void arch_setup_new_exec(void) { - current->mm->context.flags = is_compat_task() ? MMCF_AARCH32 : 0; + unsigned long mmflags = 0; + + if (is_compat_task()) { + mmflags = MMCF_AARCH32; + if (static_branch_unlikely(&arm64_mismatched_32bit_el0)) + set_tsk_thread_flag(current, TIF_NOTIFY_RESUME); + } + current->mm->context.flags = mmflags; ptrauth_thread_init_user(current); if (task_spec_ssb_noexec(current)) { diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index a8184cad8890..bcb6ca2d9a7c 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -911,6 +911,19 @@ static void do_signal(struct pt_regs *regs) restore_saved_sigmask(); } +static bool cpu_affinity_invalid(struct pt_regs *regs) +{ + if (!compat_user_mode(regs)) + return false; + + /* + * We're preemptible, but a reschedule will cause us to check the + * affinity again. + */ + return !cpumask_test_cpu(raw_smp_processor_id(), + system_32bit_el0_cpumask()); +} + asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags) { @@ -948,6 +961,19 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, if (thread_flags & _TIF_NOTIFY_RESUME) { tracehook_notify_resume(regs); rseq_handle_notify_resume(NULL, regs); + + /* + * If we reschedule after checking the affinity + * then we must ensure that TIF_NOTIFY_RESUME + * is set so that we check the affinity again. + * Since tracehook_notify_resume() clears the + * flag, ensure that the compiler doesn't move + * it after the affinity check. + */ + barrier(); + + if (cpu_affinity_invalid(regs)) + force_sig(SIGKILL); } if (thread_flags & _TIF_FOREIGN_FPSTATE)