From patchwork Thu Apr 20 18:17:11 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?q?Kristina_Mart=C5=A1enko?= X-Patchwork-Id: 9691093 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id C2A80601D4 for ; Thu, 20 Apr 2017 18:22:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B982E2844C for ; Thu, 20 Apr 2017 18:22:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id ADB5A284F2; Thu, 20 Apr 2017 18:22:22 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 4DFF22844C for ; Thu, 20 Apr 2017 18:22:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.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=a7IkkgJGNi87ZAtWgO5e0Q9rP0qdp9ZKiQMbbqdiGnQ=; b=Ocvxb2VYwo61EDEulo6cVGp64t 0Qspnn8GQ3qesjYUlAQl82nUIfvIwJPk0xLde/cTVqvFoo3LEXy4gn99OqufW3xfuU+bAbDtjfD/O 5LisUprYqDZPeidopftRjFf32awY7rwNEudwfRf3O+WES/00F/7P2nx+DhtsBNgAumnP+9P4ksLVp KfXy55dO9QlzbCKTv9Zy/n+Vm7To8fTUiZZwXx6GDBDa3Ko9+5FqFKJyAimRi0j+kSPS7HCaZkyrf MD95ksVg3SaftCOeDz6sjxrr0MKbRd0nPHHIU8J0gt+sVTTMRfIwDzwUSD+IGpZfrH53gwCe5d7NM PsYu0gJg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1d1Gia-00072h-LV; Thu, 20 Apr 2017 18:22:12 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1d1GiN-0006dw-Rr for linux-arm-kernel@lists.infradead.org; Thu, 20 Apr 2017 18:22:01 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 53C7715A2; Thu, 20 Apr 2017 11:21:43 -0700 (PDT) Received: from moonbear.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2F6FB3F3E1; Thu, 20 Apr 2017 11:21:42 -0700 (PDT) From: Kristina Martsenko To: Will Deacon , Catalin Marinas Subject: [PATCH 1/4] arm64: traps: fix userspace cache maintenance emulation on a tagged pointer Date: Thu, 20 Apr 2017 19:17:11 +0100 Message-Id: <1492712234-4950-2-git-send-email-kristina.martsenko@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1492712234-4950-1-git-send-email-kristina.martsenko@arm.com> References: <1492712234-4950-1-git-send-email-kristina.martsenko@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170420_112159_928699_B576F990 X-CRM114-Status: GOOD ( 15.10 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Andre Przywara , Dave Martin , linux-arm-kernel@lists.infradead.org, Marc Zyngier MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP When we emulate userspace cache maintenance in the kernel, we can currently send the task a SIGSEGV even though the maintenance was done on a valid address. This happens if the address has a non-zero address tag, and happens to not be mapped in. When we get the address from a user register, we don't currently remove the address tag before performing cache maintenance on it. If the maintenance faults, we end up in either __do_page_fault, where find_vma can't find the VMA if the address has a tag, or in do_translation_fault, where the tagged address will appear to be above TASK_SIZE. In both cases, the address is not mapped in, and the task is sent a SIGSEGV. This patch removes the tag from the address before using it. With this patch, the fault is handled correctly, the address gets mapped in, and the cache maintenance succeeds. As a second bug, if cache maintenance (correctly) fails on an invalid tagged address, the address gets passed into arm64_notify_segfault, where find_vma fails to find the VMA due to the tag, and the wrong si_code may be sent as part of the siginfo_t of the segfault. With this patch, the correct si_code is sent. Fixes: 7dd01aef0557 ("arm64: trap userspace "dc cvau" cache operation on errata-affected core") Signed-off-by: Kristina Martsenko --- Note that patch #3 would also fix the first bug (incorrect segfault), but not the second (wrong si_code), hence this patch. arch/arm64/kernel/traps.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index e52be6aa44ee..45c8eca951bc 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -443,7 +443,7 @@ int cpu_enable_cache_maint_trap(void *__unused) } #define __user_cache_maint(insn, address, res) \ - if (untagged_addr(address) >= user_addr_max()) { \ + if (address >= user_addr_max()) { \ res = -EFAULT; \ } else { \ uaccess_ttbr0_enable(); \ @@ -469,7 +469,7 @@ static void user_cache_maint_handler(unsigned int esr, struct pt_regs *regs) int crm = (esr & ESR_ELx_SYS64_ISS_CRM_MASK) >> ESR_ELx_SYS64_ISS_CRM_SHIFT; int ret = 0; - address = pt_regs_read_reg(regs, rt); + address = untagged_addr(pt_regs_read_reg(regs, rt)); switch (crm) { case ESR_ELx_SYS64_ISS_CRM_DC_CVAU: /* DC CVAU, gets promoted */