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=-14.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 A6197C43461 for ; Mon, 14 Sep 2020 15:20:41 +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 10B5A20639 for ; Mon, 14 Sep 2020 15:20:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Pc9FbkxH" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 10B5A20639 Authentication-Results: mail.kernel.org; dmarc=none (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=18MWzB2IZS03P8T+kfIC/IsaQ96D5jS4cxUoo9WiJaU=; b=Pc9FbkxHz0nNv2Dd5aYlYJcBiR 8/dIInftJZ2kfuC0AuuWztEcNnQS39zy4XdQWREWhmg4omJ1OKqoPM2a2mMbHCDtjBAu4nn9P54WW x/g0kmFcPaR1cmUywad+Rg7lfcrc4vjKfLM4006CDfgksAE94VjOGwaHTNXOldbc51DwRhlw5QEW2 PTYpOtIAqNmY5UWsmcZ7iLcyXCV583PZfmuU6cpW2wQQtE2mPx0ebsyWMWSTNzmMPKQOGUqq7gWpD faeHNwJSvQ26dccAo+9BVjaF10XvsdLYMzzLfIkxXMWTwCtQEqkfjDGdjQ7IptS/vXwqsBoAmNUSo KW2WNzkw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kHqFW-0004Nm-8B; Mon, 14 Sep 2020 15:18:34 +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 1kHqF8-0004FR-Dk for linux-arm-kernel@lists.infradead.org; Mon, 14 Sep 2020 15:18:15 +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 77ED111B3; Mon, 14 Sep 2020 08:18:09 -0700 (PDT) Received: from seattle-bionic.arm.com.Home (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9C39A3F718; Mon, 14 Sep 2020 08:18:08 -0700 (PDT) From: Oliver Swede To: catalin.marinas@arm.com, will@kernel.org Subject: [PATCH v5 02/14] arm64: kprobes: Drop open-coded exception fixup Date: Mon, 14 Sep 2020 15:17:48 +0000 Message-Id: <20200914151800.2270-3-oli.swede@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200914151800.2270-1-oli.swede@arm.com> References: <20200914151800.2270-1-oli.swede@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200914_111810_608078_CBF90BE9 X-CRM114-Status: GOOD ( 15.41 ) 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: robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org 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 From: Robin Murphy The short-circuit call to fixup_exception() from kprobe_fault_handler() poses a problem now that the former wants to consume the fault address too, since the common kprobes API offers us no way to pass it through. Fortunately, however, it works out to be unnecessary: - uaccess instructions themselves are not probeable, so at most we should only ever expect to take a fixable fault from the pre or post handlers. - the pre and post handler run with preemption disabled, thus for any fault they may cause, an unhandled return from kprobe_page_fault() will proceed directly to __do_kernel_fault() thanks to the faulthandler_disabled() check. - __do_kernel_fault() will immediately call fixup_exception() unless we're in an EL1 instruction abort, and if we've somehow taken one of those on what we think is the middle of a uaccess routine, then the world is already very on fire. Thus we can reasonably drop the call from kprobe_fault_handler() and leave uaccess fixups to the regular flow. Signed-off-by: Robin Murphy Signed-off-by: Oliver Swede --- arch/arm64/kernel/probes/kprobes.c | 7 ------- 1 file changed, 7 deletions(-) diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c index 5290f17a4d80..c54c8252b32f 100644 --- a/arch/arm64/kernel/probes/kprobes.c +++ b/arch/arm64/kernel/probes/kprobes.c @@ -328,13 +328,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr) */ if (cur->fault_handler && cur->fault_handler(cur, regs, fsr)) return 1; - - /* - * In case the user-specified fault handler returned - * zero, try to fix up. - */ - if (fixup_exception(regs)) - return 1; } return 0; } -- 2.17.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel