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=-5.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_PASS,URIBL_BLOCKED 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 73D13C7113B for ; Mon, 21 Jan 2019 12:20:19 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 439E72084A for ; Mon, 21 Jan 2019 12:20:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="m/IuBtMj" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 439E72084A 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+infradead-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=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:References:To:Subject:From:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ax4fkpNwtL8Kp+2QsJDDBU/2S+sGMfnrSeyJHNYv54M=; b=m/IuBtMjwXLb2E ACFDduA+gnuwfFVqUc+iJ9VGoBid6m3WNSkJIvBH/Di4EqCv80C3n5lUAUdMp7W//rpZ/QWhHA6PR dt9xJakL4+R9vK16EKzuK6wVT27V6dVEntt5Zd2cxn3Bqor3JkO/B9FyUYHyaN8Ufqhc0oC0IRx0g gISx/3gdQbRzQAWIHEHt1zjdt4bYVXZqq8Saks6hleAlilMColsNUcHzEYzpI/VRnuEQKFg8iBj4/ anbuRd8S05SJqphwO11UZRRe9sWiT6WmlwIDAzr4aIFyo8UGTHQ9JpDKJwSwNY2UYOf/Df5Vbvdi+ 0YkUicjObEbbjm6EC//Q==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1glYYp-0002mH-4O; Mon, 21 Jan 2019 12:20:15 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1glYYl-0002LV-7V for linux-arm-kernel@lists.infradead.org; Mon, 21 Jan 2019 12:20:12 +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 8B5EA80D; Mon, 21 Jan 2019 04:20:10 -0800 (PST) Received: from [10.1.196.105] (eglon.cambridge.arm.com [10.1.196.105]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 531CE3F614; Mon, 21 Jan 2019 04:20:09 -0800 (PST) From: James Morse Subject: Re: [PATCH v2 4/4] arm64: kprobes: Use arch_populate_kprobe_blacklist() To: Masami Hiramatsu References: <154753341900.31541.8135985235882849464.stgit@devbox> <154753353370.31541.14485875717131836689.stgit@devbox> Message-ID: <7f840cc8-4e62-e1d7-9035-4361204fc134@arm.com> Date: Mon, 21 Jan 2019 12:20:07 +0000 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <154753353370.31541.14485875717131836689.stgit@devbox> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190121_042011_307459_92521E15 X-CRM114-Status: GOOD ( 18.87 ) 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: Pratyush Anand , Catalin Marinas , Will Deacon , linux-kernel , "David A . Long" , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hello, On 15/01/2019 06:25, Masami Hiramatsu wrote: > Use arch_populate_kprobe_blacklist() instead of > arch_within_kprobe_blacklist() so that we can see the full > blacklisted symbols under the debugfs. > diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c > index b9e9758b6534..6c066c34c8a4 100644 > --- a/arch/arm64/kernel/probes/kprobes.c > +++ b/arch/arm64/kernel/probes/kprobes.c > @@ -465,26 +465,30 @@ kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr) > return DBG_HOOK_HANDLED; > } > > -bool arch_within_kprobe_blacklist(unsigned long addr) > +int __init arch_populate_kprobe_blacklist(void) > { > - if ((addr >= (unsigned long)__kprobes_text_start && > - addr < (unsigned long)__kprobes_text_end) || > - (addr >= (unsigned long)__entry_text_start && > - addr < (unsigned long)__entry_text_end) || > - (addr >= (unsigned long)__idmap_text_start && > - addr < (unsigned long)__idmap_text_end) || > - in_exception_text(addr)) You added this one in the previous patch, but it disappears here. > - return true; > - > - if (!is_kernel_in_hyp_mode()) { > - if ((addr >= (unsigned long)__hyp_text_start && > - addr < (unsigned long)__hyp_text_end) || > - (addr >= (unsigned long)__hyp_idmap_text_start && > - addr < (unsigned long)__hyp_idmap_text_end)) > - return true; > - } > - > - return false; > + int ret; > + ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start, > + (unsigned long)__kprobes_text_end); > + if (ret) > + return ret; Now that we have arch_populate_kprobe_blacklist(), does the arch-code need to blacklist the kprobes section itself? The weak arch_within_kprobe_blacklist() will test it at kprobe-load time, and populate_kprobe_blacklist() adds it to the list before it calls arch_populate_kprobe_blacklist(). Won't this result in duplicate entries? > + ret = kprobe_add_area_blacklist((unsigned long)__entry_text_start, > + (unsigned long)__entry_text_end); > + if (ret) > + return ret; > + ret = kprobe_add_area_blacklist((unsigned long)__idmap_text_start, > + (unsigned long)__idmap_text_end); > + if (ret || is_kernel_in_hyp_mode()) > + return ret; Hmmm, I think we have a bug here today. This is saying we can kprobe KVM when we have VHE, because all of KVMs code runs at the same exception-level as the kernel. Which is true... But KVM switches VBAR_EL1, so if we run over one of kprobes BRK instructions, we're going to hyp-panic, because KVM doesn't handle synchronous exceptions from EL2. The __hyp_text also contains the guest entry/exit code, which we mustn't probe, even on VHE. I think we should always blacklist the __hyp_text, and KVM should mark its vhe-only functions with __kprobes. I'll post patches for this. Thanks, James > + ret = kprobe_add_area_blacklist((unsigned long)__hyp_text_start, > + (unsigned long)__hyp_text_end); > + if (ret) > + return ret; > + ret = kprobe_add_area_blacklist((unsigned long)__hyp_idmap_text_start, > + (unsigned long)__hyp_idmap_text_end); > + return ret; > } > > void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs) > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel