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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id E12C8E9B37F for ; Mon, 2 Mar 2026 13:43:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Ek4bJJsM5l9dHRUyFiLAAxetRets0RMYQiCz09mj05A=; b=AH5Vk7jG6o8RhHXb/sE51NqRG0 /cMU5chrAeKoQ0sNPkzbUkUCJlx/J+TXowptiVL0lJb3lycLYpEn4KkX5+EOzfcZRhgbXBKkEX9ZQ F9fbwTm9wZ8NKVfifma/eGFqhmivxsFv+hn7FmRpLQ2rzFMsGsR+8n/ThUA1/sHqLnwpZCkGkZBPI 930bqFsmsCZOMR7poXuZDLG7POvxvuJH4Bj1Sn590Umit2q3+lWky8omyQ597A2FTInjhbXAHdGCF Zku6fFdWw6Wr/S8+pMSVnpNZvPfoqqb6YXTafMzA2Ra5pnVsDHQPd3bd9Clva5Xbfmut7Rm8FD1Vo FEEQt+Yg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vx3YV-0000000D93N-2wOs; Mon, 02 Mar 2026 13:43:27 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vx3YS-0000000D931-3hXT for linux-arm-kernel@lists.infradead.org; Mon, 02 Mar 2026 13:43:25 +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 1759714BF; Mon, 2 Mar 2026 05:43:17 -0800 (PST) Received: from J2N7QTR9R3 (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9BE4B3F73B; Mon, 2 Mar 2026 05:43:21 -0800 (PST) Date: Mon, 2 Mar 2026 13:43:18 +0000 From: Mark Rutland To: Khaja Hussain Shaik Khaji Cc: catalin.marinas@arm.com, dev.jain@arm.com, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, mhiramat@kernel.org, will@kernel.org, yang@os.amperecomputing.com Subject: Re: [PATCH v3 0/1] kernel: kprobes: fix cur_kprobe corruption during re-entrant kprobe_busy_begin() calls Message-ID: References: <20260302122338.3618334-1-khaja.khaji@oss.qualcomm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260302122338.3618334-1-khaja.khaji@oss.qualcomm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260302_054324_958021_C08004CF X-CRM114-Status: GOOD ( 18.14 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Mar 02, 2026 at 05:53:38PM +0530, Khaja Hussain Shaik Khaji wrote: > On Mon, Mar 02, 2026 at 04:23:46PM +0530, Mark Rutland wrote: > > The el1_dbg() function was removed in commit: > > > > 31575e11ecf7 ("arm64: debug: split brk64 exception entry") > > > > ... which was merged in v6.17. > > > > Are you able to reproduce the issue with v6.17 or later? > > > > Which specific kernel version did you see this with? > > The call trace was captured on v6.9-rc1. Why are you using an -rc1 release from almost two years ago? > I have not yet tested on v6.17 or later. I will test and report back. > > That said, the fix is in kernel/kprobes.c and addresses a generic > re-entrancy issue in kprobe_busy_begin/end that is not specific to the > arm64 entry path. The race -- where kprobe_busy_begin() is called > re-entrantly from within an active kprobe context (e.g. via softirq > during kretprobe entry_handler) -- can occur on any architecture where > IRQs are re-enabled before invoking kprobe handlers. AFAICT, re-enabling IRQs in that path would be a bug, and re-entrancy is simply not expected. Please see my other reply on that front. > I will verify whether the issue is still reproducible on v6.17+ and > report back. Thanks, that would be much appreciated. As would anything you can share on the specifics of your kretprobe entry_handler Mark.