From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8743B3D1ABC; Thu, 28 May 2026 10:57:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779965840; cv=none; b=Mgu+oLDe5gHgPHEXKPN9pAOFEgHoCh4zfzVXBbIDyZu+yUh0Qm4tlAPCFxu/OQN1oGRE2LA9dJEdbFXo3N13JIsEJxKASpwnq02n+QQrd912Px2/uG+oqk2ACyuqQzEZkfYUR5hJ2b+Kto9cGi2H3BaqYoNQ1S2UJTaeOLhryRw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779965840; c=relaxed/simple; bh=9t47wUhCNNof8aIgbegXoRABZWz8Z8Ikx0BlTL06w04=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=avINVhZM4QQoRWlAbx0VqQzD3iDhQGR+joZrZfDZdAx3wkUNOaHvtHX1qqVCKHlQogitDiHWMdjtebKd8ZodbJ+O/XGdn1AVyJSHlsJJTOXZeW4JprIpoXbdN4L0T5JlAoGa44jtCLjyb3WjKzNIRJSAIjFdlcn1pysXfK8dex0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nStxKLPl; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nStxKLPl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BD4F91F00A3A; Thu, 28 May 2026 10:57:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779965837; bh=9t47wUhCNNof8aIgbegXoRABZWz8Z8Ikx0BlTL06w04=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=nStxKLPl63L6txLgSYbTP+sOuHvI+kfP4z6UbWYSPsJiSfxZMp2fNjGO5veO3PSyo XeAkphExoRlXnntuA242D+FvvTCptu2kcSVlvva7ZDH4MV5P3ztKptQgCa/FL6B5if cirwL7QynGJXY/G62g/d1EG9G3So7jS9zOYQUCbmVqrLs8A40Q6rRH19sgPaz/3Zcx q7ouVtdEXPYO7PD8HTwEQTg9eCt1fYAFIDaJLjXuCFz7a8kE576HMcFPCiajjQjn9Q dpMV7Whlh7a5NK8++ip7Q3JtiVWjIePswSym8XYSZfIRoUm1FFNpjR29dQPt6HGdx4 gT0RICPCX8GPQ== Date: Thu, 28 May 2026 11:57:12 +0100 From: Will Deacon To: "Rob Herring (Arm)" Cc: Mark Rutland , Catalin Marinas , Jonathan Corbet , Shuah Khan , Anshuman Khandual , linux-arm-kernel@lists.infradead.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Subject: Re: [PATCH v4 1/6] arm64: hw_breakpoint: Disallow breakpoints in no kprobe code Message-ID: References: <20260407-arm-debug-8-9-v4-0-a4864e69b0ea@kernel.org> <20260407-arm-debug-8-9-v4-1-a4864e69b0ea@kernel.org> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260407-arm-debug-8-9-v4-1-a4864e69b0ea@kernel.org> On Tue, Apr 07, 2026 at 09:29:43AM -0500, Rob Herring (Arm) wrote: > Taking debug exceptions while manipulating the breakpoints is likely to > be unsafe. The setting kprobes in the breakpoint code is already > forbidden, but the setting of h/w breakpoints is not. Copy what x86 does > and exclude breakpoints that fall within the kprobe section. It would be good to spell this out a little more clearly, as "likely to be unsafe" is very vague. There's also plenty of breakpoint handling code outside of the arch backend (e.g. in kernel/events/) which doesn't seem to be in the no-kprobes section, so it's not clear why that's ok. Will