From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 E1FCC38757B; Thu, 6 Aug 2026 07:17:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786000674; cv=none; b=jjsDL08C+LyMEg9rBRXuWBGHWlRyci0+zL5hqgDO19Q6gai3+GKW4VNKNT9b/0CTsbmLy8y0dg+RQFv6os2d5C4qod9yLTUyOPoLIYMVriFsub99vjDekWv9YlDXJ6NbhxgZTwX1yL2URGczL4M8X+tVx0pzo+KN1q96JFlGgiQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786000674; c=relaxed/simple; bh=XCW04prNOvJN3+WT8RIPp80KBAK3kRC1ePK5xixfsD8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=G5BVcx1A+yGGN/0p+5OLUvYLNbLDvAjUjzng2h8MsI2FvfMiJBzQQtYZEnS4Wv1FFSObbBlfL3iZgC3LPWkcGsowQv/RBy61lYGTy3dBYsjG3YPPBJfQ0hPl1EaE8HgZ66dCwqECDw9/Hr92YH+4tXXiShpbqoE5J9uPsZZsyNw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=pass smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=GFuzdmqs; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="GFuzdmqs" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=vNP/V7rEoAsXhxstFtyLYmMxzfVTus4oyN4R/xdFQOI=; b=GFuzdmqsHa/BzPqNxfLbruF4VA gkWQxjN3p0wE0LGc8VyaHJh/fGrj8h14hYxJdnChJzAMwTanm49h+CO1OWKyrlnPvBG2o0X91pAxo yAaUOVbf6AdDocXmFPoSPsrvGVIzvmpPvYSciuG7KBYh46KkuoKgFGg6umT4qJGxbdmFdZCvQG2Np GPb34VL4/Cp+IEl1ADCGq6ovG4pTfAW8BDAxmzqyoUO+dWEBd+t5/3UqQSND+NY78G0TebL9EhtFn ARUeaYCGYglrZ6LkNqb2RClHXdo/Xi3m4b+4HsohCpXU6HS2HxlQMbjjPUe//HydkqtMeWXqrvHKc 5OQ7U7LA==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.99.1 #2 (Red Hat Linux)) id 1wrsME-00000008f74-2Zmd; Thu, 06 Aug 2026 07:17:38 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 6AC46301519; Thu, 06 Aug 2026 09:17:37 +0200 (CEST) Date: Thu, 6 Aug 2026 09:17:37 +0200 From: Peter Zijlstra To: Steven Rostedt Cc: "Masami Hiramatsu (Google)" , Ingo Molnar , x86@kernel.org, Jinchao Wang , Mathieu Desnoyers , Thomas Gleixner , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Alexander Shishkin , Ian Rogers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: Re: [PATCH v11 04/11] tracing: wprobe: Add watchpoint probe event based on hardware breakpoint Message-ID: <20260806071737.GK49951@noisy.programming.kicks-ass.net> References: <178565870538.714490.11309825813968306287.stgit@devnote2> <178565875046.714490.17724442147958346980.stgit@devnote2> <20260803070356.GV49951@noisy.programming.kicks-ass.net> <20260805153404.793691b8@gandalf.local.home> <20260805193909.GP776954@noisy.programming.kicks-ass.net> <20260805210629.138f6197@gandalf.local.home> Precedence: bulk X-Mailing-List: linux-trace-kernel@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: <20260805210629.138f6197@gandalf.local.home> On Wed, Aug 05, 2026 at 09:06:29PM -0400, Steven Rostedt wrote: > On Wed, 5 Aug 2026 21:39:09 +0200 > Peter Zijlstra wrote: > > > > > This seems limited to kernel addresses only? Should not also userspace > > > > addresses be supported? > > > > > > Hmm, how would that work? The address is global for all tasks, so if you > > > add a user space address, what task would that be for? The one writing the > > > probe? > > > > Schedule the watchpoint along with the task of course. Given there is > > breakpoint/perf integration this should be trivial. > > I meant, what task is it attached to? Usually the way a probe works is to > create the probe and then enable it. > > # cd /sys/kernel/tracing > # echo 'w:my_jiffies w@jiffies:8 value=+0($addr)' >> dynamic_events > # echo 1 > events/wprobes/my_jiffies/enable > > If the address is in user space, which task would that address be for? > > What would the API look like? Should we add a pid to that for a specific task? Same as uprobes?