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=-8.2 required=3.0 tests=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_SANE_1 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 72152ECE58D for ; Thu, 17 Oct 2019 20:29:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 39FEB21835 for ; Thu, 17 Oct 2019 20:29:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571344198; bh=PEewE7cb5xAZWn6VD0jRNI4cXRMWPcfpf8LoXljGvEA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=a7ktOA4O4FVyswknjRUhazwquimxBO99nd6+GiKD9Zs1+vIowH2PkKK2ahjeFcx91 p28z7okSrcJXpKEvaMrAkI1mQDbr4HI8yvocqt5ny0wpDNtGySfQWdeG/15wU+eaL6 kzKj5AB0CW1yCJtGh9rXyiJWPCb6NAhGuz4z3kaQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2438863AbfJQU34 (ORCPT ); Thu, 17 Oct 2019 16:29:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:55346 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392669AbfJQU3z (ORCPT ); Thu, 17 Oct 2019 16:29:55 -0400 Received: from localhost (unknown [104.132.0.109]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 158E620872; Thu, 17 Oct 2019 20:29:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571344194; bh=PEewE7cb5xAZWn6VD0jRNI4cXRMWPcfpf8LoXljGvEA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=caek8QEbrHYk48IbnyN1/P119xslY0U+q6qPCikPPNyILCFyOmIuZMqk6hPo+5Iua sv3td2jDvNARP64Uomzz3fDwMu1LeIHD2mUsmR6Rea0X0IQ+ioeQtMYixoh8R88RFB C4t0n+FTQdJCIMcNk+cG9iBIs1peJGoWK0LflGuY= Date: Thu, 17 Oct 2019 13:29:53 -0700 From: Greg Kroah-Hartman To: Andrey Konovalov Cc: USB list , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev , LKML , Dmitry Vyukov , Alan Stern , "Michael S . Tsirkin" , Jason Wang , Andrew Morton , Arnd Bergmann , Steven Rostedt , David Windsor , Elena Reshetova , Anders Roxell Subject: Re: [PATCH RFC 2/3] usb, kcov: collect coverage from hub_event Message-ID: <20191017202953.GB1103978@kroah.com> References: <1b30d1c9e7f86c25425c5ee53d7facede289608e.1571333592.git.andreyknvl@google.com> <20191017181943.GC1094415@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.2 (2019-09-21) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Oct 17, 2019 at 09:06:56PM +0200, Andrey Konovalov wrote: > On Thu, Oct 17, 2019 at 8:19 PM Greg Kroah-Hartman > wrote: > > > > On Thu, Oct 17, 2019 at 07:44:14PM +0200, Andrey Konovalov wrote: > > > This patch adds kcov_remote_start/kcov_remote_stop annotations to the > > > hub_event function, which is responsible for processing events on USB > > > buses, in particular events that happen during USB device enumeration. > > > Each USB bus gets a unique id, which can be used to attach a kcov device > > > to a particular USB bus for coverage collection. > > > > > > Signed-off-by: Andrey Konovalov > > > --- > > > drivers/usb/core/hub.c | 4 ++++ > > > include/linux/kcov.h | 1 + > > > include/uapi/linux/kcov.h | 7 +++++++ > > > 3 files changed, 12 insertions(+) > > > > > > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c > > > index 236313f41f4a..03a40e41b099 100644 > > > --- a/drivers/usb/core/hub.c > > > +++ b/drivers/usb/core/hub.c > > > @@ -5374,6 +5374,8 @@ static void hub_event(struct work_struct *work) > > > hub_dev = hub->intfdev; > > > intf = to_usb_interface(hub_dev); > > > > > > + kcov_remote_start(kcov_remote_handle_usb(hdev->bus->busnum)); > > > + > > > dev_dbg(hub_dev, "state %d ports %d chg %04x evt %04x\n", > > > hdev->state, hdev->maxchild, > > > /* NOTE: expects max 15 ports... */ > > > @@ -5480,6 +5482,8 @@ static void hub_event(struct work_struct *work) > > > /* Balance the stuff in kick_hub_wq() and allow autosuspend */ > > > usb_autopm_put_interface(intf); > > > kref_put(&hub->kref, hub_release); > > > + > > > + kcov_remote_stop(); > > > } > > > > > > static const struct usb_device_id hub_id_table[] = { > > > diff --git a/include/linux/kcov.h b/include/linux/kcov.h > > > index 702672d98d35..38a47e0b67c2 100644 > > > --- a/include/linux/kcov.h > > > +++ b/include/linux/kcov.h > > > @@ -30,6 +30,7 @@ void kcov_task_exit(struct task_struct *t); > > > /* > > > * Reserved handle ranges: > > > * 0000000000000000 - 0000ffffffffffff : common handles > > > + * 0001000000000000 - 0001ffffffffffff : USB subsystem handles > > > > So how many bits are you going to have for any in-kernel tasks? Aren't > > you going to run out quickly? > > With these patches we only collect coverage from hub_event threads, > and we need one ID per USB bus, the number of which is quite limited. > But then we might want to collect coverage from other parts of the USB > subsystem, so we might need more IDs. I don't expect the number of > different subsystem from which we want to collect coverage to be > large, so the idea here is to use 2 bytes of an ID to denote the > subsystem, and the other 6 to denote different coverage collection > sections within it. > > But overall, which encoding scheme to use here is a good question. > Ideas are welcome. > > > > */ > > > void kcov_remote_start(u64 handle); > > > void kcov_remote_stop(void); > > > diff --git a/include/uapi/linux/kcov.h b/include/uapi/linux/kcov.h > > > index 46f78f716ca9..45c9ae59cebc 100644 > > > --- a/include/uapi/linux/kcov.h > > > +++ b/include/uapi/linux/kcov.h > > > @@ -43,4 +43,11 @@ enum { > > > #define KCOV_CMP_SIZE(n) ((n) << 1) > > > #define KCOV_CMP_MASK KCOV_CMP_SIZE(3) > > > > > > +#define KCOV_REMOTE_HANDLE_USB 0x0001000000000000ull > > > + > > > +static inline __u64 kcov_remote_handle_usb(unsigned int bus) > > > +{ > > > + return KCOV_REMOTE_HANDLE_USB + (__u64)bus; > > > +} > > > > Why is this function in a uapi .h file? What userspace code would call > > this? > > A userspace process that wants to collect coverage from USB bus # N > needs to pass kcov_remote_handle_usb(N) into KCOV_REMOTE_ENABLE ioctl. Ugh, ok. Then you should make "unsigned int bus" a __u64 so that this actually will work on all kernels properly. thanks, greg k-h