netdev - [PATCH RFC 2/3] usb, kcov: collect coverage from hub

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Message-Id: <1b30d1c9e7f86c25425c5ee53d7facede289608e.1571333592.git.andreyknvl@google.com>
Date:   Thu, 17 Oct 2019 19:44:14 +0200
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     linux-usb@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Dmitry Vyukov <dvyukov@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alan Stern <stern@...land.harvard.edu>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Steven Rostedt <rostedt@...dmis.org>,
        David Windsor <dwindsor@...il.com>,
        Elena Reshetova <elena.reshetova@...el.com>,
        Anders Roxell <anders.roxell@...aro.org>,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH RFC 2/3] usb, kcov: collect coverage from hub_event

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 <andreyknvl@...gle.com>
---
 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
  */
 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;
+}
+
 #endif /* _LINUX_KCOV_IOCTLS_H */
-- 
2.23.0.866.gb869b98d4c-goog