Re: [PATCH RFC 0/2] kcov: collect coverage from usbhid interrupts
From: Andrey Konovalov
Date: Fri Dec 13 2019 - 07:11:40 EST
On Thu, Dec 12, 2019 at 6:15 PM Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote:
> This patchset extends kcov to allow collecting coverage from interrupts
> and then uses the new functionality to collect coverage from usbhid code.
> What I'm not sure yet about this change is if we actually want to
> selectively annotate some parts of the USB stack that are executed in
> interrupt context, or maybe we can do this with some common approach.
> For example patch #2 in this patchset annotates all functions that are
> passed as completion callbacks to usb_fill_*() in drivers/hid/usbhid.
> Maybe instead we could redefine usb_fill_*() in a way that would handle
> all such cases without manual annotations.
Although looking at this again today, it seems much more logical to
add kcov annotations around the complete() callback in
__usb_hcd_giveback_urb(). Don't know why I didn't think of that. Will
do in the next version.
> Any suggestions are welcome.
> This has allowed to find at least one new HID bug , which was recently
> fixed by Alan .
>  https://syzkaller.appspot.com/bug?extid=09ef48aa58261464b621
>  https://patchwork.kernel.org/patch/11283319/
> This patchset has been pushed to the public Linux kernel Gerrit instance:
> Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> Andrey Konovalov (2):
> kcov: collect coverage from interrupts
> HID: usbhid: kcov: add annotations for coverage collection
> Documentation/dev-tools/kcov.rst | 16 +--
> drivers/hid/usbhid/hid-core.c | 25 +++-
> drivers/hid/usbhid/usbkbd.c | 15 ++-
> drivers/hid/usbhid/usbmouse.c | 7 +-
> drivers/usb/gadget/udc/dummy_hcd.c | 1 +
> include/linux/sched.h | 3 +
> kernel/kcov.c | 196 +++++++++++++++++++----------
> lib/Kconfig.debug | 9 ++
> 8 files changed, 192 insertions(+), 80 deletions(-)