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On Wed, Oct 23, 2019 at 3:35 PM Andrey Konovalov <andreyknvl at google.com> wrote: > > On Wed, Oct 23, 2019 at 10:36 AM Dmitry Vyukov <dvyukov at google.com> wrote: > > > > On Tue, Oct 22, 2019 at 6:46 PM Andrey Konovalov <andreyknvl at google.com> wrote: > > > > > > This patch adds kcov_remote_start()/kcov_...

On Tue, Oct 22, 2019 at 6:46 PM Andrey Konovalov <andreyknvl at google.com> wrote: > > This patch adds kcov_remote_start()/kcov_remote_stop() annotations to the > vhost_worker() function, which is responsible for processing vhost works. > Since vhost_worker() threads are spawned per vhost device instance > the common kcov handle is used for...

...stop annotations to the > vhost_worker function, which is responsible for processing vhost works. > Since vhost_worker is spawned when a vhost device instance is created, > the common kcov handle is used for kcov_remote_start/stop annotations. > > Signed-off-by: Andrey Konovalov <andreyknvl at google.com> > --- > drivers/vhost/vhost.c | 15 +++++++++++++++ > drivers/vhost/vhost.h | 3 +++ > 2 files changed, 18 insertions(+) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index 36ca2cf419bf..71a349f6b352 100644 > --- a/drivers/vhost/vhost....

...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 at google.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...

...er function, which is responsible for processing vhost works. > > > Since vhost_worker is spawned when a vhost device instance is created, > > > the common kcov handle is used for kcov_remote_start/stop annotations. > > > > > > Signed-off-by: Andrey Konovalov <andreyknvl at google.com> > > > --- > > > drivers/vhost/vhost.c | 15 +++++++++++++++ > > > drivers/vhost/vhost.h | 3 +++ > > > 2 files changed, 18 insertions(+) > > > > > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > > > in...

On Tue, Oct 22, 2019 at 6:46 PM Andrey Konovalov <andreyknvl at google.com> wrote: > > This patchset extends kcov to allow collecting coverage from the USB > subsystem and vhost workers. See the first patch description for details > about the kcov extension. The other two patches apply this kcov extension > to USB and vhost. > > These...

On Wed, 23 Oct 2019 17:24:28 +0200 Andrey Konovalov <andreyknvl at google.com> wrote: > This patchset extends kcov to allow collecting coverage from the USB > subsystem and vhost workers. See the first patch description for details > about the kcov extension. The other two patches apply this kcov extension > to USB and vhost. > > These pa...

On Wed, Oct 23, 2019 at 5:24 PM Andrey Konovalov <andreyknvl at google.com> wrote: > > This patch adds background thread coverage collection ability to kcov. ... > +static struct kcov_remote *kcov_remote_add(struct kcov *kcov, u64 handle) > +{ > + struct kcov_remote *remote; > + > + if (kcov_remote_find(handle)) > +...

On Thu, 24 Oct 2019 14:47:31 +0200 Andrey Konovalov <andreyknvl at google.com> wrote: > > is it expected that the new kcov feature will be used elsewhere in the > > kernel? > > > > If the latter, which are the expected subsystems? > > Currently we encountered two cases where this is useful: USB and vhost > workers. Most pro...

...gt; Documentation/dev-tools/kcov.rst for details), each USB bus gets a unique > global handle from the USB subsystem kcov handle range. As the result kcov > can now be used to collect coverage from events that happen on a > particular USB bus. > > Signed-off-by: Andrey Konovalov <andreyknvl at google.com> > --- > drivers/usb/core/hub.c | 5 +++++ > 1 file changed, 5 insertions(+) Reviewed-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>

mb() typically uses mfence on modern x86, but a micro-benchmark shows that it's 2 to 3 times slower than lock; addl that we use on older CPUs. So we really should use the locked variant everywhere, except that intel manual says that clflush is only ordered by mfence, so we can't. Note: some callers of clflush seems to assume sfence will order it, so there could be existing bugs around

mb() typically uses mfence on modern x86, but a micro-benchmark shows that it's 2 to 3 times slower than lock; addl that we use on older CPUs. So we really should use the locked variant everywhere, except that intel manual says that clflush is only ordered by mfence, so we can't. Note: some callers of clflush seems to assume sfence will order it, so there could be existing bugs around

...> > 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 at google.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...

On Wed, 23 Oct 2019 17:24:29 +0200 Andrey Konovalov <andreyknvl at google.com> wrote: > This patch adds background thread coverage collection ability to kcov. > > With KCOV_ENABLE coverage is collected only for syscalls that are issued > from the current process. With KCOV_REMOTE_ENABLE it's possible to collect > coverage for arbitrary p...

On Thu, Oct 17, 2019 at 7:44 PM Andrey Konovalov <andreyknvl at google.com> wrote: > > Currently kcov can only collect coverage for syscalls that are issued > from the current process. This patch adds support for KCOV_REMOTE_ENABLE, > that makes it possible to collect coverage for arbitrary parts of the > kernel code, provided that this par...