| Message ID | cover.1582742673.git.andreyknvl@google.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | kcov: collect coverage from usb soft interrupts | expand |
On Wed, 26 Feb 2020 19:48:06 +0100 Andrey Konovalov <andreyknvl@google.com> wrote: > This patchset extends kcov to allow collecting coverage from soft > interrupts and then uses the new functionality to collect coverage from > USB code. > > This has allowed to find at least one new HID bug [1], which was recently > fixed by Alan [2]. I might have asked this before, but I don't see this obvious question addressed in the changelogs so maybe I didn't... Will this only ever be useful for USB? Or is it anticipated that other subsystems will use this? If the latter, which ones? Thanks.
On Thu, Feb 27, 2020 at 2:41 AM Andrew Morton <akpm@linux-foundation.org> wrote: > > On Wed, 26 Feb 2020 19:48:06 +0100 Andrey Konovalov <andreyknvl@google.com> wrote: > > > This patchset extends kcov to allow collecting coverage from soft > > interrupts and then uses the new functionality to collect coverage from > > USB code. > > > > This has allowed to find at least one new HID bug [1], which was recently > > fixed by Alan [2]. > > I might have asked this before, but I don't see this obvious question > addressed in the changelogs so maybe I didn't... You've asked this for the previous patchset about collecting coverage from background threads :) > Will this only ever be useful for USB? Or is it anticipated that other > subsystems will use this? If the latter, which ones? Any subsystem that uses softirqs (e.g. timers) can make use of this. Looking at the recent syzbot reports, an obvious candidate is the networking subsystem [1, 2, 3 and many more]. I'll add this info into the cover letter in the next version. Thanks! [1] https://syzkaller.appspot.com/bug?extid=522ab502c69badc66ab7 [2] https://syzkaller.appspot.com/bug?extid=57f89d05946c53dbbb31 [3] https://syzkaller.appspot.com/bug?extid=df358e65d9c1b9d3f5f4
This patchset extends kcov to allow collecting coverage from soft interrupts and then uses the new functionality to collect coverage from USB code. This has allowed to find at least one new HID bug [1], which was recently fixed by Alan [2]. [1] https://syzkaller.appspot.com/bug?extid=09ef48aa58261464b621 [2] https://patchwork.kernel.org/patch/11283319/ This patchset has been pushed to the public Linux kernel Gerrit instance: https://linux-review.googlesource.com/c/linux/kernel/git/torvalds/linux/+/2225 Changes RFC -> v1: - Don't support hardirq or nmi, only softirq, to avoid issues with nested interrupts. - Combined multiple per-cpu variables into one. - Used plain accesses and kcov_start/stop() instead of xchg()'s. - Simplified handling of per-cpu variables. - Avoid disabling interrupts for the whole kcov_remote_start/stop() region. - Avoid overwriting t->kcov_sequence when saving/restoring state. - Move kcov_remote_start/stop_usb() annotations into __usb_hcd_giveback_urb() to cover all urb complete() callbacks at once. - Drop unneeded Dummy HCD changes. - Split out a patch that removed debug messages. Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Andrey Konovalov (3): kcov: cleanup debug messages kcov: collect coverage from interrupts usb: core: kcov: collect coverage from usb complete callback Documentation/dev-tools/kcov.rst | 17 +-- drivers/usb/core/hcd.c | 3 + include/linux/sched.h | 3 + kernel/kcov.c | 187 ++++++++++++++++++++----------- lib/Kconfig.debug | 9 ++ 5 files changed, 147 insertions(+), 72 deletions(-)