device coredump: add new device coredump class

Many devices run firmware and/or complex hardware, and most of that
can have bugs. When it misbehaves, however, it is often much harder
to debug than software running on the host.

Introduce a "device coredump" mechanism to allow dumping internal
device/firmware state through a generalized mechanism. As devices
are different and information needed can vary accordingly, this
doesn't prescribe a file format - it just provides mechanism to
get data to be able to capture it in a generalized way (e.g. in
distributions.)

The dumped data will be readable in sysfs in the virtual device's
data file under /sys/class/devcoredump/devcd*/. Writing to it will
free the data and remove the device, as does a 5-minute timeout.

Note that generalized capturing of such data may result in privacy
issues, so users generally need to be involved. In order to allow
certain users/system integrators/... to disable the feature at all,
introduce a Kconfig option to override the drivers that would like
to have the feature.

For now, this provides two ways of dumping data:
 1) with a vmalloc'ed area, that is then given to the subsystem
    and freed after retrieval or timeout
 2) with a generalized reader/free function method

We could/should add more options, e.g. a list of pages, since the
vmalloc area is very limited on some architectures.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 809ecd680d88..d810a6fa8276 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2859,6 +2859,13 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/balbi/usb.git
 S:      Maintained
 F:      drivers/usb/dwc3/
 
+DEVICE COREDUMP (DEV_COREDUMP)
+M:      Johannes Berg <johannes@sipsolutions.net>
+L:      linux-kernel@vger.kernel.org
+S:      Maintained
+F:      drivers/base/devcoredump.c
+F:      include/linux/devcoredump.h
+
 DEVICE FREQUENCY (DEVFREQ)
 M:      MyungJoo Ham <myungjoo.ham@samsung.com>
 M:      Kyungmin Park <kyungmin.park@samsung.com>