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>
diff --git a/drivers/base/devcoredump.c b/drivers/base/devcoredump.c
new file mode 100644
index 0000000..96614b0
--- /dev/null
+++ b/drivers/base/devcoredump.c
@@ -0,0 +1,265 @@
+/*
+ * This file is provided under the GPLv2 license.
+ *
+ * GPL LICENSE SUMMARY
+ *
+ * Copyright(c) 2014 Intel Mobile Communications GmbH
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * The full GNU General Public License is included in this distribution
+ * in the file called COPYING.
+ *
+ * Contact Information:
+ * Intel Linux Wireless <ilw@linux.intel.com>
+ * Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
+ *
+ * Author: Johannes Berg <johannes@sipsolutions.net>
+ */
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/devcoredump.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/workqueue.h>
+
+/* if data isn't read by userspace after 5 minutes then delete it */
+#define DEVCD_TIMEOUT (HZ * 60 * 5)
+
+struct devcd_entry {
+ struct device devcd_dev;
+ const void *data;
+ size_t datalen;
+ struct module *owner;
+ ssize_t (*read)(char *buffer, loff_t offset, size_t count,
+ const void *data, size_t datalen);
+ void (*free)(const void *data);
+ struct delayed_work del_wk;
+ struct device *failing_dev;
+};
+
+static struct devcd_entry *dev_to_devcd(struct device *dev)
+{
+ return container_of(dev, struct devcd_entry, devcd_dev);
+}
+
+static void devcd_dev_release(struct device *dev)
+{
+ struct devcd_entry *devcd = dev_to_devcd(dev);
+
+ devcd->free(devcd->data);
+ module_put(devcd->owner);
+
+ /*
+ * this seems racy, but I don't see a notifier or such on
+ * a struct device to know when it goes away?
+ */
+ if (devcd->failing_dev->kobj.sd)
+ sysfs_delete_link(&devcd->failing_dev->kobj, &dev->kobj,
+ "devcoredump");
+
+ put_device(devcd->failing_dev);
+ kfree(devcd);
+}
+
+static void devcd_del(struct work_struct *wk)
+{
+ struct devcd_entry *devcd;
+
+ devcd = container_of(wk, struct devcd_entry, del_wk.work);
+
+ device_del(&devcd->devcd_dev);
+ put_device(&devcd->devcd_dev);
+}
+
+static ssize_t devcd_data_read(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *bin_attr,
+ char *buffer, loff_t offset, size_t count)
+{
+ struct device *dev = kobj_to_dev(kobj);
+ struct devcd_entry *devcd = dev_to_devcd(dev);
+
+ return devcd->read(buffer, offset, count, devcd->data, devcd->datalen);
+}
+
+static ssize_t devcd_data_write(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *bin_attr,
+ char *buffer, loff_t offset, size_t count)
+{
+ struct device *dev = kobj_to_dev(kobj);
+ struct devcd_entry *devcd = dev_to_devcd(dev);
+
+ mod_delayed_work(system_wq, &devcd->del_wk, 0);
+
+ return count;
+}
+
+static struct bin_attribute devcd_attr_data = {
+ .attr = { .name = "data", .mode = S_IRUSR | S_IWUSR, },
+ .size = 0,
+ .read = devcd_data_read,
+ .write = devcd_data_write,
+};
+
+static struct bin_attribute *devcd_dev_bin_attrs[] = {
+ &devcd_attr_data, NULL,
+};
+
+static const struct attribute_group devcd_dev_group = {
+ .bin_attrs = devcd_dev_bin_attrs,
+};
+
+static const struct attribute_group *devcd_dev_groups[] = {
+ &devcd_dev_group, NULL,
+};
+
+static struct class devcd_class = {
+ .name = "devcoredump",
+ .owner = THIS_MODULE,
+ .dev_release = devcd_dev_release,
+ .dev_groups = devcd_dev_groups,
+};
+
+static ssize_t devcd_readv(char *buffer, loff_t offset, size_t count,
+ const void *data, size_t datalen)
+{
+ if (offset > datalen)
+ return -EINVAL;
+
+ if (offset + count > datalen)
+ count = datalen - offset;
+
+ if (count)
+ memcpy(buffer, ((u8 *)data) + offset, count);
+
+ return count;
+}
+
+/**
+ * dev_coredumpv - create device coredump with vmalloc data
+ * @dev: the struct device for the crashed device
+ * @data: vmalloc data containing the device coredump
+ * @datalen: length of the data
+ * @gfp: allocation flags
+ *
+ * This function takes ownership of the vmalloc'ed data and will free
+ * it when it is no longer used. See dev_coredumpm() for more information.
+ */
+void dev_coredumpv(struct device *dev, const void *data, size_t datalen,
+ gfp_t gfp)
+{
+ dev_coredumpm(dev, NULL, data, datalen, gfp, devcd_readv, vfree);
+}
+EXPORT_SYMBOL_GPL(dev_coredumpv);
+
+static int devcd_match_failing(struct device *dev, const void *failing)
+{
+ struct devcd_entry *devcd = dev_to_devcd(dev);
+
+ return devcd->failing_dev == failing;
+}
+
+/**
+ * dev_coredumpm - create device coredump with read/free methods
+ * @dev: the struct device for the crashed device
+ * @owner: the module that contains the read/free functions, use %THIS_MODULE
+ * @data: data cookie for the @read/@free functions
+ * @datalen: length of the data
+ * @gfp: allocation flags
+ * @read: function to read from the given buffer
+ * @free: function to free the given buffer
+ *
+ * Creates a new device coredump for the given device. If a previous one hasn't
+ * been read yet, the new coredump is discarded. The data lifetime is determined
+ * by the device coredump framework and when it is no longer needed the @free
+ * function will be called to free the data.
+ */
+void dev_coredumpm(struct device *dev, struct module *owner,
+ const void *data, size_t datalen, gfp_t gfp,
+ ssize_t (*read)(char *buffer, loff_t offset, size_t count,
+ const void *data, size_t datalen),
+ void (*free)(const void *data))
+{
+ static atomic_t devcd_count = ATOMIC_INIT(0);
+ struct devcd_entry *devcd;
+ struct device *existing;
+
+ existing = class_find_device(&devcd_class, NULL, dev,
+ devcd_match_failing);
+ if (existing) {
+ put_device(existing);
+ goto free;
+ }
+
+ if (!try_module_get(owner))
+ goto free;
+
+ devcd = kzalloc(sizeof(*devcd), gfp);
+ if (!devcd)
+ goto put_module;
+
+ devcd->owner = owner;
+ devcd->data = data;
+ devcd->datalen = datalen;
+ devcd->read = read;
+ devcd->free = free;
+ devcd->failing_dev = get_device(dev);
+
+ device_initialize(&devcd->devcd_dev);
+
+ dev_set_name(&devcd->devcd_dev, "devcd%d",
+ atomic_inc_return(&devcd_count));
+ devcd->devcd_dev.class = &devcd_class;
+
+ if (device_add(&devcd->devcd_dev))
+ goto put_device;
+
+ if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
+ "failing_device"))
+ /* nothing - symlink will be missing */;
+
+ if (sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
+ "devcoredump"))
+ /* nothing - symlink will be missing */;
+
+ INIT_DELAYED_WORK(&devcd->del_wk, devcd_del);
+ schedule_delayed_work(&devcd->del_wk, DEVCD_TIMEOUT);
+
+ return;
+ put_device:
+ put_device(&devcd->devcd_dev);
+ put_module:
+ module_put(owner);
+ free:
+ free(data);
+}
+EXPORT_SYMBOL_GPL(dev_coredumpm);
+
+static int __init devcoredump_init(void)
+{
+ return class_register(&devcd_class);
+}
+__initcall(devcoredump_init);
+
+static int devcd_free(struct device *dev, void *data)
+{
+ struct devcd_entry *devcd = dev_to_devcd(dev);
+
+ flush_delayed_work(&devcd->del_wk);
+ return 0;
+}
+
+static void __exit devcoredump_exit(void)
+{
+ class_for_each_device(&devcd_class, NULL, NULL, devcd_free);
+ class_unregister(&devcd_class);
+}
+__exitcall(devcoredump_exit);