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