From: Johannes Berg johannes.berg@intel.com
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 --- MAINTAINERS | 7 ++ drivers/base/Kconfig | 21 ++++ drivers/base/Makefile | 1 + drivers/base/devcoredump.c | 265 ++++++++++++++++++++++++++++++++++++++++++++ include/linux/devcoredump.h | 35 ++++++ 5 files changed, 329 insertions(+) create mode 100644 drivers/base/devcoredump.c create mode 100644 include/linux/devcoredump.h
diff --git a/MAINTAINERS b/MAINTAINERS index 2f85f55c8fb8..8e31d053fb14 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -2847,6 +2847,13 @@ 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 diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig index 4e7f0ff83ae7..134f763d90fd 100644 --- a/drivers/base/Kconfig +++ b/drivers/base/Kconfig @@ -165,6 +165,27 @@ config FW_LOADER_USER_HELPER_FALLBACK
If you are unsure about this, say N here.
+config WANT_DEV_COREDUMP + bool + help + Drivers should "select" this option if they desire to use the + device coredump mechanism. + +config DISABLE_DEV_COREDUMP + bool "Disable device coredump" if EXPERT + help + Disable the device coredump mechanism despite drivers wanting to + use it; this allows for more sensitive systems or systems that + don't want to ever access the information to not have the code, + nor keep any data. + + If unsure, say N. + +config DEV_COREDUMP + bool + default y if WANT_DEV_COREDUMP + depends on !DISABLE_DEV_COREDUMP + config DEBUG_DRIVER bool "Driver Core verbose debug messages" depends on DEBUG_KERNEL diff --git a/drivers/base/Makefile b/drivers/base/Makefile index 4aab26ec0292..6922cd6850a2 100644 --- a/drivers/base/Makefile +++ b/drivers/base/Makefile @@ -21,6 +21,7 @@ obj-$(CONFIG_SYS_HYPERVISOR) += hypervisor.o obj-$(CONFIG_REGMAP) += regmap/ obj-$(CONFIG_SOC_BUS) += soc.o obj-$(CONFIG_PINCTRL) += pinctrl.o +obj-$(CONFIG_DEV_COREDUMP) += devcoredump.o
ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
diff --git a/drivers/base/devcoredump.c b/drivers/base/devcoredump.c new file mode 100644 index 000000000000..96614b04544c --- /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); diff --git a/include/linux/devcoredump.h b/include/linux/devcoredump.h new file mode 100644 index 000000000000..c0a360e99f64 --- /dev/null +++ b/include/linux/devcoredump.h @@ -0,0 +1,35 @@ +#ifndef __DEVCOREDUMP_H +#define __DEVCOREDUMP_H + +#include <linux/device.h> +#include <linux/module.h> +#include <linux/vmalloc.h> + +#ifdef CONFIG_DEV_COREDUMP +void dev_coredumpv(struct device *dev, const void *data, size_t datalen, + gfp_t gfp); + +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)); +#else +static inline void dev_coredumpv(struct device *dev, const void *data, + size_t datalen, gfp_t gfp) +{ + vfree(data); +} + +static inline 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)) +{ + free(data); +} +#endif /* CONFIG_DEV_COREDUMP */ + +#endif /* __DEVCOREDUMP_H */