From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752151AbeCXK6Y (ORCPT ); Sat, 24 Mar 2018 06:58:24 -0400 Received: from stargate.chelsio.com ([12.32.117.8]:20126 "EHLO stargate.chelsio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751980AbeCXK5t (ORCPT ); Sat, 24 Mar 2018 06:57:49 -0400 From: Rahul Lakkireddy To: netdev@vger.kernel.org, linux-fsdevel@vger.kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org Cc: davem@davemloft.net, viro@zeniv.linux.org.uk, ebiederm@xmission.com, stephen@networkplumber.org, akpm@linux-foundation.org, torvalds@linux-foundation.org, ganeshgr@chelsio.com, nirranjan@chelsio.com, indranil@chelsio.com, Rahul Lakkireddy Subject: [PATCH net-next v2 1/2] fs/crashdd: add API to collect hardware dump in second kernel Date: Sat, 24 Mar 2018 16:26:33 +0530 Message-Id: <296ffbd47fd4f30238689e636bd2480683224227.1521888444.git.rahul.lakkireddy@chelsio.com> X-Mailer: git-send-email 2.5.3 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a new module crashdd that exports the /sys/kernel/crashdd/ directory in second kernel, containing collected hardware/firmware dumps. The sequence of actions done by device drivers to append their device specific hardware/firmware logs to /sys/kernel/crashdd/ directory are as follows: 1. During probe (before hardware is initialized), device drivers register to the crashdd module (via crashdd_add_dump()), with callback function, along with buffer size and log name needed for firmware/hardware log collection. 2. Crashdd creates a driver's directory under /sys/kernel/crashdd/. Then, it allocates the buffer with requested size and invokes the device driver's registered callback function. 3. Device driver collects all hardware/firmware logs into the buffer and returns control back to crashdd. 4. Crashdd exposes the buffer as a binary file via /sys/kernel/crashdd//. Suggested-by: Eric Biederman . Suggested-by: Stephen Hemminger Signed-off-by: Rahul Lakkireddy Signed-off-by: Ganesh Goudar --- v2: - Added ABI Documentation for crashdd. - Directly use octal permission instead of macro. Changes since rfc v2: - Moved exporting crashdd from procfs to sysfs. Suggested by Stephen Hemminger - Moved code from fs/proc/crashdd.c to fs/crashdd/ directory. - Replaced all proc API with sysfs API and updated comments. - Calling driver callback before creating the binary file under crashdd sysfs. - Changed binary dump file permission from S_IRUSR to S_IRUGO. - Changed module name from CRASH_DRIVER_DUMP to CRASH_DEVICE_DUMP. rfc v2: - Collecting logs in 2nd kernel instead of during kernel panic. Suggested by Eric Biederman . - Patch added in this series. Documentation/ABI/testing/sysfs-kernel-crashdd | 34 ++++ fs/Kconfig | 1 + fs/Makefile | 1 + fs/crashdd/Kconfig | 10 ++ fs/crashdd/Makefile | 3 + fs/crashdd/crashdd.c | 233 +++++++++++++++++++++++++ fs/crashdd/crashdd_internal.h | 24 +++ include/linux/crashdd.h | 24 +++ 8 files changed, 330 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-kernel-crashdd create mode 100644 fs/crashdd/Kconfig create mode 100644 fs/crashdd/Makefile create mode 100644 fs/crashdd/crashdd.c create mode 100644 fs/crashdd/crashdd_internal.h create mode 100644 include/linux/crashdd.h diff --git a/Documentation/ABI/testing/sysfs-kernel-crashdd b/Documentation/ABI/testing/sysfs-kernel-crashdd new file mode 100644 index 000000000000..1f6b9e27bf2e --- /dev/null +++ b/Documentation/ABI/testing/sysfs-kernel-crashdd @@ -0,0 +1,34 @@ +What: /sys/kernel/crashdd +Date: March 2018 +KernelVersion: 4.16 +Contact: Rahul Lakkireddy + Ganesh Goudar +Description: + Snapshot of underlying hardware/firmware state (like register + dump, firmware logs, adapter memory, etc.), at the time of + kernel panic will be very helpful while debugging the culprit + device driver. Thus, Crash Device Dump (crashdd) module exports + API to allow device drivers to collect the device specific + snapshot of their hardware or firmware in crash recovery kernel. + The collected dumps will be exported under /sys/kernel/crashdd/ + directory in crash recovery kernel. + + The sequence of actions done by device drivers to append their + device specific hardware/firmware logs to /sys/kernel/crashdd/ + directory are as follows: + + 1. During probe (before hardware is initialized), device drivers + register to the crashdd module (via crashdd_add_dump()), with + callback function, along with buffer size and log name needed for + firmware/hardware log collection. + + 2. Crashdd creates a driver's directory under + /sys/kernel/crashdd/. Then, it allocates the buffer + with requested size and invokes the device driver's registered + callback function. + + 3. Device driver collects all hardware/firmware logs into the buffer + and returns control back to crashdd. + + 4. Crashdd exposes the buffer as a file via + /sys/kernel/crashdd//. diff --git a/fs/Kconfig b/fs/Kconfig index bc821a86d965..aae1c55a7dad 100644 --- a/fs/Kconfig +++ b/fs/Kconfig @@ -208,6 +208,7 @@ config ARCH_HAS_GIGANTIC_PAGE source "fs/configfs/Kconfig" source "fs/efivarfs/Kconfig" +source "fs/crashdd/Kconfig" endmenu diff --git a/fs/Makefile b/fs/Makefile index add789ea270a..ff398a44f611 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -128,3 +128,4 @@ obj-y += exofs/ # Multiple modules obj-$(CONFIG_CEPH_FS) += ceph/ obj-$(CONFIG_PSTORE) += pstore/ obj-$(CONFIG_EFIVAR_FS) += efivarfs/ +obj-$(CONFIG_CRASH_DEVICE_DUMP) += crashdd/ diff --git a/fs/crashdd/Kconfig b/fs/crashdd/Kconfig new file mode 100644 index 000000000000..5db9c7c98c17 --- /dev/null +++ b/fs/crashdd/Kconfig @@ -0,0 +1,10 @@ +config CRASH_DEVICE_DUMP + bool "Crash Kernel Device Hardware/Firmware Logs" + depends on SYSFS && CRASH_DUMP + default y + ---help--- + Device drivers can collect the device specific snapshot of + their hardware or firmware before they are initialized in + crash recovery kernel. If you say Y here a tree of device + specific dumps will be made available under /sys/kernel/crashdd/ + directory. diff --git a/fs/crashdd/Makefile b/fs/crashdd/Makefile new file mode 100644 index 000000000000..8dbf946c0ea4 --- /dev/null +++ b/fs/crashdd/Makefile @@ -0,0 +1,3 @@ +# SPDX-License-Identifier: GPL-2.0 + +obj-y := crashdd.o diff --git a/fs/crashdd/crashdd.c b/fs/crashdd/crashdd.c new file mode 100644 index 000000000000..996ba926578b --- /dev/null +++ b/fs/crashdd/crashdd.c @@ -0,0 +1,233 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (c) 2018 Chelsio Communications, Inc. All rights reserved. */ + +#include +#include +#include + +#include "crashdd_internal.h" + +static LIST_HEAD(crashdd_list); +static DEFINE_MUTEX(crashdd_mutex); + +static struct kobject *crashdd_kobj; + +static ssize_t crashdd_read(struct file *filp, struct kobject *kobj, + struct bin_attribute *bin_attr, + char *buf, loff_t fpos, size_t count) +{ + struct crashdd_dump_node *dump = bin_attr->private; + + memcpy(buf, dump->buf + fpos, count); + return count; +} + +static struct kobject *crashdd_mkdir(const char *name) +{ + return kobject_create_and_add(name, crashdd_kobj); +} + +static int crashdd_add_file(struct kobject *kobj, const char *name, + struct crashdd_dump_node *dump) +{ + dump->bin_attr.attr.name = name; + dump->bin_attr.attr.mode = 0444; + dump->bin_attr.size = dump->size; + dump->bin_attr.read = crashdd_read; + dump->bin_attr.private = dump; + + return sysfs_create_bin_file(kobj, &dump->bin_attr); +} + +static void crashdd_rmdir(struct kobject *kobj) +{ + kobject_put(kobj); +} + +/** + * crashdd_init_driver - create a sysfs driver entry. + * @name: Name of the directory. + * + * Creates a directory under /sys/kernel/crashdd/ with @name. Allocates + * and saves the sysfs entry. The sysfs entry is added to the global + * list and then returned to the caller. On failure, returns NULL. + */ +static struct crashdd_driver_node *crashdd_init_driver(const char *name) +{ + struct crashdd_driver_node *node; + + node = vzalloc(sizeof(*node)); + if (!node) + return NULL; + + /* Create a driver's directory under /sys/kernel/crashdd/ */ + node->kobj = crashdd_mkdir(name); + if (!node->kobj) { + vfree(node); + return NULL; + } + + atomic_set(&node->refcnt, 1); + + /* Initialize the list of dumps that go under this driver's + * directory. + */ + INIT_LIST_HEAD(&node->dump_list); + + /* Add the driver's entry to global list */ + mutex_lock(&crashdd_mutex); + list_add_tail(&node->list, &crashdd_list); + mutex_unlock(&crashdd_mutex); + + return node; +} + +/** + * crashdd_get_driver - get an exisiting sysfs driver entry. + * @name: Name of the directory. + * + * Searches and fetches a sysfs entry having @name. If @name is + * found, then the reference count is incremented and the entry + * is returned. If @name is not found, NULL is returned. + */ +static struct crashdd_driver_node *crashdd_get_driver(const char *name) +{ + struct crashdd_driver_node *node; + int found = 0; + + /* Search for an existing driver sysfs entry having @name */ + mutex_lock(&crashdd_mutex); + list_for_each_entry(node, &crashdd_list, list) { + if (!strcmp(node->kobj->name, name)) { + atomic_inc(&node->refcnt); + found = 1; + break; + } + } + mutex_unlock(&crashdd_mutex); + + if (found) + return node; + + /* No driver with @name found */ + return NULL; +} + +/** + * crashdd_put_driver - put an exisiting sysfs driver entry. + * @node: driver sysfs entry. + * + * Decrement @node reference count. If there are no dumps left under it, + * delete the sysfs directory and remove it from the global list. + */ +static void crashdd_put_driver(struct crashdd_driver_node *node) +{ + mutex_lock(&crashdd_mutex); + if (atomic_dec_and_test(&node->refcnt)) { + /* Delete @node driver entry if it has no dumps under it */ + crashdd_rmdir(node->kobj); + list_del(&node->list); + } + mutex_unlock(&crashdd_mutex); +} + +/** + * crashdd_add_dump - Allocate a directory under /sys/kernel/crashdd/ and + * add the dump to it. + * @driver_name: directory name under which the dump should be added. + * @data: dump info. + * + * Search for /sys/kernel/crashdd/<@driver_name>/ directory. If not found, + * allocate a new directory under /sys/kernel/crashdd/ with @driver_name. + * Allocate the dump file's context and invoke the calling driver's dump + * collect routine. Once collection is done, add the dump under + * /sys/kernel/crashdd/<@driver_name>/ directory. + */ +int crashdd_add_dump(const char *driver_name, struct crashdd_data *data) +{ + struct crashdd_driver_node *node; + struct crashdd_dump_node *dump; + void *buf = NULL; + int ret; + + if (!driver_name || !strlen(driver_name) || + !data || !strlen(data->name) || + !data->crashdd_callback || !data->size) + return -EINVAL; + + /* Get a driver sysfs entry with specified name. */ + node = crashdd_get_driver(driver_name); + if (!node) { + /* No driver sysfs entry found with specified name. + * So create a new one + */ + node = crashdd_init_driver(driver_name); + if (!node) + return -ENOMEM; + } + + dump = vzalloc(sizeof(*dump)); + if (!dump) { + ret = -ENOMEM; + goto out_err; + } + + /* Allocate buffer for driver's to write their dumps */ + buf = vzalloc(data->size); + if (!buf) { + ret = -ENOMEM; + goto out_err; + } + + /* Invoke the driver's dump collection routing */ + ret = data->crashdd_callback(data, buf); + if (ret) + goto out_err; + + dump->buf = buf; + dump->size = data->size; + + /* Add a binary file under /sys/kernel/crashdd/@driver_name/ */ + ret = crashdd_add_file(node->kobj, data->name, dump); + if (ret) + goto out_err; + + /* Add the dump to driver sysfs list */ + mutex_lock(&crashdd_mutex); + list_add_tail(&dump->list, &node->dump_list); + atomic_inc(&node->refcnt); + mutex_unlock(&crashdd_mutex); + + /* Return back the driver sysfs reference */ + crashdd_put_driver(node); + return 0; + +out_err: + if (buf) + vfree(buf); + + if (dump) + vfree(dump); + + crashdd_put_driver(node); + return ret; +} +EXPORT_SYMBOL(crashdd_add_dump); + +/* Init function for crash device dump module. */ +static int __init crashdd_init(void) +{ + /* + * Only export this directory in 2nd kernel. + */ + if (!is_kdump_kernel()) + return 0; + + /* Create /sys/kernel/crashdd/ directory */ + crashdd_kobj = kobject_create_and_add("crashdd", kernel_kobj); + if (!crashdd_kobj) + return -ENOMEM; + + return 0; +} +fs_initcall(crashdd_init); diff --git a/fs/crashdd/crashdd_internal.h b/fs/crashdd/crashdd_internal.h new file mode 100644 index 000000000000..9162d1a4264b --- /dev/null +++ b/fs/crashdd/crashdd_internal.h @@ -0,0 +1,24 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (c) 2018 Chelsio Communications, Inc. All rights reserved. */ + +#ifndef CRASH_DEVICE_DUMP_INTERNAL_H +#define CRASH_DEVICE_DUMP_INTERNAL_H + +/* Binary dump file's context internal to crashdd */ +struct crashdd_dump_node { + /* Pointer to list of dumps under the driver sysfs entry */ + struct list_head list; + void *buf; /* Buffer containing device's dump */ + unsigned long size; /* Size of the buffer */ + struct bin_attribute bin_attr; /* Binary dump file's attributes */ +}; + +/* Driver sysfs entry internal to crashdd */ +struct crashdd_driver_node { + /* Pointer to global list of driver sysfs entries */ + struct list_head list; + struct list_head dump_list; /* List of dumps under this driver */ + atomic_t refcnt; /* Number of dumps under this directory */ + struct kobject *kobj; /* Pointer to driver sysfs kobject */ +}; +#endif /* CRASH_DEVICE_DUMP_INTERNAL_H */ diff --git a/include/linux/crashdd.h b/include/linux/crashdd.h new file mode 100644 index 000000000000..edaba8424019 --- /dev/null +++ b/include/linux/crashdd.h @@ -0,0 +1,24 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (c) 2018 Chelsio Communications, Inc. All rights reserved. */ + +#ifndef CRASH_DEVICE_DUMP_H +#define CRASH_DEVICE_DUMP_H + +/* Max dump name length */ +#define CRASHDD_NAME_LENGTH 32 + +/* Device Dump information to be filled by drivers */ +struct crashdd_data { + char name[CRASHDD_NAME_LENGTH]; /* Unique name of the dump */ + unsigned long size; /* Size of the dump */ + /* Driver's registered callback to be invoked to collect dump */ + int (*crashdd_callback)(struct crashdd_data *data, void *buf); +}; + +#ifdef CONFIG_CRASH_DEVICE_DUMP +int crashdd_add_dump(const char *driver_name, struct crashdd_data *data); +#else +#define crashdd_add_dump(x, y) 0 +#endif /* CONFIG_CRASH_DEVICE_DUMP */ + +#endif /* CRASH_DEVICE_DUMP_H */ -- 2.14.1