diff options
Diffstat (limited to '')
| -rw-r--r-- | fs/pstore/blk.c | 361 |
1 files changed, 361 insertions, 0 deletions
diff --git a/fs/pstore/blk.c b/fs/pstore/blk.c new file mode 100644 index 000000000000..4ae0cfcd15f2 --- /dev/null +++ b/fs/pstore/blk.c @@ -0,0 +1,361 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Implements pstore backend driver that write to block (or non-block) storage + * devices, using the pstore/zone API. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/blkdev.h> +#include <linux/string.h> +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/platform_device.h> +#include <linux/pstore_blk.h> +#include <linux/fs.h> +#include <linux/file.h> +#include <linux/init_syscalls.h> +#include <linux/mount.h> + +static long kmsg_size = CONFIG_PSTORE_BLK_KMSG_SIZE; +module_param(kmsg_size, long, 0400); +MODULE_PARM_DESC(kmsg_size, "kmsg dump record size in kbytes"); + +static int max_reason = CONFIG_PSTORE_BLK_MAX_REASON; +module_param(max_reason, int, 0400); +MODULE_PARM_DESC(max_reason, + "maximum reason for kmsg dump (default 2: Oops and Panic)"); + +#if IS_ENABLED(CONFIG_PSTORE_PMSG) +static long pmsg_size = CONFIG_PSTORE_BLK_PMSG_SIZE; +#else +static long pmsg_size = -1; +#endif +module_param(pmsg_size, long, 0400); +MODULE_PARM_DESC(pmsg_size, "pmsg size in kbytes"); + +#if IS_ENABLED(CONFIG_PSTORE_CONSOLE) +static long console_size = CONFIG_PSTORE_BLK_CONSOLE_SIZE; +#else +static long console_size = -1; +#endif +module_param(console_size, long, 0400); +MODULE_PARM_DESC(console_size, "console size in kbytes"); + +#if IS_ENABLED(CONFIG_PSTORE_FTRACE) +static long ftrace_size = CONFIG_PSTORE_BLK_FTRACE_SIZE; +#else +static long ftrace_size = -1; +#endif +module_param(ftrace_size, long, 0400); +MODULE_PARM_DESC(ftrace_size, "ftrace size in kbytes"); + +static bool best_effort; +module_param(best_effort, bool, 0400); +MODULE_PARM_DESC(best_effort, "use best effort to write (i.e. do not require storage driver pstore support, default: off)"); + +/* + * blkdev - the block device to use for pstore storage + * See Documentation/admin-guide/pstore-blk.rst for details. + */ +static char blkdev[80] = CONFIG_PSTORE_BLK_BLKDEV; +module_param_string(blkdev, blkdev, 80, 0400); +MODULE_PARM_DESC(blkdev, "block device for pstore storage"); + +/* + * All globals must only be accessed under the pstore_blk_lock + * during the register/unregister functions. + */ +static DEFINE_MUTEX(pstore_blk_lock); +static struct file *psblk_file; +static struct pstore_device_info *pstore_device_info; + +#define check_size(name, alignsize) ({ \ + long _##name_ = (name); \ + _##name_ = _##name_ <= 0 ? 0 : (_##name_ * 1024); \ + if (_##name_ & ((alignsize) - 1)) { \ + pr_info(#name " must align to %d\n", \ + (alignsize)); \ + _##name_ = ALIGN(name, (alignsize)); \ + } \ + _##name_; \ +}) + +#define verify_size(name, alignsize, enabled) { \ + long _##name_; \ + if (enabled) \ + _##name_ = check_size(name, alignsize); \ + else \ + _##name_ = 0; \ + /* Synchronize module parameters with resuls. */ \ + name = _##name_ / 1024; \ + dev->zone.name = _##name_; \ +} + +static int __register_pstore_device(struct pstore_device_info *dev) +{ + int ret; + + lockdep_assert_held(&pstore_blk_lock); + + if (!dev) { + pr_err("NULL device info\n"); + return -EINVAL; + } + if (!dev->zone.total_size) { + pr_err("zero sized device\n"); + return -EINVAL; + } + if (!dev->zone.read) { + pr_err("no read handler for device\n"); + return -EINVAL; + } + if (!dev->zone.write) { + pr_err("no write handler for device\n"); + return -EINVAL; + } + + /* someone already registered before */ + if (pstore_device_info) + return -EBUSY; + + /* zero means not limit on which backends to attempt to store. */ + if (!dev->flags) + dev->flags = UINT_MAX; + + /* Copy in module parameters. */ + verify_size(kmsg_size, 4096, dev->flags & PSTORE_FLAGS_DMESG); + verify_size(pmsg_size, 4096, dev->flags & PSTORE_FLAGS_PMSG); + verify_size(console_size, 4096, dev->flags & PSTORE_FLAGS_CONSOLE); + verify_size(ftrace_size, 4096, dev->flags & PSTORE_FLAGS_FTRACE); + dev->zone.max_reason = max_reason; + + /* Initialize required zone ownership details. */ + dev->zone.name = KBUILD_MODNAME; + dev->zone.owner = THIS_MODULE; + + ret = register_pstore_zone(&dev->zone); + if (ret == 0) + pstore_device_info = dev; + + return ret; +} +/** + * register_pstore_device() - register non-block device to pstore/blk + * + * @dev: non-block device information + * + * Return: + * * 0 - OK + * * Others - something error. + */ +int register_pstore_device(struct pstore_device_info *dev) +{ + int ret; + + mutex_lock(&pstore_blk_lock); + ret = __register_pstore_device(dev); + mutex_unlock(&pstore_blk_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(register_pstore_device); + +static void __unregister_pstore_device(struct pstore_device_info *dev) +{ + lockdep_assert_held(&pstore_blk_lock); + if (pstore_device_info && pstore_device_info == dev) { + unregister_pstore_zone(&dev->zone); + pstore_device_info = NULL; + } +} + +/** + * unregister_pstore_device() - unregister non-block device from pstore/blk + * + * @dev: non-block device information + */ +void unregister_pstore_device(struct pstore_device_info *dev) +{ + mutex_lock(&pstore_blk_lock); + __unregister_pstore_device(dev); + mutex_unlock(&pstore_blk_lock); +} +EXPORT_SYMBOL_GPL(unregister_pstore_device); + +static ssize_t psblk_generic_blk_read(char *buf, size_t bytes, loff_t pos) +{ + return kernel_read(psblk_file, buf, bytes, &pos); +} + +static ssize_t psblk_generic_blk_write(const char *buf, size_t bytes, + loff_t pos) +{ + /* Console/Ftrace backend may handle buffer until flush dirty zones */ + if (in_interrupt() || irqs_disabled()) + return -EBUSY; + return kernel_write(psblk_file, buf, bytes, &pos); +} + +/* + * This takes its configuration only from the module parameters now. + */ +static int __register_pstore_blk(struct pstore_device_info *dev, + const char *devpath) +{ + int ret = -ENODEV; + + lockdep_assert_held(&pstore_blk_lock); + + psblk_file = filp_open(devpath, O_RDWR | O_DSYNC | O_NOATIME | O_EXCL, 0); + if (IS_ERR(psblk_file)) { + ret = PTR_ERR(psblk_file); + pr_err("failed to open '%s': %d!\n", devpath, ret); + goto err; + } + + if (!S_ISBLK(file_inode(psblk_file)->i_mode)) { + pr_err("'%s' is not block device!\n", devpath); + goto err_fput; + } + + dev->zone.total_size = + bdev_nr_bytes(I_BDEV(psblk_file->f_mapping->host)); + + ret = __register_pstore_device(dev); + if (ret) + goto err_fput; + + return 0; + +err_fput: + fput(psblk_file); +err: + psblk_file = NULL; + + return ret; +} + +/* get information of pstore/blk */ +int pstore_blk_get_config(struct pstore_blk_config *info) +{ + strncpy(info->device, blkdev, 80); + info->max_reason = max_reason; + info->kmsg_size = check_size(kmsg_size, 4096); + info->pmsg_size = check_size(pmsg_size, 4096); + info->ftrace_size = check_size(ftrace_size, 4096); + info->console_size = check_size(console_size, 4096); + + return 0; +} +EXPORT_SYMBOL_GPL(pstore_blk_get_config); + + +#ifndef MODULE +static const char devname[] = "/dev/pstore-blk"; +static __init const char *early_boot_devpath(const char *initial_devname) +{ + /* + * During early boot the real root file system hasn't been + * mounted yet, and no device nodes are present yet. Use the + * same scheme to find the device that we use for mounting + * the root file system. + */ + dev_t dev = name_to_dev_t(initial_devname); + + if (!dev) { + pr_err("failed to resolve '%s'!\n", initial_devname); + return initial_devname; + } + + init_unlink(devname); + init_mknod(devname, S_IFBLK | 0600, new_encode_dev(dev)); + + return devname; +} +#else +static inline const char *early_boot_devpath(const char *initial_devname) +{ + return initial_devname; +} +#endif + +static int __init __best_effort_init(void) +{ + struct pstore_device_info *best_effort_dev; + int ret; + + /* No best-effort mode requested. */ + if (!best_effort) + return 0; + + /* Reject an empty blkdev. */ + if (!blkdev[0]) { + pr_err("blkdev empty with best_effort=Y\n"); + return -EINVAL; + } + + best_effort_dev = kzalloc(sizeof(*best_effort_dev), GFP_KERNEL); + if (!best_effort_dev) + return -ENOMEM; + + best_effort_dev->zone.read = psblk_generic_blk_read; + best_effort_dev->zone.write = psblk_generic_blk_write; + + ret = __register_pstore_blk(best_effort_dev, + early_boot_devpath(blkdev)); + if (ret) + kfree(best_effort_dev); + else + pr_info("attached %s (%lu) (no dedicated panic_write!)\n", + blkdev, best_effort_dev->zone.total_size); + + return ret; +} + +static void __exit __best_effort_exit(void) +{ + /* + * Currently, the only user of psblk_file is best_effort, so + * we can assume that pstore_device_info is associated with it. + * Once there are "real" blk devices, there will need to be a + * dedicated pstore_blk_info, etc. + */ + if (psblk_file) { + struct pstore_device_info *dev = pstore_device_info; + + __unregister_pstore_device(dev); + kfree(dev); + fput(psblk_file); + psblk_file = NULL; + } +} + +static int __init pstore_blk_init(void) +{ + int ret; + + mutex_lock(&pstore_blk_lock); + ret = __best_effort_init(); + mutex_unlock(&pstore_blk_lock); + + return ret; +} +late_initcall(pstore_blk_init); + +static void __exit pstore_blk_exit(void) +{ + mutex_lock(&pstore_blk_lock); + __best_effort_exit(); + /* If we've been asked to unload, unregister any remaining device. */ + __unregister_pstore_device(pstore_device_info); + mutex_unlock(&pstore_blk_lock); +} +module_exit(pstore_blk_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("WeiXiong Liao <liaoweixiong@allwinnertech.com>"); +MODULE_AUTHOR("Kees Cook <keescook@chromium.org>"); +MODULE_DESCRIPTION("pstore backend for block devices"); |