--- /dev/null
+// 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 "../../block/blk.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/mount.h>
+#include <linux/uio.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)");
+
+/*
+ * blkdev - the block device to use for pstore storage
+ *
+ * Usually, this will be a partition of a block device.
+ *
+ * blkdev accepts the following variants:
+ * 1) <hex_major><hex_minor> device number in hexadecimal representation,
+ * with no leading 0x, for example b302.
+ * 2) /dev/<disk_name> represents the device number of disk
+ * 3) /dev/<disk_name><decimal> represents the device number
+ * of partition - device number of disk plus the partition number
+ * 4) /dev/<disk_name>p<decimal> - same as the above, that form is
+ * used when disk name of partitioned disk ends on a digit.
+ * 5) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
+ * unique id of a partition if the partition table provides it.
+ * The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
+ * partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
+ * filled hex representation of the 32-bit "NT disk signature", and PP
+ * is a zero-filled hex representation of the 1-based partition number.
+ * 6) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
+ * a partition with a known unique id.
+ * 7) <major>:<minor> major and minor number of the device separated by
+ * a colon.
+ */
+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 block_device *psblk_bdev;
+static struct pstore_zone_info *pstore_zone_info;
+static pstore_blk_panic_write_op blkdev_panic_write;
+
+struct bdev_info {
+ dev_t devt;
+ sector_t nr_sects;
+ sector_t start_sect;
+};
+
+/**
+ * struct pstore_device_info - back-end pstore/blk driver structure.
+ *
+ * @total_size: The total size in bytes pstore/blk can use. It must be greater
+ * than 4096 and be multiple of 4096.
+ * @flags: Refer to macro starting with PSTORE_FLAGS defined in
+ * linux/pstore.h. It means what front-ends this device support.
+ * Zero means all backends for compatible.
+ * @read: The general read operation. Both of the function parameters
+ * @size and @offset are relative value to bock device (not the
+ * whole disk).
+ * On success, the number of bytes should be returned, others
+ * means error.
+ * @write: The same as @read.
+ * @panic_write:The write operation only used for panic case. It's optional
+ * if you do not care panic log. The parameters and return value
+ * are the same as @read.
+ */
+struct pstore_device_info {
+ unsigned long total_size;
+ unsigned int flags;
+ pstore_zone_read_op read;
+ pstore_zone_write_op write;
+ pstore_zone_write_op panic_write;
+};
+
+static int psblk_register_do(struct pstore_device_info *dev)
+{
+ int ret;
+
+ if (!dev || !dev->total_size || !dev->read || !dev->write)
+ return -EINVAL;
+
+ mutex_lock(&pstore_blk_lock);
+
+ /* someone already registered before */
+ if (pstore_zone_info) {
+ mutex_unlock(&pstore_blk_lock);
+ return -EBUSY;
+ }
+ pstore_zone_info = kzalloc(sizeof(struct pstore_zone_info), GFP_KERNEL);
+ if (!pstore_zone_info) {
+ mutex_unlock(&pstore_blk_lock);
+ return -ENOMEM;
+ }
+
+ /* zero means not limit on which backends to attempt to store. */
+ if (!dev->flags)
+ dev->flags = UINT_MAX;
+
+#define verify_size(name, alignsize, enabled) { \
+ long _##name_ = (enabled) ? (name) : 0; \
+ _##name_ = _##name_ <= 0 ? 0 : (_##name_ * 1024); \
+ if (_##name_ & ((alignsize) - 1)) { \
+ pr_info(#name " must align to %d\n", \
+ (alignsize)); \
+ _##name_ = ALIGN(name, (alignsize)); \
+ } \
+ name = _##name_ / 1024; \
+ pstore_zone_info->name = _##name_; \
+ }
+
+ verify_size(kmsg_size, 4096, dev->flags & PSTORE_FLAGS_DMESG);
+#undef verify_size
+
+ pstore_zone_info->total_size = dev->total_size;
+ pstore_zone_info->max_reason = max_reason;
+ pstore_zone_info->read = dev->read;
+ pstore_zone_info->write = dev->write;
+ pstore_zone_info->panic_write = dev->panic_write;
+ pstore_zone_info->name = KBUILD_MODNAME;
+ pstore_zone_info->owner = THIS_MODULE;
+
+ ret = register_pstore_zone(pstore_zone_info);
+ if (ret) {
+ kfree(pstore_zone_info);
+ pstore_zone_info = NULL;
+ }
+ mutex_unlock(&pstore_blk_lock);
+ return ret;
+}
+
+static void psblk_unregister_do(struct pstore_device_info *dev)
+{
+ mutex_lock(&pstore_blk_lock);
+ if (pstore_zone_info && pstore_zone_info->read == dev->read) {
+ unregister_pstore_zone(pstore_zone_info);
+ kfree(pstore_zone_info);
+ pstore_zone_info = NULL;
+ }
+ mutex_unlock(&pstore_blk_lock);
+}
+
+/**
+ * psblk_get_bdev() - open block device
+ *
+ * @holder: Exclusive holder identifier
+ * @info: Information about bdev to fill in
+ *
+ * Return: pointer to block device on success and others on error.
+ *
+ * On success, the returned block_device has reference count of one.
+ */
+static struct block_device *psblk_get_bdev(void *holder,
+ struct bdev_info *info)
+{
+ struct block_device *bdev = ERR_PTR(-ENODEV);
+ fmode_t mode = FMODE_READ | FMODE_WRITE;
+ sector_t nr_sects;
+
+ lockdep_assert_held(&pstore_blk_lock);
+
+ if (pstore_zone_info)
+ return ERR_PTR(-EBUSY);
+
+ if (!blkdev[0])
+ return ERR_PTR(-ENODEV);
+
+ if (holder)
+ mode |= FMODE_EXCL;
+ bdev = blkdev_get_by_path(blkdev, mode, holder);
+ if (IS_ERR(bdev)) {
+ dev_t devt;
+
+ devt = name_to_dev_t(blkdev);
+ if (devt == 0)
+ return ERR_PTR(-ENODEV);
+ bdev = blkdev_get_by_dev(devt, mode, holder);
+ if (IS_ERR(bdev))
+ return bdev;
+ }
+
+ nr_sects = part_nr_sects_read(bdev->bd_part);
+ if (!nr_sects) {
+ pr_err("not enough space for '%s'\n", blkdev);
+ blkdev_put(bdev, mode);
+ return ERR_PTR(-ENOSPC);
+ }
+
+ if (info) {
+ info->devt = bdev->bd_dev;
+ info->nr_sects = nr_sects;
+ info->start_sect = get_start_sect(bdev);
+ }
+
+ return bdev;
+}
+
+static void psblk_put_bdev(struct block_device *bdev, void *holder)
+{
+ fmode_t mode = FMODE_READ | FMODE_WRITE;
+
+ lockdep_assert_held(&pstore_blk_lock);
+
+ if (!bdev)
+ return;
+
+ if (holder)
+ mode |= FMODE_EXCL;
+ blkdev_put(bdev, mode);
+}
+
+static ssize_t psblk_generic_blk_read(char *buf, size_t bytes, loff_t pos)
+{
+ struct block_device *bdev = psblk_bdev;
+ struct file file;
+ struct kiocb kiocb;
+ struct iov_iter iter;
+ struct kvec iov = {.iov_base = buf, .iov_len = bytes};
+
+ if (!bdev)
+ return -ENODEV;
+
+ memset(&file, 0, sizeof(struct file));
+ file.f_mapping = bdev->bd_inode->i_mapping;
+ file.f_flags = O_DSYNC | __O_SYNC | O_NOATIME;
+ file.f_inode = bdev->bd_inode;
+ file_ra_state_init(&file.f_ra, file.f_mapping);
+
+ init_sync_kiocb(&kiocb, &file);
+ kiocb.ki_pos = pos;
+ iov_iter_kvec(&iter, READ, &iov, 1, bytes);
+
+ return generic_file_read_iter(&kiocb, &iter);
+}
+
+static ssize_t psblk_generic_blk_write(const char *buf, size_t bytes,
+ loff_t pos)
+{
+ struct block_device *bdev = psblk_bdev;
+ struct iov_iter iter;
+ struct kiocb kiocb;
+ struct file file;
+ ssize_t ret;
+ struct kvec iov = {.iov_base = (void *)buf, .iov_len = bytes};
+
+ if (!bdev)
+ return -ENODEV;
+
+ /* Console/Ftrace backend may handle buffer until flush dirty zones */
+ if (in_interrupt() || irqs_disabled())
+ return -EBUSY;
+
+ memset(&file, 0, sizeof(struct file));
+ file.f_mapping = bdev->bd_inode->i_mapping;
+ file.f_flags = O_DSYNC | __O_SYNC | O_NOATIME;
+ file.f_inode = bdev->bd_inode;
+
+ init_sync_kiocb(&kiocb, &file);
+ kiocb.ki_pos = pos;
+ iov_iter_kvec(&iter, WRITE, &iov, 1, bytes);
+
+ inode_lock(bdev->bd_inode);
+ ret = generic_write_checks(&kiocb, &iter);
+ if (ret > 0)
+ ret = generic_perform_write(&file, &iter, pos);
+ inode_unlock(bdev->bd_inode);
+
+ if (likely(ret > 0)) {
+ const struct file_operations f_op = {.fsync = blkdev_fsync};
+
+ file.f_op = &f_op;
+ kiocb.ki_pos += ret;
+ ret = generic_write_sync(&kiocb, ret);
+ }
+ return ret;
+}
+
+static ssize_t psblk_blk_panic_write(const char *buf, size_t size,
+ loff_t off)
+{
+ int ret;
+
+ if (!blkdev_panic_write)
+ return -EOPNOTSUPP;
+
+ /* size and off must align to SECTOR_SIZE for block device */
+ ret = blkdev_panic_write(buf, off >> SECTOR_SHIFT,
+ size >> SECTOR_SHIFT);
+ return ret ? -EIO : size;
+}
+
+static int __register_pstore_blk(struct pstore_blk_info *info)
+{
+ char bdev_name[BDEVNAME_SIZE];
+ struct block_device *bdev;
+ struct pstore_device_info dev;
+ struct bdev_info binfo;
+ void *holder = blkdev;
+ int ret = -ENODEV;
+
+ lockdep_assert_held(&pstore_blk_lock);
+
+ /* hold bdev exclusively */
+ memset(&binfo, 0, sizeof(binfo));
+ bdev = psblk_get_bdev(holder, &binfo);
+ if (IS_ERR(bdev)) {
+ pr_err("failed to open '%s'!\n", blkdev);
+ return PTR_ERR(bdev);
+ }
+
+ /* only allow driver matching the @blkdev */
+ if (!binfo.devt || MAJOR(binfo.devt) != info->major) {
+ pr_debug("invalid major %u (expect %u)\n",
+ info->major, MAJOR(binfo.devt));
+ ret = -ENODEV;
+ goto err_put_bdev;
+ }
+
+ /* psblk_bdev must be assigned before register to pstore/blk */
+ psblk_bdev = bdev;
+ blkdev_panic_write = info->panic_write;
+
+ /* Copy back block device details. */
+ info->devt = binfo.devt;
+ info->nr_sects = binfo.nr_sects;
+ info->start_sect = binfo.start_sect;
+
+ memset(&dev, 0, sizeof(dev));
+ dev.total_size = info->nr_sects << SECTOR_SHIFT;
+ dev.flags = info->flags;
+ dev.read = psblk_generic_blk_read;
+ dev.write = psblk_generic_blk_write;
+ dev.panic_write = info->panic_write ? psblk_blk_panic_write : NULL;
+
+ ret = psblk_register_do(&dev);
+ if (ret)
+ goto err_put_bdev;
+
+ bdevname(bdev, bdev_name);
+ pr_info("attached %s%s\n", bdev_name,
+ info->panic_write ? "" : " (no dedicated panic_write!)");
+ return 0;
+
+err_put_bdev:
+ psblk_bdev = NULL;
+ blkdev_panic_write = NULL;
+ psblk_put_bdev(bdev, holder);
+ return ret;
+}
+
+/**
+ * register_pstore_blk() - register block device to pstore/blk
+ *
+ * @info: details on the desired block device interface
+ *
+ * Return:
+ * * 0 - OK
+ * * Others - something error.
+ */
+int register_pstore_blk(struct pstore_blk_info *info)
+{
+ int ret;
+
+ mutex_lock(&pstore_blk_lock);
+ ret = __register_pstore_blk(info);
+ mutex_unlock(&pstore_blk_lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(register_pstore_blk);
+
+static void __unregister_pstore_blk(unsigned int major)
+{
+ struct pstore_device_info dev = { .read = psblk_generic_blk_read };
+ void *holder = blkdev;
+
+ lockdep_assert_held(&pstore_blk_lock);
+ if (psblk_bdev && MAJOR(psblk_bdev->bd_dev) == major) {
+ psblk_unregister_do(&dev);
+ psblk_put_bdev(psblk_bdev, holder);
+ blkdev_panic_write = NULL;
+ psblk_bdev = NULL;
+ }
+}
+
+/**
+ * unregister_pstore_blk() - unregister block device from pstore/blk
+ *
+ * @major: the major device number of device
+ */
+void unregister_pstore_blk(unsigned int major)
+{
+ mutex_lock(&pstore_blk_lock);
+ __unregister_pstore_blk(major);
+ mutex_unlock(&pstore_blk_lock);
+}
+EXPORT_SYMBOL_GPL(unregister_pstore_blk);
+
+static void __exit pstore_blk_exit(void)
+{
+ mutex_lock(&pstore_blk_lock);
+ if (psblk_bdev)
+ __unregister_pstore_blk(MAJOR(psblk_bdev->bd_dev));
+ 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");
projects / users / hch / configfs.git / commitdiff