1 files changed, 434 insertions, 0 deletions
diff --git a/fs/pstore/blk.c b/fs/pstore/blk.c
new file mode 100644
index 000000000000..8f131c6e412e
--- /dev/null
+++ b/fs/pstore/blk.c
@@ -0,0 +1,434 @@
+// 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");