drivers/dax/device.c - linux - Git at Google

 /*
  * Copyright(c) 2016 - 2017 Intel Corporation. All rights reserved.
  *
  * 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.
  */
 #include <linux/pagemap.h>
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/pfn_t.h>
 #include <linux/cdev.h>
 #include <linux/slab.h>
 #include <linux/dax.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
 #include <linux/mman.h>
 #include "dax-private.h"
 #include "dax.h"

 static struct class *dax_class;

 /*
  * Rely on the fact that drvdata is set before the attributes are
  * registered, and that the attributes are unregistered before drvdata
  * is cleared to assume that drvdata is always valid.
  */
 static ssize_t id_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct dax_region *dax_region = dev_get_drvdata(dev);

 	return sprintf(buf, "%d\n", dax_region->id);
 }
 static DEVICE_ATTR_RO(id);

 static ssize_t region_size_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct dax_region *dax_region = dev_get_drvdata(dev);

 	return sprintf(buf, "%llu\n", (unsigned long long)
 			resource_size(&dax_region->res));
 }
 static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
 		region_size_show, NULL);

 static ssize_t align_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct dax_region *dax_region = dev_get_drvdata(dev);

 	return sprintf(buf, "%u\n", dax_region->align);
 }
 static DEVICE_ATTR_RO(align);

 static struct attribute *dax_region_attributes[] = {
 	&dev_attr_region_size.attr,
 	&dev_attr_align.attr,
 	&dev_attr_id.attr,
 	NULL,
 };

 static const struct attribute_group dax_region_attribute_group = {
 	.name = "dax_region",
 	.attrs = dax_region_attributes,
 };

 static const struct attribute_group *dax_region_attribute_groups[] = {
 	&dax_region_attribute_group,
 	NULL,
 };

 static void dax_region_free(struct kref *kref)
 {
 	struct dax_region *dax_region;

 	dax_region = container_of(kref, struct dax_region, kref);
 	kfree(dax_region);
 }

 void dax_region_put(struct dax_region *dax_region)
 {
 	kref_put(&dax_region->kref, dax_region_free);
 }
 EXPORT_SYMBOL_GPL(dax_region_put);

 static void dax_region_unregister(void *region)
 {
 	struct dax_region *dax_region = region;

 	sysfs_remove_groups(&dax_region->dev->kobj,
 			dax_region_attribute_groups);
 	dax_region_put(dax_region);
 }

 struct dax_region *alloc_dax_region(struct device *parent, int region_id,
 		struct resource *res, unsigned int align, void *addr,
 		unsigned long pfn_flags)
 {
 	struct dax_region *dax_region;

 	/*
 	 * The DAX core assumes that it can store its private data in
 	 * parent->driver_data. This WARN is a reminder / safeguard for
 	 * developers of device-dax drivers.
 	 */
 	if (dev_get_drvdata(parent)) {
 		dev_WARN(parent, "dax core failed to setup private data\n");
 		return NULL;
 	}

 	if (!IS_ALIGNED(res->start, align)
 			|| !IS_ALIGNED(resource_size(res), align))
 		return NULL;

 	dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
 	if (!dax_region)
 		return NULL;

 	dev_set_drvdata(parent, dax_region);
 	memcpy(&dax_region->res, res, sizeof(*res));
 	dax_region->pfn_flags = pfn_flags;
 	kref_init(&dax_region->kref);
 	dax_region->id = region_id;
 	ida_init(&dax_region->ida);
 	dax_region->align = align;
 	dax_region->dev = parent;
 	dax_region->base = addr;
 	if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
 		kfree(dax_region);
 		return NULL;
 	}

 	kref_get(&dax_region->kref);
 	if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
 		return NULL;
 	return dax_region;
 }
 EXPORT_SYMBOL_GPL(alloc_dax_region);

 static struct dev_dax *to_dev_dax(struct device *dev)
 {
 	return container_of(dev, struct dev_dax, dev);
 }

 static ssize_t size_show(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
 	struct dev_dax *dev_dax = to_dev_dax(dev);
 	unsigned long long size = 0;
 	int i;

 	for (i = 0; i < dev_dax->num_resources; i++)
 		size += resource_size(&dev_dax->res[i]);

 	return sprintf(buf, "%llu\n", size);
 }
 static DEVICE_ATTR_RO(size);

 static struct attribute *dev_dax_attributes[] = {
 	&dev_attr_size.attr,
 	NULL,
 };

 static const struct attribute_group dev_dax_attribute_group = {
 	.attrs = dev_dax_attributes,
 };

 static const struct attribute_group *dax_attribute_groups[] = {
 	&dev_dax_attribute_group,
 	NULL,
 };

 static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
 		const char *func)
 {
 	struct dax_region *dax_region = dev_dax->region;
 	struct device *dev = &dev_dax->dev;
 	unsigned long mask;

 	if (!dax_alive(dev_dax->dax_dev))
 		return -ENXIO;

 	/* prevent private mappings from being established */
 	if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
 		dev_info_ratelimited(dev,
 				"%s: %s: fail, attempted private mapping\n",
 				current->comm, func);
 		return -EINVAL;
 	}

 	mask = dax_region->align - 1;
 	if (vma->vm_start & mask || vma->vm_end & mask) {
 		dev_info_ratelimited(dev,
 				"%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n",
 				current->comm, func, vma->vm_start, vma->vm_end,
 				mask);
 		return -EINVAL;
 	}

 	if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) == PFN_DEV
 			&& (vma->vm_flags & VM_DONTCOPY) == 0) {
 		dev_info_ratelimited(dev,
 				"%s: %s: fail, dax range requires MADV_DONTFORK\n",
 				current->comm, func);
 		return -EINVAL;
 	}

 	if (!vma_is_dax(vma)) {
 		dev_info_ratelimited(dev,
 				"%s: %s: fail, vma is not DAX capable\n",
 				current->comm, func);
 		return -EINVAL;
 	}

 	return 0;
 }

 /* see "strong" declaration in tools/testing/nvdimm/dax-dev.c */
 __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
 		unsigned long size)
 {
 	struct resource *res;
 	/* gcc-4.6.3-nolibc for i386 complains that this is uninitialized */
 	phys_addr_t uninitialized_var(phys);
 	int i;

 	for (i = 0; i < dev_dax->num_resources; i++) {
 		res = &dev_dax->res[i];
 		phys = pgoff * PAGE_SIZE + res->start;
 		if (phys >= res->start && phys <= res->end)
 			break;
 		pgoff -= PHYS_PFN(resource_size(res));
 	}

 	if (i < dev_dax->num_resources) {
 		res = &dev_dax->res[i];
 		if (phys + size - 1 <= res->end)
 			return phys;
 	}

 	return -1;
 }

 static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax,
 				struct vm_fault *vmf, pfn_t *pfn)
 {
 	struct device *dev = &dev_dax->dev;
 	struct dax_region *dax_region;
 	phys_addr_t phys;
 	unsigned int fault_size = PAGE_SIZE;

 	if (check_vma(dev_dax, vmf->vma, __func__))
 		return VM_FAULT_SIGBUS;

 	dax_region = dev_dax->region;
 	if (dax_region->align > PAGE_SIZE) {
 		dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
 			dax_region->align, fault_size);
 		return VM_FAULT_SIGBUS;
 	}

 	if (fault_size != dax_region->align)
 		return VM_FAULT_SIGBUS;

 	phys = dax_pgoff_to_phys(dev_dax, vmf->pgoff, PAGE_SIZE);
 	if (phys == -1) {
 		dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", vmf->pgoff);
 		return VM_FAULT_SIGBUS;
 	}

 	*pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);

 	return vmf_insert_mixed(vmf->vma, vmf->address, *pfn);
 }

 static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax,
 				struct vm_fault *vmf, pfn_t *pfn)
 {
 	unsigned long pmd_addr = vmf->address & PMD_MASK;
 	struct device *dev = &dev_dax->dev;
 	struct dax_region *dax_region;
 	phys_addr_t phys;
 	pgoff_t pgoff;
 	unsigned int fault_size = PMD_SIZE;

 	if (check_vma(dev_dax, vmf->vma, __func__))
 		return VM_FAULT_SIGBUS;

 	dax_region = dev_dax->region;
 	if (dax_region->align > PMD_SIZE) {
 		dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
 			dax_region->align, fault_size);
 		return VM_FAULT_SIGBUS;
 	}

 	/* dax pmd mappings require pfn_t_devmap() */
 	if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
 		dev_dbg(dev, "region lacks devmap flags\n");
 		return VM_FAULT_SIGBUS;
 	}

 	if (fault_size < dax_region->align)
 		return VM_FAULT_SIGBUS;
 	else if (fault_size > dax_region->align)
 		return VM_FAULT_FALLBACK;

 	/* if we are outside of the VMA */
 	if (pmd_addr < vmf->vma->vm_start ||
 			(pmd_addr + PMD_SIZE) > vmf->vma->vm_end)
 		return VM_FAULT_SIGBUS;

 	pgoff = linear_page_index(vmf->vma, pmd_addr);
 	phys = dax_pgoff_to_phys(dev_dax, pgoff, PMD_SIZE);
 	if (phys == -1) {
 		dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff);
 		return VM_FAULT_SIGBUS;
 	}

 	*pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);

 	return vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd, *pfn,
 			vmf->flags & FAULT_FLAG_WRITE);
 }

 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
 				struct vm_fault *vmf, pfn_t *pfn)
 {
 	unsigned long pud_addr = vmf->address & PUD_MASK;
 	struct device *dev = &dev_dax->dev;
 	struct dax_region *dax_region;
 	phys_addr_t phys;
 	pgoff_t pgoff;
 	unsigned int fault_size = PUD_SIZE;


 	if (check_vma(dev_dax, vmf->vma, __func__))
 		return VM_FAULT_SIGBUS;

 	dax_region = dev_dax->region;
 	if (dax_region->align > PUD_SIZE) {
 		dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
 			dax_region->align, fault_size);
 		return VM_FAULT_SIGBUS;
 	}

 	/* dax pud mappings require pfn_t_devmap() */
 	if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
 		dev_dbg(dev, "region lacks devmap flags\n");
 		return VM_FAULT_SIGBUS;
 	}

 	if (fault_size < dax_region->align)
 		return VM_FAULT_SIGBUS;
 	else if (fault_size > dax_region->align)
 		return VM_FAULT_FALLBACK;

 	/* if we are outside of the VMA */
 	if (pud_addr < vmf->vma->vm_start ||
 			(pud_addr + PUD_SIZE) > vmf->vma->vm_end)
 		return VM_FAULT_SIGBUS;

 	pgoff = linear_page_index(vmf->vma, pud_addr);
 	phys = dax_pgoff_to_phys(dev_dax, pgoff, PUD_SIZE);
 	if (phys == -1) {
 		dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff);
 		return VM_FAULT_SIGBUS;
 	}

 	*pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);

 	return vmf_insert_pfn_pud(vmf->vma, vmf->address, vmf->pud, *pfn,
 			vmf->flags & FAULT_FLAG_WRITE);
 }
 #else
 static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
 				struct vm_fault *vmf, pfn_t *pfn)
 {
 	return VM_FAULT_FALLBACK;
 }
 #endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */

 static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf,
 		enum page_entry_size pe_size)
 {
 	struct file *filp = vmf->vma->vm_file;
 	unsigned long fault_size;
 	vm_fault_t rc = VM_FAULT_SIGBUS;
 	int id;
 	pfn_t pfn;
 	struct dev_dax *dev_dax = filp->private_data;

 	dev_dbg(&dev_dax->dev, "%s: %s (%#lx - %#lx) size = %d\n", current->comm,
 			(vmf->flags & FAULT_FLAG_WRITE) ? "write" : "read",
 			vmf->vma->vm_start, vmf->vma->vm_end, pe_size);

 	id = dax_read_lock();
 	switch (pe_size) {
 	case PE_SIZE_PTE:
 		fault_size = PAGE_SIZE;
 		rc = __dev_dax_pte_fault(dev_dax, vmf, &pfn);
 		break;
 	case PE_SIZE_PMD:
 		fault_size = PMD_SIZE;
 		rc = __dev_dax_pmd_fault(dev_dax, vmf, &pfn);
 		break;
 	case PE_SIZE_PUD:
 		fault_size = PUD_SIZE;
 		rc = __dev_dax_pud_fault(dev_dax, vmf, &pfn);
 		break;
 	default:
 		rc = VM_FAULT_SIGBUS;
 	}

 	if (rc == VM_FAULT_NOPAGE) {
 		unsigned long i;
 		pgoff_t pgoff;

 		/*
 		 * In the device-dax case the only possibility for a
 		 * VM_FAULT_NOPAGE result is when device-dax capacity is
 		 * mapped. No need to consider the zero page, or racing
 		 * conflicting mappings.
 		 */
 		pgoff = linear_page_index(vmf->vma, vmf->address
 				& ~(fault_size - 1));
 		for (i = 0; i < fault_size / PAGE_SIZE; i++) {
 			struct page *page;

 			page = pfn_to_page(pfn_t_to_pfn(pfn) + i);
 			if (page->mapping)
 				continue;
 			page->mapping = filp->f_mapping;
 			page->index = pgoff + i;
 		}
 	}
 	dax_read_unlock(id);

 	return rc;
 }

 static vm_fault_t dev_dax_fault(struct vm_fault *vmf)
 {
 	return dev_dax_huge_fault(vmf, PE_SIZE_PTE);
 }

 static int dev_dax_split(struct vm_area_struct *vma, unsigned long addr)
 {
 	struct file *filp = vma->vm_file;
 	struct dev_dax *dev_dax = filp->private_data;
 	struct dax_region *dax_region = dev_dax->region;

 	if (!IS_ALIGNED(addr, dax_region->align))
 		return -EINVAL;
 	return 0;
 }

 static unsigned long dev_dax_pagesize(struct vm_area_struct *vma)
 {
 	struct file *filp = vma->vm_file;
 	struct dev_dax *dev_dax = filp->private_data;
 	struct dax_region *dax_region = dev_dax->region;

 	return dax_region->align;
 }

 static const struct vm_operations_struct dax_vm_ops = {
 	.fault = dev_dax_fault,
 	.huge_fault = dev_dax_huge_fault,
 	.split = dev_dax_split,
 	.pagesize = dev_dax_pagesize,
 };

 static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
 {
 	struct dev_dax *dev_dax = filp->private_data;
 	int rc, id;

 	dev_dbg(&dev_dax->dev, "trace\n");

 	/*
 	 * We lock to check dax_dev liveness and will re-check at
 	 * fault time.
 	 */
 	id = dax_read_lock();
 	rc = check_vma(dev_dax, vma, __func__);
 	dax_read_unlock(id);
 	if (rc)
 		return rc;

 	vma->vm_ops = &dax_vm_ops;
 	vma->vm_flags |= VM_HUGEPAGE;
 	return 0;
 }

 /* return an unmapped area aligned to the dax region specified alignment */
 static unsigned long dax_get_unmapped_area(struct file *filp,
 		unsigned long addr, unsigned long len, unsigned long pgoff,
 		unsigned long flags)
 {
 	unsigned long off, off_end, off_align, len_align, addr_align, align;
 	struct dev_dax *dev_dax = filp ? filp->private_data : NULL;
 	struct dax_region *dax_region;

 	if (!dev_dax || addr)
 		goto out;

 	dax_region = dev_dax->region;
 	align = dax_region->align;
 	off = pgoff << PAGE_SHIFT;
 	off_end = off + len;
 	off_align = round_up(off, align);

 	if ((off_end <= off_align) || ((off_end - off_align) < align))
 		goto out;

 	len_align = len + align;
 	if ((off + len_align) < off)
 		goto out;

 	addr_align = current->mm->get_unmapped_area(filp, addr, len_align,
 			pgoff, flags);
 	if (!IS_ERR_VALUE(addr_align)) {
 		addr_align += (off - addr_align) & (align - 1);
 		return addr_align;
 	}
  out:
 	return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 }

 static int dax_open(struct inode *inode, struct file *filp)
 {
 	struct dax_device *dax_dev = inode_dax(inode);
 	struct inode *__dax_inode = dax_inode(dax_dev);
 	struct dev_dax *dev_dax = dax_get_private(dax_dev);

 	dev_dbg(&dev_dax->dev, "trace\n");
 	inode->i_mapping = __dax_inode->i_mapping;
 	inode->i_mapping->host = __dax_inode;
 	filp->f_mapping = inode->i_mapping;
 	filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
 	filp->private_data = dev_dax;
 	inode->i_flags = S_DAX;

 	return 0;
 }

 static int dax_release(struct inode *inode, struct file *filp)
 {
 	struct dev_dax *dev_dax = filp->private_data;

 	dev_dbg(&dev_dax->dev, "trace\n");
 	return 0;
 }

 static const struct file_operations dax_fops = {
 	.llseek = noop_llseek,
 	.owner = THIS_MODULE,
 	.open = dax_open,
 	.release = dax_release,
 	.get_unmapped_area = dax_get_unmapped_area,
 	.mmap = dax_mmap,
 	.mmap_supported_flags = MAP_SYNC,
 };

 static void dev_dax_release(struct device *dev)
 {
 	struct dev_dax *dev_dax = to_dev_dax(dev);
 	struct dax_region *dax_region = dev_dax->region;
 	struct dax_device *dax_dev = dev_dax->dax_dev;

 	if (dev_dax->id >= 0)
 		ida_simple_remove(&dax_region->ida, dev_dax->id);
 	dax_region_put(dax_region);
 	put_dax(dax_dev);
 	kfree(dev_dax);
 }

 static void kill_dev_dax(struct dev_dax *dev_dax)
 {
 	struct dax_device *dax_dev = dev_dax->dax_dev;
 	struct inode *inode = dax_inode(dax_dev);

 	kill_dax(dax_dev);
 	unmap_mapping_range(inode->i_mapping, 0, 0, 1);
 }

 static void unregister_dev_dax(void *dev)
 {
 	struct dev_dax *dev_dax = to_dev_dax(dev);
 	struct dax_device *dax_dev = dev_dax->dax_dev;
 	struct inode *inode = dax_inode(dax_dev);
 	struct cdev *cdev = inode->i_cdev;

 	dev_dbg(dev, "trace\n");

 	kill_dev_dax(dev_dax);
 	cdev_device_del(cdev, dev);
 	put_device(dev);
 }

 struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region,
 		int id, struct resource *res, int count)
 {
 	struct device *parent = dax_region->dev;
 	struct dax_device *dax_dev;
 	struct dev_dax *dev_dax;
 	struct inode *inode;
 	struct device *dev;
 	struct cdev *cdev;
 	int rc, i;

 	if (!count)
 		return ERR_PTR(-EINVAL);

 	dev_dax = kzalloc(struct_size(dev_dax, res, count), GFP_KERNEL);
 	if (!dev_dax)
 		return ERR_PTR(-ENOMEM);

 	for (i = 0; i < count; i++) {
 		if (!IS_ALIGNED(res[i].start, dax_region->align)
 				|| !IS_ALIGNED(resource_size(&res[i]),
 					dax_region->align)) {
 			rc = -EINVAL;
 			break;
 		}
 		dev_dax->res[i].start = res[i].start;
 		dev_dax->res[i].end = res[i].end;
 	}

 	if (i < count)
 		goto err_id;

 	if (id < 0) {
 		id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);
 		dev_dax->id = id;
 		if (id < 0) {
 			rc = id;
 			goto err_id;
 		}
 	} else {
 		/* region provider owns @id lifetime */
 		dev_dax->id = -1;
 	}

 	/*
 	 * No 'host' or dax_operations since there is no access to this
 	 * device outside of mmap of the resulting character device.
 	 */
 	dax_dev = alloc_dax(dev_dax, NULL, NULL);
 	if (!dax_dev) {
 		rc = -ENOMEM;
 		goto err_dax;
 	}

 	/* from here on we're committed to teardown via dax_dev_release() */
 	dev = &dev_dax->dev;
 	device_initialize(dev);

 	inode = dax_inode(dax_dev);
 	cdev = inode->i_cdev;
 	cdev_init(cdev, &dax_fops);
 	cdev->owner = parent->driver->owner;

 	dev_dax->num_resources = count;
 	dev_dax->dax_dev = dax_dev;
 	dev_dax->region = dax_region;
 	kref_get(&dax_region->kref);

 	dev->devt = inode->i_rdev;
 	dev->class = dax_class;
 	dev->parent = parent;
 	dev->groups = dax_attribute_groups;
 	dev->release = dev_dax_release;
 	dev_set_name(dev, "dax%d.%d", dax_region->id, id);

 	rc = cdev_device_add(cdev, dev);
 	if (rc) {
 		kill_dev_dax(dev_dax);
 		put_device(dev);
 		return ERR_PTR(rc);
 	}

 	rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
 	if (rc)
 		return ERR_PTR(rc);

 	return dev_dax;

  err_dax:
 	if (dev_dax->id >= 0)
 		ida_simple_remove(&dax_region->ida, dev_dax->id);
  err_id:
 	kfree(dev_dax);

 	return ERR_PTR(rc);
 }
 EXPORT_SYMBOL_GPL(devm_create_dev_dax);

 static int __init dax_init(void)
 {
 	dax_class = class_create(THIS_MODULE, "dax");
 	return PTR_ERR_OR_ZERO(dax_class);
 }

 static void __exit dax_exit(void)
 {
 	class_destroy(dax_class);
 }

 MODULE_AUTHOR("Intel Corporation");
 MODULE_LICENSE("GPL v2");
 subsys_initcall(dax_init);
 module_exit(dax_exit);
	/*
	* Copyright(c) 2016 - 2017 Intel Corporation. All rights reserved.
	*
	* 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.
	*/
	#include <linux/pagemap.h>
	#include <linux/module.h>
	#include <linux/device.h>
	#include <linux/pfn_t.h>
	#include <linux/cdev.h>
	#include <linux/slab.h>
	#include <linux/dax.h>
	#include <linux/fs.h>
	#include <linux/mm.h>
	#include <linux/mman.h>
	#include "dax-private.h"
	#include "dax.h"

	static struct class *dax_class;

	/*
	* Rely on the fact that drvdata is set before the attributes are
	* registered, and that the attributes are unregistered before drvdata
	* is cleared to assume that drvdata is always valid.
	*/
	static ssize_t id_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct dax_region *dax_region = dev_get_drvdata(dev);

	return sprintf(buf, "%d\n", dax_region->id);
	}
	static DEVICE_ATTR_RO(id);

	static ssize_t region_size_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct dax_region *dax_region = dev_get_drvdata(dev);

	return sprintf(buf, "%llu\n", (unsigned long long)
	resource_size(&dax_region->res));
	}
	static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
	region_size_show, NULL);

	static ssize_t align_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct dax_region *dax_region = dev_get_drvdata(dev);

	return sprintf(buf, "%u\n", dax_region->align);
	}
	static DEVICE_ATTR_RO(align);

	static struct attribute *dax_region_attributes[] = {
	&dev_attr_region_size.attr,
	&dev_attr_align.attr,
	&dev_attr_id.attr,
	NULL,
	};

	static const struct attribute_group dax_region_attribute_group = {
	.name = "dax_region",
	.attrs = dax_region_attributes,
	};

	static const struct attribute_group *dax_region_attribute_groups[] = {
	&dax_region_attribute_group,
	NULL,
	};

	static void dax_region_free(struct kref *kref)
	{
	struct dax_region *dax_region;

	dax_region = container_of(kref, struct dax_region, kref);
	kfree(dax_region);
	}

	void dax_region_put(struct dax_region *dax_region)
	{
	kref_put(&dax_region->kref, dax_region_free);
	}
	EXPORT_SYMBOL_GPL(dax_region_put);

	static void dax_region_unregister(void *region)
	{
	struct dax_region *dax_region = region;

	sysfs_remove_groups(&dax_region->dev->kobj,
	dax_region_attribute_groups);
	dax_region_put(dax_region);
	}

	struct dax_region alloc_dax_region(struct device parent, int region_id,
	struct resource res, unsigned int align, void addr,
	unsigned long pfn_flags)
	{
	struct dax_region *dax_region;

	/*
	* The DAX core assumes that it can store its private data in
	* parent->driver_data. This WARN is a reminder / safeguard for
	* developers of device-dax drivers.
	*/
	if (dev_get_drvdata(parent)) {
	dev_WARN(parent, "dax core failed to setup private data\n");
	return NULL;
	}

	if (!IS_ALIGNED(res->start, align)
	\|\| !IS_ALIGNED(resource_size(res), align))
	return NULL;

	dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
	if (!dax_region)
	return NULL;

	dev_set_drvdata(parent, dax_region);
	memcpy(&dax_region->res, res, sizeof(*res));
	dax_region->pfn_flags = pfn_flags;
	kref_init(&dax_region->kref);
	dax_region->id = region_id;
	ida_init(&dax_region->ida);
	dax_region->align = align;
	dax_region->dev = parent;
	dax_region->base = addr;
	if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
	kfree(dax_region);
	return NULL;
	}

	kref_get(&dax_region->kref);
	if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
	return NULL;
	return dax_region;
	}
	EXPORT_SYMBOL_GPL(alloc_dax_region);

	static struct dev_dax to_dev_dax(struct device dev)
	{
	return container_of(dev, struct dev_dax, dev);
	}

	static ssize_t size_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct dev_dax *dev_dax = to_dev_dax(dev);
	unsigned long long size = 0;
	int i;

	for (i = 0; i < dev_dax->num_resources; i++)
	size += resource_size(&dev_dax->res[i]);

	return sprintf(buf, "%llu\n", size);
	}
	static DEVICE_ATTR_RO(size);

	static struct attribute *dev_dax_attributes[] = {
	&dev_attr_size.attr,
	NULL,
	};

	static const struct attribute_group dev_dax_attribute_group = {
	.attrs = dev_dax_attributes,
	};

	static const struct attribute_group *dax_attribute_groups[] = {
	&dev_dax_attribute_group,
	NULL,
	};

	static int check_vma(struct dev_dax dev_dax, struct vm_area_struct vma,
	const char *func)
	{
	struct dax_region *dax_region = dev_dax->region;
	struct device *dev = &dev_dax->dev;
	unsigned long mask;

	if (!dax_alive(dev_dax->dax_dev))
	return -ENXIO;

	/* prevent private mappings from being established */
	if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
	dev_info_ratelimited(dev,
	"%s: %s: fail, attempted private mapping\n",
	current->comm, func);
	return -EINVAL;
	}

	mask = dax_region->align - 1;
	if (vma->vm_start & mask \|\| vma->vm_end & mask) {
	dev_info_ratelimited(dev,
	"%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n",
	current->comm, func, vma->vm_start, vma->vm_end,
	mask);
	return -EINVAL;
	}

	if ((dax_region->pfn_flags & (PFN_DEV\|PFN_MAP)) == PFN_DEV
	&& (vma->vm_flags & VM_DONTCOPY) == 0) {
	dev_info_ratelimited(dev,
	"%s: %s: fail, dax range requires MADV_DONTFORK\n",
	current->comm, func);
	return -EINVAL;
	}

	if (!vma_is_dax(vma)) {
	dev_info_ratelimited(dev,
	"%s: %s: fail, vma is not DAX capable\n",
	current->comm, func);
	return -EINVAL;
	}

	return 0;
	}

	/* see "strong" declaration in tools/testing/nvdimm/dax-dev.c */
	__weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
	unsigned long size)
	{
	struct resource *res;
	/* gcc-4.6.3-nolibc for i386 complains that this is uninitialized */
	phys_addr_t uninitialized_var(phys);
	int i;

	for (i = 0; i < dev_dax->num_resources; i++) {
	res = &dev_dax->res[i];
	phys = pgoff * PAGE_SIZE + res->start;
	if (phys >= res->start && phys <= res->end)
	break;
	pgoff -= PHYS_PFN(resource_size(res));
	}

	if (i < dev_dax->num_resources) {
	res = &dev_dax->res[i];
	if (phys + size - 1 <= res->end)
	return phys;
	}

	return -1;
	}

	static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax,
	struct vm_fault vmf, pfn_t pfn)
	{
	struct device *dev = &dev_dax->dev;
	struct dax_region *dax_region;
	phys_addr_t phys;
	unsigned int fault_size = PAGE_SIZE;

	if (check_vma(dev_dax, vmf->vma, __func__))
	return VM_FAULT_SIGBUS;

	dax_region = dev_dax->region;
	if (dax_region->align > PAGE_SIZE) {
	dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
	dax_region->align, fault_size);
	return VM_FAULT_SIGBUS;
	}

	if (fault_size != dax_region->align)
	return VM_FAULT_SIGBUS;

	phys = dax_pgoff_to_phys(dev_dax, vmf->pgoff, PAGE_SIZE);
	if (phys == -1) {
	dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", vmf->pgoff);
	return VM_FAULT_SIGBUS;
	}

	*pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);

	return vmf_insert_mixed(vmf->vma, vmf->address, *pfn);
	}

	static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax,
	struct vm_fault vmf, pfn_t pfn)
	{
	unsigned long pmd_addr = vmf->address & PMD_MASK;
	struct device *dev = &dev_dax->dev;
	struct dax_region *dax_region;
	phys_addr_t phys;
	pgoff_t pgoff;
	unsigned int fault_size = PMD_SIZE;

	if (check_vma(dev_dax, vmf->vma, __func__))
	return VM_FAULT_SIGBUS;

	dax_region = dev_dax->region;
	if (dax_region->align > PMD_SIZE) {
	dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
	dax_region->align, fault_size);
	return VM_FAULT_SIGBUS;
	}

	/* dax pmd mappings require pfn_t_devmap() */
	if ((dax_region->pfn_flags & (PFN_DEV\|PFN_MAP)) != (PFN_DEV\|PFN_MAP)) {
	dev_dbg(dev, "region lacks devmap flags\n");
	return VM_FAULT_SIGBUS;
	}

	if (fault_size < dax_region->align)
	return VM_FAULT_SIGBUS;
	else if (fault_size > dax_region->align)
	return VM_FAULT_FALLBACK;

	/* if we are outside of the VMA */
	if (pmd_addr < vmf->vma->vm_start \|\|
	(pmd_addr + PMD_SIZE) > vmf->vma->vm_end)
	return VM_FAULT_SIGBUS;

	pgoff = linear_page_index(vmf->vma, pmd_addr);
	phys = dax_pgoff_to_phys(dev_dax, pgoff, PMD_SIZE);
	if (phys == -1) {
	dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff);
	return VM_FAULT_SIGBUS;
	}

	*pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);

	return vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd, *pfn,
	vmf->flags & FAULT_FLAG_WRITE);
	}

	#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
	static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
	struct vm_fault vmf, pfn_t pfn)
	{
	unsigned long pud_addr = vmf->address & PUD_MASK;
	struct device *dev = &dev_dax->dev;
	struct dax_region *dax_region;
	phys_addr_t phys;
	pgoff_t pgoff;
	unsigned int fault_size = PUD_SIZE;


	if (check_vma(dev_dax, vmf->vma, __func__))
	return VM_FAULT_SIGBUS;

	dax_region = dev_dax->region;
	if (dax_region->align > PUD_SIZE) {
	dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
	dax_region->align, fault_size);
	return VM_FAULT_SIGBUS;
	}

	/* dax pud mappings require pfn_t_devmap() */
	if ((dax_region->pfn_flags & (PFN_DEV\|PFN_MAP)) != (PFN_DEV\|PFN_MAP)) {
	dev_dbg(dev, "region lacks devmap flags\n");
	return VM_FAULT_SIGBUS;
	}

	if (fault_size < dax_region->align)
	return VM_FAULT_SIGBUS;
	else if (fault_size > dax_region->align)
	return VM_FAULT_FALLBACK;

	/* if we are outside of the VMA */
	if (pud_addr < vmf->vma->vm_start \|\|
	(pud_addr + PUD_SIZE) > vmf->vma->vm_end)
	return VM_FAULT_SIGBUS;

	pgoff = linear_page_index(vmf->vma, pud_addr);
	phys = dax_pgoff_to_phys(dev_dax, pgoff, PUD_SIZE);
	if (phys == -1) {
	dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff);
	return VM_FAULT_SIGBUS;
	}

	*pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);

	return vmf_insert_pfn_pud(vmf->vma, vmf->address, vmf->pud, *pfn,
	vmf->flags & FAULT_FLAG_WRITE);
	}
	#else
	static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
	struct vm_fault vmf, pfn_t pfn)
	{
	return VM_FAULT_FALLBACK;
	}
	#endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */

	static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf,
	enum page_entry_size pe_size)
	{
	struct file *filp = vmf->vma->vm_file;
	unsigned long fault_size;
	vm_fault_t rc = VM_FAULT_SIGBUS;
	int id;
	pfn_t pfn;
	struct dev_dax *dev_dax = filp->private_data;

	dev_dbg(&dev_dax->dev, "%s: %s (%#lx - %#lx) size = %d\n", current->comm,
	(vmf->flags & FAULT_FLAG_WRITE) ? "write" : "read",
	vmf->vma->vm_start, vmf->vma->vm_end, pe_size);

	id = dax_read_lock();
	switch (pe_size) {
	case PE_SIZE_PTE:
	fault_size = PAGE_SIZE;
	rc = __dev_dax_pte_fault(dev_dax, vmf, &pfn);
	break;
	case PE_SIZE_PMD:
	fault_size = PMD_SIZE;
	rc = __dev_dax_pmd_fault(dev_dax, vmf, &pfn);
	break;
	case PE_SIZE_PUD:
	fault_size = PUD_SIZE;
	rc = __dev_dax_pud_fault(dev_dax, vmf, &pfn);
	break;
	default:
	rc = VM_FAULT_SIGBUS;
	}

	if (rc == VM_FAULT_NOPAGE) {
	unsigned long i;
	pgoff_t pgoff;

	/*
	* In the device-dax case the only possibility for a
	* VM_FAULT_NOPAGE result is when device-dax capacity is
	* mapped. No need to consider the zero page, or racing
	* conflicting mappings.
	*/
	pgoff = linear_page_index(vmf->vma, vmf->address
	& ~(fault_size - 1));
	for (i = 0; i < fault_size / PAGE_SIZE; i++) {
	struct page *page;

	page = pfn_to_page(pfn_t_to_pfn(pfn) + i);
	if (page->mapping)
	continue;
	page->mapping = filp->f_mapping;
	page->index = pgoff + i;
	}
	}
	dax_read_unlock(id);

	return rc;
	}

	static vm_fault_t dev_dax_fault(struct vm_fault *vmf)
	{
	return dev_dax_huge_fault(vmf, PE_SIZE_PTE);
	}

	static int dev_dax_split(struct vm_area_struct *vma, unsigned long addr)
	{
	struct file *filp = vma->vm_file;
	struct dev_dax *dev_dax = filp->private_data;
	struct dax_region *dax_region = dev_dax->region;

	if (!IS_ALIGNED(addr, dax_region->align))
	return -EINVAL;
	return 0;
	}

	static unsigned long dev_dax_pagesize(struct vm_area_struct *vma)
	{
	struct file *filp = vma->vm_file;
	struct dev_dax *dev_dax = filp->private_data;
	struct dax_region *dax_region = dev_dax->region;

	return dax_region->align;
	}

	static const struct vm_operations_struct dax_vm_ops = {
	.fault = dev_dax_fault,
	.huge_fault = dev_dax_huge_fault,
	.split = dev_dax_split,
	.pagesize = dev_dax_pagesize,
	};

	static int dax_mmap(struct file filp, struct vm_area_struct vma)
	{
	struct dev_dax *dev_dax = filp->private_data;
	int rc, id;

	dev_dbg(&dev_dax->dev, "trace\n");

	/*
	* We lock to check dax_dev liveness and will re-check at
	* fault time.
	*/
	id = dax_read_lock();
	rc = check_vma(dev_dax, vma, __func__);
	dax_read_unlock(id);
	if (rc)
	return rc;

	vma->vm_ops = &dax_vm_ops;
	vma->vm_flags \|= VM_HUGEPAGE;
	return 0;
	}

	/* return an unmapped area aligned to the dax region specified alignment */
	static unsigned long dax_get_unmapped_area(struct file *filp,
	unsigned long addr, unsigned long len, unsigned long pgoff,
	unsigned long flags)
	{
	unsigned long off, off_end, off_align, len_align, addr_align, align;
	struct dev_dax *dev_dax = filp ? filp->private_data : NULL;
	struct dax_region *dax_region;

	if (!dev_dax \|\| addr)
	goto out;

	dax_region = dev_dax->region;
	align = dax_region->align;
	off = pgoff << PAGE_SHIFT;
	off_end = off + len;
	off_align = round_up(off, align);

	if ((off_end <= off_align) \|\| ((off_end - off_align) < align))
	goto out;

	len_align = len + align;
	if ((off + len_align) < off)
	goto out;

	addr_align = current->mm->get_unmapped_area(filp, addr, len_align,
	pgoff, flags);
	if (!IS_ERR_VALUE(addr_align)) {
	addr_align += (off - addr_align) & (align - 1);
	return addr_align;
	}
	out:
	return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
	}

	static int dax_open(struct inode inode, struct file filp)
	{
	struct dax_device *dax_dev = inode_dax(inode);
	struct inode *__dax_inode = dax_inode(dax_dev);
	struct dev_dax *dev_dax = dax_get_private(dax_dev);

	dev_dbg(&dev_dax->dev, "trace\n");
	inode->i_mapping = __dax_inode->i_mapping;
	inode->i_mapping->host = __dax_inode;
	filp->f_mapping = inode->i_mapping;
	filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
	filp->private_data = dev_dax;
	inode->i_flags = S_DAX;

	return 0;
	}

	static int dax_release(struct inode inode, struct file filp)
	{
	struct dev_dax *dev_dax = filp->private_data;

	dev_dbg(&dev_dax->dev, "trace\n");
	return 0;
	}

	static const struct file_operations dax_fops = {
	.llseek = noop_llseek,
	.owner = THIS_MODULE,
	.open = dax_open,
	.release = dax_release,
	.get_unmapped_area = dax_get_unmapped_area,
	.mmap = dax_mmap,
	.mmap_supported_flags = MAP_SYNC,
	};

	static void dev_dax_release(struct device *dev)
	{
	struct dev_dax *dev_dax = to_dev_dax(dev);
	struct dax_region *dax_region = dev_dax->region;
	struct dax_device *dax_dev = dev_dax->dax_dev;

	if (dev_dax->id >= 0)
	ida_simple_remove(&dax_region->ida, dev_dax->id);
	dax_region_put(dax_region);
	put_dax(dax_dev);
	kfree(dev_dax);
	}

	static void kill_dev_dax(struct dev_dax *dev_dax)
	{
	struct dax_device *dax_dev = dev_dax->dax_dev;
	struct inode *inode = dax_inode(dax_dev);

	kill_dax(dax_dev);
	unmap_mapping_range(inode->i_mapping, 0, 0, 1);
	}

	static void unregister_dev_dax(void *dev)
	{
	struct dev_dax *dev_dax = to_dev_dax(dev);
	struct dax_device *dax_dev = dev_dax->dax_dev;
	struct inode *inode = dax_inode(dax_dev);
	struct cdev *cdev = inode->i_cdev;

	dev_dbg(dev, "trace\n");

	kill_dev_dax(dev_dax);
	cdev_device_del(cdev, dev);
	put_device(dev);
	}

	struct dev_dax devm_create_dev_dax(struct dax_region dax_region,
	int id, struct resource *res, int count)
	{
	struct device *parent = dax_region->dev;
	struct dax_device *dax_dev;
	struct dev_dax *dev_dax;
	struct inode *inode;
	struct device *dev;
	struct cdev *cdev;
	int rc, i;

	if (!count)
	return ERR_PTR(-EINVAL);

	dev_dax = kzalloc(struct_size(dev_dax, res, count), GFP_KERNEL);
	if (!dev_dax)
	return ERR_PTR(-ENOMEM);

	for (i = 0; i < count; i++) {
	if (!IS_ALIGNED(res[i].start, dax_region->align)
	\|\| !IS_ALIGNED(resource_size(&res[i]),
	dax_region->align)) {
	rc = -EINVAL;
	break;
	}
	dev_dax->res[i].start = res[i].start;
	dev_dax->res[i].end = res[i].end;
	}

	if (i < count)
	goto err_id;

	if (id < 0) {
	id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);
	dev_dax->id = id;
	if (id < 0) {
	rc = id;
	goto err_id;
	}
	} else {
	/* region provider owns @id lifetime */
	dev_dax->id = -1;
	}

	/*
	* No 'host' or dax_operations since there is no access to this
	* device outside of mmap of the resulting character device.
	*/
	dax_dev = alloc_dax(dev_dax, NULL, NULL);
	if (!dax_dev) {
	rc = -ENOMEM;
	goto err_dax;
	}

	/* from here on we're committed to teardown via dax_dev_release() */
	dev = &dev_dax->dev;
	device_initialize(dev);

	inode = dax_inode(dax_dev);
	cdev = inode->i_cdev;
	cdev_init(cdev, &dax_fops);
	cdev->owner = parent->driver->owner;

	dev_dax->num_resources = count;
	dev_dax->dax_dev = dax_dev;
	dev_dax->region = dax_region;
	kref_get(&dax_region->kref);

	dev->devt = inode->i_rdev;
	dev->class = dax_class;
	dev->parent = parent;
	dev->groups = dax_attribute_groups;
	dev->release = dev_dax_release;
	dev_set_name(dev, "dax%d.%d", dax_region->id, id);

	rc = cdev_device_add(cdev, dev);
	if (rc) {
	kill_dev_dax(dev_dax);
	put_device(dev);
	return ERR_PTR(rc);
	}

	rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
	if (rc)
	return ERR_PTR(rc);

	return dev_dax;

	err_dax:
	if (dev_dax->id >= 0)
	ida_simple_remove(&dax_region->ida, dev_dax->id);
	err_id:
	kfree(dev_dax);

	return ERR_PTR(rc);
	}
	EXPORT_SYMBOL_GPL(devm_create_dev_dax);

	static int __init dax_init(void)
	{
	dax_class = class_create(THIS_MODULE, "dax");
	return PTR_ERR_OR_ZERO(dax_class);
	}

	static void __exit dax_exit(void)
	{
	class_destroy(dax_class);
	}

	MODULE_AUTHOR("Intel Corporation");
	MODULE_LICENSE("GPL v2");
	subsys_initcall(dax_init);
	module_exit(dax_exit);