1 files changed, 481 insertions, 0 deletions

diff --git a/drivers/dax/device.c b/drivers/dax/device.c
new file mode 100644
index 000000000..25e0b84a4
--- /dev/null
+++ b/drivers/dax/device.c
@@ -0,0 +1,481 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright(c) 2016-2018 Intel Corporation. All rights reserved. */
+#include <linux/memremap.h>
+#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 "bus.h"
+
+static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
+		const char *func)
+{
+	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 = dev_dax->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 (!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)
+{
+	int i;
+
+	for (i = 0; i < dev_dax->nr_range; i++) {
+		struct dev_dax_range *dax_range = &dev_dax->ranges[i];
+		struct range *range = &dax_range->range;
+		unsigned long long pgoff_end;
+		phys_addr_t phys;
+
+		pgoff_end = dax_range->pgoff + PHYS_PFN(range_len(range)) - 1;
+		if (pgoff < dax_range->pgoff || pgoff > pgoff_end)
+			continue;
+		phys = PFN_PHYS(pgoff - dax_range->pgoff) + range->start;
+		if (phys + size - 1 <= range->end)
+			return phys;
+		break;
+	}
+	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;
+	phys_addr_t phys;
+	unsigned int fault_size = PAGE_SIZE;
+
+	if (check_vma(dev_dax, vmf->vma, __func__))
+		return VM_FAULT_SIGBUS;
+
+	if (dev_dax->align > PAGE_SIZE) {
+		dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
+			dev_dax->align, fault_size);
+		return VM_FAULT_SIGBUS;
+	}
+
+	if (fault_size != dev_dax->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, PFN_DEV|PFN_MAP);
+
+	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;
+	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;
+
+	if (dev_dax->align > PMD_SIZE) {
+		dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
+			dev_dax->align, fault_size);
+		return VM_FAULT_SIGBUS;
+	}
+
+	if (fault_size < dev_dax->align)
+		return VM_FAULT_SIGBUS;
+	else if (fault_size > dev_dax->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, PFN_DEV|PFN_MAP);
+
+	return vmf_insert_pfn_pmd(vmf, *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;
+	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;
+
+	if (dev_dax->align > PUD_SIZE) {
+		dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
+			dev_dax->align, fault_size);
+		return VM_FAULT_SIGBUS;
+	}
+
+	if (fault_size < dev_dax->align)
+		return VM_FAULT_SIGBUS;
+	else if (fault_size > dev_dax->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, PFN_DEV|PFN_MAP);
+
+	return vmf_insert_pfn_pud(vmf, *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;
+
+	if (!IS_ALIGNED(addr, dev_dax->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;
+
+	return dev_dax->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;
+
+	if (!dev_dax || addr)
+		goto out;
+
+	align = dev_dax->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 const struct address_space_operations dev_dax_aops = {
+	.set_page_dirty		= noop_set_page_dirty,
+	.invalidatepage		= noop_invalidatepage,
+};
+
+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;
+	inode->i_mapping->a_ops = &dev_dax_aops;
+	filp->f_mapping = inode->i_mapping;
+	filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
+	filp->f_sb_err = file_sample_sb_err(filp);
+	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_cdev_del(void *cdev)
+{
+	cdev_del(cdev);
+}
+
+static void dev_dax_kill(void *dev_dax)
+{
+	kill_dev_dax(dev_dax);
+}
+
+int dev_dax_probe(struct dev_dax *dev_dax)
+{
+	struct dax_device *dax_dev = dev_dax->dax_dev;
+	struct device *dev = &dev_dax->dev;
+	struct dev_pagemap *pgmap;
+	struct inode *inode;
+	struct cdev *cdev;
+	void *addr;
+	int rc, i;
+
+	pgmap = dev_dax->pgmap;
+	if (dev_WARN_ONCE(dev, pgmap && dev_dax->nr_range > 1,
+			"static pgmap / multi-range device conflict\n"))
+		return -EINVAL;
+
+	if (!pgmap) {
+		pgmap = devm_kzalloc(dev, sizeof(*pgmap) + sizeof(struct range)
+				* (dev_dax->nr_range - 1), GFP_KERNEL);
+		if (!pgmap)
+			return -ENOMEM;
+		pgmap->nr_range = dev_dax->nr_range;
+	}
+
+	for (i = 0; i < dev_dax->nr_range; i++) {
+		struct range *range = &dev_dax->ranges[i].range;
+
+		if (!devm_request_mem_region(dev, range->start,
+					range_len(range), dev_name(dev))) {
+			dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve range\n",
+					i, range->start, range->end);
+			return -EBUSY;
+		}
+		/* don't update the range for static pgmap */
+		if (!dev_dax->pgmap)
+			pgmap->ranges[i] = *range;
+	}
+
+	pgmap->type = MEMORY_DEVICE_GENERIC;
+	addr = devm_memremap_pages(dev, pgmap);
+	if (IS_ERR(addr))
+		return PTR_ERR(addr);
+
+	inode = dax_inode(dax_dev);
+	cdev = inode->i_cdev;
+	cdev_init(cdev, &dax_fops);
+	if (dev->class) {
+		/* for the CONFIG_DEV_DAX_PMEM_COMPAT case */
+		cdev->owner = dev->parent->driver->owner;
+	} else
+		cdev->owner = dev->driver->owner;
+	cdev_set_parent(cdev, &dev->kobj);
+	rc = cdev_add(cdev, dev->devt, 1);
+	if (rc)
+		return rc;
+
+	rc = devm_add_action_or_reset(dev, dev_dax_cdev_del, cdev);
+	if (rc)
+		return rc;
+
+	run_dax(dax_dev);
+	return devm_add_action_or_reset(dev, dev_dax_kill, dev_dax);
+}
+EXPORT_SYMBOL_GPL(dev_dax_probe);
+
+static int dev_dax_remove(struct dev_dax *dev_dax)
+{
+	/* all probe actions are unwound by devm */
+	return 0;
+}
+
+static struct dax_device_driver device_dax_driver = {
+	.probe = dev_dax_probe,
+	.remove = dev_dax_remove,
+	.match_always = 1,
+};
+
+static int __init dax_init(void)
+{
+	return dax_driver_register(&device_dax_driver);
+}
+
+static void __exit dax_exit(void)
+{
+	dax_driver_unregister(&device_dax_driver);
+}
+
+MODULE_AUTHOR("Intel Corporation");
+MODULE_LICENSE("GPL v2");
+module_init(dax_init);
+module_exit(dax_exit);
+MODULE_ALIAS_DAX_DEVICE(0);