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-rw-r--r--drivers/dax/dax.c575
1 files changed, 575 insertions, 0 deletions
diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
new file mode 100644
index 000000000000..b891a129b275
--- /dev/null
+++ b/drivers/dax/dax.c
@@ -0,0 +1,575 @@
+/*
+ * Copyright(c) 2016 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/slab.h>
+#include <linux/dax.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+
+static int dax_major;
+static struct class *dax_class;
+static DEFINE_IDA(dax_minor_ida);
+
+/**
+ * struct dax_region - mapping infrastructure for dax devices
+ * @id: kernel-wide unique region for a memory range
+ * @base: linear address corresponding to @res
+ * @kref: to pin while other agents have a need to do lookups
+ * @dev: parent device backing this region
+ * @align: allocation and mapping alignment for child dax devices
+ * @res: physical address range of the region
+ * @pfn_flags: identify whether the pfns are paged back or not
+ */
+struct dax_region {
+ int id;
+ struct ida ida;
+ void *base;
+ struct kref kref;
+ struct device *dev;
+ unsigned int align;
+ struct resource res;
+ unsigned long pfn_flags;
+};
+
+/**
+ * struct dax_dev - subdivision of a dax region
+ * @region - parent region
+ * @dev - device backing the character device
+ * @kref - enable this data to be tracked in filp->private_data
+ * @alive - !alive + rcu grace period == no new mappings can be established
+ * @id - child id in the region
+ * @num_resources - number of physical address extents in this device
+ * @res - array of physical address ranges
+ */
+struct dax_dev {
+ struct dax_region *region;
+ struct device *dev;
+ struct kref kref;
+ bool alive;
+ int id;
+ int num_resources;
+ struct resource res[0];
+};
+
+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_dev_free(struct kref *kref)
+{
+ struct dax_dev *dax_dev;
+
+ dax_dev = container_of(kref, struct dax_dev, kref);
+ dax_region_put(dax_dev->region);
+ kfree(dax_dev);
+}
+
+static void dax_dev_put(struct dax_dev *dax_dev)
+{
+ kref_put(&dax_dev->kref, dax_dev_free);
+}
+
+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;
+
+ dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
+
+ if (!dax_region)
+ return NULL;
+
+ 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;
+
+ return dax_region;
+}
+EXPORT_SYMBOL_GPL(alloc_dax_region);
+
+static ssize_t size_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct dax_dev *dax_dev = dev_get_drvdata(dev);
+ unsigned long long size = 0;
+ int i;
+
+ for (i = 0; i < dax_dev->num_resources; i++)
+ size += resource_size(&dax_dev->res[i]);
+
+ return sprintf(buf, "%llu\n", size);
+}
+static DEVICE_ATTR_RO(size);
+
+static struct attribute *dax_device_attributes[] = {
+ &dev_attr_size.attr,
+ NULL,
+};
+
+static const struct attribute_group dax_device_attribute_group = {
+ .attrs = dax_device_attributes,
+};
+
+static const struct attribute_group *dax_attribute_groups[] = {
+ &dax_device_attribute_group,
+ NULL,
+};
+
+static void unregister_dax_dev(void *_dev)
+{
+ struct device *dev = _dev;
+ struct dax_dev *dax_dev = dev_get_drvdata(dev);
+ struct dax_region *dax_region = dax_dev->region;
+
+ dev_dbg(dev, "%s\n", __func__);
+
+ /*
+ * Note, rcu is not protecting the liveness of dax_dev, rcu is
+ * ensuring that any fault handlers that might have seen
+ * dax_dev->alive == true, have completed. Any fault handlers
+ * that start after synchronize_rcu() has started will abort
+ * upon seeing dax_dev->alive == false.
+ */
+ dax_dev->alive = false;
+ synchronize_rcu();
+
+ get_device(dev);
+ device_unregister(dev);
+ ida_simple_remove(&dax_region->ida, dax_dev->id);
+ ida_simple_remove(&dax_minor_ida, MINOR(dev->devt));
+ put_device(dev);
+ dax_dev_put(dax_dev);
+}
+
+int devm_create_dax_dev(struct dax_region *dax_region, struct resource *res,
+ int count)
+{
+ struct device *parent = dax_region->dev;
+ struct dax_dev *dax_dev;
+ struct device *dev;
+ int rc, minor;
+ dev_t dev_t;
+
+ dax_dev = kzalloc(sizeof(*dax_dev) + sizeof(*res) * count, GFP_KERNEL);
+ if (!dax_dev)
+ return -ENOMEM;
+ memcpy(dax_dev->res, res, sizeof(*res) * count);
+ dax_dev->num_resources = count;
+ kref_init(&dax_dev->kref);
+ dax_dev->alive = true;
+ dax_dev->region = dax_region;
+ kref_get(&dax_region->kref);
+
+ dax_dev->id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);
+ if (dax_dev->id < 0) {
+ rc = dax_dev->id;
+ goto err_id;
+ }
+
+ minor = ida_simple_get(&dax_minor_ida, 0, 0, GFP_KERNEL);
+ if (minor < 0) {
+ rc = minor;
+ goto err_minor;
+ }
+
+ dev_t = MKDEV(dax_major, minor);
+ dev = device_create_with_groups(dax_class, parent, dev_t, dax_dev,
+ dax_attribute_groups, "dax%d.%d", dax_region->id,
+ dax_dev->id);
+ if (IS_ERR(dev)) {
+ rc = PTR_ERR(dev);
+ goto err_create;
+ }
+ dax_dev->dev = dev;
+
+ rc = devm_add_action(dax_region->dev, unregister_dax_dev, dev);
+ if (rc) {
+ unregister_dax_dev(dev);
+ return rc;
+ }
+
+ return 0;
+
+ err_create:
+ ida_simple_remove(&dax_minor_ida, minor);
+ err_minor:
+ ida_simple_remove(&dax_region->ida, dax_dev->id);
+ err_id:
+ dax_dev_put(dax_dev);
+
+ return rc;
+}
+EXPORT_SYMBOL_GPL(devm_create_dax_dev);
+
+/* return an unmapped area aligned to the dax region specified alignment */
+static unsigned long dax_dev_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 dax_dev *dax_dev = filp ? filp->private_data : NULL;
+ struct dax_region *dax_region;
+
+ if (!dax_dev || addr)
+ goto out;
+
+ dax_region = dax_dev->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 __match_devt(struct device *dev, const void *data)
+{
+ const dev_t *devt = data;
+
+ return dev->devt == *devt;
+}
+
+static struct device *dax_dev_find(dev_t dev_t)
+{
+ return class_find_device(dax_class, NULL, &dev_t, __match_devt);
+}
+
+static int dax_dev_open(struct inode *inode, struct file *filp)
+{
+ struct dax_dev *dax_dev = NULL;
+ struct device *dev;
+
+ dev = dax_dev_find(inode->i_rdev);
+ if (!dev)
+ return -ENXIO;
+
+ device_lock(dev);
+ dax_dev = dev_get_drvdata(dev);
+ if (dax_dev) {
+ dev_dbg(dev, "%s\n", __func__);
+ filp->private_data = dax_dev;
+ kref_get(&dax_dev->kref);
+ inode->i_flags = S_DAX;
+ }
+ device_unlock(dev);
+
+ if (!dax_dev) {
+ put_device(dev);
+ return -ENXIO;
+ }
+ return 0;
+}
+
+static int dax_dev_release(struct inode *inode, struct file *filp)
+{
+ struct dax_dev *dax_dev = filp->private_data;
+ struct device *dev = dax_dev->dev;
+
+ dev_dbg(dax_dev->dev, "%s\n", __func__);
+ dax_dev_put(dax_dev);
+ put_device(dev);
+
+ return 0;
+}
+
+static int check_vma(struct dax_dev *dax_dev, struct vm_area_struct *vma,
+ const char *func)
+{
+ struct dax_region *dax_region = dax_dev->region;
+ struct device *dev = dax_dev->dev;
+ unsigned long mask;
+
+ if (!dax_dev->alive)
+ return -ENXIO;
+
+ /* prevent private / writable mappings from being established */
+ if ((vma->vm_flags & (VM_NORESERVE|VM_SHARED|VM_WRITE)) == VM_WRITE) {
+ dev_info(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(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(dev, "%s: %s: fail, dax range requires MADV_DONTFORK\n",
+ current->comm, func);
+ return -EINVAL;
+ }
+
+ if (!vma_is_dax(vma)) {
+ dev_info(dev, "%s: %s: fail, vma is not DAX capable\n",
+ current->comm, func);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static phys_addr_t pgoff_to_phys(struct dax_dev *dax_dev, pgoff_t pgoff,
+ unsigned long size)
+{
+ struct resource *res;
+ phys_addr_t phys;
+ int i;
+
+ for (i = 0; i < dax_dev->num_resources; i++) {
+ res = &dax_dev->res[i];
+ phys = pgoff * PAGE_SIZE + res->start;
+ if (phys >= res->start && phys <= res->end)
+ break;
+ pgoff -= PHYS_PFN(resource_size(res));
+ }
+
+ if (i < dax_dev->num_resources) {
+ res = &dax_dev->res[i];
+ if (phys + size - 1 <= res->end)
+ return phys;
+ }
+
+ return -1;
+}
+
+static int __dax_dev_fault(struct dax_dev *dax_dev, struct vm_area_struct *vma,
+ struct vm_fault *vmf)
+{
+ unsigned long vaddr = (unsigned long) vmf->virtual_address;
+ struct device *dev = dax_dev->dev;
+ struct dax_region *dax_region;
+ int rc = VM_FAULT_SIGBUS;
+ phys_addr_t phys;
+ pfn_t pfn;
+
+ if (check_vma(dax_dev, vma, __func__))
+ return VM_FAULT_SIGBUS;
+
+ dax_region = dax_dev->region;
+ if (dax_region->align > PAGE_SIZE) {
+ dev_dbg(dev, "%s: alignment > fault size\n", __func__);
+ return VM_FAULT_SIGBUS;
+ }
+
+ phys = pgoff_to_phys(dax_dev, vmf->pgoff, PAGE_SIZE);
+ if (phys == -1) {
+ dev_dbg(dev, "%s: phys_to_pgoff(%#lx) failed\n", __func__,
+ vmf->pgoff);
+ return VM_FAULT_SIGBUS;
+ }
+
+ pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
+
+ rc = vm_insert_mixed(vma, vaddr, pfn);
+
+ if (rc == -ENOMEM)
+ return VM_FAULT_OOM;
+ if (rc < 0 && rc != -EBUSY)
+ return VM_FAULT_SIGBUS;
+
+ return VM_FAULT_NOPAGE;
+}
+
+static int dax_dev_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ int rc;
+ struct file *filp = vma->vm_file;
+ struct dax_dev *dax_dev = filp->private_data;
+
+ dev_dbg(dax_dev->dev, "%s: %s: %s (%#lx - %#lx)\n", __func__,
+ current->comm, (vmf->flags & FAULT_FLAG_WRITE)
+ ? "write" : "read", vma->vm_start, vma->vm_end);
+ rcu_read_lock();
+ rc = __dax_dev_fault(dax_dev, vma, vmf);
+ rcu_read_unlock();
+
+ return rc;
+}
+
+static int __dax_dev_pmd_fault(struct dax_dev *dax_dev,
+ struct vm_area_struct *vma, unsigned long addr, pmd_t *pmd,
+ unsigned int flags)
+{
+ unsigned long pmd_addr = addr & PMD_MASK;
+ struct device *dev = dax_dev->dev;
+ struct dax_region *dax_region;
+ phys_addr_t phys;
+ pgoff_t pgoff;
+ pfn_t pfn;
+
+ if (check_vma(dax_dev, vma, __func__))
+ return VM_FAULT_SIGBUS;
+
+ dax_region = dax_dev->region;
+ if (dax_region->align > PMD_SIZE) {
+ dev_dbg(dev, "%s: alignment > fault size\n", __func__);
+ 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, "%s: alignment > fault size\n", __func__);
+ return VM_FAULT_SIGBUS;
+ }
+
+ pgoff = linear_page_index(vma, pmd_addr);
+ phys = pgoff_to_phys(dax_dev, pgoff, PAGE_SIZE);
+ if (phys == -1) {
+ dev_dbg(dev, "%s: phys_to_pgoff(%#lx) failed\n", __func__,
+ pgoff);
+ return VM_FAULT_SIGBUS;
+ }
+
+ pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
+
+ return vmf_insert_pfn_pmd(vma, addr, pmd, pfn,
+ flags & FAULT_FLAG_WRITE);
+}
+
+static int dax_dev_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
+ pmd_t *pmd, unsigned int flags)
+{
+ int rc;
+ struct file *filp = vma->vm_file;
+ struct dax_dev *dax_dev = filp->private_data;
+
+ dev_dbg(dax_dev->dev, "%s: %s: %s (%#lx - %#lx)\n", __func__,
+ current->comm, (flags & FAULT_FLAG_WRITE)
+ ? "write" : "read", vma->vm_start, vma->vm_end);
+
+ rcu_read_lock();
+ rc = __dax_dev_pmd_fault(dax_dev, vma, addr, pmd, flags);
+ rcu_read_unlock();
+
+ return rc;
+}
+
+static void dax_dev_vm_open(struct vm_area_struct *vma)
+{
+ struct file *filp = vma->vm_file;
+ struct dax_dev *dax_dev = filp->private_data;
+
+ dev_dbg(dax_dev->dev, "%s\n", __func__);
+ kref_get(&dax_dev->kref);
+}
+
+static void dax_dev_vm_close(struct vm_area_struct *vma)
+{
+ struct file *filp = vma->vm_file;
+ struct dax_dev *dax_dev = filp->private_data;
+
+ dev_dbg(dax_dev->dev, "%s\n", __func__);
+ dax_dev_put(dax_dev);
+}
+
+static const struct vm_operations_struct dax_dev_vm_ops = {
+ .fault = dax_dev_fault,
+ .pmd_fault = dax_dev_pmd_fault,
+ .open = dax_dev_vm_open,
+ .close = dax_dev_vm_close,
+};
+
+static int dax_dev_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+ struct dax_dev *dax_dev = filp->private_data;
+ int rc;
+
+ dev_dbg(dax_dev->dev, "%s\n", __func__);
+
+ rc = check_vma(dax_dev, vma, __func__);
+ if (rc)
+ return rc;
+
+ kref_get(&dax_dev->kref);
+ vma->vm_ops = &dax_dev_vm_ops;
+ vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
+ return 0;
+
+}
+
+static const struct file_operations dax_fops = {
+ .llseek = noop_llseek,
+ .owner = THIS_MODULE,
+ .open = dax_dev_open,
+ .release = dax_dev_release,
+ .get_unmapped_area = dax_dev_get_unmapped_area,
+ .mmap = dax_dev_mmap,
+};
+
+static int __init dax_init(void)
+{
+ int rc;
+
+ rc = register_chrdev(0, "dax", &dax_fops);
+ if (rc < 0)
+ return rc;
+ dax_major = rc;
+
+ dax_class = class_create(THIS_MODULE, "dax");
+ if (IS_ERR(dax_class)) {
+ unregister_chrdev(dax_major, "dax");
+ return PTR_ERR(dax_class);
+ }
+
+ return 0;
+}
+
+static void __exit dax_exit(void)
+{
+ class_destroy(dax_class);
+ unregister_chrdev(dax_major, "dax");
+ ida_destroy(&dax_minor_ida);
+}
+
+MODULE_AUTHOR("Intel Corporation");
+MODULE_LICENSE("GPL v2");
+subsys_initcall(dax_init);
+module_exit(dax_exit);