/* * 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);