linux/drivers/dax/device.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/* Copyright(c) 2016-2018 Intel Corporation. All rights reserved. */
   3#include <linux/memremap.h>
   4#include <linux/pagemap.h>
   5#include <linux/module.h>
   6#include <linux/device.h>
   7#include <linux/pfn_t.h>
   8#include <linux/cdev.h>
   9#include <linux/slab.h>
  10#include <linux/dax.h>
  11#include <linux/fs.h>
  12#include <linux/mm.h>
  13#include <linux/mman.h>
  14#include "dax-private.h"
  15#include "bus.h"
  16
  17static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
  18                const char *func)
  19{
  20        struct device *dev = &dev_dax->dev;
  21        unsigned long mask;
  22
  23        if (!dax_alive(dev_dax->dax_dev))
  24                return -ENXIO;
  25
  26        /* prevent private mappings from being established */
  27        if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
  28                dev_info_ratelimited(dev,
  29                                "%s: %s: fail, attempted private mapping\n",
  30                                current->comm, func);
  31                return -EINVAL;
  32        }
  33
  34        mask = dev_dax->align - 1;
  35        if (vma->vm_start & mask || vma->vm_end & mask) {
  36                dev_info_ratelimited(dev,
  37                                "%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n",
  38                                current->comm, func, vma->vm_start, vma->vm_end,
  39                                mask);
  40                return -EINVAL;
  41        }
  42
  43        if (!vma_is_dax(vma)) {
  44                dev_info_ratelimited(dev,
  45                                "%s: %s: fail, vma is not DAX capable\n",
  46                                current->comm, func);
  47                return -EINVAL;
  48        }
  49
  50        return 0;
  51}
  52
  53/* see "strong" declaration in tools/testing/nvdimm/dax-dev.c */
  54__weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
  55                unsigned long size)
  56{
  57        int i;
  58
  59        for (i = 0; i < dev_dax->nr_range; i++) {
  60                struct dev_dax_range *dax_range = &dev_dax->ranges[i];
  61                struct range *range = &dax_range->range;
  62                unsigned long long pgoff_end;
  63                phys_addr_t phys;
  64
  65                pgoff_end = dax_range->pgoff + PHYS_PFN(range_len(range)) - 1;
  66                if (pgoff < dax_range->pgoff || pgoff > pgoff_end)
  67                        continue;
  68                phys = PFN_PHYS(pgoff - dax_range->pgoff) + range->start;
  69                if (phys + size - 1 <= range->end)
  70                        return phys;
  71                break;
  72        }
  73        return -1;
  74}
  75
  76static vm_fault_t __dev_dax_pte_fault(struct dev_dax *dev_dax,
  77                                struct vm_fault *vmf, pfn_t *pfn)
  78{
  79        struct device *dev = &dev_dax->dev;
  80        phys_addr_t phys;
  81        unsigned int fault_size = PAGE_SIZE;
  82
  83        if (check_vma(dev_dax, vmf->vma, __func__))
  84                return VM_FAULT_SIGBUS;
  85
  86        if (dev_dax->align > PAGE_SIZE) {
  87                dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
  88                        dev_dax->align, fault_size);
  89                return VM_FAULT_SIGBUS;
  90        }
  91
  92        if (fault_size != dev_dax->align)
  93                return VM_FAULT_SIGBUS;
  94
  95        phys = dax_pgoff_to_phys(dev_dax, vmf->pgoff, PAGE_SIZE);
  96        if (phys == -1) {
  97                dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", vmf->pgoff);
  98                return VM_FAULT_SIGBUS;
  99        }
 100
 101        *pfn = phys_to_pfn_t(phys, PFN_DEV|PFN_MAP);
 102
 103        return vmf_insert_mixed(vmf->vma, vmf->address, *pfn);
 104}
 105
 106static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax,
 107                                struct vm_fault *vmf, pfn_t *pfn)
 108{
 109        unsigned long pmd_addr = vmf->address & PMD_MASK;
 110        struct device *dev = &dev_dax->dev;
 111        phys_addr_t phys;
 112        pgoff_t pgoff;
 113        unsigned int fault_size = PMD_SIZE;
 114
 115        if (check_vma(dev_dax, vmf->vma, __func__))
 116                return VM_FAULT_SIGBUS;
 117
 118        if (dev_dax->align > PMD_SIZE) {
 119                dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
 120                        dev_dax->align, fault_size);
 121                return VM_FAULT_SIGBUS;
 122        }
 123
 124        if (fault_size < dev_dax->align)
 125                return VM_FAULT_SIGBUS;
 126        else if (fault_size > dev_dax->align)
 127                return VM_FAULT_FALLBACK;
 128
 129        /* if we are outside of the VMA */
 130        if (pmd_addr < vmf->vma->vm_start ||
 131                        (pmd_addr + PMD_SIZE) > vmf->vma->vm_end)
 132                return VM_FAULT_SIGBUS;
 133
 134        pgoff = linear_page_index(vmf->vma, pmd_addr);
 135        phys = dax_pgoff_to_phys(dev_dax, pgoff, PMD_SIZE);
 136        if (phys == -1) {
 137                dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff);
 138                return VM_FAULT_SIGBUS;
 139        }
 140
 141        *pfn = phys_to_pfn_t(phys, PFN_DEV|PFN_MAP);
 142
 143        return vmf_insert_pfn_pmd(vmf, *pfn, vmf->flags & FAULT_FLAG_WRITE);
 144}
 145
 146#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 147static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
 148                                struct vm_fault *vmf, pfn_t *pfn)
 149{
 150        unsigned long pud_addr = vmf->address & PUD_MASK;
 151        struct device *dev = &dev_dax->dev;
 152        phys_addr_t phys;
 153        pgoff_t pgoff;
 154        unsigned int fault_size = PUD_SIZE;
 155
 156
 157        if (check_vma(dev_dax, vmf->vma, __func__))
 158                return VM_FAULT_SIGBUS;
 159
 160        if (dev_dax->align > PUD_SIZE) {
 161                dev_dbg(dev, "alignment (%#x) > fault size (%#x)\n",
 162                        dev_dax->align, fault_size);
 163                return VM_FAULT_SIGBUS;
 164        }
 165
 166        if (fault_size < dev_dax->align)
 167                return VM_FAULT_SIGBUS;
 168        else if (fault_size > dev_dax->align)
 169                return VM_FAULT_FALLBACK;
 170
 171        /* if we are outside of the VMA */
 172        if (pud_addr < vmf->vma->vm_start ||
 173                        (pud_addr + PUD_SIZE) > vmf->vma->vm_end)
 174                return VM_FAULT_SIGBUS;
 175
 176        pgoff = linear_page_index(vmf->vma, pud_addr);
 177        phys = dax_pgoff_to_phys(dev_dax, pgoff, PUD_SIZE);
 178        if (phys == -1) {
 179                dev_dbg(dev, "pgoff_to_phys(%#lx) failed\n", pgoff);
 180                return VM_FAULT_SIGBUS;
 181        }
 182
 183        *pfn = phys_to_pfn_t(phys, PFN_DEV|PFN_MAP);
 184
 185        return vmf_insert_pfn_pud(vmf, *pfn, vmf->flags & FAULT_FLAG_WRITE);
 186}
 187#else
 188static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
 189                                struct vm_fault *vmf, pfn_t *pfn)
 190{
 191        return VM_FAULT_FALLBACK;
 192}
 193#endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 194
 195static vm_fault_t dev_dax_huge_fault(struct vm_fault *vmf,
 196                enum page_entry_size pe_size)
 197{
 198        struct file *filp = vmf->vma->vm_file;
 199        unsigned long fault_size;
 200        vm_fault_t rc = VM_FAULT_SIGBUS;
 201        int id;
 202        pfn_t pfn;
 203        struct dev_dax *dev_dax = filp->private_data;
 204
 205        dev_dbg(&dev_dax->dev, "%s: %s (%#lx - %#lx) size = %d\n", current->comm,
 206                        (vmf->flags & FAULT_FLAG_WRITE) ? "write" : "read",
 207                        vmf->vma->vm_start, vmf->vma->vm_end, pe_size);
 208
 209        id = dax_read_lock();
 210        switch (pe_size) {
 211        case PE_SIZE_PTE:
 212                fault_size = PAGE_SIZE;
 213                rc = __dev_dax_pte_fault(dev_dax, vmf, &pfn);
 214                break;
 215        case PE_SIZE_PMD:
 216                fault_size = PMD_SIZE;
 217                rc = __dev_dax_pmd_fault(dev_dax, vmf, &pfn);
 218                break;
 219        case PE_SIZE_PUD:
 220                fault_size = PUD_SIZE;
 221                rc = __dev_dax_pud_fault(dev_dax, vmf, &pfn);
 222                break;
 223        default:
 224                rc = VM_FAULT_SIGBUS;
 225        }
 226
 227        if (rc == VM_FAULT_NOPAGE) {
 228                unsigned long i;
 229                pgoff_t pgoff;
 230
 231                /*
 232                 * In the device-dax case the only possibility for a
 233                 * VM_FAULT_NOPAGE result is when device-dax capacity is
 234                 * mapped. No need to consider the zero page, or racing
 235                 * conflicting mappings.
 236                 */
 237                pgoff = linear_page_index(vmf->vma, vmf->address
 238                                & ~(fault_size - 1));
 239                for (i = 0; i < fault_size / PAGE_SIZE; i++) {
 240                        struct page *page;
 241
 242                        page = pfn_to_page(pfn_t_to_pfn(pfn) + i);
 243                        if (page->mapping)
 244                                continue;
 245                        page->mapping = filp->f_mapping;
 246                        page->index = pgoff + i;
 247                }
 248        }
 249        dax_read_unlock(id);
 250
 251        return rc;
 252}
 253
 254static vm_fault_t dev_dax_fault(struct vm_fault *vmf)
 255{
 256        return dev_dax_huge_fault(vmf, PE_SIZE_PTE);
 257}
 258
 259static int dev_dax_may_split(struct vm_area_struct *vma, unsigned long addr)
 260{
 261        struct file *filp = vma->vm_file;
 262        struct dev_dax *dev_dax = filp->private_data;
 263
 264        if (!IS_ALIGNED(addr, dev_dax->align))
 265                return -EINVAL;
 266        return 0;
 267}
 268
 269static unsigned long dev_dax_pagesize(struct vm_area_struct *vma)
 270{
 271        struct file *filp = vma->vm_file;
 272        struct dev_dax *dev_dax = filp->private_data;
 273
 274        return dev_dax->align;
 275}
 276
 277static const struct vm_operations_struct dax_vm_ops = {
 278        .fault = dev_dax_fault,
 279        .huge_fault = dev_dax_huge_fault,
 280        .may_split = dev_dax_may_split,
 281        .pagesize = dev_dax_pagesize,
 282};
 283
 284static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
 285{
 286        struct dev_dax *dev_dax = filp->private_data;
 287        int rc, id;
 288
 289        dev_dbg(&dev_dax->dev, "trace\n");
 290
 291        /*
 292         * We lock to check dax_dev liveness and will re-check at
 293         * fault time.
 294         */
 295        id = dax_read_lock();
 296        rc = check_vma(dev_dax, vma, __func__);
 297        dax_read_unlock(id);
 298        if (rc)
 299                return rc;
 300
 301        vma->vm_ops = &dax_vm_ops;
 302        vma->vm_flags |= VM_HUGEPAGE;
 303        return 0;
 304}
 305
 306/* return an unmapped area aligned to the dax region specified alignment */
 307static unsigned long dax_get_unmapped_area(struct file *filp,
 308                unsigned long addr, unsigned long len, unsigned long pgoff,
 309                unsigned long flags)
 310{
 311        unsigned long off, off_end, off_align, len_align, addr_align, align;
 312        struct dev_dax *dev_dax = filp ? filp->private_data : NULL;
 313
 314        if (!dev_dax || addr)
 315                goto out;
 316
 317        align = dev_dax->align;
 318        off = pgoff << PAGE_SHIFT;
 319        off_end = off + len;
 320        off_align = round_up(off, align);
 321
 322        if ((off_end <= off_align) || ((off_end - off_align) < align))
 323                goto out;
 324
 325        len_align = len + align;
 326        if ((off + len_align) < off)
 327                goto out;
 328
 329        addr_align = current->mm->get_unmapped_area(filp, addr, len_align,
 330                        pgoff, flags);
 331        if (!IS_ERR_VALUE(addr_align)) {
 332                addr_align += (off - addr_align) & (align - 1);
 333                return addr_align;
 334        }
 335 out:
 336        return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 337}
 338
 339static const struct address_space_operations dev_dax_aops = {
 340        .set_page_dirty         = noop_set_page_dirty,
 341        .invalidatepage         = noop_invalidatepage,
 342};
 343
 344static int dax_open(struct inode *inode, struct file *filp)
 345{
 346        struct dax_device *dax_dev = inode_dax(inode);
 347        struct inode *__dax_inode = dax_inode(dax_dev);
 348        struct dev_dax *dev_dax = dax_get_private(dax_dev);
 349
 350        dev_dbg(&dev_dax->dev, "trace\n");
 351        inode->i_mapping = __dax_inode->i_mapping;
 352        inode->i_mapping->host = __dax_inode;
 353        inode->i_mapping->a_ops = &dev_dax_aops;
 354        filp->f_mapping = inode->i_mapping;
 355        filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
 356        filp->f_sb_err = file_sample_sb_err(filp);
 357        filp->private_data = dev_dax;
 358        inode->i_flags = S_DAX;
 359
 360        return 0;
 361}
 362
 363static int dax_release(struct inode *inode, struct file *filp)
 364{
 365        struct dev_dax *dev_dax = filp->private_data;
 366
 367        dev_dbg(&dev_dax->dev, "trace\n");
 368        return 0;
 369}
 370
 371static const struct file_operations dax_fops = {
 372        .llseek = noop_llseek,
 373        .owner = THIS_MODULE,
 374        .open = dax_open,
 375        .release = dax_release,
 376        .get_unmapped_area = dax_get_unmapped_area,
 377        .mmap = dax_mmap,
 378        .mmap_supported_flags = MAP_SYNC,
 379};
 380
 381static void dev_dax_cdev_del(void *cdev)
 382{
 383        cdev_del(cdev);
 384}
 385
 386static void dev_dax_kill(void *dev_dax)
 387{
 388        kill_dev_dax(dev_dax);
 389}
 390
 391int dev_dax_probe(struct dev_dax *dev_dax)
 392{
 393        struct dax_device *dax_dev = dev_dax->dax_dev;
 394        struct device *dev = &dev_dax->dev;
 395        struct dev_pagemap *pgmap;
 396        struct inode *inode;
 397        struct cdev *cdev;
 398        void *addr;
 399        int rc, i;
 400
 401        pgmap = dev_dax->pgmap;
 402        if (dev_WARN_ONCE(dev, pgmap && dev_dax->nr_range > 1,
 403                        "static pgmap / multi-range device conflict\n"))
 404                return -EINVAL;
 405
 406        if (!pgmap) {
 407                pgmap = devm_kzalloc(dev, sizeof(*pgmap) + sizeof(struct range)
 408                                * (dev_dax->nr_range - 1), GFP_KERNEL);
 409                if (!pgmap)
 410                        return -ENOMEM;
 411                pgmap->nr_range = dev_dax->nr_range;
 412        }
 413
 414        for (i = 0; i < dev_dax->nr_range; i++) {
 415                struct range *range = &dev_dax->ranges[i].range;
 416
 417                if (!devm_request_mem_region(dev, range->start,
 418                                        range_len(range), dev_name(dev))) {
 419                        dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve range\n",
 420                                        i, range->start, range->end);
 421                        return -EBUSY;
 422                }
 423                /* don't update the range for static pgmap */
 424                if (!dev_dax->pgmap)
 425                        pgmap->ranges[i] = *range;
 426        }
 427
 428        pgmap->type = MEMORY_DEVICE_GENERIC;
 429        addr = devm_memremap_pages(dev, pgmap);
 430        if (IS_ERR(addr))
 431                return PTR_ERR(addr);
 432
 433        inode = dax_inode(dax_dev);
 434        cdev = inode->i_cdev;
 435        cdev_init(cdev, &dax_fops);
 436        if (dev->class) {
 437                /* for the CONFIG_DEV_DAX_PMEM_COMPAT case */
 438                cdev->owner = dev->parent->driver->owner;
 439        } else
 440                cdev->owner = dev->driver->owner;
 441        cdev_set_parent(cdev, &dev->kobj);
 442        rc = cdev_add(cdev, dev->devt, 1);
 443        if (rc)
 444                return rc;
 445
 446        rc = devm_add_action_or_reset(dev, dev_dax_cdev_del, cdev);
 447        if (rc)
 448                return rc;
 449
 450        run_dax(dax_dev);
 451        return devm_add_action_or_reset(dev, dev_dax_kill, dev_dax);
 452}
 453EXPORT_SYMBOL_GPL(dev_dax_probe);
 454
 455static struct dax_device_driver device_dax_driver = {
 456        .probe = dev_dax_probe,
 457        /* all probe actions are unwound by devm, so .remove isn't necessary */
 458        .match_always = 1,
 459};
 460
 461static int __init dax_init(void)
 462{
 463        return dax_driver_register(&device_dax_driver);
 464}
 465
 466static void __exit dax_exit(void)
 467{
 468        dax_driver_unregister(&device_dax_driver);
 469}
 470
 471MODULE_AUTHOR("Intel Corporation");
 472MODULE_LICENSE("GPL v2");
 473module_init(dax_init);
 474module_exit(dax_exit);
 475MODULE_ALIAS_DAX_DEVICE(0);
 476