diff options
Diffstat (limited to 'drivers/dax')
| -rw-r--r-- | drivers/dax/Kconfig | 1 | ||||
| -rw-r--r-- | drivers/dax/dax.c | 322 |
2 files changed, 323 insertions, 0 deletions
diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig index 86ffbaa891ad..cedab7572de3 100644 --- a/drivers/dax/Kconfig +++ b/drivers/dax/Kconfig @@ -1,6 +1,7 @@ menuconfig DEV_DAX tristate "DAX: direct access to differentiated memory" default m if NVDIMM_DAX + depends on TRANSPARENT_HUGEPAGE help Support raw access to differentiated (persistence, bandwidth, latency...) memory via an mmap(2) capable character diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c index 4c22a40f2335..b891a129b275 100644 --- a/drivers/dax/dax.c +++ b/drivers/dax/dax.c @@ -49,6 +49,7 @@ struct 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 @@ -57,6 +58,7 @@ struct dax_dev { struct dax_region *region; struct device *dev; struct kref kref; + bool alive; int id; int num_resources; struct resource res[0]; @@ -150,6 +152,16 @@ static void unregister_dax_dev(void *_dev) 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); @@ -173,6 +185,7 @@ int devm_create_dax_dev(struct dax_region *dax_region, struct resource *res, 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); @@ -217,9 +230,318 @@ int devm_create_dax_dev(struct dax_region *dax_region, struct resource *res, } 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) |