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/*
* 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>
#include "dax.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 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
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