umem.c 7.4 KB
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/*
 * Copyright (c) 2005 Topspin Communications.  All rights reserved.
 * Copyright (c) 2005 Cisco Systems.  All rights reserved.
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 * Copyright (c) 2005 Mellanox Technologies. All rights reserved.
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 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/mm.h>
#include <linux/dma-mapping.h>
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Alexey Dobriyan 已提交
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#include <linux/sched.h>
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#include <linux/export.h>
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#include <linux/hugetlb.h>
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#include <linux/dma-attrs.h>
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#include <linux/slab.h>
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#include "uverbs.h"

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static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int dirty)
{
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	struct scatterlist *sg;
	struct page *page;
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	int i;

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	if (umem->nmap > 0)
		ib_dma_unmap_sg(dev, umem->sg_head.sgl,
				umem->nmap,
				DMA_BIDIRECTIONAL);
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Jens Axboe 已提交
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	for_each_sg(umem->sg_head.sgl, sg, umem->npages, i) {
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		page = sg_page(sg);
		if (umem->writable && dirty)
			set_page_dirty_lock(page);
		put_page(page);
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	}
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	sg_free_table(&umem->sg_head);
	return;

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}

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/**
 * ib_umem_get - Pin and DMA map userspace memory.
 * @context: userspace context to pin memory for
 * @addr: userspace virtual address to start at
 * @size: length of region to pin
 * @access: IB_ACCESS_xxx flags for memory being pinned
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 * @dmasync: flush in-flight DMA when the memory region is written
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 */
struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
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			    size_t size, int access, int dmasync)
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{
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	struct ib_umem *umem;
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	struct page **page_list;
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	struct vm_area_struct **vma_list;
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	unsigned long locked;
	unsigned long lock_limit;
	unsigned long cur_base;
	unsigned long npages;
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	int ret;
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	int i;
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	DEFINE_DMA_ATTRS(attrs);
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	struct scatterlist *sg, *sg_list_start;
	int need_release = 0;
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	if (dmasync)
		dma_set_attr(DMA_ATTR_WRITE_BARRIER, &attrs);
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	if (!can_do_mlock())
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		return ERR_PTR(-EPERM);
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	umem = kzalloc(sizeof *umem, GFP_KERNEL);
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	if (!umem)
		return ERR_PTR(-ENOMEM);
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	umem->context   = context;
	umem->length    = size;
	umem->offset    = addr & ~PAGE_MASK;
	umem->page_size = PAGE_SIZE;
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	umem->pid       = get_task_pid(current, PIDTYPE_PID);
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	/*
	 * We ask for writable memory if any access flags other than
	 * "remote read" are set.  "Local write" and "remote write"
	 * obviously require write access.  "Remote atomic" can do
	 * things like fetch and add, which will modify memory, and
	 * "MW bind" can change permissions by binding a window.
	 */
	umem->writable  = !!(access & ~IB_ACCESS_REMOTE_READ);
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	/* We assume the memory is from hugetlb until proved otherwise */
	umem->hugetlb   = 1;

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	page_list = (struct page **) __get_free_page(GFP_KERNEL);
	if (!page_list) {
		kfree(umem);
		return ERR_PTR(-ENOMEM);
	}
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	/*
	 * if we can't alloc the vma_list, it's not so bad;
	 * just assume the memory is not hugetlb memory
	 */
	vma_list = (struct vm_area_struct **) __get_free_page(GFP_KERNEL);
	if (!vma_list)
		umem->hugetlb = 0;

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	npages = PAGE_ALIGN(size + umem->offset) >> PAGE_SHIFT;
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	down_write(&current->mm->mmap_sem);

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	locked     = npages + current->mm->pinned_vm;
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	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
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	if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) {
		ret = -ENOMEM;
		goto out;
	}

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	cur_base = addr & PAGE_MASK;
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	if (npages == 0) {
		ret = -EINVAL;
		goto out;
	}

	ret = sg_alloc_table(&umem->sg_head, npages, GFP_KERNEL);
	if (ret)
		goto out;

	need_release = 1;
	sg_list_start = umem->sg_head.sgl;

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	while (npages) {
		ret = get_user_pages(current, current->mm, cur_base,
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				     min_t(unsigned long, npages,
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					   PAGE_SIZE / sizeof (struct page *)),
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				     1, !umem->writable, page_list, vma_list);
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		if (ret < 0)
			goto out;

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		umem->npages += ret;
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		cur_base += ret * PAGE_SIZE;
		npages   -= ret;

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		for_each_sg(sg_list_start, sg, ret, i) {
			if (vma_list && !is_vm_hugetlb_page(vma_list[i]))
				umem->hugetlb = 0;

			sg_set_page(sg, page_list[i], PAGE_SIZE, 0);
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		}

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		/* preparing for next loop */
		sg_list_start = sg;
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	}

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	umem->nmap = ib_dma_map_sg_attrs(context->device,
				  umem->sg_head.sgl,
				  umem->npages,
				  DMA_BIDIRECTIONAL,
				  &attrs);

	if (umem->nmap <= 0) {
		ret = -ENOMEM;
		goto out;
	}

	ret = 0;

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out:
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	if (ret < 0) {
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		if (need_release)
			__ib_umem_release(context->device, umem, 0);
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		put_pid(umem->pid);
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		kfree(umem);
	} else
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		current->mm->pinned_vm = locked;
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	up_write(&current->mm->mmap_sem);
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	if (vma_list)
		free_page((unsigned long) vma_list);
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	free_page((unsigned long) page_list);

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	return ret < 0 ? ERR_PTR(ret) : umem;
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}
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EXPORT_SYMBOL(ib_umem_get);
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static void ib_umem_account(struct work_struct *work)
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{
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	struct ib_umem *umem = container_of(work, struct ib_umem, work);

	down_write(&umem->mm->mmap_sem);
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	umem->mm->pinned_vm -= umem->diff;
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	up_write(&umem->mm->mmap_sem);
	mmput(umem->mm);
	kfree(umem);
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}

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/**
 * ib_umem_release - release memory pinned with ib_umem_get
 * @umem: umem struct to release
 */
void ib_umem_release(struct ib_umem *umem)
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{
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	struct ib_ucontext *context = umem->context;
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	struct mm_struct *mm;
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	struct task_struct *task;
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	unsigned long diff;
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	__ib_umem_release(umem->context->device, umem, 1);
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	task = get_pid_task(umem->pid, PIDTYPE_PID);
	put_pid(umem->pid);
	if (!task)
		goto out;
	mm = get_task_mm(task);
	put_task_struct(task);
	if (!mm)
		goto out;
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	diff = PAGE_ALIGN(umem->length + umem->offset) >> PAGE_SHIFT;

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	/*
	 * We may be called with the mm's mmap_sem already held.  This
	 * can happen when a userspace munmap() is the call that drops
	 * the last reference to our file and calls our release
	 * method.  If there are memory regions to destroy, we'll end
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	 * up here and not be able to take the mmap_sem.  In that case
	 * we defer the vm_locked accounting to the system workqueue.
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	 */
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	if (context->closing) {
		if (!down_write_trylock(&mm->mmap_sem)) {
			INIT_WORK(&umem->work, ib_umem_account);
			umem->mm   = mm;
			umem->diff = diff;

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Tejun Heo 已提交
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			queue_work(ib_wq, &umem->work);
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			return;
		}
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	} else
		down_write(&mm->mmap_sem);

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	mm->pinned_vm -= diff;
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	up_write(&mm->mmap_sem);
	mmput(mm);
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out:
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	kfree(umem);
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}
EXPORT_SYMBOL(ib_umem_release);

int ib_umem_page_count(struct ib_umem *umem)
{
	int shift;
	int i;
	int n;
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	struct scatterlist *sg;
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	shift = ilog2(umem->page_size);
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	n = 0;
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	for_each_sg(umem->sg_head.sgl, sg, umem->nmap, i)
		n += sg_dma_len(sg) >> shift;
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	return n;
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}
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EXPORT_SYMBOL(ib_umem_page_count);