umem.c

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/*
 * Copyright (c) 2005 Topspin Communications.  All rights reserved.
 * Copyright (c) 2005 Cisco Systems.  All rights reserved.
 * Copyright (c) 2005 Mellanox Technologies. All rights reserved.
 *
 * 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>
#include <linux/sched.h>
#include <linux/export.h>
#include <linux/hugetlb.h>
#include <linux/dma-attrs.h>
#include <linux/slab.h>

#include "uverbs.h"

#define IB_UMEM_MAX_PAGE_CHUNK                      \
    ((PAGE_SIZE - offsetof(struct ib_umem_chunk, page_list)) /  \
     ((void *) &((struct ib_umem_chunk *) 0)->page_list[1] -    \
      (void *) &((struct ib_umem_chunk *) 0)->page_list[0]))

static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int dirty)
{
    struct ib_umem_chunk *chunk, *tmp;
    int i;

    list_for_each_entry_safe(chunk, tmp, &umem->chunk_list, list) {
        ib_dma_unmap_sg(dev, chunk->page_list,
                chunk->nents, DMA_BIDIRECTIONAL);
        for (i = 0; i < chunk->nents; ++i) {
            struct page *page = sg_page(&chunk->page_list[i]);

            if (umem->writable && dirty)
                set_page_dirty_lock(page);
            put_page(page);
        }

        kfree(chunk);
    }
}

struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
                size_t size, int access, int dmasync)
{
    struct ib_umem *umem;
    struct page **page_list;
    struct vm_area_struct **vma_list;
    struct ib_umem_chunk *chunk;
    unsigned long locked;
    unsigned long lock_limit;
    unsigned long cur_base;
    unsigned long npages;
    int ret;
    int off;
    int i;
    DEFINE_DMA_ATTRS(attrs);

    if (dmasync)
        dma_set_attr(DMA_ATTR_WRITE_BARRIER, &attrs);

    if (!can_do_mlock())
        return ERR_PTR(-EPERM);

    umem = kmalloc(sizeof *umem, GFP_KERNEL);
    if (!umem)
        return ERR_PTR(-ENOMEM);

    umem->context   = context;
    umem->length    = size;
    umem->offset    = addr & ~PAGE_MASK;
    umem->page_size = PAGE_SIZE;
    /*
     * 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);

    /* We assume the memory is from hugetlb until proved otherwise */
    umem->hugetlb   = 1;

    INIT_LIST_HEAD(&umem->chunk_list);

    page_list = (struct page **) __get_free_page(GFP_KERNEL);
    if (!page_list) {
        kfree(umem);
        return ERR_PTR(-ENOMEM);
    }

    /*
     * 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;

    npages = PAGE_ALIGN(size + umem->offset) >> PAGE_SHIFT;

    down_write(&current->mm->mmap_sem);

    locked     = npages + current->mm->pinned_vm;
    lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;

    if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) {
        ret = -ENOMEM;
        goto out;
    }

    cur_base = addr & PAGE_MASK;

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

        if (ret < 0)
            goto out;

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

        off = 0;

        while (ret) {
            chunk = kmalloc(sizeof *chunk + sizeof (struct scatterlist) *
                    min_t(int, ret, IB_UMEM_MAX_PAGE_CHUNK),
                    GFP_KERNEL);
            if (!chunk) {
                ret = -ENOMEM;
                goto out;
            }

            chunk->nents = min_t(int, ret, IB_UMEM_MAX_PAGE_CHUNK);
            sg_init_table(chunk->page_list, chunk->nents);
            for (i = 0; i < chunk->nents; ++i) {
                if (vma_list &&
                    !is_vm_hugetlb_page(vma_list[i + off]))
                    umem->hugetlb = 0;
                sg_set_page(&chunk->page_list[i], page_list[i + off], PAGE_SIZE, 0);
            }

            chunk->nmap = ib_dma_map_sg_attrs(context->device,
                              &chunk->page_list[0],
                              chunk->nents,
                              DMA_BIDIRECTIONAL,
                              &attrs);
            if (chunk->nmap <= 0) {
                for (i = 0; i < chunk->nents; ++i)
                    put_page(sg_page(&chunk->page_list[i]));
                kfree(chunk);

                ret = -ENOMEM;
                goto out;
            }

            ret -= chunk->nents;
            off += chunk->nents;
            list_add_tail(&chunk->list, &umem->chunk_list);
        }

        ret = 0;
    }

out:
    if (ret < 0) {
        __ib_umem_release(context->device, umem, 0);
        kfree(umem);
    } else
        current->mm->pinned_vm = locked;

    up_write(&current->mm->mmap_sem);
    if (vma_list)
        free_page((unsigned long) vma_list);
    free_page((unsigned long) page_list);

    return ret < 0 ? ERR_PTR(ret) : umem;
}
EXPORT_SYMBOL(ib_umem_get);

static void ib_umem_account(struct work_struct *work)
{
    struct ib_umem *umem = container_of(work, struct ib_umem, work);

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

void ib_umem_release(struct ib_umem *umem)
{
    struct ib_ucontext *context = umem->context;
    struct mm_struct *mm;
    unsigned long diff;

    __ib_umem_release(umem->context->device, umem, 1);

    mm = get_task_mm(current);
    if (!mm) {
        kfree(umem);
        return;
    }

    diff = PAGE_ALIGN(umem->length + umem->offset) >> PAGE_SHIFT;

    /*
     * 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
     * up here and not be able to take the mmap_sem.  In that case
     * we defer the vm_locked accounting to the system workqueue.
     */
    if (context->closing) {
        if (!down_write_trylock(&mm->mmap_sem)) {
            INIT_WORK(&umem->work, ib_umem_account);
            umem->mm   = mm;
            umem->diff = diff;

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

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

int ib_umem_page_count(struct ib_umem *umem)
{
    struct ib_umem_chunk *chunk;
    int shift;
    int i;
    int n;

    shift = ilog2(umem->page_size);

    n = 0;
    list_for_each_entry(chunk, &umem->chunk_list, list)
        for (i = 0; i < chunk->nmap; ++i)
            n += sg_dma_len(&chunk->page_list[i]) >> shift;

    return n;
}
EXPORT_SYMBOL(ib_umem_page_count);