/*
 * 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/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);
        }
}

/**
 * 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
 * @dmasync: flush in-flight DMA when the memory region is written
 */
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->locked_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->locked_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->locked_vm -= umem->diff;
        up_write(&umem->mm->mmap_sem);
        mmput(umem->mm);
        kfree(umem);
}

/**
 * ib_umem_release - release memory pinned with ib_umem_get
 * @umem: umem struct to release
 */
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->locked_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);