/*
 * 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/signal.h>
#include <linux/sched/mm.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <rdma/ib_umem_odp.h>

#include "uverbs.h"

static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int dirty)
{
        struct sg_page_iter sg_iter;
        struct page *page;

        if (umem->nmap > 0)
                ib_dma_unmap_sg(dev, umem->sg_head.sgl, umem->sg_nents,
                                DMA_BIDIRECTIONAL);

        for_each_sg_page(umem->sg_head.sgl, &sg_iter, umem->sg_nents, 0) {
                page = sg_page_iter_page(&sg_iter);
                if (umem->writable && dirty)
                        put_user_pages_dirty_lock(&page, 1);
                else
                        put_user_page(page);
        }

        sg_free_table(&umem->sg_head);
}

/* ib_umem_add_sg_table - Add N contiguous pages to scatter table
 *
 * sg: current scatterlist entry
 * page_list: array of npage struct page pointers
 * npages: number of pages in page_list
 * max_seg_sz: maximum segment size in bytes
 * nents: [out] number of entries in the scatterlist
 *
 * Return new end of scatterlist
 */
static struct scatterlist *ib_umem_add_sg_table(struct scatterlist *sg,
                                                struct page **page_list,
                                                unsigned long npages,
                                                unsigned int max_seg_sz,
                                                int *nents)
{
        unsigned long first_pfn;
        unsigned long i = 0;
        bool update_cur_sg = false;
        bool first = !sg_page(sg);

        /* Check if new page_list is contiguous with end of previous page_list.
         * sg->length here is a multiple of PAGE_SIZE and sg->offset is 0.
         */
        if (!first && (page_to_pfn(sg_page(sg)) + (sg->length >> PAGE_SHIFT) ==
                       page_to_pfn(page_list[0])))
                update_cur_sg = true;

        while (i != npages) {
                unsigned long len;
                struct page *first_page = page_list[i];

                first_pfn = page_to_pfn(first_page);

                /* Compute the number of contiguous pages we have starting
                 * at i
                 */
                for (len = 0; i != npages &&
                              first_pfn + len == page_to_pfn(page_list[i]) &&
                              len < (max_seg_sz >> PAGE_SHIFT);
                     len++)
                        i++;

                /* Squash N contiguous pages from page_list into current sge */
                if (update_cur_sg) {
                        if ((max_seg_sz - sg->length) >= (len << PAGE_SHIFT)) {
                                sg_set_page(sg, sg_page(sg),
                                            sg->length + (len << PAGE_SHIFT),
                                            0);
                                update_cur_sg = false;
                                continue;
                        }
                        update_cur_sg = false;
                }

                /* Squash N contiguous pages into next sge or first sge */
                if (!first)
                        sg = sg_next(sg);

                (*nents)++;
                sg_set_page(sg, first_page, len << PAGE_SHIFT, 0);
                first = false;
        }

        return sg;
}

/**
 * ib_umem_find_best_pgsz - Find best HW page size to use for this MR
 *
 * @umem: umem struct
 * @pgsz_bitmap: bitmap of HW supported page sizes
 * @virt: IOVA
 *
 * This helper is intended for HW that support multiple page
 * sizes but can do only a single page size in an MR.
 *
 * Returns 0 if the umem requires page sizes not supported by
 * the driver to be mapped. Drivers always supporting PAGE_SIZE
 * or smaller will never see a 0 result.
 */
unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem,
                                     unsigned long pgsz_bitmap,
                                     unsigned long virt)
{
        struct scatterlist *sg;
        unsigned int best_pg_bit;
        unsigned long va, pgoff;
        dma_addr_t mask;
        int i;

        /* At minimum, drivers must support PAGE_SIZE or smaller */
        if (WARN_ON(!(pgsz_bitmap & GENMASK(PAGE_SHIFT, 0))))
                return 0;

        va = virt;
        /* max page size not to exceed MR length */
        mask = roundup_pow_of_two(umem->length);
        /* offset into first SGL */
        pgoff = umem->address & ~PAGE_MASK;

        for_each_sg(umem->sg_head.sgl, sg, umem->nmap, i) {
                /* Walk SGL and reduce max page size if VA/PA bits differ
                 * for any address.
                 */
                mask |= (sg_dma_address(sg) + pgoff) ^ va;
                if (i && i != (umem->nmap - 1))
                        /* restrict by length as well for interior SGEs */
                        mask |= sg_dma_len(sg);
                va += sg_dma_len(sg) - pgoff;
                pgoff = 0;
        }
        best_pg_bit = rdma_find_pg_bit(mask, pgsz_bitmap);

        return BIT_ULL(best_pg_bit);
}
EXPORT_SYMBOL(ib_umem_find_best_pgsz);

/**
 * ib_umem_get - Pin and DMA map userspace memory.
 *
 * If access flags indicate ODP memory, avoid pinning. Instead, stores
 * the mm for future page fault handling in conjunction with MMU notifiers.
 *
 * @udata: 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_udata *udata, unsigned long addr,
                            size_t size, int access, int dmasync)
{
        struct ib_ucontext *context;
        struct ib_umem *umem;
        struct page **page_list;
        unsigned long lock_limit;
        unsigned long new_pinned;
        unsigned long cur_base;
        struct mm_struct *mm;
        unsigned long npages;
        int ret;
        unsigned long dma_attrs = 0;
        struct scatterlist *sg;
        unsigned int gup_flags = FOLL_WRITE;

        if (!udata)
                return ERR_PTR(-EIO);

        context = container_of(udata, struct uverbs_attr_bundle, driver_udata)
                          ->context;
        if (!context)
                return ERR_PTR(-EIO);

        if (dmasync)
                dma_attrs |= DMA_ATTR_WRITE_BARRIER;

        /*
         * If the combination of the addr and size requested for this memory
         * region causes an integer overflow, return error.
         */
        if (((addr + size) < addr) ||
            PAGE_ALIGN(addr + size) < (addr + size))
                return ERR_PTR(-EINVAL);

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

        if (access & IB_ACCESS_ON_DEMAND) {
                umem = kzalloc(sizeof(struct ib_umem_odp), GFP_KERNEL);
                if (!umem)
                        return ERR_PTR(-ENOMEM);
                umem->is_odp = 1;
        } else {
                umem = kzalloc(sizeof(*umem), GFP_KERNEL);
                if (!umem)
                        return ERR_PTR(-ENOMEM);
        }

        umem->context    = context;
        umem->length     = size;
        umem->address    = addr;
        umem->writable   = ib_access_writable(access);
        umem->owning_mm = mm = current->mm;
        mmgrab(mm);

        if (access & IB_ACCESS_ON_DEMAND) {
                if (WARN_ON_ONCE(!context->invalidate_range)) {
                        ret = -EINVAL;
                        goto umem_kfree;
                }

                ret = ib_umem_odp_get(to_ib_umem_odp(umem), access);
                if (ret)
                        goto umem_kfree;
                return umem;
        }

        page_list = (struct page **) __get_free_page(GFP_KERNEL);
        if (!page_list) {
                ret = -ENOMEM;
                goto umem_kfree;
        }

        npages = ib_umem_num_pages(umem);
        if (npages == 0 || npages > UINT_MAX) {
                ret = -EINVAL;
                goto out;
        }

        lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;

        new_pinned = atomic64_add_return(npages, &mm->pinned_vm);
        if (new_pinned > lock_limit && !capable(CAP_IPC_LOCK)) {
                atomic64_sub(npages, &mm->pinned_vm);
                ret = -ENOMEM;
                goto out;
        }

        cur_base = addr & PAGE_MASK;

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

        if (!umem->writable)
                gup_flags |= FOLL_FORCE;

        sg = umem->sg_head.sgl;

        while (npages) {
                down_read(&mm->mmap_sem);
                ret = get_user_pages(cur_base,
                                     min_t(unsigned long, npages,
                                           PAGE_SIZE / sizeof (struct page *)),
                                     gup_flags | FOLL_LONGTERM,
                                     page_list, NULL);
                if (ret < 0) {
                        up_read(&mm->mmap_sem);
                        goto umem_release;
                }

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

                sg = ib_umem_add_sg_table(sg, page_list, ret,
                        dma_get_max_seg_size(context->device->dma_device),
                        &umem->sg_nents);

                up_read(&mm->mmap_sem);
        }

        sg_mark_end(sg);

        umem->nmap = ib_dma_map_sg_attrs(context->device,
                                  umem->sg_head.sgl,
                                  umem->sg_nents,
                                  DMA_BIDIRECTIONAL,
                                  dma_attrs);

        if (!umem->nmap) {
                ret = -ENOMEM;
                goto umem_release;
        }

        ret = 0;
        goto out;

umem_release:
        __ib_umem_release(context->device, umem, 0);
vma:
        atomic64_sub(ib_umem_num_pages(umem), &mm->pinned_vm);
out:
        free_page((unsigned long) page_list);
umem_kfree:
        if (ret) {
                mmdrop(umem->owning_mm);
                kfree(umem);
        }
        return ret ? ERR_PTR(ret) : umem;
}
EXPORT_SYMBOL(ib_umem_get);

static void __ib_umem_release_tail(struct ib_umem *umem)
{
        mmdrop(umem->owning_mm);
        if (umem->is_odp)
                kfree(to_ib_umem_odp(umem));
        else
                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)
{
        if (!umem)
                return;

        if (umem->is_odp) {
                ib_umem_odp_release(to_ib_umem_odp(umem));
                __ib_umem_release_tail(umem);
                return;
        }

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

        atomic64_sub(ib_umem_num_pages(umem), &umem->owning_mm->pinned_vm);
        __ib_umem_release_tail(umem);
}
EXPORT_SYMBOL(ib_umem_release);

int ib_umem_page_count(struct ib_umem *umem)
{
        int i, n = 0;
        struct scatterlist *sg;

        for_each_sg(umem->sg_head.sgl, sg, umem->nmap, i)
                n += sg_dma_len(sg) >> PAGE_SHIFT;

        return n;
}
EXPORT_SYMBOL(ib_umem_page_count);

/*
 * Copy from the given ib_umem's pages to the given buffer.
 *
 * umem - the umem to copy from
 * offset - offset to start copying from
 * dst - destination buffer
 * length - buffer length
 *
 * Returns 0 on success, or an error code.
 */
int ib_umem_copy_from(void *dst, struct ib_umem *umem, size_t offset,
                      size_t length)
{
        size_t end = offset + length;
        int ret;

        if (offset > umem->length || length > umem->length - offset) {
                pr_err("ib_umem_copy_from not in range. offset: %zd umem length: %zd end: %zd\n",
                       offset, umem->length, end);
                return -EINVAL;
        }

        ret = sg_pcopy_to_buffer(umem->sg_head.sgl, umem->sg_nents, dst, length,
                                 offset + ib_umem_offset(umem));

        if (ret < 0)
                return ret;
        else if (ret != length)
                return -EINVAL;
        else
                return 0;
}
EXPORT_SYMBOL(ib_umem_copy_from);