/*
 * Copyright (c) 2005 Topspin Communications.  All rights reserved.
 * Copyright (c) 2005 Cisco Systems.  All rights reserved.
 * Copyright (c) 2005 Mellanox Technologies. All rights reserved.
 * Copyright (c) 2020 Intel Corporation. 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 <linux/count_zeros.h>
#include <rdma/ib_umem_odp.h>

#include "uverbs.h"

#define RESCHED_LOOP_CNT_THRESHOLD 0x1000

static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int dirty)
{
        bool make_dirty = umem->writable && dirty;
        struct scatterlist *sg;
        unsigned int i;

        if (dirty)
                ib_dma_unmap_sgtable_attrs(dev, &umem->sgt_append.sgt,
                                           DMA_BIDIRECTIONAL,
                                           DMA_ATTR_REQUIRE_COHERENT);

        for_each_sgtable_sg(&umem->sgt_append.sgt, sg, i) {
                unpin_user_page_range_dirty_lock(sg_page(sg),
                        DIV_ROUND_UP(sg->length, PAGE_SIZE), make_dirty);

                if (i && !(i % RESCHED_LOOP_CNT_THRESHOLD))
                        cond_resched();
        }

        sg_free_append_table(&umem->sgt_append);
}

/**
 * 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)
{
        unsigned long curr_len = 0;
        dma_addr_t curr_base = ~0;
        unsigned long va, pgoff;
        struct scatterlist *sg;
        dma_addr_t mask;
        dma_addr_t end;
        int i;

        umem->iova = va = virt;

        if (umem->is_odp) {
                unsigned int page_size = BIT(to_ib_umem_odp(umem)->page_shift);

                /* ODP must always be self consistent. */
                if (!(pgsz_bitmap & page_size))
                        return 0;
                return page_size;
        }

        /* The best result is the smallest page size that results in the minimum
         * number of required pages. Compute the largest page size that could
         * work based on VA address bits that don't change.
         */
        mask = pgsz_bitmap &
               GENMASK(BITS_PER_LONG - 1,
                       bits_per((umem->length - 1 + virt) ^ virt));
        /* offset into first SGL */
        pgoff = umem->address & ~PAGE_MASK;

        for_each_sgtable_dma_sg(&umem->sgt_append.sgt, sg, i) {
                /* If the current entry is physically contiguous with the previous
                 * one, no need to take its start addresses into consideration.
                 */
                if (check_add_overflow(curr_base, curr_len, &end) ||
                    end != sg_dma_address(sg)) {

                        curr_base = sg_dma_address(sg);
                        curr_len = 0;

                        /* Reduce max page size if VA/PA bits differ */
                        mask |= (curr_base + pgoff) ^ va;

                        /* The alignment of any VA matching a discontinuity point
                        * in the physical memory sets the maximum possible page
                        * size as this must be a starting point of a new page that
                        * needs to be aligned.
                        */
                        if (i != 0)
                                mask |= va;
                }

                curr_len += sg_dma_len(sg);
                va += sg_dma_len(sg) - pgoff;

                pgoff = 0;
        }

        /* The mask accumulates 1's in each position where the VA and physical
         * address differ, thus the length of trailing 0 is the largest page
         * size that can pass the VA through to the physical.
         */
        if (mask)
                pgsz_bitmap &= GENMASK(count_trailing_zeros(mask), 0);
        return pgsz_bitmap ? rounddown_pow_of_two(pgsz_bitmap) : 0;
}
EXPORT_SYMBOL(ib_umem_find_best_pgsz);

/**
 * ib_umem_get - Pin and DMA map userspace memory.
 *
 * @device: IB device to connect UMEM
 * @addr: userspace virtual address to start at
 * @size: length of region to pin
 * @access: IB_ACCESS_xxx flags for memory being pinned
 */
struct ib_umem *ib_umem_get(struct ib_device *device, unsigned long addr,
                            size_t size, int access)
{
        struct ib_umem *umem;
        struct page **page_list;
        unsigned long lock_limit;
        unsigned long new_pinned;
        unsigned long cur_base;
        unsigned long dma_attr = DMA_ATTR_REQUIRE_COHERENT;
        struct mm_struct *mm;
        unsigned long npages;
        int pinned, ret;
        unsigned int gup_flags = FOLL_LONGTERM;

        /*
         * 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)
                return ERR_PTR(-EOPNOTSUPP);

        umem = kzalloc_obj(*umem);
        if (!umem)
                return ERR_PTR(-ENOMEM);
        umem->ibdev      = device;
        umem->length     = size;
        umem->address    = addr;
        /*
         * Drivers should call ib_umem_find_best_pgsz() to set the iova
         * correctly.
         */
        umem->iova = addr;
        umem->writable   = ib_access_writable(access);
        umem->owning_mm = mm = current->mm;
        mmgrab(mm);

        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;

        if (umem->writable)
                gup_flags |= FOLL_WRITE;

        while (npages) {
                cond_resched();
                pinned = pin_user_pages_fast(cur_base,
                                          min_t(unsigned long, npages,
                                                PAGE_SIZE /
                                                sizeof(struct page *)),
                                          gup_flags, page_list);
                if (pinned < 0) {
                        ret = pinned;
                        goto umem_release;
                }

                cur_base += pinned * PAGE_SIZE;
                npages -= pinned;
                ret = sg_alloc_append_table_from_pages(
                        &umem->sgt_append, page_list, pinned, 0,
                        pinned << PAGE_SHIFT, ib_dma_max_seg_size(device),
                        npages, GFP_KERNEL);
                if (ret) {
                        unpin_user_pages_dirty_lock(page_list, pinned, 0);
                        goto umem_release;
                }
        }

        if (access & IB_ACCESS_RELAXED_ORDERING)
                dma_attr |= DMA_ATTR_WEAK_ORDERING;

        ret = ib_dma_map_sgtable_attrs(device, &umem->sgt_append.sgt,
                                       DMA_BIDIRECTIONAL, dma_attr);
        if (ret)
                goto umem_release;
        goto out;

umem_release:
        __ib_umem_release(device, umem, 0);
        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);

/**
 * 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_dmabuf)
                return ib_umem_dmabuf_release(to_ib_umem_dmabuf(umem));
        if (umem->is_odp)
                return ib_umem_odp_release(to_ib_umem_odp(umem));

        __ib_umem_release(umem->ibdev, umem, 1);

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

/*
 * 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("%s not in range. offset: %zd umem length: %zd end: %zd\n",
                       __func__, offset, umem->length, end);
                return -EINVAL;
        }

        ret = sg_pcopy_to_buffer(umem->sgt_append.sgt.sgl,
                                 umem->sgt_append.sgt.orig_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);