/*
 * SPDX-FileCopyrightText: Copyright (c) 2016-2017 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 * SPDX-License-Identifier: MIT
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * 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.
 */
#ifndef __NV_MM_H__
#define __NV_MM_H__

#include "conftest.h"

#if !defined(NV_VM_FAULT_T_IS_PRESENT)
typedef int vm_fault_t;
#endif

/* get_user_pages
 *
 * The 8-argument version of get_user_pages was deprecated by commit
 * (2016 Feb 12: cde70140fed8429acf7a14e2e2cbd3e329036653)for the non-remote case
 * (calling get_user_pages with current and current->mm).
 *
 * Completely moved to the 6 argument version of get_user_pages -
 * 2016 Apr 4: c12d2da56d0e07d230968ee2305aaa86b93a6832
 *
 * write and force parameters were replaced with gup_flags by -
 * 2016 Oct 12: 768ae309a96103ed02eb1e111e838c87854d8b51
 *
 * A 7-argument version of get_user_pages was introduced into linux-4.4.y by
 * commit 8e50b8b07f462ab4b91bc1491b1c91bd75e4ad40 which cherry-picked the
 * replacement of the write and force parameters with gup_flags
 *
 */

#if defined(NV_GET_USER_PAGES_HAS_ARGS_WRITE_FORCE)
    #define NV_GET_USER_PAGES get_user_pages
#elif defined(NV_GET_USER_PAGES_HAS_ARGS_TSK_WRITE_FORCE)
    #define NV_GET_USER_PAGES(start, nr_pages, write, force, pages, vmas) \
        get_user_pages(current, current->mm, start, nr_pages, write, force, pages, vmas)
#else
    #include <linux/mm.h>
    #include <linux/sched.h>

    static inline long NV_GET_USER_PAGES(unsigned long start,
                                         unsigned long nr_pages,
                                         int write,
                                         int force,
                                         struct page **pages,
                                         struct vm_area_struct **vmas)
    {
        unsigned int flags = 0;

        if (write)
            flags |= FOLL_WRITE;
        if (force)
            flags |= FOLL_FORCE;

    #if defined(NV_GET_USER_PAGES_HAS_ARGS_TSK_FLAGS)
        return get_user_pages(current, current->mm, start, nr_pages, flags,
                              pages, vmas);
    #else
        // remaining defination(NV_GET_USER_PAGES_HAS_ARGS_FLAGS)
        return get_user_pages(start, nr_pages, flags, pages, vmas);
    #endif
    }
#endif

/*
 * get_user_pages_remote() was added by commit 1e9877902dc7
 * ("mm/gup: Introduce get_user_pages_remote()") in v4.6 (2016-02-12).
 *
 * The very next commit cde70140fed8 ("mm/gup: Overload get_user_pages()
 * functions") deprecated the 8-argument version of get_user_pages for the
 * non-remote case (calling get_user_pages with current and current->mm).
 *
 * The guidelines are: call NV_GET_USER_PAGES_REMOTE if you need the 8-argument
 * version that uses something other than current and current->mm. Use
 * NV_GET_USER_PAGES if you are refering to current and current->mm.
 *
 * Note that get_user_pages_remote() requires the caller to hold a reference on
 * the task_struct (if non-NULL and if this API has tsk argument) and the mm_struct.
 * This will always be true when using current and current->mm. If the kernel passes
 * the driver a vma via driver callback, the kernel holds a reference on vma->vm_mm
 * over that callback.
 *
 * get_user_pages_remote() write/force parameters were replaced
 * with gup_flags by commit 9beae1ea8930 ("mm: replace get_user_pages_remote()
 * write/force parameters with gup_flags") in v4.9 (2016-10-13).
 *
 * get_user_pages_remote() added 'locked' parameter by commit 5b56d49fc31d
 * ("mm: add locked parameter to get_user_pages_remote()") in
 * v4.10 (2016-12-14).
 *
 * get_user_pages_remote() removed 'tsk' parameter by
 * commit 64019a2e467a ("mm/gup: remove task_struct pointer for
 * all gup code") in v5.9-rc1 (2020-08-11).
 *
 */

#if defined(NV_GET_USER_PAGES_REMOTE_PRESENT)
    #if defined(NV_GET_USER_PAGES_REMOTE_HAS_ARGS_TSK_WRITE_FORCE)
        #define NV_GET_USER_PAGES_REMOTE    get_user_pages_remote
    #else
        static inline long NV_GET_USER_PAGES_REMOTE(struct task_struct *tsk,
                                                    struct mm_struct *mm,
                                                    unsigned long start,
                                                    unsigned long nr_pages,
                                                    int write,
                                                    int force,
                                                    struct page **pages,
                                                    struct vm_area_struct **vmas)
        {
            unsigned int flags = 0;

            if (write)
                flags |= FOLL_WRITE;
            if (force)
                flags |= FOLL_FORCE;

        #if defined(NV_GET_USER_PAGES_REMOTE_HAS_ARGS_TSK_FLAGS)
            return get_user_pages_remote(tsk, mm, start, nr_pages, flags,
                                         pages, vmas);
        #elif defined(NV_GET_USER_PAGES_REMOTE_HAS_ARGS_TSK_FLAGS_LOCKED)
            return get_user_pages_remote(tsk, mm, start, nr_pages, flags,
                                         pages, vmas, NULL);
        #else
            // remaining defined(NV_GET_USER_PAGES_REMOTE_HAS_ARGS_FLAGS_LOCKED)
            return get_user_pages_remote(mm, start, nr_pages, flags,
                                         pages, vmas, NULL);
        #endif
        }
    #endif
#else
    #if defined(NV_GET_USER_PAGES_HAS_ARGS_TSK_WRITE_FORCE)
        #define NV_GET_USER_PAGES_REMOTE    get_user_pages
    #else
        #include <linux/mm.h>
        #include <linux/sched.h>

        static inline long NV_GET_USER_PAGES_REMOTE(struct task_struct *tsk,
                                                    struct mm_struct *mm,
                                                    unsigned long start,
                                                    unsigned long nr_pages,
                                                    int write,
                                                    int force,
                                                    struct page **pages,
                                                    struct vm_area_struct **vmas)
        {
            unsigned int flags = 0;

            if (write)
                flags |= FOLL_WRITE;
            if (force)
                flags |= FOLL_FORCE;

            return get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
        }
    #endif
#endif


/*
 * The .virtual_address field was effectively renamed to .address, by these
 * two commits:
 *
 *  struct vm_fault: .address was added by:
 *   2016-12-14  82b0f8c39a3869b6fd2a10e180a862248736ec6f
 *
 *  struct vm_fault: .virtual_address was removed by:
 *   2016-12-14  1a29d85eb0f19b7d8271923d8917d7b4f5540b3e
 */
static inline unsigned long nv_page_fault_va(struct vm_fault *vmf)
{
#if defined(NV_VM_FAULT_HAS_ADDRESS)
    return vmf->address;
#else
    return (unsigned long)(vmf->virtual_address);
#endif
}

static inline void nv_mmap_read_lock(struct mm_struct *mm)
{
#if defined(NV_MM_HAS_MMAP_LOCK)
    mmap_read_lock(mm);
#else
    down_read(&mm->mmap_sem);
#endif
}

static inline void nv_mmap_read_unlock(struct mm_struct *mm)
{
#if defined(NV_MM_HAS_MMAP_LOCK)
    mmap_read_unlock(mm);
#else
    up_read(&mm->mmap_sem);
#endif
}

static inline void nv_mmap_write_lock(struct mm_struct *mm)
{
#if defined(NV_MM_HAS_MMAP_LOCK)
    mmap_write_lock(mm);
#else
    down_write(&mm->mmap_sem);
#endif
}

static inline void nv_mmap_write_unlock(struct mm_struct *mm)
{
#if defined(NV_MM_HAS_MMAP_LOCK)
    mmap_write_unlock(mm);
#else
    up_write(&mm->mmap_sem);
#endif
}

static inline int nv_mm_rwsem_is_locked(struct mm_struct *mm)
{
#if defined(NV_MM_HAS_MMAP_LOCK)
    return rwsem_is_locked(&mm->mmap_lock);
#else
    return rwsem_is_locked(&mm->mmap_sem);
#endif
}

static inline struct rw_semaphore *nv_mmap_get_lock(struct mm_struct *mm)
{
#if defined(NV_MM_HAS_MMAP_LOCK)
    return &mm->mmap_lock;
#else
    return &mm->mmap_sem;
#endif
}

#endif // __NV_MM_H__
