// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.

#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/shm.h>
#include <linux/sched.h>
#include <linux/random.h>
#include <linux/io.h>

#define COLOUR_ALIGN(addr,pgoff)                \
        ((((addr)+SHMLBA-1)&~(SHMLBA-1)) +      \
         (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))

/*
 * We need to ensure that shared mappings are correctly aligned to
 * avoid aliasing issues with VIPT caches.  We need to ensure that
 * a specific page of an object is always mapped at a multiple of
 * SHMLBA bytes.
 *
 * We unconditionally provide this function for all cases.
 */
unsigned long
arch_get_unmapped_area(struct file *filp, unsigned long addr,
                unsigned long len, unsigned long pgoff,
                unsigned long flags, vm_flags_t vm_flags)
{
        struct mm_struct *mm = current->mm;
        struct vm_area_struct *vma;
        int do_align = 0;
        struct vm_unmapped_area_info info = {
                .length = len,
                .low_limit = mm->mmap_base,
                .high_limit = TASK_SIZE,
                .align_offset = pgoff << PAGE_SHIFT
        };

        /*
         * We only need to do colour alignment if either the I or D
         * caches alias.
         */
        do_align = filp || (flags & MAP_SHARED);

        /*
         * We enforce the MAP_FIXED case.
         */
        if (flags & MAP_FIXED) {
                if (flags & MAP_SHARED &&
                    (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
                        return -EINVAL;
                return addr;
        }

        if (len > TASK_SIZE)
                return -ENOMEM;

        if (addr) {
                if (do_align)
                        addr = COLOUR_ALIGN(addr, pgoff);
                else
                        addr = PAGE_ALIGN(addr);

                vma = find_vma(mm, addr);
                if (TASK_SIZE - len >= addr &&
                    (!vma || addr + len <= vm_start_gap(vma)))
                        return addr;
        }

        info.align_mask = do_align ? (PAGE_MASK & (SHMLBA - 1)) : 0;
        return vm_unmapped_area(&info);
}