// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
 */
#include <linux/export.h>
#include <linux/hugetlb.h>
#include <linux/io.h>
#include <linux/kfence.h>
#include <linux/memblock.h>
#include <linux/mm.h>
#include <linux/mman.h>

#define SHM_ALIGN_MASK  (SHMLBA - 1)

#define COLOUR_ALIGN(addr, pgoff)                       \
        ((((addr) + SHM_ALIGN_MASK) & ~SHM_ALIGN_MASK)  \
         + (((pgoff) << PAGE_SHIFT) & SHM_ALIGN_MASK))

enum mmap_allocation_direction {UP, DOWN};

static unsigned long arch_get_unmapped_area_common(struct file *filp,
        unsigned long addr0, unsigned long len, unsigned long pgoff,
        unsigned long flags, enum mmap_allocation_direction dir)
{
        struct mm_struct *mm = current->mm;
        struct vm_area_struct *vma;
        unsigned long addr = addr0;
        int do_color_align;
        struct vm_unmapped_area_info info = {};

        if (unlikely(len > TASK_SIZE))
                return -ENOMEM;

        if (flags & MAP_FIXED) {
                /* Even MAP_FIXED mappings must reside within TASK_SIZE */
                if (TASK_SIZE - len < addr)
                        return -EINVAL;

                /*
                 * We do not accept a shared mapping if it would violate
                 * cache aliasing constraints.
                 */
                if ((flags & MAP_SHARED) &&
                    ((addr - (pgoff << PAGE_SHIFT)) & SHM_ALIGN_MASK))
                        return -EINVAL;
                return addr;
        }

        do_color_align = 0;
        if (filp || (flags & MAP_SHARED))
                do_color_align = 1;

        /* requesting a specific address */
        if (addr) {
                if (do_color_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.length = len;
        info.align_offset = pgoff << PAGE_SHIFT;
        if (filp && is_file_hugepages(filp))
                info.align_mask = huge_page_mask_align(filp);
        else
                info.align_mask = do_color_align ? (PAGE_MASK & SHM_ALIGN_MASK) : 0;

        if (dir == DOWN) {
                info.flags = VM_UNMAPPED_AREA_TOPDOWN;
                info.low_limit = PAGE_SIZE;
                info.high_limit = mm->mmap_base;
                addr = vm_unmapped_area(&info);

                if (!(addr & ~PAGE_MASK))
                        return addr;

                /*
                 * A failed mmap() very likely causes application failure,
                 * so fall back to the bottom-up function here. This scenario
                 * can happen with large stack limits and large mmap()
                 * allocations.
                 */
        }

        info.low_limit = mm->mmap_base;
        info.high_limit = TASK_SIZE;
        return vm_unmapped_area(&info);
}

unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr0,
        unsigned long len, unsigned long pgoff, unsigned long flags,
        vm_flags_t vm_flags)
{
        return arch_get_unmapped_area_common(filp,
                        addr0, len, pgoff, flags, UP);
}

/*
 * There is no need to export this but sched.h declares the function as
 * extern so making it static here results in an error.
 */
unsigned long arch_get_unmapped_area_topdown(struct file *filp,
        unsigned long addr0, unsigned long len, unsigned long pgoff,
        unsigned long flags, vm_flags_t vm_flags)
{
        return arch_get_unmapped_area_common(filp,
                        addr0, len, pgoff, flags, DOWN);
}

int __virt_addr_valid(volatile void *kaddr)
{
        unsigned long vaddr = (unsigned long)kaddr;

        if (is_kfence_address((void *)kaddr))
                return 1;

        if ((vaddr < PAGE_OFFSET) || (vaddr >= vm_map_base))
                return 0;

        return pfn_valid(PFN_DOWN(PHYSADDR(kaddr)));
}
EXPORT_SYMBOL_GPL(__virt_addr_valid);

/*
 * You really shouldn't be using read() or write() on /dev/mem.  This might go
 * away in the future.
 */
int valid_phys_addr_range(phys_addr_t addr, size_t size)
{
        /*
         * Check whether addr is covered by a memory region without the
         * MEMBLOCK_NOMAP attribute, and whether that region covers the
         * entire range. In theory, this could lead to false negatives
         * if the range is covered by distinct but adjacent memory regions
         * that only differ in other attributes. However, few of such
         * attributes have been defined, and it is debatable whether it
         * follows that /dev/mem read() calls should be able traverse
         * such boundaries.
         */
        return memblock_is_region_memory(addr, size) && memblock_is_map_memory(addr);
}

/*
 * Do not allow /dev/mem mappings beyond the supported physical range.
 */
int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
{
        return !(((pfn << PAGE_SHIFT) + size) & ~(GENMASK_ULL(cpu_pabits, 0)));
}