/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2011 Wind River Systems,
 *   written by Ralf Baechle <ralf@linux-mips.org>
 */
#include <linux/compiler.h>
#include <linux/elf-randomize.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/export.h>
#include <linux/personality.h>
#include <linux/random.h>
#include <linux/sched/signal.h>
#include <linux/sched/mm.h>

unsigned long shm_align_mask = PAGE_SIZE - 1;   /* Sane caches */
EXPORT_SYMBOL(shm_align_mask);

#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_mask = do_color_align ? (PAGE_MASK & shm_align_mask) : 0;
        info.align_offset = pgoff << PAGE_SHIFT;

        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);
}

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

        if ((vaddr < PAGE_OFFSET) || (vaddr >= MAP_BASE))
                return false;

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