/*
 * arch/sh/mm/mmap.c
 *
 * Copyright (C) 2008 - 2009  Paul Mundt
 *
 * 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.
 */
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/module.h>
#include <asm/page.h>
#include <asm/processor.h>

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

#ifdef CONFIG_MMU
/*
 * To avoid cache aliases, we map the shared page with same color.
 */
static inline unsigned long COLOUR_ALIGN(unsigned long addr,
                                         unsigned long pgoff)
{
        unsigned long base = (addr + shm_align_mask) & ~shm_align_mask;
        unsigned long off = (pgoff << PAGE_SHIFT) & shm_align_mask;

        return base + off;
}

static inline unsigned long COLOUR_ALIGN_DOWN(unsigned long addr,
                                              unsigned long pgoff)
{
        unsigned long base = addr & ~shm_align_mask;
        unsigned long off = (pgoff << PAGE_SHIFT) & shm_align_mask;

        if (base + off <= addr)
                return base + off;

        return base - off;
}

unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
        unsigned long len, unsigned long pgoff, unsigned long flags)
{
        struct mm_struct *mm = current->mm;
        struct vm_area_struct *vma;
        unsigned long start_addr;
        int do_colour_align;

        if (flags & MAP_FIXED) {
                /* 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;
        }

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

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

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

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

        if (len > mm->cached_hole_size) {
                start_addr = addr = mm->free_area_cache;
        } else {
                mm->cached_hole_size = 0;
                start_addr = addr = TASK_UNMAPPED_BASE;
        }

full_search:
        if (do_colour_align)
                addr = COLOUR_ALIGN(addr, pgoff);
        else
                addr = PAGE_ALIGN(mm->free_area_cache);

        for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
                /* At this point:  (!vma || addr < vma->vm_end). */
                if (unlikely(TASK_SIZE - len < addr)) {
                        /*
                         * Start a new search - just in case we missed
                         * some holes.
                         */
                        if (start_addr != TASK_UNMAPPED_BASE) {
                                start_addr = addr = TASK_UNMAPPED_BASE;
                                mm->cached_hole_size = 0;
                                goto full_search;
                        }
                        return -ENOMEM;
                }
                if (likely(!vma || addr + len <= vma->vm_start)) {
                        /*
                         * Remember the place where we stopped the search:
                         */
                        mm->free_area_cache = addr + len;
                        return addr;
                }
                if (addr + mm->cached_hole_size < vma->vm_start)
                        mm->cached_hole_size = vma->vm_start - addr;

                addr = vma->vm_end;
                if (do_colour_align)
                        addr = COLOUR_ALIGN(addr, pgoff);
        }
}

unsigned long
arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
                          const unsigned long len, const unsigned long pgoff,
                          const unsigned long flags)
{
        struct vm_area_struct *vma;
        struct mm_struct *mm = current->mm;
        unsigned long addr = addr0;
        int do_colour_align;

        if (flags & MAP_FIXED) {
                /* 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;
        }

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

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

        /* requesting a specific address */
        if (addr) {
                if (do_colour_align)
                        addr = COLOUR_ALIGN(addr, pgoff);
                else
                        addr = PAGE_ALIGN(addr);

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

        /* check if free_area_cache is useful for us */
        if (len <= mm->cached_hole_size) {
                mm->cached_hole_size = 0;
                mm->free_area_cache = mm->mmap_base;
        }

        /* either no address requested or can't fit in requested address hole */
        addr = mm->free_area_cache;
        if (do_colour_align) {
                unsigned long base = COLOUR_ALIGN_DOWN(addr-len, pgoff);

                addr = base + len;
        }

        /* make sure it can fit in the remaining address space */
        if (likely(addr > len)) {
                vma = find_vma(mm, addr-len);
                if (!vma || addr <= vma->vm_start) {
                        /* remember the address as a hint for next time */
                        return (mm->free_area_cache = addr-len);
                }
        }

        if (unlikely(mm->mmap_base < len))
                goto bottomup;

        addr = mm->mmap_base-len;
        if (do_colour_align)
                addr = COLOUR_ALIGN_DOWN(addr, pgoff);

        do {
                /*
                 * Lookup failure means no vma is above this address,
                 * else if new region fits below vma->vm_start,
                 * return with success:
                 */
                vma = find_vma(mm, addr);
                if (likely(!vma || addr+len <= vma->vm_start)) {
                        /* remember the address as a hint for next time */
                        return (mm->free_area_cache = addr);
                }

                /* remember the largest hole we saw so far */
                if (addr + mm->cached_hole_size < vma->vm_start)
                        mm->cached_hole_size = vma->vm_start - addr;

                /* try just below the current vma->vm_start */
                addr = vma->vm_start-len;
                if (do_colour_align)
                        addr = COLOUR_ALIGN_DOWN(addr, pgoff);
        } while (likely(len < vma->vm_start));

bottomup:
        /*
         * 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.
         */
        mm->cached_hole_size = ~0UL;
        mm->free_area_cache = TASK_UNMAPPED_BASE;
        addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
        /*
         * Restore the topdown base:
         */
        mm->free_area_cache = mm->mmap_base;
        mm->cached_hole_size = ~0UL;

        return addr;
}
#endif /* CONFIG_MMU */

/*
 * You really shouldn't be using read() or write() on /dev/mem.  This
 * might go away in the future.
 */
int valid_phys_addr_range(unsigned long addr, size_t count)
{
        if (addr < __MEMORY_START)
                return 0;
        if (addr + count > __pa(high_memory))
                return 0;

        return 1;
}

int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
{
        return 1;
}